Air Venturi G9 high-pressure hand pump.
This report covers:
- History
- How a 3-stage hand pump works
- HOWEVER!!!
- Heat — your pump’s enemy
- Dirt — another enemy
- The G9 pump
- Evolution of high-pressure hand pumps
- But BB
- Elmer Fudd
- Summary
Today we start looking at modern high-pressure hand pumps. I will be referring back to things we learned in Parts 1 and 2, so please try to stay with me, or refer back to those earlier parts to catch up.
Reader Elmer Fudd asked several questions about hand pumps. He said, “Maybe some information on the various hand pumps that are available would be helpful. How does a 3-stage pump work? Are the more expensive hand pumps worth the difference in price? Do the more expensive hand pumps reduce the pumping effort required for higher pressures? What is required to operate and maintain a hand pump properly?”
History
I remember back in 1996, when someone talked about a hand pump that could fill a Career 707 precharged pneumatic (PCP) air rifle. I thought he was crazy, but before the year was out I bought one for The Airgun Letter.
Within two years I learned the following:
1. High-pressure hand pumps do exist and they do work.
2. They are easy to pump until the pressure builds up, and then easy becomes hard.
3. You don’t fill a PCP as fast as you fill a bicycle tire.
4. People weighing under 150 pounds will (would?) struggle after the pressure builds to 2,500 psi. I say “would” because I haven’t started to test the Air Venturi G9 hand pump. It may be a lot easier than I remember.
5. It doesn’t matter if you are filling a large reservoir or a small one, pressure is still pressure and the work to operate the pump remains the same. There is just more of it, the larger the reservoir you are filling.
6. You have to allow the pump time to rest and cool down. This is not understood by many who are new to high-pressure hand pumps and they burn out their o-ring seals in minutes. And it is/are ALWAYS the same seal(s) that burn(s)!
We will talk about that today. And Elmer, I will answer your question about how a 3-stage pump works right now.
How a 3-stage hand pump works
You remember how a single-stage pump works. You also remember that the smaller the surface area of the pump head, the easier it is to build pressure. But we know that a small pump head compresses a smaller volume of air. What if the air it has to compress is already pre-compressed just a bit in a first-stage pump? Then a stage two pump that is connected to that pump could work on that higher-pressure air that used to be a larger volume of uncompressed air. The new volume of compressed air would be small enough to fit into a smaller stage-two pump, even though it was too large to fit before it was compressed.
Let’s say the air that flows into this second stage is already compressed to 400 psi by the first stage. It started out as a larger volume of air than the smaller stage two pump volume could handle, but since it is already compressed a bit, there is room in stage two for it and all stage two has to do is boost it to, say, 1,200 psi. Easy-peasy lemon squeezy!
And what if that air that’s now compressed a lot more in stage two flows into an even smaller third stage that has a real tiny pump piston? Since this air is now compressed a lot, it may just be a small amount of air by volume, but the pressure is already quite high. And this final stage compresses it even further, to say, 3,000 psi. Voila — a three-stage hand pump!
Since the pump pistons are increasingly smaller, the rods they are on can fit inside each other in a unit that on the outside looks like a single-stage bicycle pump. Think of a Russian nesting doll. I can’t begin to tell you all the people at airgun shows who see a high-pressure airgun hand pump for the first time and think it is a simple bicycle pump. It’s about the same number of folks who wonder if their shop compressor will fill a PCP. Sure it will — all the way to 175 psi.
Russian nesting doll.
I haven’t mentioned that between each nested pump stage there is a one-way air valve that allows the air to flow into the next stage but not back out. If that wasn’t there the pump wouldn’t work.
Before we move forward, I need to know, Elmer Fudd — did I answer the question about how a three-stage hand pump works to your satisfaction? I will go slowly and methodically to answer every question you asked, so I need to know if I answered that first one.
HOWEVER!!!
Now we have some learning to do. With single-stage hand pumps we know that there are things that need to be addressed, like the oil that seals the pump piston. But as the pump stages and the pressures increase the things we need to consider become increasingly more critical.
