FIRE Pistons By Docfire PB

[docfire]

FIRE Piston for ID, WGP, Res, & MacDev – Docfire Paintball

[superman]

I noticed a difference with nummech piston. I will likely have to pick up a few for my other markers. I am sure some people may or may not see the benefit in this, but i think these are cool for the guy trying to squeeze every drop out of his marker.

[Psycho91]

What do these do

[superman]

What do these do

"Replace your Damaged or Low Flowing regulator piston. These pistons are higher flow which will allow you to run a lover operating pressure*. 6061 anodized pistons will stand the test of time. "

[Frmrspec]

This thread is useless without reg dyno’s .. show us that improved recharge/flow/consistency

[ford]

As a buffoon, I appreciate the washer patterns anodized on the pistons.

[zinger565]

As a buffoon, I appreciate the washer patterns anodized on the pistons.

Yeah, me too. Saves having to look it up or try to analyze a picture I may or may not have taken beforehand.

[Axel]

As a buffoon, I appreciate the washer patterns anodized on the pistons.

Yeah, me too. Saves having to look it up or try to analyze a picture I may or may not have taken beforehand.

It's one of those little details that I really appreciate.

[Frmrspec]

Still no dyno

[docfire]

Not yet.

[flyweightnate]

I'm a little confused. A higher flowing piston to allow a lower operating pressure, or tank input pressure? Flow through the piston should only be relevant immediately after the shot, when the reg opens... and the idea is that a typical reg piston starves the gun if you run too low an OP, but not at higher OPs?

If my memory serves, volumetric flow depends exclusively on the port diameter/ geometry if there's a good difference between the two pressures (e.g. dropping from 800psi to 350), but that flow will slow down as downstream pressure, that is, operating pressure, increases.

I'm interested in a dyno test, with upstream pressure known and downstream at several setpoints, as much to understand the velocity through the reg piston as anything. I'd recommend at least one point at a 2:1 upstream to downstream ratio, one above, and a couple below.

A look at the seat-end corners would be interesting, too - namely, the radii.

The engineer in me is starting to nerd out. I apologize.

[docfire]

Feel free to PM me as I have questions. we can talk over the phone.

[flyweightnate]

Cool, will do.

[docfire]

sent you info

[latches109]

"higher flow which will allow you to run a lower operating pressure"

The spring stack will change the pressure output irrespective of flow. For example: I can take my stock inception reg and flip one washer to achieve lower pressure or add a washer to increase pressure. The inner diameter of the piston would not affect the pressure.

But I get what you are trying to do... the larger inner diameter should increase the response time since the piston will open less height, equaling a reduction in pressure drop from shot to shot. I could, run a really low recharge rate reg at low pressures, if, my flow requirement is only 1shot/5sec. Of the many WGP piston iterations, I do notice these benefits from a larger piston diameter base(pictured left below)

These are all the same dimension in length:




Another mod I have done for flow, is drill extra holes in the reg seat on WGP LPRs and HPRs air supply, this upstream will choke out the downstream. I don't have a good picture of a modded one, but this will give you an idea. edit: this was off an eBay gun I bought titled leaking, I found the leak.

[k_obeastly]

Once again, guns were shooting 20bps w/o shootdown 20+ years ago. How is this relevant at 10.5 bps? Other than the spring stack etching, which is nifty for those that can’t remember.

[docfire]

"higher flow which will allow you to run a lower operating pressure*"

*Lower operating pressure will vary depending on setup, paint quality and barrel paint match.

The spring stack will change the pressure output irrespective of flow. For example: I can take my stock inception reg and flip one washer to achieve lower pressure or add a washer to increase pressure. Can you explane why this is true? The inner diameter of the piston would not affect the pressure. What are you calling the "inner dia"? if it s the size of the hole going through the piston then yes it can affect the force on the piston face, "Surface area" Pounds per square inch PSI.

