cooling water seals 1

[RobertHasty]

Hi,

Does anybody have any experience regarding cooling water (glycol + water) compatibility with FKM and NBR seals?
I am referring to the O-rings which can be found on hydraulic hose fittings.

I found this compatibility table from Parker:

https://www.parker.com/literature/O-Ring%20Division%20Literature/Section%20VII.pdf

Page 7-26 states that FKM & NBR are satisfactory in combination with Glycols.

Page 7-27 has an example for Houghto-Safe 620 Water/Glycol and states FAir for FKM and Satisfactory for NBR.

Any experience from board members?
Thank you in advance.

 

[EdStainless]

Temperature will be the controlling variable.
We used NBR for this service.
But we specified the compound as we found that some worked better than others.

 

[btrueblood]

EPDM will be superior to either of those above about 200 deg. F.

FKM aka Viton is variable - the base polymer is not well controlled by that specification, and varying types of Viton have been developed to get better hydrolysis resistance. NBR is ok up to 180F, and HNBR is good to about 210-220F. EPDM is good to 250F in pressurized water/glycol systems.

 

[RobertHasty]

Temperature will be the controlling variable.
We used NBR for this service.
But we specified the compound as we found that some worked better than others.

Thanks for the answer.

I don not know the exact compound yet.
Since the temperature is the main issue, I am afraid the NBR will not do the job for me.

 

[RobertHasty]

EPDM will be superior to either of those above about 200 deg. F.

FKM aka Viton is variable - the base polymer is not well controlled by that specification, and varying types of Viton have been developed to get better hydrolysis resistance. NBR is ok up to 180F, and HNBR is good to about 210-220F. EPDM is good to 250F in pressurized water/glycol systems.

Thanks for the reply.
The problem with EPDM is that is not available in various sizes.

 

[btrueblood]

What type of fitting exactly?

McMaster sells EPDM orings in all of the SAE Oring boss fitting standard sizes, if you are in the USA. There are other shops that will sell them cheaper if you ask. I've been able to find shops with all of the ISO metric sizes as well, but typically you need to buy a reasonable quantity (hundreds)