LN2 pumping problems
LN2 pumping problems
(OP)
Greetings Cryo Experts! I'm new here and was hoping to get some information about a problem we're having with our LN2 pumping system.
First, here's some specs on our system:
Pump - DPD series footmount recip by Pittsburgh Cryo, 4000psi max, not sure of GPM
Tank - 1500 gal, 96" high, topped off weekly
Suction line - 1" from tank, 1-90 deg turn into pump, total length about 30"
Running time - about 30-40 minutes once every 2 hours
Vapor return line installed back to tank
We're pumping through an evaporator to supply N2 gas to our facility at 2500psi
Our problem is that the pump frequently loses prime and ceases to pump liquid into the evaporator. Our maintenance supervisor has discovered that we can regain prime and start pumping by spraying a garden hose continuously onto the suction line before the pump. We've purchased refurbished cold ends and warm ends and still have the problem. This garden hose trick works in any weather, winter and summer, below freezing to over 100 degF.
Questions - Why does the garden hose trick work? Is he heating or cooling the line?
What are the possible solutions to our problem?
Thanks for your help!
Paul
First, here's some specs on our system:
Pump - DPD series footmount recip by Pittsburgh Cryo, 4000psi max, not sure of GPM
Tank - 1500 gal, 96" high, topped off weekly
Suction line - 1" from tank, 1-90 deg turn into pump, total length about 30"
Running time - about 30-40 minutes once every 2 hours
Vapor return line installed back to tank
We're pumping through an evaporator to supply N2 gas to our facility at 2500psi
Our problem is that the pump frequently loses prime and ceases to pump liquid into the evaporator. Our maintenance supervisor has discovered that we can regain prime and start pumping by spraying a garden hose continuously onto the suction line before the pump. We've purchased refurbished cold ends and warm ends and still have the problem. This garden hose trick works in any weather, winter and summer, below freezing to over 100 degF.
Questions - Why does the garden hose trick work? Is he heating or cooling the line?
What are the possible solutions to our problem?
Thanks for your help!
Paul





RE: LN2 pumping problems
The water is sprayed on the VAPOR RETURN LINE, not the suction line. Sorry for the confusion. Any ideas?
RE: LN2 pumping problems
RE: LN2 pumping problems
Maybe you could use a regulator and bleed some of your gas back into the tank to keep the pressure up.
Have you inadvertently installed too big of a pump or done anything to reduce tank pressure?
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RE: LN2 pumping problems
RE: LN2 pumping problems
RE: LN2 pumping problems
Thanks again for all your help.
Paul