CO2 Sublimation

A client inquired why a CO2 vessel can be full by weight, but no product will come out. They mentioned that they'd been able to feed NF Nitrogen into the vessel and then get CO2 out.

"I think the principle issue here is one of pressure. CO2 is one of a few substances that go straight from the gas to solid phase and vice versa at atmospheric pressure. The only way to keep it in liquid form is to maintain adequate pressure as shown on this chart http://www.school-for-champions.com/science/dry_ice.htm.

We’ve found it necessary to use pressure to convert the sold back to a liquid once CO2 turns to dry ice (solid) due to a drop in pressure below the level needed to stay as a liquid. This can be done a number of ways and the addition of N2 as you have done is one. The key in your approach is to be certain that flow is tightly controlled and there are reliefs on all hoses and other trap points to prevent rupturing lines or tanks. Complete removal of all CO2 from the vessel can be pretty time consuming and take several days to accomplish. Once all CO2 is removed from the vessel, it is suggested that you use liquid nitrogen to test all functions of the vessel and perform a thorough leak check.

If you have a leak in a pressure building line or regulator, for instance, you get exactly the opposite result from the one desired when you open the PB isolation valve. The same can occur due to a leak in a valve stem or packing. When the valve is opened and a resultant leak occurs pressure will drop and then dry ice will form."

AWS Fabtech 2009

Bob Burg and John David Mann provide an interesting perspective in a passage of "The Go-Giver" where The Chairman explains, "Most of us have grown up seeing the world as a place of limitation rather than a place of inexhaustible treasures. A world of competition rather than one of co-creation."

The great joy of this year's Fabtech show was the incredible number of "Co-Creators" we had the pleasure of visiting with. People from all over the U.S. and the world had incredibly inspiring success stories to share... both past and in the making. All sorts of industries (both cryogenics related and not) were included. And- there was no regard for the actual location. People from Iowa, Michigan, Alabama, Texas, New York, Eastern Europe, Latin American, Asia and anywhere else you could imagine all had great experiences and enthusiasm to share. It was a cup we gladly drank from and are still savoring.

Most assuredly, people all over had confronted issues this year, but the prevailing attitude was that it was just another challenge like so many before.

All I can really say is THANK YOU to everyone who made this last week so enjoyable. It will be a big part of this year's Thanksgiving celebration remembrances.

4L DOT Standards- Size by Default

A client called today with an issue related to a 4L-DOT cryogenic liquid vessel. At question was the size of the vessel and the concern was that the vessel was over 119 gallons.

It will be interesting to see how their issue is resolved since according to the 49CFR Sec. 178.57 Specification 4L welded insulated cylinders. "(a) Type, size, service pressure, and design service temperature. A DOT 4L cylinder is a fusion welded insulated cylinder with a water capacity (nominal) not over 1,000 pounds water capacity and a service pressure of at least 40 but not greater than 500 psig......"

Since water weighs 8.3453 pounds per gallon this means that the absolute maximum capacity of a 4L vessel would be 119.83 gallons. Most vessels have some head space allowance so nominal capacities for the largest 4L cryogenic liquid cylinders tend to be under 119 gallons. But- depending on the specific vessel, the water capacity could technically be 119 point something, but under 120 gallons.

So- like I said, it will be interesting to see what comes of their question. As always- any comments on this are welcomed.

Cryogenic Liquid Cylinder Hot Fill

A recent call (summarized):

"Our client purchased some new cryogenic liquid cylinders, filled them and put them into service. They seem to be venting excessively and they are concerned. Can you crack the inner vessel of a new cryogenic liquid cylinder if you improperly fill it? Is there a Hot Fill Procedure that should be followed to avoid excessive venting?"

I've never heard of a cryogenic liquid cylinder with a stainless inner vessel actually cracking..... even after sitting out in Houston or Phoenix sun for awhile. It would be interesting to hear from an engineering or physics standpoint just how much temperature differential a vessel can tolerate, but it is not something that is a cause for concern in everyday applications.

As for Hot Fill Procedures- Yes. It is important to cool liquid cylinders that are new or have been sitting around "hot."

During one memorable problem solving activity a client commented that his cryogenic liquid cylinders "are not hot. They are <0 degrees F inside." True or False?

Think about a hot (400 degree) skillet used for blackening or stir frying. Throw a little water into it and see what happens. The water will flash vaporize because the skillet is nearly 200 degrees above the boiling point of water.

Go back to a cryogenic vessel that is 0 to 80 degrees F inside. Run some liquid nitrogen, oxygen or argon into it that is about -300 degrees F and you can be sure that you will get violent flashing since the vessel is 300 to 400 degrees above the boiling point of the cryogenic liquid.

There are a number of ways to cool a hot cryogenic liquid cylinder and thereby decrease the normal vaporization and consequent venting of your liquid nitrogen, oxygen or argon. A very simple one is to:

a) Open the vent;
b) Connect your source line to the vessel; Open the liquid fill line and the open the source just enough to slowly run liquid into the cryogenic cylinder;
c) Very heavy venting will occur. Keep running liquid slowly into the cryogenic cylinder until it is about 1/4 full. Shut off the fill and leave the vent open.
d) Allow the vessel to vent until the venting becomes very moderate. This can take 1-2 hours.
e) Slowly fill the vessel the rest of the way until the full weight is reached; Some more heavy venting can occur;
f) Let the vessel vent until venting is almost completely stopped; Top off the vessel if more product is needed.

Remember- Fully venting cryogenic vessels is important when filling whether the vessel is hot or not. For more notes on this you can see http://cryonews.blogspot.com/2009/09/cryogenic-liquid-cylinder-filling.html

4L DOT Cryogenic Liquid Cylinders - Age Coding

Client X has a few dozen liquid cylinders that they are considering repairing and want to be sure that they aren’t too old to be worth the trouble. So- Their very good question:

“Is there any way to tell from the data plate what year a DOT 4L- class vessel was manufactured?”

I’ll give you what I got from some quick targeted research and will appreciate any information you might have to share with the rest of us:

TAYLOR-WHARTON- The last letter in the serial number identifies the year of manufacture.
A=1985 to H=1992
J=1993 to N=1997
P=1998 to X=2005
BB=2005 to FF=2009

UCAR- Purchased by Taylor-Wharton in 1985 so anything UCAR is 1985 or before

CHART/MVE- Beginning in 1995 the Year of Manufacture was inserted right in the middle of the serial number. So this is the most obvious… 97, 99, 02, etc. If the unit is before 1995 then the only way to know is to call the number and ask.

CSI- Purchased by Chart in 1995 (?). No defined date code system.

CYLTEC- No date code imbedded in the serial number, but virtually all are 2005 or newer.

Cryogenic Fill Hose Safety Reliefs- An absolute necessity

Why are safety reliefs installed on all cryogenic liquid oxygen, nitrogen, argon or carbon dioxide fill hoses?

In fact- safeties are not only to be installed on all fill hoses. They are also installed on any cryogenic line that is sealed on both sides. This is because cryogenic liquid trapped in a line will vaporize and expand exponentially creating tremendous pressure in hoses, piping or tubing. This expanding liquid nitrogen, oxygen, argon, or CO2 can easily build enough pressure to cause the line or hose to explode with great force.

This is a danger that is easily overlooked and one that is not obvious to someone without prior knowledge or training. And- it is something that can be missed by even the most experienced personnel who are hooking up a new line out of necessity or otherwise in a hurry.

