Tuning Regulator Question

[JackHughs]

I have a HUMA regulator set to 140 BAR in my .22 700 Panthera. I shoot this rifle tethered to a Nuvair external regulator. Up to now, I've set the external reg to 250 BAR because the HUMA internal reg seems to recover faster with high bottle pressure. The question is: Does the internal HUMA reg respond better, considering both performance and wear, to a large pressure differential (250 BAR/140 BAR) or would it be better to turn the external reg down to say, 200 BAR.

JackHughs

 

[MushroomPsyche]

If it was my, I will definitely turn down the external regulator closer to the Huma Air. Probably around 50 bars higher, so 200 sounds good.

 

[Motorhead]

Internal reg likely has the flow restriction screw within the adjuster bonnet, reason a higher upstream pressure seems to recover faster ( Harder push getting air past restriction screw )

Just a guess tho ????

 

[Mrshosted]

All things considered, if the huma regular is working properly. I don’t see any reason why the bottle regulator pressure matters.
If it a case, it’s want you have to go use. I get it, I’d set the bottle regular somewhere around 225-250 bar. My thought is, it will similar to a normal fill operation range middle point.

 

[1handwill.gc]

If I was you, I would remove the internal regulator and then use the bottle at 200 or 225 bar and you’ll see how fast your new regulator works but that’s me that’s your equipment

 

[Trucker3573]

Just a personal use preference. I personally don’t believe 250 bar is going to over stress or hurt the huma one bit. If the faster refresh rate is a nice bonus I’d just leave it.

 

[Sergey1972]

If incomming pressure is too close to 140 bar then on gun reg doesn't open very wide creating the flow restriction. In addition to potential intentional flow restriction on "filling tank" setup.

 

[Tricky-Dicky]

Swings and roundabouts, regs recover quicker with bigger pressure differential but also suffer more wear to the sealing surfaces and more creep as a result.

 

[JackHughs]

Thank you all for your considered replies. In an abundance of caution, I will incrementally back-off the external reg to perhaps relieve stress on the HUMA reg and see if (or when) HUMA reg performance suffers. If I discover anything noteworthy, I'll report back.

JackHughs

 

[JackHughs]

Thank you all for your considered replies. In an abundance of caution, I will incrementally back-off the external reg to perhaps relieve stress on the HUMA reg and see if (or when) HUMA reg performance suffers. If I discover anything noteworthy, I'll report back.

JackHughs

This is a late reply but it's taken quite a bit of tinkering with this rifle to be able to post a meaningful response.

The HUMA regulator in my Panthera does, in fact follow bottle pressure. I adjusted the reg to 115 Bar with the bottle pressurized to 230 Bar. I then shot the bottle down to 150 Bar. At 150 Bar bottle, the reg pressure dropped to app. 112 Bar. I then pressurized the bottle to 250 Bar. The reg pressure went up to 118 Bar. These small excursions in reg pressure translated to large excursion in group size at 100 yards.

So now I have another question ( I have read other posts on this subject). This rifle is only shot tethered to an quality external regulator. The internal reg is redundant. I would like to set the internal reg to 150 Bar and then use my external reg to set plenum pressure in the 100-120 Bar range. Will this cause any any damage to the internal reg?


JackHughs

 

[Sergey1972]

Single stage regs have proportional movement to the incoming pressure, how much depends on the ratio of internal diameters. Both the tank and gun regs are single stage. If you run them both you have a dual reg setup, most consistent. Set gun reg where you want while tank reg is 30-50 bar higher. You want the tank reg a bit higher so the gun reg actually functions. If the tank reg is too close the gun reg will be less consistent.

 

[JackHughs]

Single stage regs have proportional movement to the incoming pressure, how much depends on the ratio of internal diameters. Both the tank and gun regs are single stage. If you run them both you have a dual reg setup, most consistent. Set gun reg where you want while tank reg is 30-50 bar higher. You want the tank reg a bit higher so the gun reg actually functions. If the tank reg is too close the gun reg will be less consistent.

This is how I currently run the gun - except that I set the external reg above 200 Bar to help assure quick recovery on the internal reg.
I would like to have a finer and faster means to adjust the regulated plenum. The external reg provides that functionality but I don't want to do anything that might damage the internal reg. Therefore the question, can I run the regulated plenum below the internal reg set point for an extended period of time without damaging the internal reg?

JackHughs

 

[Sergey1972]

This is how I currently run the gun - except that I set the external reg above 200 Bar to help assure quick recovery on the internal reg.
I would like to have a finer and faster means to adjust the regulated plenum. The external reg provides that functionality but I don't want to do anything that might damage the internal reg. Therefore the question, can I run the regulated plenum below the internal reg set point for an extended period of time without damaging the internal reg?

JackHughs

If the Source reg is below the internal gun reg, then the gun reg will just sit in the "open" position and do nothing. No harm no foul, it's what actually happens when you shoot your gun down below reg set point. Regs are typically damaged by running beyond specification input pressure and it would take a lot. Some regs are sensitive to "setting adjustment to lower pressure" while under pressure.

 

[JimD]

Jack,

It might just be me but your terminology is driving me crazy. It seems like you are calling the guns regulator the "internal reg". But then you refer to the "regulated plenum". Are you talking about setting the gun's plenum pressure above the regulator on your bottle? So the gun's regulator never opens? If so, I think it should work OK but to keep from cycling the gun's regulator you would need a gap between the regulators bigger than any pressure changes during the refill of the plenum of the gun.

