Chiller HP Checks

[readie2]

Hi everyone, first post.I've been told to go to one of our sites on Friday to show to the buildings insurance company that the HP/LP safety devices are working ok. Other than disconnecting the condenser fans(presuming its air cooled) how else would you go about doing it other than pumping down and testing with ofn.Also would you say is the best way to test LP just to carry out pump down on system? Thanks in advanced.Dave

[Brian_UK]

You could try lowering the HP setting pressure to prove the operation of the switch prior to testing at the design pressure.

If you can detach the switch from the system then yes use OFN unless you have a controls tester pump.

LP should b easier by performing a pumpdown.

[Magoo]

If chiller has transducers and a display screen use a multi-turn potentiometer ( 0 > 10kohm range )connect to plug on transducer and wind away and watch result on screen.

[Grizzly]

Welcome to the forum readie2.

I am confused as to why you are asking for LP checks.
HP yes because it is a requirement for the pressure vessel regs.
Never ever come across an Insurance Inspector that wanted to witness LP cutouts!

As Brian states, with mechanical switches the easiest way is to lower the pressure towards the working pressure and witness when the comp cuts out.
On software setting controlled versions again change the cutout, to just above the normal running and induce a higher pressure by switching of condenser fans.
You need to know your Plant mind as there are some with internal bursting disks or no PRV'S.
These may have to be approached differently.
Grizzly

[aramis]

The best way for a novice is do a bench test like Brian_UK suggests! The problem is that you need a way to disconnect the devices without venting and vacuum the lines after reinstalling.

You have to be careful to move the pressure slowly if you follow Magoo’s and Grizzly’s method or you could end up with wrong measurements ... if you don't have their experience! :)

[Gibbo]

Zurich Insurance for one usually ask to see LP trips / HP trips i doubt you will have enough time to test anything prior to showing the Insurance rep, plus with some HP's such as on Carrier 30GX in particular pretty hard to get to it or worse it can't be altered in situ due to how its fitted.
The rep will also look at any PRV's fitted to see if they need changing (every 5 years)

[Grizzly]

Zurich Insurance for one usually ask to see LP trips / HP trips i doubt you will have enough time to test anything prior to showing the Insurance rep, plus with some HP's such as on Carrier 30GX in particular pretty hard to get to it or worse it can't be altered in situ due to how its fitted.
The rep will also look at any PRV's fitted to see if they need changing (every 5 years)

Hi Gibbo.
Funy thing is We annually test for Zurich on various site in the Southwest U.K.
And have yet to be asked to trip a plant on *H.P.*
(Sorry guys the H.P. should read L.P *)
Would you happen to know why your Inspector is asking to test LP switches / settings?

I would be very interested as to why.
What sort of size plant are you talking about?
Grizzly

[aramis]

Hi Gibbo.
I would be very interested as to why.
Grizzly

The PSSR 2000 requires you to establish the safe operating limits (pressure and temperature) of the system.

Readie2 may not have equipment information and is collecting this data from the switches?

[Gibbo]

Just did one last week and that was what he asked for but as the Carrier chillers did not have any LP's (30GX 082) he was ok and just concentrated on HP's and PRV's. Don't know why he wanted LP's I never asked, but i have been asked a few times to do it.

Gibbo

[Brian_UK]

They probably have the LP switch on their 'tick list' so it has to be looked at.

Also, of course, because they are working from tick lists they may be concerned that the system will implode if the LP goes into a vacuum. ;)

[Grizzly]

They probably have the LP switch on their 'tick list' so it has to be looked at.

Also, of course, because they are working from tick lists they may be concerned that the system will implode if the LP goes into a vacuum. ;)

Thanks for the reply Gibbo.

Brian.
We are on the same wavelength.. No doubt about it!

Readie2
How did you get on?

Grizzly

[readie2]

Thanks for all your replies. Turned up Friday and got familiar with the plant. Only to get a phone call from the insurance guy saying he was off sick and will be re arranged for this friday. I'll try again then!

[Brian_UK]

Tell him you want to see a Risk Assesment of his state of health before you allow him within coughing distance. :)