leak on rhoss chiller help

[casino]

Hi

We have 2 rhoss chillers on site and one has developed a leak, lost all refrigerant.

Using ofn the leak seems to be a little sporadic in where it would lose the ofn reasonably fast then slow, say 140psi in a day then over night only 20psi so on and so forth.

I cannot currently find the leak and am now pointing towards the exchanger and my question is what’s the best way of leak testing these exchangers, my thoughts was to remove the flow and return, charge with refrigerant and point my sniffer inside the exchanger.

Does this sound feasible or is there a better way.

Can I point out that I don’t deal with chillers normally, just ac (sorry)

any help though would be appreciated.

Cheers

C

[Brian_UK]

Bear in mind that you can't use refrigerant as a leak source.

Try OFN with a trace additive to help detection.

Is it possible to section off/valve off parts of the system in an attempt to locate the leak.

Or, can you valve off the water side and fit a pressure gauge to it. Then if it is leaking across the circuits then as your OFN pressure goes down the water pressure should increase.

[nike123]

Class 3. Temperature Dependent Leaks (TDL) are
leaks associated with the heat of expansion. TDL usually
occurs from high ambient air, condenser blockage
or during defrost.

TESTING TEMPERATURE DEPENDENT LEAKAGE (TDL)

All mechanical connections expand when heated. The connections on a refrigeration
system are usually of soft metals such as copper, brass or aluminum.
These metals actually warp when heated, then contract and seal when
heat is removed.
1. Place the unit in operation and raise the operating
temperature by partially blocking the
condenser air intake.
2. Spray coat with soap solution all metal connections, one at
a time, and observe for leakage. Re-wet any
extremely hot surface with water to keep the
fluid from evaporating too quickly.
3. When testing Evaporator components, you
may induce heat by placing the unit into defrost.

http://efficientcomfort.net/documents/BigBlue_Leak_Detection_Manual.pdf

[nike123]

Try OFN with a trace additive to help detection.


What is that aditive which goes with OFN?

[Brian_UK]

What is that additive which goes with OFN?
Sorry Nike, maybe additive was the wrong word.

BOC Gases do a Helium/OFN mix.

http://www.boconline.co.uk/products/products_by_type/refrigerant_gases/leak_detection_gases.asp

[nike123]

Sorry Nike, maybe additive was the wrong word.

BOC Gases do a Helium/OFN mix.

http://www.boconline.co.uk/products/products_by_type/refrigerant_gases/leak_detection_gases.asp

Ok, thanks for clarification. Then use of soap solution and ultrasound detector is way to find leak.
What about temperature (and vibration) dependant leaks I mentioned before? We need hot working system to find them!

[Brian_UK]

Ok, thanks for clarification. Then use of soap solution and ultrasound detector is way to find leak.
What about temperature (and vibration) dependant leaks I mentioned before? We need hot working system to find them!
Oh yes, I agree, it seems that warmer daytime temperatures are opening the leaks well enough.

[Tesla]

You can do a google search for bigblu buble test and it will tell you all about the different types of leaks. Also if you use a trace and isolate sections you could use plastic taped around suspect areas with a little pocket for the trace gas to fill, then when leak testing cut a small hole into the plastic.

[casino]

thanks for the info guys.

nike123 i'm thinking more along your lines here as over the weekend it did not loose any preasure at all and stayed firm at 440psi. lost 60psi during friday daytime but nothing over the weekend.

had to add an isolating valve to the return water side as there was not one there to isolate the second chiller. so as to gain access to the heat exchanger.

also looking at the logs this chiller has had leaks before. its only 2 years old.:eek:

[Fri3Oil System]

I thought you may find this video interesting. How to find a leak in a heat exchanger with ultrasounds, using an ultrasonic tone generator:

http://www.fri3oilsystem.com/ingles/ultraprobe_video.html

Regards,

Nando.

[casino]

This chiller held pressure for over 2 weeks.
We have since charged the unit with R410a and has been running ok for a few weeks now with gauges connected and running pressures holding steady.
No signs of leaks using a refrigerant detector at all.

Strange thing about this is that it had a service about 2 weeks before all the refrigerant went missing by the company who services them every 6 months.
Running pressures were ok at the time of servicing.

Made me think if it was a sticky Schrader valve problem or foreign object got caught in the valve.

Monitoring daily at the moment.

C.