Regulator test rig you don't need to suck.

[Open Ocean Diver]

@Open Ocean Diver thanks for the schematic.
@rsingler uses just an adjustable vent with the PWM speed control.

I tried an aquarium airline valve as a vent, but wasn't seeing much difference. Possibly just a poor valve and/or my lack of understanding what to look for. It is easy enough to experiment with the valves externally to see what works. Getting something precice and small enough to fit may be difficult.

I had also thought of a venting valve to load the output side which may be adventagous for packaging.

Have you tested yours yet, do you have needle bounce?

 

[Open Ocean Diver]

@Open Ocean Diver thanks for the schematic.
@rsingler uses just an adjustable vent with the PWM speed control.

I tried an aquarium airline valve as a vent, but wasn't seeing much difference. Possibly just a poor valve and/or my lack of understanding what to look for. It is easy enough to experiment with the valves externally to see what works. Getting something precice and small enough to fit may be difficult.

I had also thought of a venting valve to load the output side which may be adventagous for packaging.

I’ve tried various configurations including an adjustable vent. I found the needle would still bounces at the low end. With the motor at base speed the pulse frequency is much higher and the gauge will have almost zero bounce from zero all the way up with the inline needle valve. You can buy low pressure valves that are small enough to fit in your case, best to look for a used one you can repurpose. For the vent I just use 3 feet of tubing coiled up works great. I have verified the calibration with another system I have to check cracking effort and its spot on. Smooth control from zero to whatever your pump will give you. You will see a dip in the mag gauge before you see the iP dip when the valve cracks. (as @rsingler has said) Takes a little bit of getting used to but it works great and you have consistent repeatable readings.

 

[-JD-]

Have you tested yours yet, do you have needle bounce?

I’ve tried various configurations including an adjustable vent. I found the needle would still bounces at the low end. With the motor at base speed the pulse frequency is much higher and the gauge will have almost zero bounce from zero all the way up with the inline needle valve. You can buy low pressure valves that are small enough to fit in your case, best to look for a used one you can repurpose. For the vent I just use 3 feet of tubing coiled up works great. I have verified the calibration with another system I have to check cracking effort and its spot on. Smooth control from zero to whatever your pump will give you. You will see a dip in the mag gauge before you see the iP dip when the valve cracks. (as @rsingler has said) Takes a little bit of getting used to but it works great and you have consistent repeatable readings.

Disclaimer: I'm untrained and just starting down this path. The gauge-box and vac builds are in anticipation of doing the HOG/D6 course in the (probably now post-Covid) future.

With my motor/PWM board combo, it does bounce around a bit when lower. By the time I get near cracking, the pump is going pretty hard (50%+ rpms,) the dynamics seem to me to be more about the cracking and stabilizing then pump-pulsing - the mag-dip you note. With the pump, the cracked-flow is so low that the IP gauge barely twitches. With the HOG that I was working with, it would typically stabilize around 1.2 - the highest variability seems to be mostly in the reg itself depending on how hard it was last cycled (a couple 10ths max). It may be a little sticky given the fresh water soup that I frequently dive in. (Admittedly worse than normal circumstances, but last dive my buddy was up against my side, touching me, I looked over and couldn't see him, just his light if it was shining at me and a "glow" from his white tank. This was early afternoon on a sunny day in < 20'.)

Out of curiosity, are you using a similar pump to what I'm using? I'd expect similar performance from the various sourced in that size/form-factor.

 

[Open Ocean Diver]

Disclaimer: I'm untrained and just starting down this path. The gauge-box and vac builds are in anticipation of doing the HOG/D6 course in the (probably now post-Covid) future.

With my motor/PWM board combo, it does bounce around a bit when lower. By the time I get near cracking, the pump is going pretty hard (50%+ rpms,) the dynamics seem to me to be more about the cracking and stabilizing then pump-pulsing - the mag-dip you note. With the pump, the cracked-flow is so low that the IP gauge barely twitches. With the HOG that I was working with, it would typically stabilize around 1.2 - the highest variability seems to be mostly in the reg itself depending on how hard it was last cycled (a couple 10ths max). It may be a little sticky given the fresh water soup that I frequently dive in. (Admittedly worse than normal circumstances, but last dive my buddy was up against my side, touching me, I looked over and couldn't see him, just his light if it was shining at me and a "glow" from his white tank. This was early afternoon on a sunny day in < 20'.)

Out of curiosity, are you using a similar pump to what I'm using? I'd expect similar performance from the various sourced in that size/form-factor.

What’s the scale on your mag?

Here’s my pump and power supply, it just sits on my coffee table work bench. wife’s in Florida I have the place to myself. Lol

It has a brushless motor, the commutation controller is built in. Makes it easy to work with, only need to feed DC voltage to it.

 

[-JD-]

What’s the scale on your mag?

Here’s my pump and power supply, it just sits on my coffee table work bench. wife’s in Florida I have the place to myself. Lol

It has a brushless motor, the commutation controller is built in. Makes it easy to work with, only need to feed DC voltage to it.

View attachment 606250

0-2" There is a back-story, but that is what I ended up with.

Ok, now I see why you need both a throttling valve and a vent. My motor/pump consumes about a third of my Pi case - yours is closer to a brick!

FWIW, mine is rated @ 2.4W, 3.2l/min. Approx 1"+ dia, 2.5" long.

 

[Open Ocean Diver]

0-2" There is a back-story, but that is what I ended up with.

Ok, now I see why you need both a throttling valve and a vent. My motor/pump consumes about a third of my Pi case - yours is closer to a brick!

FWIW, mine is rated @ 2.4W, 3.2l/min. Approx 1"+ dia, 2.5" long.

My pump has dual sides 2.5 lpm per side I only use one side. Without the valve it works fine on the 0-3 mag but it starts out bouncing till it reaches .5 then smooths out (via varying the speed). I just prefer the valve and having the needle run smooth across its range. One nice thing about it being smooth at the low end you can see if the lever is pulling in smoothly. I found one of my 109 lever tabs catching in the barrel this way.

Where on the scale does yours stop bouncing?

 

[Open Ocean Diver]

I just discovered another benefit to this amazing setup. I don’t have an HP manager so to test cracking effort at high and low and anywhere in between tank pressures, all you have to do is pressurize your fist stage then shut the tank valve off and now the HP chamber becomes a vary vary small tank. Light purge to set your SPG to the desired pressure you want and test. Works great.

 

[rhwestfall]

@rsingler @Open Ocean Diver (or others), parts inbound to build one. Any thoughts on a needle valve for the vacuum relief? I have a "drip head" arriving, but also have a needle valve here I can mount in the box....

Need the parts to arrive to see what tubing fittings/adapters I need.....

See where this build goes. I have some interesting parts kicking around that may "fancy" it up...

 

[Open Ocean Diver]

@rsingler @Open Ocean Diver (or others), parts inbound to build one. Any thoughts on a needle valve for the vacuum relief? I have a "drip head" arriving, but also have a needle valve here I can mount in the box....

Need the parts to arrive to see what tubing fittings/adapters I need.....

See where this build goes. I have some interesting parts kicking around that may "fancy" it up...

You won’t need one... what I do with my shutoff valve in the LP line is to shut off the LP, and then pull a vacuum, next shut the power supply off and watch your mag gauge. You can get an idea if the cases has any leaks. You’ll see around 15 second before you loose vacuum if all you connections and case is good.

 

[rhwestfall]

I mean instead of the drip valve....