Canadian Airgun Forum

I have an at44 .22 cal with an adrius regulator. My concern is how it is supposed to work.
Heres my problem.. I fill the gun to 2700 psi. Hammer spring set 3 turns out. The first shot starts off low, 760 + or - 10 fps, then slowly climbs at 4 or 5 fps each shot to 900 ish fps, then levels off for 20 shots with a 10 fps extreme spread, then slowly drops back down. The curve from start to finish, far excedes my unregulated tube by 100 fps. This is not great numbers for a regulated gun.
So I tested the regularor and it was set for 2500 psi. Soooo Using a u tube video, I took apart the regulator, polished all the internal surfaces and replaced the o rings. Then I rearranged the spring washers and removed 2 out of 14. The test showed the regulator now at 1000 psi. When I tested the gun again, the initial shots started at 550 fps, but again climbed by 4 or 5 fps per shot to over 800 fps.
next I tried adjusting the hammer spring out 5 turns and the first shot was again 750 fps and again climbed to over 900 fps.
Since the regulator on the test stand shows it is working properly, why am I not
getting a flat string ?
the way I understand regulators is the air on the outlet side contained in the stand off and valve body, should be all the air available per shot. How is it possible to get
900 fps with a 14.? Gr pellet from 1000 psi of air ?
Oh and I also tried a thick wall piece of plastic hose in the stand off, thinking there
might be too much air available, since the regulator was initially set for 900 and something fps. But I got the same slow climb, level off and slow decline.
One cubic inch of compressed air at 1000 psi should only be able to push a 14+gr pellet a finite speed. No matter how many turns out on the hammer spring, or how big the TP is. As I understand physics. Or am I just under estimating how much power 1 cubic inch of air at 1000 psi has ?
I forgot to mention. I am only trying to get a flat string. Ideally at around 800 fps. But a flat string at any speed would be encouraging.
There is on other important factor I forgot to mention. The valve spring is slightly lighter than a stock spring.

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If I had only one wish, it would be to be able to "unsay" things.

Regulator installed backwards would make all that come true.
Not saying it was, just that it would explain the similar plateau of unregulated with spring biased restriction mixed in.

Deffinetly installed correctly. Big end of the plunger on the low pressure side.
And as mentioned the reg works on the test stand. The only two factors that I can see, is the length of the stand off tube, thus, too much air for the lower pressure and pellet speed I'm trying to attain, or the valve spring too weak, or a combination of the two. However if the pressure and volume of air is constant as well as the hammer strike and valve spring, so should each shot. No ?

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If I had only one wish, it would be to be able to "unsay" things.

Near as I can figure, the reg. is not working.... Is the tube vented?.... supposed to be vented?.... Whether or not your plenum is large or small, you should get a constant velocity within about 1%.... The larger the plenum, the higher the velocity, but it's not linear.... A 1" long space isn't too much volume....

RE the velocity at 1000 psi, 900 sounds too fast with 14.3 gr.... but my AT44 shot that at 115 bar (~1700 psi) when stock....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

I was hoping to hear from you Bob. Yes properly installed with vent. No air leaks from the vent or through the plunger. It works perfectly on tthe test stand never going above 1000 psi on the valve side. I filled the tube to 2500 psi and the outlet side stayed at 1000 psi. I let out some air through the bleed valve. The pressure dropped momentarily and then returned to 1000 psi each time. I think I'll try a heavier valve spring, and a teflon plug in the stand off to mimic less air space. I'm thinking the problem might be the weaker valve spring. The valve might be opening too far and staying open longer allowing some air in from the high pressure side to combine with the air in the stand off as it exits the valve. On high pressure the rush of air from the high pressure side might cause 2 things. First it makes opening the valve harder, so the pellet speed is low, as in my non regulated gun. Secondly, as the high pressure drops, the valve stays open longer allowing more air through the valve ant the pellet speed increases as the pressure drops. Then it passes a certain point around 1400 psi when everything reverses and pellet speed drops. When the pressure drops to 800 pse, the gun vents all the remaining air unless I cock the gun to stop it. The only problem with this theory is the hammer strike should not be affected by the high pressure side on striking, as the counter pressure should only be 1000 psi constant. However the incoming air is high, so it rushes in faster to refill the stand off and valve,so should have the affect of starting off with a higher pellet speed and drop steadily as the pressure drops.

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If I had only one wish, it would be to be able to "unsay" things.

Joe i am following this tread with interest as i have the same problem with my hatsan and a regulator from Altaros. I has a vent also.
Is a constant small venting sound from the the valve bottom is normal.