But I get what you are trying to do... the larger inner diameter should increase the response time since the piston will open less height, equaling a reduction in pressure drop from shot to shot. Yes and no. the larger inner dia will allow more flow to the regulated sided of the piston with in turn will decrease to time to equalize the force on the piston surface compared to the force of the springs. I could, run a really low recharge rate reg at low pressures, if, my flow requirement is only 1shot/5sec. Of the many WGP piston iterations, I do notice these benefits from a larger piston diameter base(pictured left below)

These are all the same dimension in length: Two are LPR piston which are not relevant to refresh rate and flow IMO. As long at the LPR works and regulates between 50 to 80 psi you are good on a COCKER...... As for the other two one looks modified




Another mod I have done for flow, is drill extra holes in the reg seat on WGP LPRs and HPRs air supply, this upstream will choke out the downstream. I don't have a good picture of a modded one, but this will give you an idea. edit: this was off an eBay gun I bought titled leaking, I found the leak. I'm lost here on what you are doing. If you are adding holes to the reg seat base that have the hole drilled in the side for degassing then your are accomplishing noting, except degassing faster maybe. Also that rege seat is trashed.

[docfire]

To be clear i hate typing, fat finger the keyboard and 30 years of typing investigative reports burned me out). Plus I'm somewhat blunt when typing can people get butt hurt over that. That's why I generally do videos of talk over the phone. Sorry for my bluntness and possible making you feel hurt, offended or sad.....not my intention.

[flyweightnate]

I had an interesting phonecall with DocFire. I was skeptical of the claims because of the wording used, but had some hunches. Learned a bit, too.

First thing, the ID of the stem is larger. This will increase recharge rate, because, in most situations, a reg piston is seeing choke flow. That's a technical term for the gas moving at the speed of sound, so diameter is the only thing changing volumetric flow. Increasing this ID makes a big difference.

The second thing is that the ID expands near the end of the piston, effectively shortening the length of this small ID portion. I'm not convinced this is relevant to flow in these specific conditions but it can't hurt. I'm curious what the critical Reynold's number is for the piston, and how close each design is to that number. I'll do some homework.

The third thing is that the counterbore on the top of the piston face adds downstream volume. We all know thirsty guns like volume.

So the reg flows better. OK, so what?

What was interesting were the discussion of some earlier dyno tests that showed the reg opening DURING the shot - which makes sense now that I think about it. If the speed of sound is conservatively 1000 ft/sec (higher at higher pressures), it only takes a millisecond for that pressure wave to travel a foot, and the dwell is much more than a millisecond. For a really low pressure, high volume gun (like an LP tuned Merlin), this means the reg flow doesn't just affect shot-to-shot recharge, but it impacts the pressure profile of the chamber DURING the shot. That kind of blew my mind. So it is, then, conceivable for a very "thirty" gun to see higher velocities at the same setpoint with a higher flowing reg piston.

The last thing he mentioned was some pretty extensive Belleville washer testing. Obviously I have no evidence, but if he cares about the quality of the Belleville stack, and got better consistency, that can have a lot of impact on the setpoint and also the rate at which the stack opens (since Bellevilles are highly nonlinear, giving them unique advantaged - if chosen correctly - over a coil spring).

All in all, really fun conversation and I think there might be more to the design than meets the eye.

[docfire]

Now blow your mind and do the cal's to determina how many CU of air and at what PSI to shoot a round object weighing 3.4g down a 14" barrel with a friction coefficient..........Hint this number will be the same for every marker.......

[docfire]

And yes it was supper nice meeting and talking with a fellow tinker. And a person who appreciate the work that goes into making products for paintball and bring them to market.

[flyweightnate]

Rule of thumb I always heard was 100psi x cubic inch. I wonder what efficiency that assumes.

While both pistons are turbulent, that doesn't mean subsonic; choke flow occurs whenever the upstream to downstream ratio is greater than around 2 (for air... there's a formula on my shelf somewhere). So still very much dependent solely upon diameter for flow rate.