Heat– your pump’s enemy
Reader shootski said it first and he said it best. Don’t allow your hand pump to overheat! And you think everything should be okay because the room you are standing in while you are pumping is 70 degrees F/21 degrees C. That’s fine for you. What about the pump piston seal on the head of the smallest and final stage of the pump? After you reach 1,000 psi pressure that head and seal are at 240 degrees F/116 degrees C. And 1,000 psi is no sweat for anyone to reach. A nine-year-old kid can do it. So you think the pump is doing fine. It shouldn’t be overheated yet because you aren’t.
And it really isn’t overheated — yet. But that teeny-tiny (a technical term that means very small) o-ring, or rings in some pumps, is/are taking all the heat that that final pump stage generates. Oh, people will tell you these seals are the same space-spec seals that NASA uses on the Space Shuttle. Well, bully for NASA. They rebuild the shuttle after every flight. Do you want to do that with your hand pump? No? Then — GO SLOW!
Dirt — another enemy
Each shaft of the multi-stage hand pump is lubricated to slide easily inside the next larger pump stage. O-rings positioned at critical places keep these shafts clean. But that lubricant on the outside of each shaft is like flypaper for catching dirt.
I remember taking a hand pump to the field when we were filming a hunt for the first episode of American Airgunner. I took a tarpaulin to set the pump base on when I filled the rifles. But when I turned my back for a minute another person who was unfamiliar with PCPs and hand pumps took the pump off the tarp because he thought it was too slippery. He set the base of the pump directly on the ground, then pumped it and bled the air into the dirt, causing a cloud of dust to get on the first stage pump shaft. Goodbye hand pump!
Of course I wiped it off after seeing what he did, but the damage was done. Wiping it was as effective as brushing your teeth after kissing someone who has Bubonic Plague! Keep your hand pump clean!
The G9 pump
As I told you, Pyramyd AIR donated an Air Venturi G9 hand pump to the blog. I was willing to buy it because with Crosman’s 3622 (and hopefully 3677 soon) I have a good reason to use it. But they were generous, so I plan to use this pump a lot and to report on it a lot — just like I’m doing with the RovAir Portable Compressor.
Unlike the hand pumps of the past, this one comes with an instruction manual that even tells you how to rebuild the pump. It also comes with parts, a combination wrench to perform all maintenance including a complete overhaul, oil for lubrication, a test plug whose operation I will describe in a future report, a microbore pump hose to conserve air and an in-line water filter. And all this sells for $100 LESS than the first Swedish hand pumps sold for in the mid 1990s! This is so similar to the price point PCPs we saw in years past.
Evolution of high-pressure hand pumps
I have seen modern high-pressure hand pumps from their beginning. I have watched them as they evolved from units that worked through various stages of improvements into what I now see in the G9. What I see now is a mature design with the buyer given the parts and instructions for a rebuild, when necessary.
One of my jobs when I worked at AirForce Airguns was rebuilding hand pumps. I hated that job because almost invariably the failure of a hand pump was that teeny-tiny white o-ring at the bottom of the stage three pump rod. Could I get more of them? Not on your life! I requested o-rings to rebuild the pumps and the Asian manufacturers always sent me sets of common o-rings that I also had in abundance. But that little white guy? Never! They had problems getting them too, and they weren’t going to give any away. So I had about 20 broken pumps on hand and could fix perhaps two or three — the ones whose teeny tiny o-rings were still good. DON’T OVERHEAT YOUR HAND PUMP!!!
But BB
But BB, you say. Why are you talking about 3000 psi when modern high-pressure hand pumps go up to 4500 psi? Well THEY may go that high, but most of you won’t be able to! Trust me; I know what I’m talking about. Technically it is possible to pump 4,500 psi, but no sane person should even plan to. In fact, 3000 psi isn’t that easy to reach. That’s another reason why I got so excited about the Crosman 3622. It tops out at 2,000 psi — a pressure I used to be able to pump one-handed while sitting down. I probably can’t still do that, but I should be able to do it standing up — even with three hernias.
Elmer Fudd
In this report I HOPE I have answered your question about how a three-stage hand pump works. I have also partially addressed how to maintain a hand pump, but I’ve given you nothing yet on how to operate one. That question I’ll answer as these reports progress, plus I’ll address it in reports on the Crosman 3622/77.
I HAVE NOT answered :
Are the more expensive hand pumps worth the difference in price?
Do the more expensive hand pumps reduce the pumping effort required for higher pressures?
