Rubber O-Rings and valve pieces failing in glycol engine cooling system

[USAeng]

Hey guys,

We have (3) MWM biogas engines at our plant all with same issue. Failing rubber parts in the glycol system. It’s closed loop about 40PSI 180F propylene glycol 40% mixed with deionized water

Engines are about 5 years old with 24,000hours. This problem is costing a large amount of money due to difficulty getting to the O-rings

Above are pics of typical cylinder liner O-rings and shutoff valves around the pumps. We had some other O-rings around the system with same look

Any ideas what could cause this?

We tested glycol recently at 8.5pH which is good per manufacturer specs. It is approved glycol for the engine.

We do not know what the seals are made from as MWM does not publish that

 

[GrahamBennett]

I suggest you contact MWM in the first instance to discuss this problem in case they have a readily available alternative O ring.

According to the information I have available to me O rings made out of EPDM compounds should be satisfactory in this type of service. If you want to go the whole hog and spend a shed-load of money on a solution then O rings made from Kalrez (perfluoroelastomer - DuPont) will do the trick.

forumtowers.com

 

[btrueblood]

Yeah, and diamond coat the Kalrez for extra protection .

Seriously, EPDM is the compound you want.

 

[romke]

from the looks the rings have become brittle and have changed in hardness and lost elasticity. that can be caused by several things: to high a temperature, incompatibility with the coolant etc. i suggest you contact MWM first and show them the images - they may well have encountered similar problems and maybe have changed the type of rubber used for the O-rings over time. if they fail to give a satisfactorily answer you could contact a reputable supplier of O-rings and ask whether they can supply O-rings in the size you need that can withstand the temperatures encountered while in contact with a glycol/water mixture. you also might find some useful info here:

http://mykin.com/rubber-technical-resources