Whether you are filling medical oxygen bases, transfilling liquid from one DOT4L vessel to another or otherwise filling from a bulk source it is essential to have a relief for expanding vapor. So- never forget to be sure the hose you are using to fill has a properly rated safety relief installed somewhere between the valves or other connectinos that could trap liquid.

MedTrade Day 3

Clare Ulik of Cryovations sent these photos from Day 2 that tell the tale..... lots of folk with great attitudes.

Of course.... as always... Day 3 didn't have nearly the number of people, but moods were still great. And- the reduced activity allows for some more in depth discussions so all was good.

In the world of medical liquid oxygen delivery there are obviously still opportunities for operational improvements and optimizing gains from improved efficiency. And then there is also the situation presented by those with smaller client bases. For those with 5-25 or so patients with no real expectation of growth the option of subcontracting liquid delivery can often make a lot of sense.

How is it that an Airgas Puritan Medical or a Lifegas or others can turn a profit where a smaller company can't? Consolidation.

Trying to be profitable delivering to two or three patients in a given area can be almost impossible. Add them to a route that already has 10-15 patients and all the sudden they offer a great return as all the real cost of getting into the territory has been covered and everything extra is where the real return is made. It might seem obvious, but is still not universal knowledge.

MedTrade Day 2

Don't talk with your hands. I've heard it many, many times and still haven't learned.

Oh, and what a great day today at MedTrade. The good news/ bad news is that we'll be back next year. It was great to see a goodly number of client friends and new friends that we would not have seen otherwise. Also encouraging was the presale of booth space for next year's show.

And then there was the neat little information tidbit related to the BPR Medical FireSafe TM device for respiratory oxygen cannulas. This link http://www.lifegas.com/files/firesafeV2.htm will get you to a little video showing how it works.

MedTrade Day One 2009

Color me surprised and pleasantly so.

I was told that attendance at this year's MedTrade is down significantly and would have plenty of reason to believe this is true. Nonetheless, activity today was by no means the worst I've experienced at a trade show and the quality of discussions was was superior.

The ability to really converse with people and have in-depth visits about the needs and challenges of their business is one of the collateral benefits of this year's downturn. And- people have an interest in considering options that would reduce their costs of operations. One new introduction today was eTankPro (Roger MacClellan) and he seems to be one of those businesses keyed in on really helping clients reduce costs through improved efficiencies.

And a goodly number of people that might previously have brushed past or just quickly introduced and grabbed a card had a chance to consider how maybe 3 trucks with 290 gallon vessels delivery medical liquid oxygen could be a world more productive than 5 with 119s. This was especially true for one fellow who goes 30 miles everyday to fill a 119 and then only has enough liquid to fill 8-10 patient bases. This was a real case in point for what a difference a 290 gallon UltraSeries vessel could make. Just cutting trips to the bulk fill by 50% is huge without even taking into account the ability to make 5-15 more stops per week with the larger volume of liquid and time he'd have available.

Cryogenic Bulk Tanks- Vacuum & Leaks (d)

The principle differences between Bulk Tank and 4L-Liquid Cylinder vacuum investigations?

A) Size and B) More parts and Penetrations

Bulk Tank size matters a great deal when it comes to the ability to conduct and effective vacuum investigation. A liquid cylinder can typically be thoroughly investigated in less than an hour. A perlite bulk tank can take weeks just to get a vacuum good enough on it to perform an effective investigation. Investigating in place will also frequently require the use of a manlift or other device to get all the way up and around the vessel seams, lift plate, etc. Add just a little breeze and it can be well nigh impossible to get a accurate investigation completed due to helium dispersal. The only answer is tenting or bagging section of the vessel which further increases the time required.

Add to Size issues related to additional parts- especially the probe tube. Probe tubes frequently leak through causing vacuums to go bad just by trying to read them. This has been true in many cases even with new probe tubes. There have also been a number of leaks in the probe tube isolation valve handles that are sometimes only present with the valve open. Then there is the vacuum lift plate used on many bulk tanks. This plate is o-ring and lube sealed by the vacuum pulled on the tank. And unlike 4L- Liquid Cylinders which have all piping run through a single head boss, bulk tanks are loaded with line penetrations. None of these issues are overly challenging for a capable investigator using helium mass spec equipment. But they do help explain why those not performing full investigations can get a good vacuum pulled on a tank and leave believing the tank is fixed.

We go back to size and semi-permanent installation. Unlike a liquid cylinder it is a huge undertaking to remove a bulk tank, send it in for vacuum investigation and restoral and reinstall. And, there is typically not a ready supply of spares to pop in place while a bulk tank is being repaired. Hence- It is almost always easiest to send 4L- Liquid Cylinders in for repair while it is frequently justifiable to perform bulk investigations in the field. Justifiable…… but often costly nonetheless making it all the more critical that the right tools and right people are used.

Cryogenic Bulk Tanks- Vacuum & Leaks (c)

How do bulk cryogenic vacuum investigations differ from liquid cylinder vacuum investigations?

The principle differences relate to the size of the vessels and the more permanent nature of bulk cryogenic tank installations. There is also an issue with added penetrations and connections on a bulk tank which mean more potential leak points. There are also a couple of other nuisances related to probe tubes, lift plates, vacuum valve and perlite insulation. First- The principles of helium mass-spec leak detection are the same for almost all double-walled, vacuum-insulated cryogenic liquid storage vessels and include:

A) A vacuum evacuation port of some type must be installed on the outer vessel allowing a vacuum pump to be connected to pull molecules from the annular space. These are specialized connections capable of pulling down to very low atmospheric (high vacuum) levels without leaking past. On smaller 4L-DOT type vessels this is typically a port and plug assembly that are pulled on using a fixture that allows the plug to be pulled and replaced under vacuum. A larger vacuum diaphragm valve is used with bulk tanks

B) A helium mass-spec leak detector is set up on a slip stream of the vacuum line to allow sampling for helium molecules. The leak detector can only be used effective after vacuum has been pulled down far enough to get a helium reading. If the vacuum will not come then the leak will have to be found by other means and some repair performed prior to performing the full helium mass spec leak investigation. Vacuum valves, vacuum probe tubes and probe tube isolation valves are often replaced prior to performing an investigation due to their propensity for being large leak points. It is also common to break the vacuum seal on a vessel and reseal lift plates where present (including o-ring replacement and vacuum lube addition). Perlite is also added at this point for perlite insulated vessels. It is worth noting that breaking vacuum improperly can be a major source of moisture contamination and can also cause permanent damage to the vessel.

C) The initial leak investigation consists of spraying helium molecules around the outside of the vessel and all penetration points. This process can be painstakingly slow and tedious as a leak can both provide a positive indication and flood the annular space with helium that can take hours (or days) to evacuate. Also- getting a positive reading is only a start. It is often necessary to work through a series of tests where small portions of the vessel seams or other penetrations are masked off to ultimate isolate the leak point. And- repairs requiring welding will likewise require careful breaking of the vacuum, completion of the repair, and then pulling the vacuum back down on the vessel to start testing all over again.

D) Once the outside of a vessel has been determined to be leak-free then helium is added to the inner vessel and some pressure added behind it to look for possible inner leaks. Fortunately, inner leaks are not that common on cryogenic bulk tanks- especially stationary tanks- since they are not subjected to the kind of rough handling that 4L Liquid Cylinder and smaller open top nitrogen dewars are. I say “fortunately” as isolating and repairing inner leaks is most complicated and worthy of another full set of articles.

But what about the differences between Liquid Cylinder and Bulk Tank vacuum investigations?

We’ll hit more on this next.