And I have not told you very much about the AirVenturi G9 hand pump — yet. I’ll do that as I use the pump in future reports.
Summary
So far we have learned :
DON’T OVERHEAT YOUR HAND PUMP, and
KEEP YOUR HAND PUMP CLEAN!!!
B.B.
As Challenger disaster should have taught us. O-rings fail when they freeze. Do not leave your hand pump in an unheated garage.
Love the new/old formate of the blog main page.
So what is the max force required to reach 2000psi, 3,000 psi and 4,000 psi?
-Yogi
Yogi,
I also hope the format does not change, again.
I would really like to have suggestions from experience of how you proceed with pumping in the field. Range, woods, desert or whatever. Thanks in advance.
Bill,
You plan your pumping to keep the pump clean. That’s why I used the tarp. But when the person who was unfamiliar with a pump put it directly on the ground bad things happened.
BB
BB
That exact unfortunate/mindless behavior is the reason I want to have real facts about pumping in the great outdoors. Backyard and range are easy to deal with, if you give it some thought that is.
Nice summary BB.
This is the only reason why I’m happy to be too heavy – while using the airgun pump! I think below 160lbs weight you can forget to fill more than up to 200bar. My largest air volume is 100ccm @200bar so it is tiny compared to some other airguns. Not to mentioned 300bar pressure. I can not imagine pumping some high power PCP to 300bar using a hand pump 🙂 You will get fitness training definately 🙂
BB,
I have a very old non-functioning AirForce hand pump in my closet. Once upon a time Sun Optics had instructions and parts for rebuilding the AirForce/Crosman/Sun Optics hand pumps. I never did find my round tuit for that pump.
After it quit working, I bought a Hill. It is a much better built pump. I have given it to my grandson and have a G9 in my Wish List although I may still buy another Hill. I do hope he takes care of that Hill.
Although I have never put much faith in the intake moisture filter of the Hill, I like it as an input dirt/dust filter and would recommend such for every HP hand pump. I myself have always used mine inside. Although I have an AV compressor, it is nice to keep a functioning hand pump around, just in case.
As is pointed out by Yogi, I much prefer this new/old format. Let us see how long it is kept.
P.S. For those contemplating buying one of those Wang Po Industries hand pumps, please read the reviews, most especially the bad ones. The new Crosman hand pump only has a ninety-day warrantee. The G9 has a one-year warrantee. The Hill has a five-year warrantee. Hmmm.
BB
PA sent my G9 pump a few years ago. I store mine inside at 73 degrees Fah in a plastic bag (the ones laundries put your ironed shirts in) to keep out house lint. I bleed the air (moisture) out using the included plug both before and after using. I pause after every 20 pumps to let the seals cool down. I have not had any problems but it doesn’t get much use now since getting the portable compressor.
Hoping you will mention using non petroleum chamber oil in fill probes. There are pros and cons for doing it to control moisture corrosion especially with regulated PCP’s. Maybe that is academic since the G9 is a hand pump and won’t be filling high pressure reservoirs typical for PCP’s with regulators. Also I would like to know how often to use the included grease on the probe seals. Perhaps that is a moot question too for a hand pump.
Deck
Deck,
I have always used a drop or two of silicon oil every so often to fill my PCPs. It will migrate to any small leaks and help seals them. It will also lubricate the o-rings and help extend their life. I have not thought of regulators, but it could possibly help there. Even if you use a compressor, it will not hurt to add a drop or two every so often.
Will it help with moisture? That I do not know, but it will certainly not hurt.
WARNING! DO NOT USE A PETROLEUM BASED LUBRICANT! YOU WILL RISK HAVING AN EXPLOSION! This warning is for the newbies and those who should know better. Yes, there are mental midgets (pardon me, mentally vertically challenged people) everywhere.
Once upon a time, FM drove an MG Midget. Now it would have to be branded as an “MG VC” – as in Vertically Challenged. Miss that Midget – it fit FM like a glove. Not OJ’s glove now!
FM,
Once upon a time, I tried to fit inside one of those cars. As you can well imagine, I did not fit.
RR
Some believe that putting the correct type and amount of chamber oil where the fill probe goes will eliminate moisture problems. But some believe the oil can cause regulators settings to wander or even fail. I still use it but very infrequently. I don’t know if I’m doing the right thing or not.
