charging centrifical

[TaintedJohn]

while taking my engineers practical the engineer asked a question "it has been leak checked and is at zero". Thinking he wanted me to charge it I went into the procedure he stopped me and said you dont understand it's at zero can anyone tell me what he ment? by the way it was on a Trane Centrivac.

[Dan]

My guess is that he was referring to gauge pressure. But what was his question?

[bigmax]

I would evac to 500 microns and do a 24 hour standing vac test. if it rose over 1000 microns, you have a leak. If it holds, go ahead and charge. Make sure you have water flow thru the evap, while charging until your saturated temp is over 32 deg F.
This is assuming chiller has no refrig in it and has been pressurized with nitrogen. If there is still refrig in it and pressure has been raised to leak check by using a boiler to heat chilled water then, you need to reduce water temp to get refrig press in a vaccum and run purge to remove any non-condensibles. Then determine your refrig level and decide if you need to add any.

[Mike Hopkins]

Taintedjohn,

I'd say what he means is that the leak test was blown down and the machine was at 0 psig and ready to be evacuated prior to charging or a standing vacuum test. Just a thought.

Mike Hopkins

[Robearbam]

How could it be leaked checked at Zero? ??? maybe?