Cryogenic Bulk Tanks- Vacuum & Leaks (b)

Shortly after posting yesterday’s article I saw an advertisement for cryogenic equipment noting, “We Do Revacs.” And….. so do lots of people. But- Does this include full vacuum investigation and repair?

As mentioned previously, there are very frequent occurrences of people putting a vacuum pump on a tank and pulling the vacuum down within specification limits. Because the vacuum pulls down to where it needs to be the assumption is made that the vessel must be good now. The fly in the ointment here is that a tank with a small leak can easily be pumped on to the point that the vacuum reading is good. This is fairly simple as all you have to do is have a pump that pulls molecules out of the vessels annular space faster than they come in through the leak.

This is very much like a leaky boat. My good friend, John, told the story of an off-shore fishing trip where they struck a piece of driftwood or some other debris and started to take on water. This was particularly problematic since they were catching lots of fish and did not want to quit. So, they turned on the bilge pumps and fortunately were able to pump out water faster than it came in. Returning home the leak grew and they had to pull the plugs in the back of the boat to allow water to flow out. All was OK until they stopped at the boat ramp and jumped out to go get the trailer. Once stopped, the boat sank almost immediately and had to be floated up from the bottom with lift bags.

Interestingly enough, we never talked about it, but the final excess flow might have come from a failure to get the plugs in fast enough once stopped. This has a parallel to cryogenic vessels that will be touched on in a moment.

But, first- If we assume that a cryogenic vessel was originally constructed in a leak tight fashion and this was proven out over years of operation then where did a leak come from? There are several primary sources of vessels leaks:

a) The Vacuum Rupture Disk and/or Lift Plate
b) The Vacuum Probe Tube and/or Probe Tube Isolation Valve
c) The Vacuum Evacuation Valve
d) Piping Penetrations, Doublers and Other External Welds
e) Occasional Inner Leaks

Time, corrosion and/or damage (intentional or otherwise) can cause leaks in each of these areas. Unlike a boat leak, though, it is rare that they are visible with the naked eye. In most cases, these are leaks that have developed very slowly over time and are allowing just a few molecules to seep in little by little. And- as vacuum loss is typically a boiled frog progression (slow and with almost imperceptible progress) it is also difficult to link the leak to any cause or event.

So how do you find the cause and location of a leak?

Helium Mass Spec Leak Detection.

This testing utilizes mass spectrometry equipment specially calibrated for detection of helium molecules along with a vacuum pump to sniff out leaks. Helium is used since the molecules are so small they will travel through the tiniest leaks.

Next we’ll do some review of Helium Mass Spec Testing and the principle causes of leaks in tanks.

Cryogenic Bulk Tanks- Vacuum and Leaks

"Nature abhors a vacuum."

When conducting cryogenic vessel classes we often discuss the fact that, other than occassional flashes between my ears, natural vacuums do not exist within the earth's atmosphere. Given time and opportunity, all vacuums will draw in molecules to the point that atmospheric balance is restored.

It is no great wonder then that vacuum insulated cryogenic bulk tank and other liquid cryogenic vessels lose their vacuums and related insulation capacity over time. And, when the vacuum is lost, the vessel loses all or the greatest part of its insulating capacity and can no longer protect the liquid from heat resulting in excessive loss of oxygen, argon, or nitrogen liquid product. The mystery (and fun CSI part) of the job comes from determining the how, where, and why of a lost vacuum.

All too often, vessels with bad vacuums are hooked up to a vacuum pump until a good reading is once again achieved. The pump is then disconnected and the vessel returned to use only to find that it is again losing product within days, weeks or months. The process is repeated with the unsurprising recurrence of the problem.

There is another way and we'll discuss it next.....

Oxygen Effects on Wine Production

This article http://www.practicalwinery.com/sepoct09/impact2.htm "IMPACT of oxygen level in wine when bottling" was recently forwarded to me. It provides some specific technical background that might be interesting not only for those in wine production, but also in other industries utilizing nitrogen and CO2 inert gas blanketinig.

Cryogenic Liquid Cylinder Filling- The Venting Dividend

Standard cryogenic liquid cylinder filling procedure for many facilities is to:

1) Connect the source

2) Open the Vent valve; Open the Liquid valve; open the Source

3) Fill by weight

4) Close the Source; Close the Liquid valve; Close the Vent Valve

Others vary Step 4 to:

4+) Close the Source; Close the Liquid valve; Leave the Vent valve open until venting stops (15 minutes to one hour) and then: Close the Vent valve.

The benefits gained from 4+) are significant:

a) High Pressure Liquid Stabilized- When liquid cylinders are filled from a bulk tank with over 40psi there is gas entrapped in the liquid. The higher the pressure of the source tank the more gas is transferred in the liquid. Venting allows this gas to escape instead of crowding up the the liquid cylinders head space building pressure.

b) Hot Liquid Cylinders are Cooled- Liquid Cylinders that sit empty for awhile get warm inside. Allowing the vessel to cool fully prior to closing the vent also reduces the buildup of gas in the head space.

Both of these benefits share the effect of lengthening the flattened, left-hand tail of the pressure building curve. Put another way- Pressure building can be expressed as an accelerating curve. The higher pressure gets the faster the pressure builds steepening the curve to the venting point. The more liquid is allowed to stabilize and cool the longer and flatter the curve.

The net result of all this is that initial time to vent is lengthened and product life is extended.

Sense and Insensibility in Medical Oxygen

Homecare Magazine recently had two articles that might be interesting to those interested in homecare oxygen delivery. The first, "Providing Oxygen Sensibly" http://homecaremag.com/oxygen/select-right-oxygen-technology-200907/ gives some overview of alternative delivery methods, costs, and returns.

The second article, "Vladeck: Home Oxygen Is 'Nothing but Air'" http://homecaremag.com/oxygen/vladeck-congress-reimbursement-cut-20090831/ highlights some of the misperception challenges faced by homecare oxygen providers.

And- Don't forget to mark your calendars for the upcoming MedTrade conference in Atlanta October 12th - 15th. http://www.medtrade.com/ It is one of the few places where you can find so many of the key homecare oxygen manufacturing and service players all together. If you do make it to MedTrade be sure to drop by booth 1131 (West Cryogenics) and say hi.

Liquid Cylinder Reliefs- Getting it Right

You have a relief on a liquid cylinder that is opening like it is supposed to, but won't reseat properly so you decide to replace it. How are you going to determine what relief to replace it with?

a) Look at the relief that is in the vessel and replace it with one just like it?

b) Look up in the owner's manual and see what it says to do?

c) Look at a reference sheet provided by a reputable provider that translates the 4L-DOT ratings and helps specify the "proper" relief, burst disk and presure gauge for your unit.

"A" is an uncomfortably common response. "B" or "C" are the way to go.

Unfortunately- Information on the maximum pressure settings for reliefs and burst disks or pressure ranges is not obvious or plainly stated on cryogenic liquid cylinder data plates. It requires some knowledge of DOT 4L parlance to know that a 4L-292 liquid cylinder will typically have a 350 psi relief and 0-600 psi pressure gauge. The necessity of looking up information is a problem since most users and many distributors don't have handbooks or reference charts readily available at hand. The risk is that an relief and/or burst disk will be installed that is at too high a pressure for the 4L rating of a vessel. This creates a hazard resulting in a possible explosion of the vessel.

If you need help on determining the right relief, burst disk or pressure gauge for your unit drop me a note. I'll be happy to help.

Implosions Are Also A Mess......

There have been several posts in Cryogenic News regarding cryogenic tanks rupturing as a result of over-pressuring. This is important due to the real danger posed by tanks and cylinders that are improperly modified or otherwise malfunctioning.

