Huma regulator performance in Impact

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13brv3

13brv3

Member
Feb 1, 2017
342
9
TN, United States
(make sure you read the later posts, because the reg worked normally on the next tests)



Greetings,

I got my Huma Extra High Pressure reg yesterday, and installed it with no issues at all. Today I had a chance to do some velocity testing, and I was somewhat surprised at the results. The first surprise was the pressure that maxes out velocity. I started at 110 bar and went up to 160 for the 30gr NSA, and 120-150 for the JSB 25.39. Note that this version of the Huma is only supposed to be from 145 bar to 190 bar, but it didn't have any problems regulating down to 110 bar. 





I've run this test with the stock regulator before, but it was with 18gr pellets a year ago. According to my notes the speed went up until I hit 140, then dropped slightly at 150. Maybe the curve is just lower with heavier projectiles, but I was surprised to see the max velocity at 120 bar. It clearly seems hammer limited. 

The biggest, and most unwelcome surprise was the comparison to the factory regulator. Prior to swapping the regulator, I documented a velocity average of 834 fps for the 30 gr NSA at 150 bar. Now with the Huma I'm only getting 727 fps at 150 bar. Even the max at 120 bar is only 796 fps, so I seem to have lost power with the swap. 

Can anyone explain this? Has anyone else done a similar before and after test when receiving the new Huma? The reg holds pressure just fine, but maybe has a different amount of flow compared to the stock reg? I'm just guessing here. 

One other thing I noticed is that it's not so easy to bleed off the pressure to run the adjustment screw back in. With the stock reg, you could just start to back out the reg adj with the bottle removed, and it would bleed it all out. You could (maybe not supposed to) fire one shot and that would cause all the pressure to bleed out. The Huma doesn't bleed with a shot, and only one time did I ever get it to bleed some when I backed out the adj screw slightly. I resorted to unscrewing the regulator pressure gauge slowly to remove the pressure. 

Thanks,

Rusty (going backwards)


 
That is interesting. Do you think the quick refresh rate doesn’t allow the pressure in the plenum to drop as much and this shuts the valve more quickly?

Michael
Click to expand...


I honestly don't know. I'm hoping someone else has received one of these and can post their results. I expected no change in power for the same pressure, and was only hoping for the ability to set higher power, and maybe have tighter regulation. I really should put the stock reg back in, and run the same test, but I'm hesitant to do that until I give this some more thought, and maybe hear from someone else who's tried it. 

Rusty


 
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Unless the plenum volume has changed, you should indeed get the same velocity for the same pressure. The pellet does not know or care whose regulator gave it that kick in the pants...er, skirt :)

The only other common reason I can think of is that an O-ring was damaged on disassembly or reassembly which is allowing blowby on the shot cycle. In other words, the gun would not be leaking / losing reservoir pressure, it would just divert air when the trigger is pulled. Possible bad breech seal, transfer port, barrel O-ring, etc.


 
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You always have to consider o-rings, but I was extremely careful, and nothing seems to be leaking. No other o-rings were touched, so it would be a really unfortunate coincidence if one of those just decided to go bad at the same time I made the reg change.

I've done some thinking about this, and I can see how a regulator could make a difference. If the reg was manually held closed when taking a shot, it would have no effect of course. What I don't know is the timing of all this. Does the valve open and close before the reg has time to open, or is there a time when the valve and reg are both open? I'm still pretty new at this, so I simply don't know how this works yet. 

For consistency sake, I'd think you wouldn't want the regulator to open until after the valve is closed. That would give you the same fixed plenum volume every time. For max power, you would want to add as much air as possible, as fast as possible, to effectively increase the plenum volume. If the valve and reg are both open at the same time, then the specifics of the reg (time to open, flow rate when opened) will make a difference in power. 

If nothing else, it's a fun mental exercise. 

Rusty


 
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I wonder if you now need to be able to open the valve further/ longer to utilise the higher pressure and balance things out. . Huma does state both a minimum and maximum regulator pressure for the different washer configurations. Although the regulator will maintain a lower than specified pressure the spring stack won’t need to flex much at all and would open more quickly when pressure dropped. 

Between the operating pressure stated by Huma the spring stack would flex and travel further between open and closed this would take more time or slow the refresh rate. 

For it all to work in balance you might need more hammer weight. 
 
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Have You stacked the spring washers in order for high pressure range as in Huma manual? My reg (for regular pressure) came with washers stacked in no particular order so I needed to sort them myself. Here it is on last page: http://foto.huma-air.com/foto/Installation%20guide%20FX%20Impact.pdf

It looks like You need to dial HST with 1,5mm hex a bit more for shooting with reg on 120+ bar.

One possibly stupid question, is Your chrono in perfect order?

Sorry for my bad English, it is not my native language.
 
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Out of interest I just watched a video of a mates regulator gauge as he shoots. It’s an Impact with Huma HP regulator. The regulator is set at 140bar. With each shot the wiki gauge dips to around 100bar. The pressure may drop further but the gauge can’t keep up. 

Would be interesting to know what drop in pressure you get after you fire the gun. Sorry I couldn’t download the video. 
 
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Greetings,

Thanks for all the comments. I have the day off, so I decided to go into full blown test mode. I connected the digital gauge to the Impact, and reinstalled the stock reg. Of course the next thing I did was remove the stock reg again to replace an o-ring I seem to have damaged. Man, those o-rings on the adjuster are really small. I ran the same test as before, then reinstalled the Huma after verifying the washers. When I repeated the same test, everything worked like it should, though I can't explain why. Both had velocity increases with pressure, and the 150 bar velocity happened to be exactly the same for both, which is just what I'd expect. . 





My previous 150 bar speed for these slugs was 834. That was with a different chrono, and since then I took the last bits of play out of the hammer spring adjustment. The only other thing I noticed today was that my probe was loose. That started on the last session I'm sure, because I had noticed the probe seemed to be hitting the edge of my single shot tray, which is just a rough 3D printed thing with plenty of slop. I noticed it again about mid session today, and tightened the set screw, but didn't see any change other than not hanging up on the tray.

The instructions do say the regulator has to bed in, but it sounds like that's just to be as stable as possible on pressure. I don't think yesterday's test was instability, but I'm not sure what it was. If one of the o-rings on the Huma was leaking slightly yesterday, maybe I fixed it when re-installing today. It's still a mystery, but I'm glad it's working. Now I just need more hammer power.

Thanks,

Rusty




 
Upvote 0
I wonder if you now need to be able to open the valve further/ longer to utilise the higher pressure and balance things out. . Huma does state both a minimum and maximum regulator pressure for the different washer configurations. Although the regulator will maintain a lower than specified pressure the spring stack won’t need to flex much at all and would open more quickly when pressure dropped. 

Between the operating pressure stated by Huma the spring stack would flex and travel further between open and closed this would take more time or slow the refresh rate. 

For it all to work in balance you might need more hammer weight.
Click to expand...


You're probably right that the amount of flex in the stack has a part in their stated pressure range. The stacking order for the extra high pressure has a lot less flex available. I left it at 180 bar after the testing today, so I'll hope that doesn't leak, and start looking into hammer mods to take advantage of the pressure.

Rusty


 
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