Liquid cylinder repair and maintenance can add up to big bucks for gas distributors – but it doesn’t have to. We have one simple tip that can keep cylinders in good working order and result in significant cost savings.
Liquid Cylinders 101: The Vacuum
First, a quick review of the basic design element that makes a cryogenic cylinder work so well: an extremely strong vacuum between the inner vessel and the outer stainless-steel shell. As James Dewar discovered back in the late 1800s, that vacuum makes all the difference for the longevity of a cryogen.
Without a strong vacuum, the cylinder is essentially inoperable. Under normal conditions, a cylinder loses about 1-2 percent of its contents per day. But without that vacuum, cryogens boil off incredibly fast – almost like pouring liquid nitrogen into a bucket.
The Achilles Heel: A Tiny O-Ring
Nearly all cryogenic cylinders are manufactured with a vacuum port welded onto the crown, in varying diameters and sizes. Inside that port is a simple o-ring. Inevitably, dirt and exposure to UV rays compromises the o-ring’s integrity, causing them to dry out and slowly lose their vacuum quality.
Here’s the Tip: Always Check and Maintain That O-Ring.
Letting an o-ring deteriorate is what leads to very costly repairs and tank downtime. Whenever the tank goes in for a refill, make the following standard procedure:
Check the dust cap. Make sure it’s not cracked or broken, and fits nice and snug. Replace a cap that’s not doing its job.
Check the o-ring for dirt and debris, and remove any you find.
Put a small bead of O2-safe grease around the seal and vacuum valve and replace the cap.