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Hatsan At44 Tactical .22
Steyr hunting 5 automatic
Ruger air magnum .22
Weirhauch HW100 .22
Gamo Expomatic .177
Benjamin Marauder DougP custom stock
Theoben SlR98 .22
AlEx Custom gun .22 (JezX built masterpiece)
Hatsan Atp2

No, a constant venting sound indicates a leak, either in the O-rings on either side of the vent hole, or inside the regulator....

Joe, if the reg. is working properly, it should hold a constant output pressure, and produce constant velocities, within about 1% ES....

Bob

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Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

Constant air noise definitely means a leak, and i have had leaks that you can't hear. only a submersion will detect "any" leak.

And yes Bob. I should definitely be getting constant or near constant out flow. According to Robert Lane though. If the TP and the hammer spring and valve spring are all not at the proper settings, too much or too little energy can happen and a power loss as pressure drops can also happen. My next testing will be on finding the right balance .

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If I had only one wish, it would be to be able to "unsay" things.

So i have a leak.
What i know is the altaros is venting in the atmosphere from the top by taking off the o ring on the top and letting .5mm of the brass valve part unscrewed.
Those bobs tune of the 5 holes plug would be a major factor in having those problem.
I presume with bobs tune there must be a particular setting to do valve and hammer spring.
Like you say Joe.

Please keep us inform of your process Joe! I cant wait to have this thing working

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Hatsan At44 Tactical .22
Steyr hunting 5 automatic
Ruger air magnum .22
Weirhauch HW100 .22
Gamo Expomatic .177
Benjamin Marauder DougP custom stock
Theoben SlR98 .22
AlEx Custom gun .22 (JezX built masterpiece)
Hatsan Atp2

Couple of things.... I didn't come up with the idea of plugging 5 holes in a Hatsan valve, that was somebody else, right here on the CAF (and I'm embarrassed to say I can't remember who)....

Secondly, Robert Lane's statement about the velocity dropping as the pressure drop has nothing to do with your problem, Joe.... your velocity is INCREASING as the pressure drops, just as if there were no regulator present....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!

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May the cry of the pack be with you upon your hunt

Whitewolf

Interesting. Is the regulator single or double stage? If it's single isn't there a fair amount of change in the output pressure with changes in the input pressure? When you bench tested the reg, did you test over a range of input pressures?

If it's not changes in the static pressure that the regulator is giving, perhaps it's a dynamic affect. If the regulator can supply a non-negligible amount of air during the valve dwell time then it's likely that will change dramatically with input pressure, even if the static pressure is well regulated. You could minimize dynamic effects by restricting the flow between the regulator output and the valve body.

Jim

Well ralphtonka definetly had a great idea.
Whitewolf thank you.
But now for the matter on hand...
Would it be Joe's theory and our problem would be a too weak valve spring?

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Hatsan At44 Tactical .22
Steyr hunting 5 automatic
Ruger air magnum .22
Weirhauch HW100 .22
Gamo Expomatic .177
Benjamin Marauder DougP custom stock
Theoben SlR98 .22
AlEx Custom gun .22 (JezX built masterpiece)
Hatsan Atp2

Intersting Jim.
How can i know if it is a one or two stage regulator. Thos this means it needs a bigger plenum for the air to the valve.

Here is the regulator i have : http://www.altaros.cz/regulators/hatsan-at44/

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Hatsan At44 Tactical .22
Steyr hunting 5 automatic
Ruger air magnum .22
Weirhauch HW100 .22
Gamo Expomatic .177
Benjamin Marauder DougP custom stock
Theoben SlR98 .22
AlEx Custom gun .22 (JezX built masterpiece)
Hatsan Atp2

Sorry, but as far as I can see, whatever your problem is, springs, hammers, or other components that should always react the same way to a given pressure can't really be the problem.... If the pressure is a constant, then the total force required to open the valve and release the air, and consequently the dwell, has to be constant, and would therefore produce a constant velocity.... The fact that the velocity is starting low, climbing, and then declining, exactly as I an uregulated PCP, to me indicates the regulator isn't regulating.... It may be reducing the pressure (and therefore the velocity), but not holding it constant over varying input (reservoir) pressures....

Bob

_________________
Dominion Marksman Silver Shield - 5890 x 6000 in 1976, and downhill ever since!
Airsonal; Too many! Springers, Pumpers, CO2, but I love my PCPs and developing them!
Proud Member of the 2000+fps Club!