Implosion is also a very real concern and Wil Ferch (Owner/Principal at Nordstern Associates LLC) has graciously allowed me to reprint his recent article "Don't Let This Happen to You!!" below without endorsement.

Interestingly enough, as I was reading Wil's article I remembered that Dan Ariely (of Predictably Irrational fame) is also a director with The Center for Advanced Hindsight which you can visit at http://web.mit.edu/ariely/www/MIT/thecenter.shtml.

Ideally, employing the lessons shared by Wil and others can help you avoid status as a case study for Dan's group so here it is:

"Don't Let This Happen to You !!!

The industrial gas industry, (producers of liquid oxygen, nitrogen and argon...amongst other products of air), require large site-erected tanks to be built in order to store these liquids for later use. These tanks can range in size up to 2 million gallons or more, and cost millions of dollars. The stored product, like liquid oxygen, exists at about minus 300 degrees Fahrenheit.

In the process of bringing such a newly constructed tank into service, it must first be carefully "cooled-down" such that it can accept incoming cold liquid later. Here is a photo of a typical tank on a representative plant site---> http://gazettextra.com/photos/2008/oct/02/10382/

Nordstern Associates LLC - CASE STUDY # 7

A major global producer of industrial gases, recently "cooled-down" such a tank as part of their commissioning process, utilizing their own qualified personnel and historical procedures. This time, however, things went horribly wrong, and their 450,000 gallon tank went from being a multi-million dollar asset... to nearly scrap metal value, in a fraction of a second ! In the process of cooling down the tank, it vacuum collapsed ! To illustrate the violence, sudden-ness and uncontrolled nature of the collapse, here is a YouTube film clip showing a similar ( this time, on purpose ! ) tank collapse of a railway tanker.---> http://www.liveleak.com/view?i=72e_1208694365&p=1

Also, when such a flat-bottom tank vacuum collapses, it may implode the top and side walls, and also start to "lift" the center of the flat floor. See here of what such damage looks like in yet another example ( once the web page is opened...move down to title, " Plastic bag vs. Storage tank" for photos and text.)----> http://www.driedger.ca/dp-1/Dirty%20Pictures%201.html

After the damaged tank was repaired, Wil Ferch of Nordstern Associates LLC was enlisted to provide both a revised cool-down procedure, and on-site supervision of the new attempt to cool-down the tank. Result?--> a perfect cool-down with no damage ! Wil Ferch, principal at Nordstern Associates had over 20 years of experience cooling down these types of tanks with a 100% recorded success rate throughout his career !

So....don't let this happen to you !

The industrial gas business has lost much in the way of retained skill sets and nuance-driven knowledge with long-term staff changes. Enlist people who have the training and knowledge to do this correctly. Call upon Nordstern Associates, LLC.

Contact--> Wil Ferch, principal at Nordstern Associates, LLC and let us discuss this.... or other support needs. ( ferch.wil@gmail.com .... business tel : +1 716 983 4089, alt tel: +1 716 662 7173). "

Predictably Irrational & Cryogenics

One of my favorite writers is Dan Ariely of "Predictably Irrational" (both book and blog) fame. In his most recent blog at http://www.predictablyirrational.com/ ("Are We More Rational Than Our Fellow Animals?" Dan uncovers some of the advantages we humans enjoy through possession of a neocortex. According to Dan, this is "the most recently evolved part of the brain and the center of higher mental functions" and "it’s thanks to our neocortex that we are able to plan for the future." The gist of his article is that our ability to think at a higher level and plan does not always add up to brilliantly rational actions benefitting our own best interest.

Witness the 4L-DOT cryogenic liquid cylinder shown above with both the safety relief and burst disk plugged.


What is the rational solution for a relief that continues to vent and make irritating noise? Someone apparently figured removing the relief and replacing it with a plug would do the job.


And then what do you do when the pressure builds so high that it blows the burst disk and pressure is lost? One solution is apparently to remove the blown burst disk safety and replace it with a plug.


OK- so maybe the planning capacity of the neocortex wasn't fully developed in this case....... as witnessed by the ultimate result of an overpressurized (exploded) liquid cylinder. The most fortunate part of all of this is the fact it happened at 3:00 a.m. which is about the only time where someone would not be in the lab to get hurt.


A more in depth article on this incident can be found at http://ucih.ucdavis.edu/docs/chemistry_301a.pdf. It is great reading for anyone open to learning from the mistakes of others.

Lifetime Learning

"......but tho' an old man, I am but a young gardener." - Thomas Jefferson to Charles Willson Peale, August 20, 1811

Jefferson's information request sent to one of his time's most noted gardeners speaks volumes. The fact is that, for all the things Jefferson did, it is quite fair to say his real lifetime hobby was learning.

As a model of "the more I learn, the more I realize I don't know" he personified one of the greatest joys there is by constantly pursuing new endeavours from architecture and design to philosophy, education, gardening and more.

Why do I mention this?

This is going to be another of those great weeks where I get to "learn as I teach" with at least three days at client sites delving into operations and working together towards continuous improvement. Not to mention a weekend of gardening, energy conservation, farmer's markets and Saturday morning cooking class........ (a special thanks to Monica Pope at T'Apia in Houston).

And herein also rests the beauty of the cryogenics and gases industry where there is so much to learn and so many really neat people to learn it with......

Low-Loss Liquid Fill- What Price Success?

Companies delivering liquid nitrogen, oxygen, and argon are fortunate these days to have some choices:

a) Pumped Systems- many of which have low transfer loss features

b) Pressure Driven Systems- some with MC-338 options allowing them to travel under pressure without venting between stops.

c) Pressure Driven Systems with Gas Use Capabilities- allowing them to be used not only for liquid delivery, but also for gas use for welding, purging, cutting, etc.

Which is best?

Of course- again we hit the millenium answer- It depends.

And it really does depend on what you are doing with the vessel- How much liquid you are delivering, what other uses (if any) you might have for the tank, and your budget.

The question crystallized after a client visit where it turns out they'd have been able to purchase two GOrilla 500s and a GOrilla 1500 (all tricked out with trailers) for what they paid for one low loss pumping truck. This is an irrelevant comparison where you need the pumping truck. Where you don't, it could be interesting to further explore where you get the most from your investment dollars.

Using High Pressure Gas Cylinders to Push Liquid Cylinder Output- Not Advised

Several conversations have occurred recently where people mentioned their use of high pressure gas cylinders to boost cryogenic liquid cylinder output. Specifically, they are hooking a high pressure liquid cylinder to the vent of a liquid cylinder to push liquid out of the cylinder faster or to maintain a higher pressure for gas withdrawal.

Is there a risk and, if so, what?

As with almost anything..... maybe. The concern here would be that gas coming out of the high pressure liquid cylinder will increase the pressure in the liquid cylinder faster than the relief and rupture disk can relieve it. The net result of this is that the vessel could eventually reach burst pressure and blow.

As for me- I'd be interested in exploring how the equipment might be used to function as designed and still get the job done.....

Cryogenic & High Pressure Nitrogen Gas Options for Laser Feed

A client called yesterday regarding problems he was having with a nitrogen feed for a laser system. The system has been in service for a few years and working fine until recently. Something had changed. The change turned out to be different material being cut which changed the feed gas flow and pressure requirements. The best solution turned out to be temporarilly supplying the laser system with high pressure gas 16-packs since the user's need is short-term and requires a relatively low total volume of nitrogen.

The link below is to an article I ran across while doing more research. It helps define some of the issues and options related to nitrogen feed options for laser cutting.

http://www.thefabricator.com/LaserCutting/LaserCutting_Article.cfm?ID=1741

E-mails with links to other helpful information on this subject are welcomed.