You indicate you see large accuracy changes from small regulator changes (apparently, what you know I presume is the regulator gauge changes and the accuracy changes). Have you measured velocity? Is it moving consistent with the regulator changes? I'm asking because it seems the accuracy change is either due to changing velocity or possibly because the gun is responding different harmonically to seemingly small changes. Or perhaps the regulator is changing due to harmonics of the gun.

Jim

 

[Sergey1972]

Jack,

It might just be me but your terminology is driving me crazy. It seems like you are calling the guns regulator the "internal reg". But then you refer to the "regulated plenum". Are you talking about setting the gun's plenum pressure above the regulator on your bottle? So the gun's regulator never opens? If so, I think it should work OK but to keep from cycling the gun's regulator you would need a gap between the regulators bigger than any pressure changes during the refill of the plenum of the gun.

You indicate you see large accuracy changes from small regulator changes (apparently, what you know I presume is the regulator gauge changes and the accuracy changes). Have you measured velocity? Is it moving consistent with the regulator changes? I'm asking because it seems the accuracy change is either due to changing velocity or possibly because the gun is responding different harmonically to seemingly small changes. Or perhaps the regulator is changing due to harmonics of the gun.

Jim

Jim,

I think I can clarify what Jack intended and add information. Gun plenum is after the internal regulator. If the internal regulator is set higher than the incomming pressure, then the plenum pressure is being adjusted by the tethered tank regulator. This allows quick external adjustment.

You totally on point with your analysis of accuracy. A causational possibility is that the hammer strike is not adjusted to the pressure so small variations in pressure cause big changes in velocity (either at the vapor lock end or open too long end, both unstable for small pressure variation). As you pointed out velocity has to be checked. Normally spring loaded hammer/poppet type guns are adjusted to be forgiving to some pressure variation (I suspect you have experience with this, just stating for anyone else reading this).

 

[JackHughs]

Jack,

It might just be me but your terminology is driving me crazy. It seems like you are calling the guns regulator the "internal reg". But then you refer to the "regulated plenum". Are you talking about setting the gun's plenum pressure above the regulator on your bottle? So the gun's regulator never opens? If so, I think it should work OK but to keep from cycling the gun's regulator you would need a gap between the regulators bigger than any pressure changes during the refill of the plenum of the gun.

You indicate you see large accuracy changes from small regulator changes (apparently, what you know I presume is the regulator gauge changes and the accuracy changes). Have you measured velocity? Is it moving consistent with the regulator changes? I'm asking because it seems the accuracy change is either due to changing velocity or possibly because the gun is responding different harmonically to seemingly small changes. Or perhaps the regulator is changing due to harmonics of the gun.

Jim

You ask some really interesting questions. Let me try to answer them.

1. My rifle has one internal regulator, a 300 cc high pressure bottle, and a 156 cc regulated plenum.
2. The 300 cc bottle is tethered to an external regulator.
3. The internal regulator is a HUMA which is a particular pain to adjust to a lower set point. Unlike the AMP reg, one cannot de-gas the plenum by simply turning up the set point. With the HUMA reg, I have to remove the plenum gauge to de-gas.
4. What I want to do is to bypass the internal reg and make all plenum pressure adjustments with the external reg. Effectively, the regulated plenum would now consist of both the on-board 300 cc bottle and the on-board 156 cc plenum - a 456 cc plenum regulated solely by the external reg.
5. I'm shooting 40 grain Altaros King and 40.1 ACE slugs. Both are happy between 900 and 920 fps.
6. With the hammer installed on my rifle, the "plateau" is about 920 fps at approximately 115 Bar. There is no reason to go above 115 Bar.
7. The rifle is fussy. At the above settings, five clicks on the micro will not change the muzzle velocity but will change how hard the hammer hits the valve. This slight change in hammer strike can, and will, affect accuracy. The Altaros and the ACE slugs vary a bit in how much hammer strike is called for.
8. The rifle provides for fine tuning the hammer strike. The external regulator would allow me to fine tune the plenum pressure.
9. I would like to set the internal reg at 150 Bar and then rely solely on the external reg to make quick and easy plenum pressure adjustments in the 100 to 120 Bar range.
10. My question is whether or not running the rifle below the internal reg set point for an extended period would damage the internal regulator.
11. So far, the answer is that running below the set point will not hurt the internal reg.

JackHughs

 

[JimD]

Jack,

Thank you for a through and very easy to understand explanation. I think you could ask your questions as "Will it hurt my guns Huma regulator to stay open for an extended period of time?". I cannot see how you could say "yes" to this. The reg remaining open means the spring washers are pushing on the stem they are on hard enough to move the point of that stem off the plastic disc it seals against. These washers are always exerting force on the stem, it is just a question of whether it is enough to move the valve open. I guess there is a chance that the valve staying open for an extended time will kind of "freeze" it in that position but in my mind that wouldn't represent damage done to it. It would either "unfreeze" itself with higher pressure in the main chamber or you might have to take it out and lube it. But either way, the regulator should be fine, there is a chance it might need service. That's my guess anyway.

Jim