Tuning New Huma regulator with a loose screw in the bag?

[LDM]

I recently ordered a new Huma Reg for my Taipan Mutant and it arrived with a very small allen head screw rolling around in the bag. I have sent two e-mails to Huma over the past month, neither has been replied to. Can anyone tell me if this screw belongs in the brass fitting end of the Reg - the fitting that you turn to adjust the pressure? It's the only place it appears to go. And, if it goes in that screw hole, should it be tightened fully?

Thanks in advance!

Don

 

[hawkeye69]

Check this thread: https://www.airgunnation.com/topic/huma-regulator-small-screws-purpose/

 

[elh0102]

They put a small machine screw in some kits, which is used to make removal easier, screw it in a little, then the head is easy to grab with needle nose pliers. But, that's clearly not a machine screw, can't imagine it's purpose.

 

[LDM]

Hawkeye - Thanks for the Huma instructions. That must be the screw that is in the bag. I guess I'll put it in, then see if the gun works. There were no instructions with the Reg.

Elh - Appreciate the reply. I have used a machine screw to remove regs in the past. This one didn't come with that screw.



Don

 

[Enkey]

Hi

If you put the screw your regulated air chamber will fill slowly and if you don't put it it will fill faster

Regards 

Enkey 

 

[LDM]

Hey Enkey, 

What would you do - put it in for a slower fill or leave it out. I installed several Regs now in different guns but haven't run into this. I have a Huma Reg in my Wildcat so I guess I could pull it and see if it came with the screw inserted, but I really don't want to do that if I don't have to.

Thanks!

 

[Enkey]

I don't know what to tell you, I have airguns that from the factory have a slow air flow and others fast, I don't know what the reason is

 

[douger]

id use the directions that guy posted 

 

[LDM]

Thanks All!!!!

 

[madeintheuk]

I’ve found that if you use fairly low reg pressures, you will benefit from the slower refill rate for more precise regulation. If you use higher reg pressures, the faster refill will be fine by there’s a good amount of pressure against those Belleville washers to help keep it precise. That being said, if you install it, it’ll be just as pre use at low and high reg pressures, but if you have a good sized plenum, you may need to wait 5-10 seconds between shots for the plenum to fill back up. 

 

[elh0102]

Hi

If you put the screw your regulated air chamber will fill slowly and if you don't put it it will fill faster

Regards 

Enkey

I don't doubt you at all, but I struggle to make sense of it. Seems like a given amount of pressure is going to have a certain effect, regardless of how quickly applied. The list of things I don't understand is getting mighty long!

 

[madeintheuk]

Hi

If you put the screw your regulated air chamber will fill slowly and if you don't put it it will fill faster

Regards 

Enkey

I don't doubt you at all, but I struggle to make sense of it. Seems like a given amount of pressure is going to have a certain effect, regardless of how quickly applied. The list of things I don't understand is getting mighty long!

Simple physics. The screw makes the hole the air passes through smaller than it is without it. Restrict the flow of air through a passage, and it fills slower. Simple!

 

[elh0102]

I don't doubt you at all, but I struggle to make sense of it. Seems like a given amount of pressure is going to have a certain effect, regardless of how quickly applied. The list of things I don't understand is getting mighty long!

Simple physics. The screw makes the hole the air passes through smaller than it is without it. Restrict the flow of air through a passage, and it fills slower. Simple!

Yup, I get that, but full is full. When the pressure reaches the reg set point, that's it, no more air, regardless of the air flow velocity. But then, I never did well in physics. 

 

[madeintheuk]

I don't doubt you at all, but I struggle to make sense of it. Seems like a given amount of pressure is going to have a certain effect, regardless of how quickly applied. The list of things I don't understand is getting mighty long!

Simple physics. The screw makes the hole the air passes through smaller than it is without it. Restrict the flow of air through a passage, and it fills slower. Simple!

Yup, I get that, but full is full. When the pressure reaches the reg set point, that's it, no more air, regardless of the air flow velocity. But then, I never did well in physics.

The spring pressure of the Belleville stack is what holds the valve in the reg shut. When the plenum side is empty, the difference in pressure allows it to open and let air in. If the air rushes in fast, and the reg is set to a lower pressure, there’s the possibility that the regulated side fills faster than the valve can close. This would cause pressure to be higher than the reg set pressure. Slow that air down, and the valve can close on time keeping the pressure consistent where it needs to be. 

 

[Jacksn]

I’ve found that if you use fairly low reg pressures, you will benefit from the slower refill rate for more precise regulation. If you use higher reg pressures, the faster refill will be fine by there’s a good amount of pressure against those Belleville washers to help keep it precise. That being said, if you install it, it’ll be just as pre use at low and high reg pressures, but if you have a good sized plenum, you may need to wait 5-10 seconds between shots for the plenum to fill back up.

So basically you get the faster fill rate at higher pressure (and more power?), but maybe less longevity on the internals of the regulator due to the higher pressure?

 

[Enkey]

Hi elh0102

I would like to be able to explain it to you but as I said in a previous publication I don't know what the reason is, I have my own conjectures but I can't affirm something that I don't know. One guess is the one explained by jacksn and the other is to prolong the useful life of the regulator I think it has to do with (water hammer or Zhukowski pulse)

Regards 

Enkey 

 

[elh0102]

I'm sure the Huma engineers, and most everyone else, know more about regulators than I. One would think that such a tuning feature would be explained in the instructions. None of my regs, including Huma, have this feature, and they work extremely well. It would be interesting to see a test of performance with and without its use. Maybe an energetic member will undertake the task and post results. 

 

[LDM]

Hey all, Huma got back to me and I put their answer below: 

Hello Don,



That screw can be screwed into the bronze adjustment screw to reduce flow through the regulator for optimal precision and to keep out debris. Screw it in as far as it goes then back off 3 full turns.



Unfortunately, we do not get every rifle in for development of a regulator but sometimes develop one in conjunction with a client. Without a rifle here we need to reply on our customers for pictures etc. this is an example where we were able to make a fitting regulator but have not been able to make fitting instructions for it.




All the best



Team HuMa-Air,



Marc




And el0102, I will let you know if I try it with and without.

Thanks everyone!

 

[Enkey]

Hi Don

I'm glad you got an answer directly from Huma. Many years ago Marc of Huma also made me a regulator according to the measurements and photos I sent him

Regards 

Enkey 

 

[elh0102]

Maybe it's just me, cause I'm nursing a recent rotator cuff surgery and I'm grumpy. But, if I owned a company, and an employee told a customer that we made a product for them, but we "have not been able" to make instructions for its use, he and I would have a discussion about such an asinine response. I mean really, a 2 sentence explanation is something they are unable to do? Good grief, but maybe I'm wrong, as my wife often suggests.