Tried a GOrilla; Bought Fifteen More

Hope's Hope asked if there is more to this article than the published 6-Word Novel. More expertly written 6-Word Novels such as Hemmingway's "For sale: baby shoes, never worn" obviously do a better job of telling their story.


"Tried a GOrilla; Bought 15 more" is also true which hurts the "novel" classification.


This is the story of a gas distributor who tried something new and used it as a great tool to exploit a niche. The point here is that experimentation and innovation is alive and well in the gases industry. And- we are in one of those great times when people can do things that allow them to write their own success stories by using "the liberating force of adversity" to their advantage.


Also- candidly- it is a lot of fun to help others succeed and then celebrate their accomplishments.

A Six Word Cryogenic Success Story

Tried a GOrilla; Bought 15 more.

Liquid Only Liquid Cylinders- Cruddy or The Good Stuff?

A gas distributor took me on a tour of their facility and showed me where they keep their good liquid cylinders and where they keep those needing repair. On a side of their yard was a third group of about two dozen liquid cylinders that I pointed out and was told they were scraps. When asked if they were inner leakers or otherwise beyond repair the client said essentially "Oh, no. They are just those cruddy old liquid-only vessels. No one uses them anymore."

Another distributor took over the business at a very large mixed use facility with a number of labs using nitrogen liquid. Scattered about the labs was a large number of liquid-only style liquid cylinders. The client was told that instead of liquid-only vessels they would be getting "the good stuff" all through their plant...... meaning VGLs.

Both cases share a pretty common perception and contributed to a belief among some users that vendors are somehow denying them top quality when they provide Liquid-Only liquid cylinders for applications where the only need is for nitrogen in a liquid form.

A counterpoint to this perception is the fact that liquid-only style 4L-DOT liquid cylinders will contain nitrogen in a liquid state longer than a same sized liquid cylinder with Gas Use capabilities.

Why?

Absent the gas use function, Liquid-Only liquid cylinders do not have Gas Use Vaporization Coils, Pressure Building Coils, Regulators and other heat syncs that transmit energy (heat) into the liquid and cause it to boil off more quickly.

The funny thing is that the myth of Liquid-Only vessels being "cruddy" is so pervasive that a large percentage of people are unaware you can even still buy Liquid-Only containers. And even those that do know you can are reluctant to get them due to backlash they often get from users who feel they are somehow being short-shrifted.

Paradigm shift?

LCCM Conversion- NOT

The photo above shows a modification done to a cryogenic liquid cylinder to convert from an LCCM pressure building/ economizer regulator to a more common style regulator.

This is not a manufacturer's approved modification and is a case where the possible risks likely outweigh any gain. Some of these risks include:

- the refusal of some or all repair centers (except the modifiying vendor's) to work on liquid cylinders that have been substantively altered from their original design. The potential liability resulting from the failure of a modified vessel is just not worth the minimal profit that might be made from rehab work.

- the possibility that knowledgeable end users might also consider these conversions to be unacceptable.

- the fact that liquid cylinders that are modified in this manner can never be returned to their original LCCM operation.

LCCM regulators are indeed expensive to replace, but most can be rebuilt. And- trying to convert to a less expensive regulator by substantially modifying an original manufacturer's design of a DOT vessel can have the appearance of a dime getting in the way of a dollar........

Adversity Liberates new GOrilla 1500

A post from a few weeks ago discussed "the liberating force of adversity" and the paradox of great innovation in difficult times. This week's release of the new West Cryogenics 1500 gallon GOrilla is another prime example. While this vessel has been on the books for development a long while now there was a major challenge in trying to work the design in between so many competing priorities.

Well- get a little break from the mad rush of things and see what you get......

Once again, West Cryogenics has managed to innovate at a level not regularly matched. The new GOrilla will include all the standard features found on the existing 500 gallon and 850 gallon GOrilla portable cryogenic vessels:

- Combo Top Bottom Fill

- Robust Pressure Building System

- Road Relief Valve Allowing for Liquid Transport

- Gas Output with Economizer and External Vaporizer

It will also have an auxillary 2" liquid withdrawal line for those who want to add pumping systems for liquid delivery. Rated at 250psi mawp this vessel will afford flexibility to serve both gas feed and liquid delivery systems for liquid oxygen, nitrogen or argon. And- it can be paired up with its smaller 290 to 500 gallon cousins, cryogenic liquid cylinders or gas cylinders for an almost unlimited variety of Hospital and Medical Emergency Backup and Rapid Deployment applications or fitted with mixers for direct distribution of blended welding gases.

No- West Cryogenics does not enjoy economic downturns at all. But- once again- a little downturn has provided a great opportunity for innovative development.

There has been a tradition of using downtime to come out even stronger for the future and no one at West Cryogenics can see a reason to break that tradition this time.

Simple Set Screw Solution- Shrink Seal

Today’s suggestion: Shrink Seal the set screws on your cryogenic liquid cylinder pressure building and economizer regulators.

There has been a lot of emphasis in this post on the difference between flow and pressure. The primary focus of discussion has been to try and clarify the fact that higher pressure does not equate to higher flow. Point: Cranking up the pressure builder setting on your liquid oxygen, nitrogen or argon 4L-DOT liquid cylinders does little or nothing to provide higher flow and can cause a number of negatives……..

- Out of Balance Economizers,
- Broken PB Regulators,
- Excessive Venting and more.

Solution- Leave the set screw alone. The odds of this happening- It depends.

Make it harder to mess with the screw and you might find an ounce of prevention to be worth a pound of cure. Where necessary- Create consequences for tampering with pressure builders and you might deter even more tinkering.

Oh, and yes- West Cryogenics has been doing this for years and sells both shrink seal material and heat guns.

www.westcryogenics.com

Progress Paradox

“And I must say: I find the liberating power of adversity to be one of the more disquieting facts of life.”
- John H. Lienhard

In Episode 1603 of The Engines of Our Ingenuity, Lienhard discusses the adverse life, imprisonment, and great grief of Galileo. It seems that absent the opportunity provided by Galileo’s isolation he might never have performed his world changing work that has done so much to shape modern engineering, material science and astronomy. And, Lienhard’s writing as well as numerous other texts, such as “Selling Soap. Literally” in this month’s Fast Company, go a long way to show how adversity can spawn innovation.

West Cryogenics’ move into manufacturing is a case in point. Long interested in developing and producing new products, the company was always “too busy” to move forward in this area. The downturn following the 9/11 tragedy and some other unexpected turns created a unique moment where time, talent and market converged allowing for development of West’s Ultra Series liquid delivery vessels. The follow up development of GOrilla portable cryogenic vessels and packaged systems along with Dragon vaporizers has now positioned West Cryogenics as a nationally recognized manufacturer of quality solutions for cryogenic liquid argon, oxygen and nitrogen delivery and gas use systems.

T. Boone Pickens’ writing introduced me to the phrase “It’s root hog or die.” And that is often the case. Current rooting is leading to the development of several new product lines, systems, and relationships that will not only sustain through tough times, but also create opportunities to thrive in times of plenty.

None of us wish for tough times to make us better and the fact they can is indeed disquieting. It is also a reassurance for those who have stared into the abyss and found inspiration, innovation and purpose that we might otherwise have been too busy to see.

Cleaning for Oxygen Service

What is CFOS and why do we care?

