cgossett
Mechanical
- Apr 8, 2002
- 5
I am rather new to the cryogenic liquid field, and I would like for someone to either confirm my understanding on this issue or straighten me out.
I work for a manufacurer's representative, supplying pressure control manifolds for medical gases to hospitals. The manifold regulates the delivery pressure from a liquid oxygen vessel (1000 liter typical size). The vessel has a "pressure building" regulator that delivers oxygen gas at approximately 300 psig to our manifold. The manifold has two functions: (1) to reduce the O2 pressure to 50 psi as required by the hospital gas distribution system; and (2) to automatically switch the supply to a second liquid vessel upon depletion of the first. An adjustable "switchover" pressure switch tells the manifold when to switch to the second vessel. This switchover pressure is normally set at roughly 100 psig.
I have a specific problem with one hospital that could be resolved by changing the switchover pressure from 100 psig to 200 psig. I have discussed this possibility with my customer and received an objection based on his belief that this change will substantially increase the amount of O2 left in the "depleted" vessel.
I believe that the pressure decrease in the depleted vessel only occurs after all of the liquid has been evaporated. So the difference between the amount of O2 at 200 psig and the amount at 100 psig is very small compared to the liquid capacity of the vessel. Am I wrong in this understanding?
I work for a manufacurer's representative, supplying pressure control manifolds for medical gases to hospitals. The manifold regulates the delivery pressure from a liquid oxygen vessel (1000 liter typical size). The vessel has a "pressure building" regulator that delivers oxygen gas at approximately 300 psig to our manifold. The manifold has two functions: (1) to reduce the O2 pressure to 50 psi as required by the hospital gas distribution system; and (2) to automatically switch the supply to a second liquid vessel upon depletion of the first. An adjustable "switchover" pressure switch tells the manifold when to switch to the second vessel. This switchover pressure is normally set at roughly 100 psig.
I have a specific problem with one hospital that could be resolved by changing the switchover pressure from 100 psig to 200 psig. I have discussed this possibility with my customer and received an objection based on his belief that this change will substantially increase the amount of O2 left in the "depleted" vessel.
I believe that the pressure decrease in the depleted vessel only occurs after all of the liquid has been evaporated. So the difference between the amount of O2 at 200 psig and the amount at 100 psig is very small compared to the liquid capacity of the vessel. Am I wrong in this understanding?