Here’s How To Use A HPA Hand Pump – Part Two
This article about using an airgun HPA hand pump first appeared in the Umarex USA blog. It gives some great tips on how to use a High Pressure Air (HPA) hand pump for filling PCP airguns. You can find Part One here.
Thanks to Umarex USA for allowing HAM to re-publish this information in a slightly modified form!
HPA Hand Pump Tip 4 – Your Weight
A high-pressure airgun hand pump is built so that you can use the entire weight of your body.
When the handle is extended fully, use the full weight of your body- or as much as you can – to push the pump down. And be sure to use the full stroke of the hand pump.
You’ll find that pumping is fairly “easy” up to 1,500 PSI. After pressure in the gun reaches 2,000 PSI, you’ll start to notice increased resistance. Around 2,500 PSI you may want to have a buddy alternate with you!
When you get to this point, straighten your arms, lock your elbows and wrists and bend at the knees, letting your body weight carry you through the downward pump stroke. Remember to pump just five minutes at a time…
HPA Hand Pump Tip 5 – The Most Common Leak
Some PCP airguns use a fill probe to connect the pump to the gun. The Umarex AirSaber and the new Umarex Origin are examples. These typically have two O rings around the probe.
Below. The Umarex AirSaber uses a fill probe.
If you hear leaking air when filling, it’s often associated with these fill probe O rings. Use diver’s silicone grease or any other pure silicone grease on these seals to help them make the seal. That should fix the problem.
WARNING – DO NOT use any petroleum-based lubrication products for this job. Petroleum becomes violently explosive when subjected to high-pressure air!
HPA Hand Pump Tip 6 – Pump Slowly
We recommend that you pump with slow, deliberate, full strokes. Stop at the top and bottom of each stroke to let the airflow through the tiny holes inside the air pump.
A good rule of thumb is to pause one full second at the top and bottom of each stroke. Three-stage air gun hand pumps work during both the up and downstroke. You will feel the most resistance on the downstroke but don’t discount the upstroke.
Bottom line: Go all the way to the end of each stroke, as most of the work is accomplished in the last inch of travel.
Below. Umarex USA put together this video as a simple guide to hand pumping. You’ll get a sneak peak of the new Umarex Origin PCP air rifle there, too!
Hand Pump Tip 7 – The Gauge Needle May Rise and Fall
It can be disheartening to see the needle on an air gauge rise and then fall. It may even take several strokes to raise the needle by a mere 100 PSI…
The reason the needle rises and falls is that the air is flowing from the base of the pump, through the gauge and into the reservoir that’s being filled.
The larger the reservoir, the more pump strokes it takes for the needle to rise and remain there. A larger reservoir (like a 24 cubic inch vs a 14 cu in cylinder), delivers more shots per fill. It may take more pumps to fill it to capacity, but it evens out on the shooting end.
Hand Pump Tip 8 – Don’t Forget the Pump’s Bleed Screw
When your airgun is filled to the pressure you want, bleed the pump at its base. Then disconnect the hose from the gun, in that order.
Airgun Hand Pump Tip 9 – Hand Pump Maintenance
We recommend you just don’t do it!
DO NOT DISASSEMBLE a hand pump beyond what is shown in the owner’s manual! There’s a ton of O rings in these things and special grease and… well, just don’t do it.
Do not wipe off or remove any lubricant from the pump shaft. It’s essential to its operation. The best maintenance you can do for your air pump is to use it as directed.
Give it a cool-down break and bleed it correctly.
You can also periodically lightly lubricate the O-rings of your fill probes, but remember that grease attracts and holds dirt. So they must be protected if they are lightly greased.
Just know that airgun HPA hand pumps will NOT tolerate a lot of abuse! Treat yours well, follow these tips and you’ll be well on the way to generating as much High Pressure Air as your PCP needs…