H.P switch testing

[bernard]

Hi

How do you all test H.P. switches and do you consider slowly winding in the H.P. valve as a safe method of testing.

Many thanks

Bernard

[chillin out]

Hi Bernard,
I would use nitrogen to test them.
I think that winding in the comp head stop valve would be a big no no . What would hapen if the h/p switch didn`t work and youre hanging over the comp with youre ratchet in hand trying to open it back up again and the hose burst?
remember ..... be safe (get the app to do it lol)

[Snowman123]

Cane use ofn to test the switch, or a hand pressure pump form H.R.P. I always use ofn its alot better, plus can see on the hp gauge what it trips at.

[frank]

Hi Bernard

Most of the posts refer to testing the HP prior to fitting but you do need to soak test the HP every year during maintenance inspections. To do this we bypass the stat and let the compressor run until the HP trips. Adjustments are sometimes made to set the correct cut out dependant on the gas used.

[Latte]

Hi Guys,

I always check with OFN if fitting one, but for one that's already in use what you can do is set the switch lower than it's normally set at eg 300psi PSI on 404 and either cover the condenser or SLOWLY !!! front seat the discharge to see if it cuts out and check the calibration at a more sensible level. Then if it works at the set cut out you can re-adjust it.

Regards

Fatboy

[gerryboy00]

I consider slowly winding in the H.P. valve is a safe method.
You can actually control/raise pressure couples pounds at a time.

[Temprite]

I would use nitrogen to test new HP switch.

Also cover up condenser to bring in fans,and test HP switch, this is simulating proper running conditions.Also use this method to check thermal overload suspected of tripping prematurly.

Quick check wind in discharge service valve. Make sure gauge is connected to keep eye on pressure.

[benijoseph]

Mr, Bernard.

connect the H.P switch to nitrogen cylinder which

must have a max 300 psi regulator ( guage connected.)

slowley open the regulator for requred pressure and set

the switch , Is it easy ?


beni joseph.

[bernard]

Hi all

I have always used ofn in the past but I recently had about 20 switches to test so I wound in the hp valve,I,ve been told there is a internal safety valve within the compressor which will pass straight into the suction if there is any problems.I suppose the advantages of not using ofn is less things to disconnect so less chances for leaks.Does anyone know at what pressure the internal valve works.

Regards bernard

[Peter_1]

http://www.refrigeration-engineer.co...=bypass+scroll from 09-09-2004, hey...my wedding date

[bernard]

Hi peter

I don,t understand what you mean please can you explain

Regards bernard

[Peter_1]

Hi peter

I don,t understand what you mean please can you explain

Regards bernard

What? My wedding date? LOL
No, if you read through that thread, you will find the answers for your questions, at least for the scrolls compressors.

[bernard]

Hi peter

Sorry my fault,this time I was refering to recips,I believe if the pressure gets to high that there is a valve inside the compressor that will blow and send the discharge straight into the suction?

Regards Bernard

[ecclesk]

the grasso comps i have on site have an overfow safety valve (releif valve) which opperates at 22.5 bar and as you say, it allows the discharge to bypass into the suction.

We normally test our pressure switches every 6 months, testing the hp by closing the dicharge valve slowly.

system using R22, hp cut out set to 17bar

[Mark]

Hi.

Using OFN you have the risk of pushing non condensibles into the sytem.
Testing adjustable switches can simply be done by dropping cut out below operating pressure,this will prove the switch is wired correctly and generates an alarm.As well as the switches contacts breaking.
I would be reluctant in winding in discharge valves to test switches.

Best regards. Mark

[Mark]

Hi.

Using OFN you have the risk of pushing non condensibles into the system.
Testing adjustable switches can simply be done by dropping cut out below operating pressure,this will prove the switch is wired correctly and generates an alarm.As well as the switches contacts breaking.
I would be reluctant in winding in discharge valves to test switches.

Best regards. Mark

[adam]

to test h.p switches i usually just isolate/disconnect the condenser fans.
p.s what's ofn?

[dill]

hi adam, ofn stands for oxygen free nitrogen or white spot as I used to call it. As you know it is an inert gas and being totaly moisture free it is ideal for testing hp switches, stopping oxidisation whilst brazing and good old pressure testing. dill. ps, as mentioned it is vital that all of it is removed from the system after use as it does not condense well and is brilliant at picking up water.

[frank]

Adam

Have a look here http://www1.boc.com/uk/sds/

[adam]

yeah, we just call it dry nitrogen. cultural differences

[Mark]

The risk of non condensibles through using OFN on a pack via valves letting by,does not warrant the risk.

[chemi-cool]

I usually disconnect the condenser fans, pressure climbs slow and its easy to follow the increasing pressore.

HP controlls should be tested at work conditions and not in a lab.

chemi