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.

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.

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.

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……..

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.........

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.

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.

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.

Cryogenic Liquid Cylinder Operation- Part 3- Pressure Building System

The April 16th article http://cryonews.blogspot.com/2009/04/cryogenic-liquid-cylinder-operation_16.html discussed why it is necessary to have a gas use coil that pulls liquid from the bottom of a 4L DOT Cryogenic Liquid Cylinder and vaporize it for gas use supply.

And- It was noted that a pressure building system is needed to help maintain pressure within a specified operating range. So, how does the pressure building system work?

Liquid cylinders equipped with gas use coils also have another set of coils brazed to the inside skin of the outer jacket. Just like the gas use coils- the pressure building coils pull liquid from the bottom of the liquid cylinder and vaporize it. Vaporization happens by exposing the liquid to temperatures above its boiling point.

Unlike the Gas Use system, the Pressure Building system returns vaporized gas back to the head space of the liquid cylinders. Crowding gas molecules into this head space raises the pressure of the liquid cylinder. The pressure building regulator controls the flow of liquid into the coils and stops the flow of gas back into the head space.

It is important to note, though, that this does not stop pressure from building. Once pressure is raised on a liquid cylinder and warmer air is introduced into the top of it normal evaporation of liquid nitrogen, argon or oxygen will increase. Be sure that the valves feeding pressure building regulators are closed if the vessel is not going to be used over night or over a several day period. Venting of pressure and release of hotter air can also help minimize product lost due to normal evaporation.

Homecare Medical Oxygen- Fuzzy Math

The Medicare Benefits related to oxygen were changed three years ago limiting collection of rental for respiratory oxygen equipment to 36 months for individual patients. There are a number of articles and talks discussing the direct impact of this new guideline on oxygen providers. And there is some fuzzy math being used. As mentioned by an old boss, figures lie……

It is purported by the Office of the Inspector General that 22% of Medicare patients receive care for over 36 months. Does this mean then that 22% of oxygen rentals just went away at the36 month point?

This is not likely.

Medicare does not account for 100% of rental billing. Even if it did, the only way January could account for 22% instant reduction would be for providers to have set up no new accounts since January 2006. Not.........

Yes. The Medicare guidelines are most certainly having a big impact on oxygen providers. But- there are homecare oxygen companies who continue to grow and very many who do not have business plans built around reliance on Medicare.

Cryogenic Liquid Cylinder Operation- Part 2C- Gas Withdrawal

A typical customer service call:

“Hello. This is ___________ and there is frost on the outside of our cryogenic liquid oxygen cylinder. Is this a problem?”

How do we determine without a game of 21 questions?

Q: Is the ice or frost all over the vessel or is it more localized?

A: Oh no. It is just at the bottom and some up on the pipes?

Q: Does the unit frost up all the time or only when in use?

A: Only when in use. And, the more gas used the worse it gets.

Conclusion- In all likelihood this is normal…. Especially in humid environments like the Gulf Coast and Northwest U.S. .

Remember. If the pressure of the liquid cylinder contents is below the economizer set point then Gas used is originating from the bottom of the liquid cylinder as liquid. This liquid is being exposed to outside heat via a set of coils brazed to the outside wall of the vessel. Exposing it to heat raises the temperature of the liquid above the boiling point to make it gas.

This liquid is coming out of the bottom of the liquid cylinder at something around -300 degrees Fahrenheit. It is only normal for outside cold are to frost up on the outside of a container that is exchanging energy at this level. Also, It is completely reasonable that the more gas you use the more frost will grow.

Is there a limit to how much liquid can be vaporized by the gas use coil?

Manana….

Cryogenic Liquid Cylinder Operation- Part 2B- Gas Withdrawal

The last two posts covered 4L DOT Liquid Cylinder Liquid Withdrawal and Vent operation. Summarizing- When the liquid valve is opened, liquid is drawn up from the bottom of the vessel through a dip tube. When the vent valve is opened gas is the top head space of the vessel is released. And- it was determined that the gas use valve cannot withdraw gas in the same manner as the vent or pressure would rapidly drop below needed levels.

“If gas doesn’t just pull right off the top, then where does it come from?”

Would you believe “It depends?”

And, in this case, what does it depend on?

It depends on the pressure of the contents compared to the setting for the pressure builder and economizer regulators which will be discussed next time. For now- the economizer setting will typically be about 15psi higher than the pressure builder setting. So, if your pressure builder regulator is set at 125 psi the economizer regulator actuate at about 140 psi.

When the contents pressure is below the economizer set point then the gas coming out of the cryogenic liquid cylinder actually originates from the bottom of the liquid cylinder. It comes out of the inner vessel through a small copper tube that is brazed to and circles around the inside of the outer vessel. Confusing? Not too. The key here is that, up to the point of needing gas, the purpose of the cryogenic liquid cylinder has been to protect the liquid oxygen, nitrogen or argon from outside energy (heat) in order to keep it in liquid form.