Deck
I do not know about moisture problems or how regulators can be affected, but I have sealed minor leaks with such. Ask BB and FawltyManuel about the Edge and the Maximus.
BB, I just found this video that shows how an airgun handpump works. It may help us to understand what is going on internally when the pump goes through it’s pump stroke.
https://youtu.be/OdMNjYB4fC0?si=PHgxGaQlbROuvTfB
David Enoch
DavidEnoch,
Great find!
Thank you,
shootski
Thank you for answering my questions BB. Yes, I think I have a grasp of the concept of how a 3-stage hand pump works now. Your explanation is easy enough for even me to understand. 😉 This is turning out to be a very informative and valuable series and a practical guide for what to do and what not to do when using a high pressure hand pump.
BB,
I learned something new today. Of course, that is one of the main reasons I hang around here and bother you so much.
I was not aware that the old AirForce hand pumps were three-stage, or the old Hill pumps either. Do you suspect a four-stage is in the future or will the new wave of portable compressors make such a moot point?
You did not mention such, most likely to keep from causing any confusion, but the Austrian army which at one time used the Girandoni extensively, had a cart very similar to the old horse drawn water pumpers that the fire departments used. Two poor soldiers would pump up a reservoir with air to fill the air rifle cylinders for the battalion. This cart had long lever handles on each side with a pump fastened to such to fill the reservoir.
RR
Better to be on the pump wagon than on a white line facing volleyball fire from the blue line 50 yards ahead and marching against you with bayonets ready…
Colors refer to the Austrian and French uniforms.
Since there were never more than 1500 Girandonis in use at any one time,, in an army of 500,000, I’m guessing that those “pumpers” were whoever was available among the cooks, cobblers and hangers-on.
Seems strange to me, tho, that although the pressures in the reservoirs were 800 to 850 psi, the rifles were claimed to be accurate to 100 yards and capable of up to forty shots. I’ve seen no evidence that this is currently available.
Perhaps there was some exaggeration involved.
Ed
Ed,
Go on Dr. Beeman’s website. He write3s about testing his Girardoni that he gave to the Army War College and got a shot count.
BB
BB
Thanks a lot,,,, I just spent the last two hours there.
It is definitely interesting so I bookmarked it for future reading.
Ed
edlee,
very good point – about the number of distant shots versus available air pressure – , but, an exaggeration of the truth – or how about, an ‘enhancement’? – , in this case, is not for us to verify! 🙂
We just have to hear what we’re told, file it under ‘incredible history’, and get back to reality, of shooting within the limitations of our hundreds of years’ more advanced and modern airguns…
Oh, and if you’re offered a beautiful blue beaded necklace for your beaver fur coat, it’s a bargain! 🙂
hihihi,
Before you say much more you really need to read about the airgun in the Beeman writings as well as the reproduction(s) built by Ernie Cowan and Richard Keller.
Brief excerpt:
“As of May 2003 they were only willing to indicate that this system could project a lead ball, of about one-half inch diameter, of about 210 grains to a muzzle velocity of at least 500 fps for about 117 ft. lbs. of muzzle energy. Colin Currie reported (personal communication May 18, 2003) that the Royal Armories of Leeds, England recently charged the Heiberger .433 caliber air rifle, a formerly single shot air rifle made about 1750 but converted to a 23 shot Girandoni-style repeating system[10], apparently in the early to mid-1800s, to about 800 lbs/sq. inch and achieved a muzzle velocity of over 900 fps with balls of 120.4 grains for a muzzle energy of 217 ft. lbs. He reported that 1500 strokes were needed to pump up the Heiberger‘s buttstock reservoir to operating pressure after 20 shots had been fired from one charging/loading.”
None of my Big Bores barrels come close to the length of the barrels on the Girardoni and believe me length makes a hugh difference in MV at the expense of handling; back then a 80-90cm barrel length was all they knew in firearms. So the gun handling would not have been the issue we modern shooters would ever put up with!
shootski
edlee,
I don’t think there was any exaggeration on the performance of the Girardoni air rifles. Based on my reading on Beemans as well as following the reproduction efforts by Ernie Cowan and Richard Keller; and my own experience shooting the much shorter barreled Quackenbush airguns in .25, .308, .458, and .58 caliber the last shooting 283 grain Lead balls and 310 grain Mr Hollowpoint bullets out of a 20″ (50.8 icm) barrel to 100 yards.
