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.
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.
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