Seal failure happen due to so many reason but, as you said you have found scratches on Sight glass similar to sand blasting on metals.

It seems, during Refrigerant charging if proper care is not done in that case something like sand etc. may enter in the system that might causing the Seal failure and scratches on sight glass.

I hope, the compressor is lubricated type & mech seal flushing by the same oil and so, check oil first ?

Did you took Oil sample and checked it ??

Do you have Compressor suction strainer with PDI ? Did you checked it when you replaced Mech. seal. ??

with regards,

Nilesh.

You should take this up with the refrigerant manufacturer, get samples of refrigerant analysed as there appears to be a chemical reaction which is attacking the glass of the sight glass. R 134a is a mixture of several chemicals which have different boiling points. If you have a leak, it is possible that you will loose the highest boiling point chemical first, leaving a slurry of the low BP chemical. There could be a problem there which we are not familliar with. Please keep us informed of the test results.

Hope this helps

Phil

I know absolutely nothing about this sort of thing, but, if the composition of the refrigerant has changed significantly then surely it's performance will also have changed:-

rudy_fernando5r Apart from the damage: has the performance of the chiller changed in any way? Just monitoring the power consumed by both machines in similar circumstances may reveal a difference.

You say Chillers are identical, but are operating and environmental condition identical?

R134a when exposed to excessive temperatures can break-down and form HYDROFLOURIC ACID and possibly CARBONYL FLOURIDE (per DuPont M.S.D.S. dated 08/24/95, page 5, Decomposition).

Thanks for your response.

Re operating and environmental conditions, both machines are located at the same plant room (air conditioned room). They are installed about 20 meters apart.

Cheers,

Rudy C. Fernando

Sounds like you've "been there and done that" a couple times GA

Question 1: Why are you using R 134a for a 5000T unit? There are much more energy efficient refrigerants for use in large systems like yours. R-134a requires an extremely DRY system and meticulous attention to avoid any hot surfaces anywhere to avoid serious decomposition--which produces HF and other aggressive acids.

HF will etch glass surfaces like the sight glass. Immediately have the acid and moisture levels in the system checked. If wet, change the drier and keep changing it until the system is completely dry. If wet, the system is probably very acidic, which drastically accelerates 134a decomposition--as well as attacking all the metal and elastomers in the entire system. MAJOR damage will certainly result if left uncorrected.

Excess acidity CAN be removed/neutralized with the appropriate chemical treatment, but this is a job for Professional large scale refrigeration EXPERTS. The synthetic olube oil will also have to be drained and replaced. Contact the system manufacture and ask for assistance. The high acid level may be attacking the shaft seal components.

There is also the possibility that there has been some pump casting fragmentation. That is causing the problems. Any filter on the system?

Thanks for your response and other responses received.

After a few months operation of chiller no. 1 , the refrigerant could not be clearly seen from the sight glass, filters were installed to get rid of possible moisture/ contamination.

Both units (chillers 1 and 2) are in good operating conditions except the contamination noted in unit 1.

Cheers,

Rudy C. Fernando