AirForce ePump - expensive - not the fastest - BUT runs off 3.2amp 12v DC

I also received an E-pump from Pyramid Air. Fit and finish is excellent. I just filled my Talon ss factory tank 490 cc, it took 1 hour give or take a few minutes from 0 to 3000psi. Very quiet and when it finished there was no noticeable heat any where on the case of the pump, the motor was a little warm. When i opened the bleed valve no noticeable moisture. So far VERY happy.

Just completed my first tank fill with some very important lessons learned along the way and shared to help others. The time-line at https://www.airgunnation.com/topic/airforce-epump-overpriced-under-performing-but-runs-off-3-2amp-12v-dc/#post-449569 has been updated.

I have ordered https://www.amazon.com/Trident-Silicone-Grease-Jar/dp/B00V2G2BWQ as well (not affiliated with this vendor/manufacturer)

There is a large moisture ball in the bottom of the calcium chloride pre-filter desiccant slightly larger than the size of a golf ball. The size is slighter larger than what has been observed with 15 or so hand pumping sessions using the same filter attached to the Hill MK3.

I think I've found a good setup combination -- 7 fills from the Ninja 90cu-in with EZ valve into the Gamo Urban. The ePump is now connected to a 12VDC deep cycle that is charged via a solar panel. Fill time for the bottle from 3100 PSI to 4500 PSI was exactly 1 hour and 15 minutes. Keeping the shaft lubricated seems to be the most important thing with the ePump and my tub of silicone grease showed up. The DC side is operated via the singular DC/OFF/AC selector switch. The AC side has a dedicated On/Off in addition to the DC/OFF/AC selector switch. Pump seemed to operate better on 12VDC than through the AC/DC conversion through the PSU.

Nice thing is since this is a glorified hand pump (a well engineered one) there was no pressure shock when topping off the bottle. I connected the fill hose to the fitting on the neck below the valve and pressure slowly built in the hose until it was equal to and greater than the bottle pressure at which point the check valve in the bottle opens and begins filling.

Bleed the system at 30 minutes, again at 60 minutes, and a final bleed once done pumping. Nothing but moisture vapor out the bleed screw and no standing water. Pumping a bottle from 0 to 4500 PSI is a large task but forward-going this should be easy.

So far I have about 5 bottle fills on the E-Pump from ~3100 PSI to 4500 PSI. Looks like the silicone grease lubrication on the shaft works very well just like a hand pump. I'd say at this point past initial break-in lubricate the shaft sparingly. From a bottle-fill aspect lubricate heavily if you're filling the bottle from 0 PSI. Perform light lubrication every 5 hours of run-time. Purging via the bleed valve every 30 minutes only produces fine mist. Total run time on the ePump is about 10 hours now and no issues.

I did learn from the solar battery setup that around 12-11.8V on the battery at 4300 PSI the pump action can stall. Make sure you have plenty of amperage/voltage if pumping from battery. Indicators will be arrhythmic pumping at increased pressure and stall on completion on the pump down-stroke. I flipped over to AC and finished the bottle fill. I'm not sure if this would cause relay burn-out or motor burn-out due to lack of cycling action.

Figured I'd post an update -- the ePump is still going strong. No issues and I'm on my 8th bottle fill at this point.

Dansker, how'd your rebuild kit go?

I got my e-pump a couple of months ago and after some adjustments, it works the way it is supposed to. What I don’t like: having to disassemble the case with all its screws in order to lubricate the piston is not exactly what I consider good engineering. There is a simple solution to this problem: cutting out the ventilation grid next to the piston gives enough access for lubrication needs. I designed a hatch that fits the hole and can easily be removed. If anybody wants to make the same modification, I put the hatch on shapeways: https://www.shapeways.com/product/NSKWVJTSV/airforce-epump-maintenance-hatch?optionId=160822043&li=shops

I hope yours lasts and I mean that sincerely. I am surprised AirForce is still selling these because I believe they suffer from a major design flaw. As it approaches 4500 PSI there is significant frame twist that results in the gear box rod guide collar popping off and eventually jamming and stalling the motor.

https://www.airgunnation.com/topic/catastrophic-airforce-epump-failure/ is my experience

If you're not taking it up to 4500 PSI and are using it for direct fill I suspect you won't have the same issues I did. I used Trident divers silicone grease to sparingly lubricate the shaft.

