Adjusting spring tension on regulator to control freeflow/breathing resistance

[DazedAndConfuzed]

I have a Oceanic Delta 3 2nd stage. I was wondering if there is a difference between adjusting the internal spring pressure in the regulator so that it free flows more, then tighting up the resistance knob until it stops freeflowing. Versus adjusting the internal spring so that it almost stops freeflowing, and only tightening up a bit on the external knob.

Would the 2 different methods result in different break pressure vs constant breathing effort required?

On first assumption, it would be the same, since its like 2 springs working on the same valve and it would be the net force/pressure on the seat. But the regulator spring is a heavy duty type while the one for the external knob is much flimsier.

 

[redacted]

I was really hoping someone knowledgeble would tackle this one.

I am not a tech & I only service my own Scubapro regs.

Looking at Vance Harlow's book, I find an Oceanic Delta II which is a downstream second with an external adjustment. I assume the Delta 3 is also because you talk of 2 springs. The external adjuster should be set at mid-range to start with and at least 4 threads should show on the poppet above the lock nut that adjusts lever height. Then you adjust the orifice until it just stops freeflowing. Harlow's instructions call for using an inline tool. But by removing the hose, adjusting and bracketing the point of freeflow, and reattaching the hose and giving it a try between each adjustment, you should get there. I think I would start with the orifice open so I could blow air (breath) thru it and tighen that down to get a good startpoint - then go a half to a quarter turn at a time. Then, if the LEVER ARM is too loose, adjust the nut making sure the poppet doesn't also turn.
When finished, the adjuster should cause freeflow if opened all the way and be hard but breathable if closed all the way. The adjuster should not be able to shut off air supply.

This one sounds like a pita to adjust right but the external adjuster should give you some leaway.

Caps above is an important edit. I wrote spring and ment lever arm that is acted on by the diaphram. Shake the reg and if the arm rattles, then it is too loose and should be raised to contact the diaphram.

 

[ifukuda]

Many times, a regulator that is prone to freeflow is caused by the intermediate pressure being too high. If this is the case, the first stage will need to be adjusted, or maybe the HP seat may have to be replaced.

My advice:
If small an adjustement on your second stage did not stop the freeflow, don't keep messing around with it. Have your LDS tech take a look at it.

 

[redacted]

I edited my original post. What I originally called a spring should have been the LEVER ARM.

After rereading the original post, using the external adjuster to tune the reg should be OK so long as you can adjust it to a position that it breaths satisfactorily and you can NOT SHUT OFF THE AIR SUPPLY OR MAKE THE REG UNUSABLE WITH THAT ADJUSTER. Otherwise it needs a proper tuneup.

 

[DazedAndConfuzed]

awac,

I don't know if it is 2 springs in the poppet valve area since I didn't disassemble that area. I know there is at least one there and another one in the user adjustable knob area.

So the lock nut is purely for the adjustment of play on the demand lever? Wouldn't tightening down the orafice pick up the slack on demand lever also?

I guess with a properly tuned first stage, One doesn't need to accurately tune the second stage, since 1/2 turn of the external knob after free flow stops is equiv to breathing resistance of a non-adjustable 2nd stage.

Also, I am not clear about this. I was under the assumption any combination of adjustment on the orafice, knock nut and external knob to the point where it stops free flow would provide the exact same break pressure and breathing pattern. Or does a tigher orafice spring and looser adjustment knob spring differ from a looser orafice spring and tighter adjustment knob spring? (don't know where that demand lever lock nut comes into play.)

 

[redacted]

I believe you are right. It looks like one continuous train from the orifice to the adjustment knob. So tightening either one tightens both sptings in the circuit. It looks like the locknut mearly adjusts the lever height, but it might also have some effect on the poppet spring tension (demand valve). I know it does on my Scubapro R190 and you have to go back and forth a bit to get it adjusted. For small adjustments to get cracking pressure right, it looks like it should make little difference as to whether you adjust the orifice or the knob. In fact, the user would normally only be using the knob. It should be OK as long as the knob can not be use the excessively restrict or cut off air flow. That would be a safety problem that would need to be corrected by adjusting the orifice.

 

[DazedAndConfuzed]

Thanks for the info awap,

So this is not like those dual spring rate coil-springs, with one section thicker than the other. Although it does have the depth compensation adjustment spring, which from reading the patent, is a very simple idea of contact pressure of equal surface area as orafice being counter-balanced by spring instead of 2nd stage internal air pressure.

Also, while testing above water, when I set the external knob so that it just stops freeflowing and take a deep breath through the regulator, I will notice that it started freeflowing slightly. Sometimes it happens even when I turn the recommended half turn past the stop of freeflow. This is probably due to the diaphram not returning all the way back to previous position.

Would adjusting the lock nut help fix this issue? Or should it not be a concern, since with the exhale breath, it usually results in the stop of freeflow.

I also noticed there is a slight play in the movement of the demand lever. Should there be play on it to compensate for the diaphram's resting position? From what I observe above, the diaphram is already pressing down on the demand lever after inhalation.

 

[redacted]

Sounds like everything is doing what it is supposed to do. I suggest you put it in the water and try it. Even a bath tub will work. See that you can get the FF under control with the adjustment knob once it is wet. The demand lever should be a little loose but not so loose that it rattles when you shake the reg. If you get it too tight, that can cause a FF with the lease little pressure on the diaphram.

 

[DazedAndConfuzed]

Thanks awap.

I tried it in the tub before, after my fine tuning, I will try again.

Freeflow outside the water is not the same as freeflow in the tub. Outside water free-flow's gets lesser and lesser, while tub's freeflow abruptly stops. So the position of the knob is different for the two. Must be something with surface tension of the water.