[PSUBS-MAILIST] air compensation

Tue Aug 1 20:04:42 EDT 2023

 Alec, yes, the HP port of first stage has a tiny hole and is made to measure pressure. Having said that because of the high tank pressure you can still pass a significant amount of air.  As an example, on my Titan 1st state, it is approximately 0.03" diameter.  A quick calculation assuming 3000 psig tank and 70F tank temperature, the flow rate through this tiny hole is 32 scf/min.   At 1000 psig tank pressure, the rate would be 16 scf/min.  These rates are independent of water ambient pressure because the flow is in critical flow.  The rates would change somewhat with tank temperature.  Would need to complete the calculation to see what the demand would be to fill the four thrusters on the descent but their volume of 37 fl oz each is quite small. My guess it would work off both the HP or LP ports but I need to finish the calc.  

Cliff
    On Tuesday, August 1, 2023 at 04:09:41 PM CDT, Alec Smyth via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 Hi Cliff,
"The Tescom 44-4069 regulator would be a clean installation with just a single 1/4 SS tubing run from the HP port of the 1st stage regulator to the input port of Tescom 44-4069 regulator."
There's a little problem with this plan, though easy to work around. The HP ports on regulators have a tiny orifice, in order to prevent rapid loss of air if a hose or SPG fails. These ports cannot provide the sort of flow you would want. 
Best,Alec
On Tue, Aug 1, 2023 at 12:17 PM Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 Sean, the specs do look good on this unit.  To me the issue is going to be the cost.  As background, the Parker regulator that Hugh, Alec and I have used for this application is the 364-02BSS/M1 Parker Watts Pneumatic Regulator.
https://store.livhaven.com/r364-02bss-m1-watts-fluidair-pneumatic-regulator at $217.51.  I purchased mine off ebay for a fraction of this.

When I had the Parker 364-02BSS/M1 installed for pressure compensating for my four MK 101s, it was connected to the LP port from my AquaLung Titan balanced diaphragm first stage regulator. I had the Parker 364-02BSS/M1 adjusted to give about 2 psi over ambient.  I had the first stage set to 50 psi over ambient water pressure.  I use this for BIBBS and blowing the MBTs. 
The Tescom 44-4069 regulator would run directly off the HP air tank pressure then output go directly to thrusters.  It would be interesting to compare the Cv's for both regulators to get a feel on how much air flow rate they can provide to the thrusters descending and venting when ascending.  
The Tescom 44-4069 regulator would be a clean installation with just a single 1/4 SS tubing run from the HP port of the 1st stage regulator to the input port of Tescom 44-4069 regulator.  From the output port of the Tescom 44-4069 a single 1/4 SS tubing to a Swagelok Tee that branched off to two more "T"s to give four 1/4 SS tubing runs to the thrusters.

We need to get a RFQ on one of these regulators.  Do you have a preferred supplier?
Cliff

    On Monday, July 31, 2023 at 09:47:29 PM CDT, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  

 I would be inclined to use a Tescom 44-4069 regulator for this purpose. Not sure what these sell for.

Sean

-------- Original Message --------
On Jul. 31, 2023, 20:37, Cliff Redus via Personal_Submersibles < personal_submersibles at psubs.org> wrote:

My original air competition for the R300 used the regulator that Hugh Fulton has on QSub.  These are pricey new but you can get them used on eBay.  I was operating all four of my Minn kotas 101 off this single regulator.  It was a special ss pressure reducing/pressure releasing regulator.  I had it installed on my last Florida dive which I went down about 100 ft .  Unit worked fine.  My first failure was on Flathead lake expedition in which one of my aft thrusters flooded.  After that I switched to oil compensation.  Alec is using same regular on his articulated arm and not the thrusters. He felt issue with the regulator was that the port for releasing pressure on ascent was too small.  I believe he has addressed this by adding a pressure release valve or OP valve.  He can elaborate more on his current strategy.
Cliff

Sent from my iPhone

On Jul 31, 2023, at 9:14 PM, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

John,I am happy with both air & oil. Am intending to fill my thrusters with oil, but have the oil pressurized off my air comp system. This will reduce air use to just whats in the lines.My electric manipulator will be air compensated off the same unit. Putting oil in it adds another layer of complexity.I think I need to put out a long video once I've finished thisair compensator.From what I am hearing from Cliff, he didn't get enough air delivery from the single regulator he was using. However I thought this was the same unit that Alec is using & was now happy with.Alan

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  On Tue, 1 Aug 2023 at 1:29 pm, Jon Wallace via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   _______________________________________________
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