There are 2 major cryogenic pump manufacturers in the US, and 1 or 2 in Europe I'm aware of. There are also numerous copy cat manufacturers that build cryogenic pumps who's designs date from the 1950's. The two major US pump manufacturers are ACD
and CVI, now a division of Chart Industries
For reciprocating seals at low pressure (ie: less than 400 psig) they typically use Teflon based, spring loaded U cup seals. There are other types of reciprocating seals called "Hat Seals" which are very similar in concept to the U cup seals, and have been in use for over 50 years. They work very well also. For static seals, both high and low pressure, annealed copper gaskets are very common. Contact stresses are important when designing copper gaskets, but they are the most effective ones available in my experience. They are not generally made by seal manufacturers because they are so inexpensive and low tech, nevertheless, they work the best. Piston rings are another story. These two manufacturers churn out a few hundred pumps a year for high pressure cylinder filling operations and transfer use. Most are recips but ACD also does a line of centrifugal pumps for transfer operations such as from truck to customer tank. (CVI used to, but they're not into that much any more.) Centrifugals often use rotating seals such as are available from John Crane
In Europe, Cryostar is the biggest name. They also sell pumps internationally. Both recip and centrifugal.
In all fairness, Barber Nichols
is another cryogenic pump manufacturer in the US that makes pumps primarily on a special order basis. These are typically low pressure centrifugals that are often hermetically sealed and made for a very specific purpose.
Some of the industrial gas companies also make their own pumps, Air Products and Chemicals being perhaps the most noteworthy. These pumps are not generally for sale though, they are leased. You have to purchase their product to get their pump. For higher pressures, they are typcially the best available.
