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I used a Hill MkII with DryPac for two years with no signs of any moisture

July 15 2017 at 10:48 AM
Alan  (Login AlanMcD)

Response to FX and Hill pumps

I used it fill a .22 Marauder that I shot a lot. When I took it apart to do some upgrades, I saw no signs of moisture in the gun at all.

The Hill beads are not silica - they are molecular sieve and are NOT indicating and Hill says they can't be regenerated. They dry the air much better than silica does though.

The lack of any indicating feature means you pretty much have to replace them based on time, and they are not cheap (although at ~$170 per repair that pays for a lot of beads). But used as directed, they do work.

To preserve the function of the beads as much as possible, I would remove the DryPac and place it in a Ziploc when the pump was not in use - the beads will draw moisture out of ambient air and become saturated if you don't do something to keep them separated from it. I am sure that this fact is tied into the guidance from Hill to change the beads every three months, which I pretty much still did, so I probably was changing them more than needed - but with an indicator you have no idea if the beads are still working or not. But I chose the better safe than sorry route . . .

The real key to avoid passing much moisture into your gun with a hand pump is to use the pump slow and steady for short sessions of less than 50 strokes, then vent it and let it cool down before continuing - the cool base of the pump condenses the moisture out of the compressed air, and once you have pumped more than about about 50 strokes the base will heat up and that increases the amount of water vapor that can pass into the gun (plus it helps with the longevity of the pump o-rings, which is the usual reason for this advice). Hand pumps don't technically pass "water" into the guns, but they do pass "water vapor" than condenses into water when the air charge cools in the gun. The cooler that air charge is, the less water vapor can be held in it to be passed into the gun. Using a upstream dryer properly can help further.

I have moved on to tanks and a Shoebox, and a use a big Wilkerson silica bead dryer (it holds about a pound and a half) to feed it and I see no signs of moisture using that either. So if the dryer is big enough (and used correctly) it can clearly work.

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