test hp cut out

[martinw58]

haveing argument about the safe way to test hp cut out

[chillin out]

Use nitrogen to test the cut out of the hp switch.

You could also stop the cond fan and let it cut out but this may prove dangerous.

Chillin:):)

[philfridge]

Yer i agree with chillin just stop the condenser fan and test with gauges on high side . No problem with this method and easy

[bernard]

Hi

Stick the gauges on and very slowly wind the discharge valve in.I,m sure some will disagree but there is a internal safety valve in the comp.Switching the condenser fan off is the best way for single compressor but if your working on packs then this is time consuming plus the electronics will stage the compressors off.You can use ofn but again time consuming.

Regards Bernard

[Latte]

Winding the discharge in slowly is the way i would do it also but also check first what pressure relief valve are installed first and that some joker hasnt gone in and wound the HP switch up first to stop it tripping out. The comapny i work for has taken on some new contracts and tha amount of hp switches set at 400 psi is beyond me

regards

Fatboy

[Toosh]

Hi, If you can remove the connection to the system Then the only good way to do it is Nitrogen and regulator and a gauge that is accurate, then then presurize it and then you can see when the switch opens

Norm

[Billy Ray]

martinw58,

all the above methods are 'safe methods' assuming being completed by a competent person.

i would add initially do a 'dry run' with the compressor fuses removed. This will then prove your electric circuit is wired correctly. If you have an oil presure switch in circuit, this will trip after the time delay, so you will have to be quick!!

Doing the above procedure, you can test your oil pressure switch at the same time.

Billy Ray

[Refrigerologist]

Winding the discharge valve in very slowly on a single comressor system can be risky, although I do occassionaly do this myself. But care must be taken. I once did this on a Denco out door unit, unfortunatley the mechanical link between the HP bellows and the switch were missing and so the bellows actually burst before I managed to throw the unit isolator. It is also something I would be a bit wary of when some of the safety pressure cut outs are at 450lbs per in"2 or considerably higher now with 410A. Nitrogen or a hand pump is safest.

[750 Valve]

agreed nitro is the safest, second would be switching off cond fans or water supply if water cooled, third would be shutting comp discharge - this one can get real hairy and should only done by those with experience on the old ratchet key and be prepared to take VERY FAST action if things go astray.

[paul_h]

If you can backseat the service valve to remove the HP controller inlet flare, use nitrogen to test, that's always the best option.
I'd only use shutting the fan/discharge/water off method if you could not shut any valve to the HP control port in order to remove it to test with nitrogen. I.e, it's a weld in, or on a service valve port that back seating won't isolate it for removal without losing all the refrigerant.

[taz24]

I agree with the others.

No1 Test the switch with N2 or a hand pump if you have one (real ball ache if your doing hp though).

2nd Test by dropping the cond fan or blocking air flow over cond.

and C Test by front seating the discharge service valve if fitted (extreme care to be taken).

taz.

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