I'm looking for some suggestions here. At one of our outreach units, they have 2 K machines that are failing the neg. pressure test first thing in the morning but then pass when they re-run the pressure tests and are then fine for the rest of the day. Have any of you seem this problem before and if so what was the remedy for it.
Thanks!

Check the dearation pressure to ensure its -24mmHg. Also, make sure that the machine is up to temp. before going into test. Do you have tempered water? In the morning is the water on the cold side and then warms up? The colder the water the more difficult it is to remove air by the dearation pump.

I agree with orc on the deaeration pressure.

Thanks for the suggestions, unfortunatly they didn't fix the prob. Yes, we have tempered water (72 degree F)and our dearation pressure is fine. Anyone else got any ideas?

Several things can cause this issue...
The test is done by the UF pump creating a Neg P of -300mmHg. The system must hold this pressure for 30 sec. +/- 21mmHg.

Have PM's just been completed on the these machines?...
Sometimes the filter (74)or one of the checkvalves do not get locked completely together and can cause this problem under negative pressure.
If the UF pump is not calibrated correctly or is leaking at one of the in or out Check Valves or poppets.

Other possiblities are...
*leaking at V43 oring
*Leak at top of Air Sep. Trap (69)
*A pin hole in the tubing.

Good luck.

Try replacing hanson o-rings. Do you have diasafe filters and if so when was it replaced last.
Hope this helps. if not perform a induced pressure holding test.
let us know what fixed the prob.

Thanks for all the suggestions, I think we may have found the problem. It appears that when the hansen orings were replaced on the last pm that inadvertantly one of us nicked the plastic hansen connector body just enough that it allows a small amount of air to leak by when the machine is cold. I'll update if it turns out to be something else.