HP hose with adaptor to lp port

[Anthony A.]

Im looking to use a HP hose with a 3/8" adaptor and put it on one of my spare lp ports. This is kind of an experiment but my main purpose is to try and get the flow rate to under 1 lpm. I know I can buy flow restrictors but I havent found anything under 1 lpm. So I am thinking of putting a HP hose (since it has a tiny hole) into a lp port (because its pressure is obviously less than the hp port) and then allowing the air to exit the hose freely. Is there anything bad that can happen using the hp hose on a lp port (ie. too much back pressure and it will blow up)? Any thoughts (apart from "this is a useless experiment" )

 

[herman]

I can't think, of any issue, obviously the pressure is not an issue. You have 2 options. Old school HP hoses used the same 3/8-24 thread as the LP ports and those hoses are still available from any Trident dealer although most shops don't carry them so you would have to order them (VDH might have them) or you can buy a 7/16-20 male to 3/8-24 female adapter. Most dive shops have those or there are plenty of places on line to buy them.

 

[northernone]

Works fine, I've done it trying to check IP with a SPG (to see if the spg was accurate against a known pressure), not sure what the metered flow rate will be but suspect it is higher than you need. They come in various orifice sizes I've noticed.

If your going ahead with this project I am willing rig one up here and check the flow rate with a 2l bottle in the sink with a timer if you'd like before you spend money on it.

Cameron

 

[rsingler]

I'd guess that even if the flow rate is high thru the pinhole of an adapted HP hose, the OP can get his desired 1 lpm by decreasing the IP until he gets the flow he wants. Which means a diaphragm reg is going to be better for this experiment than a piston. Even a Mk25 adjustable still has a minimum IP that may be too high, whereas most diaphragms can be adjusted all the way from zero.

 

[rhwestfall]

how are you determining you are actually at 1 lpm? How critical is it to be at 1 lpm?

As an example, my CO meter needs 0.5 lpm. As this is a monitor at my compressor, I have a restrictor that cuts it to (supposedly) 1 lpm, and then have a Dwyer adjustable calibrated laboratory type flow meter (0.2 - 1 lpm range, IIRC) off that to have the correct flow to the monitor.

For me, the manufacturer of my monitor states 0.5 lpm to be used for testing as well as calibration, or the readings can be off...

Just some food for thought....

 

[Anthony A.]

Thanks for the reply guys.

Cameron, if its not a lot of trouble to do that test I would appreciate so much.

Rsingler, i never thought about that. I have a first stage that i have dedicated to this project and can tune the ip down. Is it really possible to detune any first stage all the way to 1lpm?

Rhwestfall, this experiment is also for use with a CO meter. I need the flow at 0.5lpm and unfortunately cant find any flow restrictors that low. It would have to be portable for when i check tanks on a small boat.

 

[W W Meixner]

Thanks for the reply guys.

Cameron, if its not a lot of trouble to do that test I would appreciate so much.

Rsingler, i never thought about that. I have a first stage that i have dedicated to this project and can tune the ip down. Is it really possible to detune any first stage all the way to 1lpm?

Rhwestfall, this experiment is also for use with a CO meter. I need the flow at 0.5lpm and unfortunately cant find any flow restrictors that low. It would have to be portable for when i check tanks on a small boat.

Anthony...

What is it you're trying to accomplish...

The end opposite to the end which screws into the first stage regardless of the thread size of the adapter fitting has a special fitting to attach an SPG...IT IS NOT INTENDED FOR ANYTHING ELSE...AND WITHOUT THE SPG SPOOL WILL NOT SEAL...

Sounds as though you are attempting to alter a 1st stage regulator to be used as a 1 LPM orifice to cobble together some sort of rebreather...

KNOWLEDGE GAINED THROUGH TRAINING AND PRACTICAL EXPERIENCE LEAVES YOU FAR LESS SUSCEPTIBLE TO BAD IDEAS...

Others...please make sure your makeshift suggestions are defend-able...

Dive Safe...

Warren

 

[Anthony A.]

Anthony...

What is it you're trying to accomplish...

The end opposite to the end which screws into the first stage regardless of the thread size of the adapter fitting has a special fitting to attach an SPG...IT IS NOT INTENDED FOR ANYTHING ELSE...AND WITHOUT THE SPG SPOOL WILL NOT SEAL...

Sounds as though you are attempting to alter a 1st stage regulator to be used as a 1 LPM orifice to cobble together some sort of rebreather...

KNOWLEDGE GAINED THROUGH TRAINING AND PRACTICAL EXPERIENCE LEAVES YOU FAR LESS SUSCEPTIBLE TO BAD IDEAS...

Others...please make sure your makeshift suggestions are defend-able...

Dive Safe...

Warren

Im not using this for diving. I am looking for a way to test CO gas from a tank into a CO meter. Basically a hose that spits out air very slowly. I wont die doing this

 

[rhwestfall]

(you type faster...) he is just using the restriction on the 1st stage side to create a flow drop as the increase in the downstream hose diameter after the pinhole restriction will thus further reduce the flow rate (Q =V*A).... The open end will then feed the meter some way...

 

[rhwestfall]

thing is, my flow meter is a little bigger (about twice the diameter, and about the same length) than a BIC cigarette lighter