Orings Viton Vs Hnbr?

[SeanAT]

I used Aflas 80A in my Hill pump. Aflas can handle slightly higher temps than Viton. Seems to be holding up just fine.

[D14Jeff]

my o-rings arrived today
only 5 days shipping time including the weekend

[airgunnertoo]

After reassembly, I was pleased to find the weaker spring had solved the problem I was having.  It also eliminated the weird squeaking sound that the pump had always made at the bottom of the compression stroke.  So over the course of the last 2 weeks, the pump was much more enjoyable to use.  Felt great and pumped great.

 are you still using the same spring? if so, do you have any other information about the spring you installed? I would like to eliminate that noise. I would like to eliminate that noise too.

[nervoustrigger]

Yes, the lighter spring is still installed and working great.  Sorry, I didn't measure it...I just rifled around through my Sour Cream Container O' Springs until I found something that would just barely press the bullet-shaped check valve against its seat when the brass plug was screwed in.  Back pressure from the outlet takes care of the rest.

[airgunnertoo]

Yeah, extruding was also my best guess as to how it would fail so soon.  I would have expected as much had it been a 60A but I figured the 75A would have fared at least better than roughly 10 rather sedate pumping sessions.  It's what I had on hand so figured I would try it.  Next time I go in, I'll get a small bag of 90A Viton and try again.

forgot to ask which oring would you recommend? im getting vacuum on the upstroke on my Benjamin pump. I will be taking it apart and cleaning it soon. is the polyurethane holding up?

[nervoustrigger]

I had good longevity from the 90A polyurethane until finally burning it up while pumping _really_ fast, pumping a rifle from zero that had a leaky valve seat.  After getting it to 500psi or so, it sealed but the O-ring was toast.

As mentioned, the Viton 70A did not last long at all but it failed due to extrusion rather than heat which leads me to believe a hard O-ring (90A) is most important in this application.  So a Viton 90A seems like a good choice, or an Aflas type like Sean recommended.

[airgunnertoo]

is the oring store a $5 flat rate or am I missing something?

http://www.theoringstore.com/index.php?main_page=shippinginfo

I was thinking of ordering one of each out of three and bulk order the one that lasts longest.

[D14Jeff]

thats what they charged me .....