CFOS is an acronym for Clean (Cleaned or Cleaning) For Oxygen Service. It is critical that parts used for pure or high concentration Oxygen service be properly cleaned to assure they are free of all flamable and toxic residue or contamination. This is both to help reduce risks of fire or explosions as well as to prevent poisoning in medical gas applications.

Concerns related to liability often inhibit companies and individuals from sharing procedures and other information to the degree they might like to. Anyone involved in the cleaning or use of parts and equipment for Oxygen service needs to take all proper care, though, to be sure that the work they are doing is safe...... both for themselves, those using their products and those around the products. A lot of the Clean for Oxygen Service work done involves lower pressure and lower temperature medical gas and industrial applications. It is very possible that requirements might vary due to different applications and conditions so be sure the information you are using matches your use.

There are some really good resources for gathering information on this subject for development of procedures and testing methods.

First, is the Compressed Gas Association and this link http://www.cganet.com/customer/publication_detail.aspx?id=G-4.1 will take you to their a specific guideline publication. They can also have numerous other publications and can direct you to resources that might have specific information for your application. You might also want to check with the Cryogenics Society at www.cryogenicsociety.org. And then there is a company (Modern Chemical, Inc.) who makes a product called BlueGold Cleaner that is considered an industry standard for many applications. You can find them at http://www.bluegoldcleaner.com.

Many people have great cleaning procedures, but lack controls for cleaned parts. Full prepartion will also consider use of black and white light inspection procedures, proper drying methods and sealed bagging/tagging/storage of parts that will not be used immediately.

Investment in Medical Liquid Oxygen Delivery

Yesterday’s post discussed a fairly easy to evaluate choice between the purchase of a new 210 gallon Ultra vessel or reconditioned 190 gallon. It is pretty much a no-brainer to see the value of investing a few thousand dollars for additional capacity to allow 1-3 extra fills per day when the client base is there.

What if you have an opportunity to use a 500 or 850-gallon GOrilla vessel for delivery? The 500 or 850 truck, vessel and upfit could be $20,000 to $30,000 or more over what it takes to set up a smaller truck with a 210 class vessel.

Surprisingly enough, there are cases where the economics strongly favor use of a larger vessel. This is particularly true for more institutional providers who are serving extended care facilities, contract filling for others or running multiple trucks in a concentrated area. In some of these cases, a single driver with a larger vessel has been able to do the work in a standard work week previously requiring multiple drivers with overtime.

Granted- the Law of Marginal Utility applies and you can have too much of a good thing. Balance remains the key. The point here is that vendors with alternative outlooks can be an asset and open up ways of looking at business that might otherwise be missed. Helping clients find ways to save money through improved operations or open opportunities to grow their business is a joy. It is even more fun when it is possible to do both- Save and Grow.

Expense or Investment- Medical Liquid Oxygen Delivery

If you pay $2000 more for a new 210 gallon liquid oxygen delivery vessel than you might pay for a reconditioned, used 190 gallon vessel is that an expense or an investment?

Of course, it depends. The dependent factors center around Opportunity Costs. If you have all the capacity you need to fill all your clients each delivery day and have no opportunity to for growth or efficiency improvement then a larger tank is just an expense. This would be especially true if you pay more for the larger vessel.

On the other hand, what about the client who fills his current 190s six times a week to go fill Nursing Home and other group clients? This drivers for this company are regularly (almost daily) showing up at sites, filling, and leaving without having completed filling of all empty vessels. Now they are adding trucks and trying to decide. For this client, the additional $2000 they might spend would be fairly easy to justify. Currently, all the expense of getting to the client has been incurred, but they are leaving money behind when they leave. With a slightly larger vessel the driver would have the opportunity each day to increase billing by $25 to $100 without incurring any additional incremental expense. In this case, the total time to recover the additional capital invested would be from one to three months. They would then keep making money on that investment for years to come. It is no real wonder that there are so many smaller vessels showing up in the used equipment market.

Jay Levinson pointed out in Guerilla Marketing that one of the greatest failures is the Failure to Exploit. Hmmmm……..

Liquid Oxygen Delivery: Safety and Compliance Considerations

Respiratory management has an article this month that provides some resource links related to homecare liquid oxygen delivery. You can access it at http://respiratorymgmt.com/articles/2009/06/01/liquid-oxygen-delivery.aspx

A Better Fix for Less?

A client called this morning inquiring about current pricing for 350psi (4L-292) cryogenic liquid cylinders (VGLs) and said his customer’s are requesting them instead of the 235psi (4L-200) VGLs he has been providing. Interestingly enough, he was also requesting repairs on six of his liquid cylinders with a note to be sure and check the pressure builders.

Possibility: End users have been cranking down on the pressure builders of his liquid cylinders to try and get more flow out of them.

The rub is that the flow from a DOT 4L-200 or a 4L-292 is just almost identical (+/- 300scfh depending on the model and whether you are vaporizing liquid oxygen, nitrogen or argon). So, higher pressure will not make higher flow. What will provide extra flow is to add some downstream vaporization allowing for a doubling or more of the gas withdrawal rate.

Suggestion: Put a hang-on Vap on the liquid cylinder at a cost of around $1000 to $2000. This is:

a) a lot less expensive than purchasing six new higher pressure liquid cylinders at $2000 to $3000 each;
b) actually better since it solves the problem which the new liquid cylinders would not;
c) and keeps the existing liquid cylinders in service and generating revenue.

Granted- this is assuming that the real issue is flow. We discussed visiting with the customer first to get a better idea of their application. There are just so many more applications that run at 80 to 110psi versus over 200psi means that it is likely they really don’t need 350psi liquid cylinders.


Pay a lot less and get what you really need? Hmmm.........

The "DO" Verb and Excellence

This past weekend presented an opportunity to go back through part of Tom Peters’ “A Passion for Excellence.” One passage recaptured my attention as it has for years. A business school group is discussing Disney’s success and one team is pointing out their “obsessive commitment to park cleanliness” as one possible contributor to it. Another group notes that “Anybody can provide a clean park.” Same goes for McDonald’s and their “uniformly high standards of service” where again there is a group that contends “anyone can do that.”

As Tom concludes: “Anyone can, but only McDonalds does.”

His point: Anyone can do a lot of things. Some actually do.

Bulk Cryogenic Portability and Utility

Can any horizontal cryogenic storage tank be fitted with a road valve and used for liquid transport?

No. Many horizontal cryogenic liquid storage vessels are manufactured for stationary use only. The support structures for their inner vessel, outside shell strength and other factors are built more simply than those designed to handle the stresses and strains of portable service. Vessels manufactured for portable service have advertising, specifications or other material specifically designating them as portable. Since portables will inevitably be a bit higher priced than stationary vessels the manufacturer will certainly want to make a point of their portability.

Also, some portable vessels are designed for transporting liquid only and are not intended for gas use. Others might have gas use outlets, but they need to be properly piped in order to use them for gas withdrawal service. Just connecting to an outlet marked “Gas” might not assure you a proper operation for gas service. Many vessels have the outlet present to make gas an available option, but lack the proper plumbing to be used effectively for gas service such as pressure building regulators, economizer regulators and economizer circuits.

More and more users are becoming aware of the convenience of operating with mid-sized portable cryogenic bulk tanks at 500 to 850 gallons or more capacity. If you are purchasing a new or reconditioned cryogenic tank it will be helpful to define your needs and be sure the vessel meets them. Odds are you might want to use the tank for something else one day or sell it so you might also want to be sure is fitted with everything you need which could include:

- Full-sized standard fill connections,
- Liquid withdrawal connections,
- Gas use connections,
- Pressure building vaporization and regulator,
- Economizer regulator and plumbing,
- Sufficient external gas use vaporization,
- Dual reliefs,
- Road valve,

While all this might sound a bit trite or redundant, it might surprise you to know how often costly assumptions are made.

