Question about frying pump seals

[Smaug]

I've seen it said often that one should give a hand pump a break every 50 pumps or so, so the O-rings don't fry.

My question is, when the O-rings do need to be replaced, couldn't they simply be replaced with silicone rings and never have to worry about heat again? Silicone is extremely heat resistant. They make muffin pans out of them for less than $10 that go right in the oven at up to 500°F. So why not in a $200+ air pump?

Is there some other components that are heat-sensitive?

[neric]

I've rebuilt my Air Force pump 4 times.  I finally came across a box of various sized O-rings at Harbor Freight which were also designed to with stand heat,, Viton I believe is the material.  Anyhow I haven't had to rebuild my pump since I've started using those O-rings.  

The other thing I've found that is problematic is the moly-lube that was originally used in these pumps (I have two, Air Force and Benjamin, which are the same inside, only different connectors).  The original lube turns to charcoal grit which then tears up the O-rings.

So I started using Permatex brand Anti-Seize Lubricant,,,its the stuff mechanics put on the spark plug threads of auto engines,,,it withstands 1600 degrees F,,,and I find it is far, far better than original manufacturer's lube.  I used the Permatex lube on the regular O-rings and they last a lot longer with it.  But with both the Permatex and Viton O-ring I haven't had to rebuild since.

There is one more thing that is heat sensitive and that is the spring at the third stage.  The first time I rebuilt,,that spring was fried badly.  I went to my local hardware store and got something similar and it works just fine.  I have never used factory replacement parts.  Only things I've had to replace is the O-rings and the spring.  Well,,I replaced the original lube during the cleaning.

I only pump 10 to 15 strokes at a time then let it cool for about 5 minutes.  I also watch the hygrometer and I don't pump at all unless the humidity is less than 50 percent,,,otherwise you'll be pumping water into your gun.

[Bullit]

Good post neric!  Especially on the pumping of less than 20 strokes and humidity.  This heating effect, (after some good amount of pressurization takes place), doesn't get a lot of attention...and also the humidity consideration, as here in the Southeast the humidity is generally over 60%.