Doug Wall’s Experience With A Yong Heng HPA Compressor

HAM reviewer Doug Wall purchased a Yong Heng HPA compressor recently. Here’s his thoughts and experience so far…

“I NEED MORE AIR”. With the evolution of airguns from springers, and CO2, to the more common, and often much higher quality, PCP airguns these days, this phrase is heard more and more. The tendency for a lot of PCPs towards higher, and higher powers, also means more air is needed.

I’m no exception to this. After several years of watching the Yong Heng HPA compressor go through teething pains, and lack of parts, I feel it has matured to the point where this can actually work for the average airgunner. There are dozens of videos on Youtube that will give you information on almost all aspects of these compressors.

After watching a lot of these videos, and reading lots of reviews and posts, I finally decided to “pull the trigger” on this project. People ask who to buy it from, and I’m not sure that I can answer that question. I picked a U.S. seller on Amazon that had a high rating, and a decent price and went with that. The compressor arrived via FedEx within a few days, and I filled it with Royal Purple Compressor Oil. I then went to work designing my set-up.

First of all, I do not consider myself to be a “compressor expert”. I do have a background as a research scientist, with lots of experience dealing with high pressure gasses and safety. I also have a lifetime of airgun experience, and making things out of all kinds of materials.

My “requirements” were a small footprint set-up that I could easily move around my workshop. I decided to go with a hand cart type design.

Below. Two views of Doug’s complete compressor system.

Yong Heng HPA Compressor

Having quite a bit of assorted lumber around the shop, I decided on 2 x 3 Inch framing with plywood shelves. This compressor weighs about 35 Lbs., and when you throw the weight of the water bucket in, we’re probably talking in the range of 75 Lbs. for the whole thing. The wheels make this work. Because of the weight, I used multiple screws and glue for all joints.

I added a small padded shelf across the back, where you can rest the butt end of a rifle stock. There’s a small bungee cord at the top to hold the rifle upright.

Then I Velcroed the power cords together so that when you go to plug in, both plugs are right there.

Keeping The Temperature Down

The Yong Heng HPA compressor has a reputation for running hot, so I used the experience of others, and my own science, design and tinkering skills to work to see what I could do.

The next thing was to make sure that the water flow keeps running!

I read where someone had used a clear fuel filter as a flow indicator. So I took the filter guts out of one, and added a small plastic fishing bobber that bounces around when the water is flowing.

Having some brass tubing around, I also bent up a “radiator” to experiment with. It currently hangs on the outside of the bucket.

The stainless tubing on the cylinder output lines of the Yong Heng get very hot when running. I had some thin, soft brass tubing in my junk box, so I wound it around these tubes. In addition, I made up an aluminum heat sink to sit on the top fitting. All of this will add surface area to dissipate heat.

Then I added a muffin fan (with a very good flow) to the front, to blow on the first stage cylinder fins and the tubes. We’ll see how this all works in use…

Yong Heng HPA Compressor

My usage is limited to filling guns and small tanks. So my run times are limited to a couple of minutes, and the 2.5 gallons of water that I’m using are plenty.

For larger tanks, Yong Heng specifies a 5 gallon bucket, and I’ve seen some people use up to 7 gallons, with lots of ice, or even continuous water flow from a faucet. I’ll add a bucket temperature sensor later.

My initial indication is that since the temperature sensor sits at the top of the first stage, and the bottom of the second stage, it heats up faster than the water can remove the heat. My short runs heat up the compressor head, but the water temperature doesn’t go up too much.

Controlling Humidity

Another concern with compressors (or hand pumps) is water getting into guns or tanks. Some people dismiss this concern. But there are multiple reports of liquid water corroding the inside of tanks to the point where they will not pass inspection.

Reports from people who repair PCPs professionally indicate that most that fail, fail due to moisture induced corrosion.

My solution to this includes several things:

Cooling the lines to promote as much condensation in the pump as possible, so that it will purge out when the pressure is released.

The black filter that comes with the Yong Heng has a cotton section in it that will catch some moisture, and any oil mist.

The gold filter has glass beads in it, and will act as a condenser. Any liquid water that forms should blow downwards, back towards the purge valve, when the pressurized system is purged before disconnecting the gun or tank.

The large blue filter originally came with a cartridge that contained 2/3 activated charcoal, and 1/3 desiccant. I dumped the charcoal, and filled it up with indicating desiccant.

Results So Far

I’ve only had my Yong Heng HPA compressor and accessories for a couple of weeks, but so far, it seems good. A couple examples for fill times, that include pressurizing the whole system, are:
– Walther Dominator 1250 – Fill from 2000 psi to 4000 psi = 1min 19sec.
– 13 tank- Fill from 1000 psi to 3000 psi = 1 min 10 sec.
– 68 tank- Fill from 3000psi to 4000 psi = 2 min 11 sec.

I expect that my Yong Heng may end up being as much a journey as a destination. My next upgrade is to add a vibration based hour meter. It’s on order right now. That will give me a good reading for maintenance.

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