Road Valves for Portable Cryogenic Vessels

“Road Valves” were mentioned in the last article without defining them. A Road Valve consists of a 25psi or less relief device and an isolation valve installed as a bypass to the main safety relief on a portable cryogenic vessel. The purpose of this bypass system is to assure that pressure does not exceed 25psi while the vessel is transporting cryogenic liquid oxygen, nitrogen or argon over the road. The 25 psi mark is noted in the DOT exception found in 49CFR 173.320 and also outlined in specific exemptions established for a variety of cryogenic transports and portable vessels.

Compliance with the applicable exception or exemption typically requires that the vessel pressure be maintained at a level below 25.3 psi so most valves are set at 22-24psi for added assurance. It is the responsibility of the transporting driver to vent the vessel down below 25psi and open the road relief isolation valve prior to traveling with contents. Not all portable cryogenic vessels are fitted with road valves. For instance- Those built under DOT-4L or MC-338 specifications are typically able to travel at their full operating pressure.

The critical point here is that it is very important to understand the applicable guidelines and legalities for transporting cryogenic liquids with whatever vessel you are using. Ignorance of the law is no defense and fines related to DOT violations can be enormous. Most importantly- the guidelines were established not only for the safety of the operator, but also for those around them.

NOT PORTABLE- Skid Mounted Vertical Cryogenic Tanks.

What do you say when someone asks you to install a Road Valve on a vertical cryogenic bulk tank that is mounted on a fork pocket style palletized base and designed for stationary use only?

No.

There are tanks that are made to hold liquid for stationary applications only and are, in turn, not suitable for transporting cryogenic liquids. Many small vertical bulk tanks are now being fitted with fork pocket bases because it makes them so easy to move to a new installation site and set in place. In many applications the base also serves as the pad for the tank to support the legs. They also allow for pre-plumbing of final line manifolds and vaporizers. But- your typical 300 gallon or larger vertical cryogenic bulk tank is not made to be moved with liquid in it which is the common differentiator for “portable.”

True portable tanks are typically horizontal vessels that are built under DOT specs, exemption or exception and are designed to be moved full of liquid. Putting a base on a stationary tank does not make it all of the sudden qualified to be portable. And putting a Road Valve on a liquid oxygen, nitrogen or oxygen tank designed specifically for stationary use does not make it legal for transporting cryogenic liquids.

Granted- There are vertical vessels that are designed for transporting liquid including your typical DOT 4L cryogenic liquid cylinders and some of the micro-bulk vessels that are larger than the DOT 4L class. But- only certain specifically designed and classified vessels are for liquid transport. And the manufacturers of these vessels justifiably charge more for them so they provide very clear information on those vessels that are designed for transport.

There is significant risk associated with moving stationary-only vessels that are full of cryogenic liquids. Hazards include injury caused by tipping and turning over forklifts or other handling equipment. Inner vessel supports on stationary vessels are also not made to sustain movement of full vessels creating a lot of potential for damage to equipment and personnel. Stationary micro bulk vessels not designed for movement with liquid are regularly seen with broken neck tubes and other damage caused by someone improperly moving them full of liquid. These repairs are very expensive and not always even possible.

Let’s also not forget that improper transport of cryogenic liquids can result in very large fines. If you are not positive that your equipment is designed for liquid transport it is suggested that you ask a reliable source. There is nothing wrong with clarifying. And-You might just save someone from a serious injury.

4L DOT Cryogenic Liquid Cylinder Excessive Venting

The very best training sessions are those that get really conversational. Discussing case studies and reviewing alternative strategies are the root of “I learn as I teach.” One question asked this week was, “Do clients know to turn on their pressure builder isolation valves as soon as they receive their liquid cylinders?” The conclusion was that all too many users don’t know not to turn on the pressure builders on receipt.

A somewhat difficult issue applies when a system is set up with a primary and secondary bank of liquid cylinders tied into an automatic switch over control system. When the online bank of liquid oxygen, nitrogen or argon liquid cylinders runs low the system automatically switches over to the other bank. Since this could happen at almost any time the pressure builder(PB) valves have to remain open on the reserve bank.

If, though, it is known that the reserve bank will not go on line for several days then it is advisable to not turn on the PB valves right away. This is especially true if you have a Friday delivery to a facility that does not operate over the weekend. Just waiting until Monday to turn on the PB valve can add many days to the life of the liquid cylinders and greatly reduce product wasted to venting.

Boosting Brain Power-

Thanks to Traci Duez for providing a Linked In connection to the article "Six Ways to Boost Brain Power" http://www.scientificamerican.com/article.cfm?id=six-ways-to-boost-brainpower.

There is a lot of news coming out and related discussion regarding the ability to shape out thinking, moods, and attitudes. Any other neat links are welcomed.

PB Leaks & Excessive Product Loss

Yesterday was interesting.

Two of twelve 4LDOT cryogenic liquid cylinders tested at a client site had a combination of issues not commonly seen.

When liquid cylinders marked “bad” are returned trouble shooting is done to determine what (if anything) is “bad.” After initial visual inspection the next step is typically to put a little liquid nitrogen or oxygen into the vessel to build pressure and then leak check all up components on the vessel. This is necessary prep for NER or Simple NER testing.

Well, today while leak testing a dozen vessels, two were found to have leaks in the line between the Pressure Builder (PB) valve and the PB Regulator. This would normally not be noteworthy except for the fact that the PB isolation valve was closed on both vessels. Hence there was no way for pressure to hit this point in the line except for the fact that the PB isolation valve was obviously leaking by.

The net effect is excessive product loss that looks just like a vacuum problem.

See…. If the PB valve does not secure the PB vaporization line then liquid is allowed to leak into the line and vaporize. This liquid normally goes back into the top of the vessel creating excessive pressure. In the case of an external PB control line leaking this excess pressure leaks off. When doing an NER this would look like excessive vaporization requiring a trip to West Cryogenics for repair.

The trickiest thing about this particular issue is that neither of the leaks was apparent until the vessel was being filled with liquid. And the leaks were so small they’d have been hard to see during testing if the vessels were in a warm area.

Quality- Half Way to the Wall

Motorola presented a National Quality Day segment several years ago where they discussed “Half Way to the Wall.” It is a pretty neat concept that doesn’t seem to have become cliché, but possibly should.

Summarizing- Initial targets for quality are established by determining current baselines and then cutting the defect rate in half. If you are currently 50% good at something the idea is to move this up to 75%. A 75% you go for 87.5% good. There are several neat points to this system:

1) Fact-Based Decision Making is required. It is cliché to say you can’t make good decisions with bad information. The challenge in this age of TMI (too much information) is deciding what you really need to know and then gathering the information accurately;
2) Initial Gains are relatively much easier than later gains. It is as easy (or easier) to move from 80% to 90% than it is to move from 90% to 95%. The next step to 97.5% is even more challenging. Once defect rates become very low the challenge in keeping them good is not only not slipping back to old ways, but also not allowing new defects to creep in.
3) Marginal Utility (aka Law of Diminishing Returns) also comes into play at a point. The question “at what price success?” has value. The cost of training, test equipment, inspectors or other cures necessary to make small incremental gains just might not be worth it.

These concepts can be and are actively applied to liquid cylinder repairs by West Cryogenics and our clients. One of the most valuable tools used is the ability West has to monitor incoming vacuum levels on previously repaired liquid cylinders. Active use of this information allows for identification of potential issues so we can work together with clients to find root causes and affect solutions. A large percentage of cylinders returned with good vacuums can indicate operational or training issues at the client side. A rise from 2% to 8% “bad vacs” could indicate an issue at the supplier or user side.