I know what 200+ foot-pounds delivered in .308 does to a Whitetail at reasonable range i can imagine what the .50 caliber ball would do out of the LONG barrel on the Girardoni.
See also my comments to hihihi above.
shootski
edlee,
Moden airguns have become shorter, which directly affects power levels. Something else so many overlook is the valve system. The airguns of old had very complicated, but very efficient valves. Today’s valves are very simple to manufacture. I have seen some very efficient modern valves, but most are not being massed produced, or are very expensive. Read Hubben and American Air Arms.
Bill,
Indeed. I myself would not even think of fighting in such a manner, though they still tried to do such into WWI.
B.B.
I was one of the cadets (not being a PCP owner) that asked if I could use a shop compressor. My question was more on prefilling it to 150 psi. At that time I had no idea that you didn’t shoot a PCP to 0 psi. I had figured it was like a C02 gun or what have you. Funny looking back on it now, but it you don’t know, you don’t know.
My question now has more to do with water/moisture created by the pump/pumping. I’ve been told it’s better to “pump” up in the AC during the humid summer if possible. I’ve read about the little pump “filters” help remove moisture. Some even have suggested some silicon (pure air gun type silicon not the spray stuff at the parts/big box store) in the fill port to help. Now I’ve read where a guy said a mistake a lot of people make is laying the gun down to fill it. He thought it was important to keep the gun standing up (fill port pointing up) to reduce the moisture from getting into the gun. I guess I could see this it it was producing a lot of water. Your or any PCP owner’s thoughts?
I’m not on the dark side yet, but the 2000 psi gun (or guns to come) and this article by the great enabler (The Godfather) is pushing me that way.
Doc
I bought a used Air Arms PCP from a friend last year. Even though it cost some money, I went right to the Air Venturi RovAir 4500 Portable Compressor. I’m really glad I did. The fill only takes about three minutes. Money well spent!
Mike
B.B. and Readership,
Tom please pass on my thanks for the return to the previous format for the blog; now if only the Airgun Academy could return!
Readers new and old This IS a Great Blog topic if you are at all interested in PCPs. It has information in the Blog as well as the comments of readers that are of value.
I have a few direct comments to readers comments:
Bill asked about pumping in the great outdoors. My answer is don’t if at all possible. As you read in B.B.’s reply to Bill even when you think you have it covered the unexpected happens. I recommend you get a small Buddy Bottle or a small Carbon Fiber tank that you fill with your pump(s) in a low humidity/dehumidified environment. If you don’t have that low humidity environment for pumping don’t fill in the morning since the Relative Humidity (RH) is usually lowest in the last half of the afternoon. On the pump read the guidance about bleeding the pump’s moisture trap and then do it at least twice as often as recommended; it also cools the pump internally!
Also, remember if you think you are going to NEED one pump you really need two pumps to have one according to the US Navy SEAL Team philosophy of “One is NONE, TWO is ONE.”. Syou are best off if you have three like i do even though i use SCUBA 240 BAR and Carbon Fiber 310 BAR tanks because i shoot GAS HOG (2-5 FULL POWER SHOTS) BIG BORE PCPs that i fill to 250+ BAR from a CASCADE System with Dive Shop air.
Decksniper and Doc Holiday wrote: “There are pros and cons for doing it to control moisture corrosion especially with regulated PCP’s.” and “Now I’ve read where a guy said a mistake a lot of people make is laying the gun down to fill it. He thought it was important to keep the gun standing up (fill port pointing up) to reduce the moisture from getting into the gun. I guess I could see this it it was producing a lot of water. Your or any PCP owner’s thoughts?”
What is your information source? B.B. has written any number of times about the test about water in PCPs the he and Dennis Quackenbush did many years ago.
I don’t know what kind of regulator has problems with SILICON grease or Silicon Chamber oil. Dive Regulators are used with Food Grade SILICON grease in my experience.
tomek and Yogi: I am 75 years old have never weighed more than 170lbs (78 kilograms) have no problem pumping to 200 BAR (2,900 PSI) I would, however, submit that the techniques that B.B. will discuss in the future will enlighten many of the READERSHIP!