When gas is needed, all we have to do is expose the liquid to energy (via direct exposure to the outside wall of the vessel) to bring it above its boiling point. Now we have gas. By withdrawing liquid from the bottom and converting it to gas the head pressure of the liquid cylinder contents can be maintained far more easily. This provides more consistent output and allows the supported process to run normally.

The other aids to maintaining pressure within a usable range are the pressure building (PB) regulator, PB coil and economizer regulator. Stay tuned for more…….

Cryogenic Liquid Cylinder Operation- Part 2A- Gas Withdrawal

Open the Gas Use valve on a filled cryogenic liquid cylinder and gas will come out. Interestingly enough, the same thing happens if you open the Vent valve. So……. Does the gas coming out of each valve come from the same place inside the vessel?

If you answered “yes” or “no” you are sometimes right. As they say, though, even a broken clock has the right time twice each day. It is more accurate to say “It depends.” To understand the “why” of this, it is helpful to first look at the Vent connection.

We previously affirmed that liquid withdrawn from a 4L-DOT liquid cylinder comes from the bottom of the vessel. This is easy since the liquid is heavier. Gas that is formed by the normal evaporation of liquid nitrogen, argon or oxygen collects in the top of the liquid cylinder inner vessel “head space”. As more and more molecules crowd into the head space the inner vessel contents pressure increases. This pressure is useful to push liquid back out through the dip tube when the liquid valve is opened.

When the Vent valve is opened, free gas molecules are allowed to escape and the pressure goes down. If the Vent valve and Gas Use valves were both connected to the head space only then there would be no reason for both. There would also be a big operational problem.

Let’s consider a case where Mike the Scrapper is using oxygen from a cryogenic liquid cylinder to feed a cutting torch or oxygen lance. If he were using a simple LS (Liquid Service Only) vessel then his work cycle would look very much like the profile of a wedge or the topography of the White Cliffs of Dover. He’d have a long wait while pressure built in the liquid cylinder. Then, once the pressure was high enough he’d fire up his torch and start pulling off gas. The pressure would drop precipitously until it got too low and the torch would go out. Mike would then have to wait a long time again for pressure to build and then fire up for a little while, lose pressure and go out. This would be unlikely to occur more than a couple of times before Mike would give up on the liquid cylinder and go back to high pressure cylinders that would give him a constant supply of gas until empty.

If gas doesn’t just pull right off the top, then where does it come from?

Cryogenic Liquid Cylinder Operation- Part 1- Liquid Withdrawal

Is pressure good or bad in terms of cryogenic liquid cylinders?

A) Good
B) Bad
C) It Depends? (The Millennium Answer)

Right- It depends. Pressure is necessary for liquid and gas withdrawal from a liquid cylinder. Too much pressure, though, can cause excessive venting or even severe damage if safety devices are absent or malfunction.

As a first simple step it is important to understand that when liquid is filled into a cryogenic liquid cylinder it goes in through a dip tube that goes down to near the bottom of the liquid cylinder. When liquid is withdrawn it comes back up from the bottom of the tank through the same dip tube. Since the valves and connections for a liquid cylinder are at the top it is necessary to have some head pressure on the liquid in order to push liquid oxygen, nitrogen or argon back up and out the liquid valve.

The simplest liquid cylinders then contain only two valves (Liquid and Vent) and are often referred to as “LS” vessels. They are used for liquid service only and typically fitted with 22psi reliefs to avoid spraying liquid out with too much force when withdrawn. They really on normal product evaporation to create head pressure for liquid withdrawal.

This is all pretty simple, right?. Next we’ll discuss “VGLs” and Gas Withdrawal.

High Pressure Options for Oxygen, Nitrogen & Argon

How can efficiency be optimized in cases where high pressure is needed for purging, testing or other high pressure applications? First, it is important to understand the application and the factors that play into system design. Once the application is better understood then consideration needs to be made for the specific installation and location. Sometimes, the “best” method is not the most practical or cost effective. And supply of materials or availability of services can be a restraint.

One of the major justifications for liquid cylinders or cryogenic bulk tanks is the ability to get molecules to a user in a lighter and more compact package. Depending on the gas used, one liquid cylinder might be a direct replacement for a 12- or 16- pack of high pressure gas cylinders. This one 4L DOT cryogenic liquid cylinder full takes up only a 21” square footprint and weighs well under 1000lbs versus the high pressure pack with a 4x4 or so footprint weighing 3000 pounds plus. And- a 500 gallon GOrilla portable cryogenic vessel could take the place of ten high pressure packs at only 8000 pounds or so full.

An application can be a real bear when the minimum pressure is high enough to require high pressure gas cylinders or tubes and the volume of gas used is fairly high. In many cases, this can result in the need for a dozen or more high pressure 12- or 16-packs on site with a like amount committed back at the plant for exchange. This becomes an even bigger issue when the volume of oxygen, nitrogen or argon molecules needed necessitates a high pressure tube pack or trailer. If tubes are exhausted it becomes necessary to:

a) have a complete replacement pack;
b) have a spare for exchange stock or
c) have the ability to “bump” the tubes in the field.

More exploration of these options and consequences soon…….