One case found that a client’s cylinders were being exposed to excessive levels of cleaning chemicals resulting in high corrosion. Another found that liquid cylinders were too close to a welding or cutting procedure. Sparks from the procedure were melting tiny holes in vacuum rupture disks.

Large Tip Cutting Torch Oxygen Flow

Large tip cutting torches require high oxygen flow rates to operate properly. Flow rate requirements of +/- 1000 scfh are commonly encountered. It is also common for users to try and feed these large tip torches from a single liquid cylinder that has a vaporizing flow capacity of only +/- 300 scfh. The ineffectiveness of this has been discussed in previous articles, but never shown like this new video from Victor

http://www.jenobi.com/clientsites/thermadyne/video.htm

Hit the link and it should load right up. It provides a great explanation of the challenge of running large tip torches and the benefits of having proper liquid oxygen vaporization.

By the way- The side mount vaporizers shown are manufactured by West Cryogenics, Inc. and distributed by Eddie's Welding Supply and other gas and welding distributors.

Venting Cryogenic Vessels- Is Product Lost?

“OK- So you recommend venting cryogenic liquid cylinders and portable vessels down “fully” after filling. But- Doesn’t this waste product?”

Answer: Define “product.”

If the “product” you are referencing is liquid oxygen, nitrogen or argon then No. Venting off gas created during the fill process will actually help preserve liquid in your 4L DOT Liquid Cylinder, Medical Liquid Oxygen delivery vessel or other portable container. The fact is that the gas in the vessel that you would be venting off has already been lost and is no longer liquid product.

Remember- Pressure building tends to be an accelerating curve the higher the pressure in you vessel the shorter the time before you start venting. If you vent down all the way back to right at zero then you stabilize the liquid in your tank moving you back away from the venting time point. You also remove gas which is by definition hotter than liquid. Getting this gas out also helps remove energy that raises the temperature of your liquid product. As a last point- A filled vessel with pressure on it also has a potential to push liquid into the venting system which will boil off and create pressure.

If the “product” you are referencing is gaseous oxygen, nitrogen or argon then you might be wasting a little product. BUT- this is only true if you plan to immediately use the vessel and you will be able to harvest the oxygen, nitrogen or argon gas right away for cutting, purging or some other use. If you are not using it right away then leaving gas pressure in the vessel will just lead to faster venting and the product will be lost anyhow. You will also lose additional gas created by liquid boiling off sooner than it needed to.

Overfilling Portable Cryogenic Liquid Vessels

There are several negative consequences that can result from overfilling portable cryogenic liquid vessels used for transport or delivery of liquid oxygen, nitrogen or argon. While there are also concerns with 4L-DOT liquid cylinders and stationary bulk tanks this article is more focused on horizontal vessels from approximately 119 gallons up that are used for medical oxygen delivery, construction and demolition or other portable applications.

If you fill portable horizontal cryogenic tanks do you always stay in close attendance while filling?Do you use the Full Trycock as your indicator for when to stop? Or do you have a “full” mark on your liquid level indicator to tell you when to stop filling that is well below the point that liquid would come out the vent?

If you answered “yes” to these questions then you are less likely to have some of the problems that are common with overfilling.

First, let’s note that most portable horizontal cryogenic liquid vessels are fitting with a Full Trycock. This line and the vent are to be fully open when transfilling liquid into the portable vessel. The trycock and vent lines run into the top of the vessel. The Trycock line is lower inside the vessel than the vent so that liquid will come out the trycock before reaching the vent. Shutting off the fill as soon as liquid starts to come out the trycock reduces the incidence of liquid getting all the way up to the fill line.

It is not uncommon to hear of situations where the trycock was not used or the liquid source was not shut off quickly enough. Liquid was then allowed to flow out the vent. This can result in:

a) Liquid running up through a roof or side vent and ruining paint or cracking the metal or windshield of a vehicle in hot weather.
b) Uncontrolled liquid oxygen flow running to areas which will be saturated increasing fire risks;
c) Liquid being trapped in the vent line when the fill line and vent line are closed with inadequate head space left in the vessel.

Incident “C” is a common reason for vessels building excessive pressure. Liquid trapped in the line will rapidly vaporize creating pressure in the vessel and causing it to vent excessively. It can also result in blown head safety rupture disks. Users often mistake this overfilling for a vacuum related problem as the net result (over pressuring) is very similar.

A lot of discussion occurs in this post about the importance of fully venting cryogenic liquid vessels when they are filled. This means that after shutting off the liquid fill source you need to vent until there is no evident positive air flow from the vent line prior to closing it. There are few more important things that can be done to help prevent premature and excessive venting of cryogenic liquid vessels. Venting will also help correct some of the ills of over filling and hot filling.

But- Is product wasted when we vent fully?

Quality- What is it?

“Trifles make perfection and perfection is no trifle.”
- Michelangelo

Last week provided an opportunity for one of the more pleasant dinner evenings ever. Besides the general joy of being with a large group of gas sales and marketing executives there was also a terrific discussion on the mid-90’s Austin/ Dallas/ San Antonio semiconductor surge. For those less familiar, this was the when the electronics Third Coast was flourishing with the construction of many new fabs for companies like AMD, MOTOROLA, TI, SEMATECH, HITACHI, ST MICROELECTRONICS, and NATIONAL SEMICONDUCTOR. Of equal import for many of us was the great influx of suppliers to the industry such as Applied Materials and Tokyo Electron not to mention the dozens of specialty mechanical and cleanroom contractors, chemical suppliers, and analytical services.

An almost cliché, but largely unmet maxim is: “People don’t buy because they understand. They buy because they feel understood.” This is largely unmet mostly because developing a true understanding of client needs and then actually meeting or exceeding them can be hard work.

Inherent to success in the electronics market rush was the ability to meet the stringent quality demands of the industry. Those of us who prospered found opportunities to go beyond keeping up and actually become drivers of the standards expected for service providers. First, though, we had to come to grips with what was actually needed and what could be done. For many of us, the leap from our normal life to Semiconductor-Grade was a jolt.

Dan Driessen formed Ultrapure & Industrial Services as a division of Driessen Culligan to develop a team focused on the needs and opportunities inherent in the growing markets for semiconductor, electronics and medical device manufacturing. As a novel first step in truly understanding client needs the Ultrapure group set up a series of roundtable discussions with some of the area companies most recognized for formal quality. These included 3-M, Motorola, Sematech, AMD, Huntsman Chemical and The UT Microelectronics Research Center. Over the course of three separate monthly round table events these clients shared their definitions of quality, their perceptions of the industry’s specific needs and the gaps Ultrapure would need to close to become a recognized player.

What these clients had to say definitely upset our homeostasis and created huge doubts regarding both the ability to perform as needed and the ultimate profit to be gained in consideration of costs. Yet, the decision was made in short order to move forward. The next several years proved to be both challenging and rewarding beyond expectations. And a lot of lessons were learned that will benefit us and those we have the opportunity to serve for the rest of our lives.

Last week’s dinner brought up a lot of great memories. It especially helped with connecting the dots to the needs of clients using cryogenic vessels and their service support needs. CryoNews is intended to help meet those needs for both suppliers and users. The underlying themes of all articles in this post are Quality and Best Practices as they relate to meeting Producer, Distributer and User needs and eliminating waste. Your suggestions related to topics that will advance this mission are always appreciated.