Implications of the spring adjustment knob

[Divor]

Hi,

I was just wondering: as opposed to a regulator without a spring adjustment knob, does a regulator that has one have a different design on the inside because there is a range of air flows (from min to max) which introduce variability in obtaining a laminar flow?

Thanks in advance.

 

[fppf]

I'm not aware of any reg that can claim to have laminar flow.

Having an adjustment knob does not drive the overall design. Most designs incorperate an adjustment method.

 

[cerich]

Hi,

I was just wondering: as opposed to a regulator without a spring adjustment knob, does a regulator that has one have a different design on the inside because there is a range of air flows (from min to max) which introduce variability in obtaining a laminar flow?

Thanks in advance.

You do know that what you wrote above is one of those things you need to read a couple times and you'll still not be sure you follow the drift?

The air flow isn't really impacted so much as cracking effort

Is there a EDGE and/or HOG specific question in this?

 

[Divor]

I'm sorry, I didn't mean to burden you, it's just that it was your reg that I took apart, so it would have been easier to visualise. It is indeed a more general question. Cheers

 

[Peter_C]

There are other brands than HOG that offer the same reg body and internals without the external adjustment knob for less money. Effectively charging much more for adding in the external adjustment. HOG does not do this and offers a top quality adjustable reg for one of the most reasonable prices out there.

 

[herman]

Let me take a shot at this, I think I see where he is going.

First off, the cracking pressure knob has no effect at all on case design, gas flow within the case or for that matter total overall flow rates of the second stage, basically all it does is vary the spring pressure on the internal parts of the LP seat. For all intents and purposes, removing the internal spring and replacing it with a stiffer/lighter one would have the same effect, just not externally accessable. This will only cause the cracking pressure- the amount of force needed to open the LP seat to vary but it has no effect on the amount of gas the reg is capable of delivering.

On the other hand, the venturi control lever does have an effect on case geometry and hence the flow of gas within the case (but not on total available flow). Set to max, the flow is directed from the LP seat outlet into the mouthpiece of the reg, this creates a venturi effect and reduces the pressure under the diaphram, reducing the effort needed to hold the LP seat open. If the reg is started flowing (purge button pressed) and there is no back pressure (ie. no one breathing on the reg)the effect will likely be high enough to keep the reg freeflowing and increase until the reg is in full freeflow. Set to the minimum position, the airflow between the LP seat outlet and the mouthpiece is disrupted causing less of a venturi effect and less vaccuum behind the diaphram.

Neither the cracking pressure knob or the venturi assist lever have any effect on the volume of gas the reg can flow, they just make getting it easier for the diver. Does that help or did I just muddy the water more.

 

[Divor]

Neither the cracking pressure knob or the venturi assist lever have any effect on the volume of gas the reg can flow, they just make getting it easier for the diver. Does that help or did I just muddy the water more.

No you cleared it up, this is a great answer to my question. I'll pick up that book you mentioned in the other thread and read it before bothering you guys again

Thanks for taking the time to write such an extensive answer.

 

[herman]

Happy to help and it’s no bother; I really encourage divers to learn about their gear. The book has so many good illustrations and examples that are hard to reproduce here that really help you understand the internal working of a regulator. It delves into the how and whys of regs but at a level most anyone with a little technical background can grasp. I reread it every so often to brush up on what I know; it's worth rereading from time to time.

 

[cerich]

Happy to help and it’s no bother; I really encourage divers to learn about their gear. The book has so many good illustrations and examples that are hard to reproduce here that really help you understand the internal working of a regulator. It delves into the how and whys of regs but at a level most anyone with a little technical background can grasp. I reread it every so often to brush up on what I know; it's worth rereading from time to time.

did you recommend Reg Savvy?

 

[herman]

Yep...well guess yep is too short, got nasty gramed. Yes I did.