Test dove 4 DH regs today, 3 for the first time.

[elmer fudd]

One other option would be to put your mushroom valve right in the center of your main diaphragm and then vent the exhaust right into the can and out the center of the diaphragm. There might be a little bit of CO2 build up but it wouldn't be hard to do.

 

[John C. Ratliff]

The mushroom valve right in the center of the diaphragm would work (it has on other regulators), but would have some flow problems. I don't think there would be a CO2 buildup problem, as the amount of CO2 would be very small in relationship to the volume of air coming out. Maybe I can do some calculations on that later.

I am toying with a the regulator and found out a couple of things yesterday. With a sensitive exhaust diaphragm, you absolutely need both non-return valves in the mouthpiece. Without them, the system does not work. Another idea is the weighting of the exhaust diaphragm. This concept works well in all but the head-down position. The ScubaMaster regulator (which really never hit the market much) had a weighted mushroom valve. If a weight could be balanced in the exhaust diaphragm such that it only pushed against the diaphragm in the head-down position, the balance problems of this concept may be solved.

SeaRat

 

[Eric Sedletzky]

I don't know if I like the idea of returning the exhaust back into the fresh air chamvber. I think the fresh air chamber should be sealed and the less possible failure points to introduce water intrusion the better. I know the diaphram in that case would be a weak link so why not other weak links, what's the difference. The difference is you have to have a diaphram and they are tough and completely sealed. If I could find some urethane to make an exhaust membrane as dependable as a diaphram then it would be a possibility to keep that system especially if the silicone was flexible and stretchy enough to allow a good exhalation and then seal well from the pressure of the fresh air chamber.
Sealing the urethane patch would be another thing I would be anal about, I wouldn't want it to come loose or come off so that would have to be figured out too.
A tough rubber band would be better than a wire.

 

[John C. Ratliff]

ZKY,

I agree that the exhaust mushroom on the diaphragm is not really a good idea. It is technically feasible, and the Northill Air-Lung does that but it would introduce not only potentially water, but also other exhaust contaminants to the chamber.

I am going to work on the weighted membrane idea. That is also technically feasible, and would preserve the high flow of this exhaust (equivalent to the duckbill), while potentially solving the imbalance problem which admits water into the exhaust hose. I am working out the details in my mind right now with materials I have on hand.

John

 

[elmer fudd]

I don't really think a diaphragm mounted mushroom valve is a great idea myself, but I'm looking at the inside of a HW Scuba right now and I really don't see a lot of other good places to mount one. Perhaps between the exhaust horn and the membrane valve, but that's going to be a tight squeeze.

The biggest drawback I find to the diaphragm mounted exhaust is that it allows in small amounts of water. It's not a whole lot, but I'd prefer not to get any salt water in the innards of my regulator.

 

[Luis H]

With an exhaust valve on the diaphragm, think about how you are going to clear a flooded mouthpiece. Where is the water going to go? You will not be able to exhale all the water out and at some point you may inhale some water.

The Northill Airlung has a DSV (Dive surface Valve) mouthpiece valve to keep the breathing loop dry, similar to a re-breather. You are supposed to close the mouthpiece DSV valve before you take the mouthpiece out of the mouth. This minimizes any water in the loop.

I don’t know much about the Northhill, but using a conventional mouthpiece doesn’t sound like a good idea if you ever want to take the mouthpiece out of your mouth. I think you will have a real hard time with a fully flooded mouthpiece.

Here are some good pictures of a Northill for those who haven’t seen one:
The Northill Airlung was made of

The only other double hose regulator that I am aware of having a diaphragm mounted exhaust was the Dacor, but it also had two diaphragms to separate the dry chamber from the wet chamber.


There have been several single hose regulators with exhaust mounted on the diaphragm, but those are intentionally wet chambers. The chambers are small and easy to clear any water out of them. In a double hose you don’t only have a large chamber, but two long large hoses that would need clearing.

 

[duckbill]

And definitely never puke into the mouthpiece on a double hose regulator having a diaphragm mounted exhaust valve!:amazed:

 

[John C. Ratliff]

And definitely never puke into the mouthpiece on a double hose regulator having a diaphragm mounted exhaust valve!:amazed:

Oh YUK!!! That applies to all regulators, but especially double hose regulators. It's a major cleanup project if this happens, and may be the end of the hoses.

SeaRat

 

[herman]

And definitely never puke into the mouthpiece on a double hose regulator having a diaphragm mounted exhaust valve!:amazed:

Now there is one of the best reasons for a Phoenix I have ever heard.....use your octo when puking and then swap back to the DH

 

[duckbill]

Yeah, I meant a double hose regulator like you guys have been talking about that recycles your exhaust back to the intake chamber to be exhausted through the main diaphragm. Your next few breaths would include breakfast all over again!