One hint: it isn’t your Gross weight that matters it is your EFFECTIVE weight that is critical in making the pumping easier…
OKAY! One more hint: Even though the pumps have two foot stirrup you NEVER stand on both at the same time for to attain MAXIMUM EFFECTIVE weight!
Elmer Fudd: I told you you asked great questions and i’ll add you did it the right place on the internet to get GOOD information!
One final thought: when the pump cylinder feels almost hot but WARM on a multi stage hand pump your little white seal may already be gone or soon to be BURNT! DUMP MOISTURE and cool that Seal OFTEN!
DO NOT OVERHEAT YOUR PUMP INSIDES!
shootski
Shootski thank you for your response.
Bill,
Your welcome!
You asked so i shared what i have learned from experience as well as from those more experienced and knowledgeable than i am who chose to share.
shootski
I wonder how large a piece of tarp is required to keep the pump clean. Would a piece that is 2‘ x 2‘ be enough? If so, that same piece of tarp would also work as a nice sit pad in the woods.
David Enoch.
BB
I understand the way multistaged pumps work better now, and if I were given three separate pumps with each having a different piston area, I think I could connect them properly so that three people, pumping them in turn, beginning with the largest piston and ending with the smallest, could get a very high pressure to build in a vessel at the end of it all. What I, personally, am having trouble with is visualizing the construction of such a pump so that a single person is accomplishing the same thing sharing a single pump handle and shaft.
Can you sketch the innards of a three stage pump or point me to an illustration of the insides. An exploded parts drawing might help and an animation of the pump cycle would be perfect, if you know of any to seek out.
One other thing that I’ve been curious about is that, as you mentioned, the pump shaft is vulnerable to collecting contaminants and they can easily be ingressed past the wipers and seals, over time, and prohibit valves from seating and also ruining the finish on cylinder walls. This happens in industrial hydraulic systems all the time, but in especially dirty applications, such as traversing a surface grinder’s table back and forth, the shaft is shielded inside an accordion-like bellows that stretches out then retracts as the shaft moves. The debris never reaches the shaft. Why hasn’t this been done to airgun pumps to improve their longevity.
Half
half,
I have no idea.
BB
Halfstep,
Still looking for a great schematic…a diagram of the parts will need to do and another verbal description:
https://spares.bagnallandkirkwood.co.uk/fx/fx-3-stage-pump-air-rifle-gun-spare-parts-list/
https://www.airgundepot.com/vault/articles/3-stage-hand-pumps/#:~:text=Air is drawn into the,stage for the final compression.
I believe you will figure it out from the above combined resources.
shootski
PS: Check out that number 30…LOL! https://spares.bagnallandkirkwood.co.uk/product/fx-3-stage-pump-full-o-ring-seal-kit-ref-j/
B.B. and Readership,
“Tom please pass on my thanks for the return to the previous format for the blog; now if only the Airgun Academy could return!”
With sadness i must respectfully withdraw my thanks since P-air has quickly returned to the Campfire Blogs format!
Maybe asking for the return of Airgun Academy was a Bridge Too Far!
shootski
PS: i just dropped the hammer on two 9L 4,500 (310 BAR) Carbon Fiber (CF) Tanks and an Off Board adjustable regulator.
My other two CF Cylinders are due for 5 year visual Inspection and Hydro test. Next cycle, at 15 years will require them to have the NDI, SLE (Non Destructive Inspection, Service Life Extension) and will probably be a month gone for that. The new cylinders and my SCUBA Tanks will keep me in CASCADE for the rest of my days and the older ones will just be gravy on the top.
The price of CF cylinders has certainly zoomed along with everything else but the Life Operating Cost still beat compressors of any type, make, or size given my fill prices at the local Dive Shop.
B.B. 2 questions. Where is the G9 made and what is the difference between it and a comparable 3 stage pump made by Hill?
Roamin,
The G9 is made in China. The differences? I don’t know and to guess would be unfair.
BB
Some experienced PCP reader (Kevin?) warned us about using any safe oil, even non petroleum chamber oil, in regulated PCP fill inlets. While it helps prevent moisture corrosion, it can cause either regulator failure or settings to vary to the detriment of velocity consistency.
Apparently commenters on this report either are unaware or don’t agree with this concern.
Deck