I suspect there are no issues reaching 250 bar, above that, too much force is required which results in the frame twist I spoke of earlier.

Nice work on the cut-away, looks like a reall good enhancement. I had issues with the case screws once removed some would not fully reseat/re-thread. They were not machine thread and were coarse thread tapered, something I would more commonly expect with wood not metal.

 

@ LMNOP. Thank you for your comments. I thought I’d like to share all the thoughts that led to the modifications I made to the pump. Maybe it helps some folks keep their pumps running. I was close to wrecking the pump before really using it. The first time I switched it on it failed. I removed the case to see that almost all! the screws weren’t tightened properly. This led to the sensors reversing the direction of the motor being loose. After fixing that and having the pump operating I noticed - as many others - that the motor was overheating. I already got a bag for the pump so the bag got an integrated fan which really works well. I use the motor’s 24V current to run the fan. Then I noticed the same frame twist you mentioned, especially when coming close to 4500 psi. Anybody can imagine that sooner or later this results in device failure - I just wonder how this slipped out of the attention of airforce. So the next thing I did was to screw a 12 mm aluminum plate to the base. Twisting is reduced to a minimum now. One last thing I changed was to remove the cage with the desiccant and fit in a cartridge with o-rings that prevents the air from just passing beside the side of the cage. This makes a big difference when opening the bleed screw. I think the idea behind the e-pump is great, but airforce could have done better. A lot better. It looks more like a prototype that went straight into production without testing. I just don’t understand why a company with quality products pushes a product into sales that has so many flaws. One last thing: I also use divers silicone grease.

Bendminx, I'm honestly at a loss for words at how impressive the changes you've made are. Exceptional engineering and fixing of flaws. I bet your E-Pump will last as I cannot think of anything from my negative experiences that you've not addressed and solved.

I really liked the concept of the E-Pump but like you mentioned, it appeared it was direct from China. Mine had the origin label cut off the box and an AirForce sticker slapped on.

I failed to be aware of the frame twist issue until it became a catastrophic failure, I am very happy to see you've identified it ahead of time and cross braced it. I don't think you'll have the same frame twist I did at all.

Thanks for the pictures, they are stunning. Engineered quality instead of handiman fixes, just amazing.

Anyone tried the cigarette lighter outlet yet?

I think there is a typo on the pump, it's 32amps max. not 3.2.

Look at the size of the mains to 12DV converter that's not a 3.2amp one like a wall wart, thats a 35Amp one.

I suspect the motor to be in the 350-400Watt range and that reflects on the fill times.

12V x 3.2A = 38.4Watt thats akin to a ceiling fan not a powerfull 4500psi compressor.



In all expect the compressor to be connected directly to the battery to avoid frying car electrics!

Keep up the good work.

I don't think a standard 15A/12VDC connection would work at pressure. It might work for 250 bar. Since this is a mechanized hand pump as pressure increases so does the mechanical force needed to cycle the pump action which translates to increased current draw.

Hard to know for sure, I do not recommend this pump unless you're willing to resolve the issues as bendminx has done.

Here's an image of the "guts" from some photos I had when I owned it:





As you can see above at increased pressure, which translates to increased resistence, which translates to increased force because the pump is offset to the gearbox (IE: not a wormdrive) it results in excessive lateral force expressed across the frame. Because there is no crossbar/crossmember the frame twist offsets the position of the pump and gear rod. Eventually it tears the guide collar off and then all hell breaks (and brakes, lol) loose.

When I owned this pump prior to breakage and refund the VDC side came with light weight copper coated battery clamps. The wire was copper, I want to say 16GA braided.

Here's a video I took of the pump in action. Honestly, having owned this in the past, I think bendminx has solved a lot of the issues I experienced with the device. I think as-is from AirForce the pump will destroy itself at anything above 232-250 bar.