[PSUBS-MAILIST] oil compensation

[Alan via Personal_Submersibles]

Hank,
I did a lot of initial experimentation with the system Cliff is using.
I bought 4 relieving regulators & pulled them apart. Unless the 
regulator is fully stainless, you need to change out parts in the
spindle section. At the time I was looking at $40- plastic "Festo" regulators,
but couldn't find a suitable replacement spring. Cliff's little regulator
was going to cost me about NZ $400 & I had wanted one for each
thruster. 
The system Cliff is using is good in that if you have an oil compensated
thruster the oil would just be replaced with air if it leaked out.
He is using his on air compensated motors, so the volume going through
the regulator, & being relieved, is huge compared with what would flow
with a air over oil system.
It's good to bounce this off people. I am thinking I would need a dedicated
air tank for Cliff's system to be G.L. or ABS compliant. So more volume cost
& hassle.
If I had air over oil I could have one regulator & still see if one thruster was 
leaking more than another. If I go with the traditional rolling diaphragm & 
spring type compensator it will be easy for me to put in a low level switch.
If I went with my weight instead of the spring, then I may add 25lb more
weight than is necessary.
Will ponder this some more!
Cheers Alan



Sent from my iPad

> On 17/09/2017, at 6:52 AM, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Alan,
> I would have to vote for the set up Cliff has unless you are planning to be able to jettison the motors.  Oil compensating is so much easier to jettison.  I suppose though you could have a HP tank jettison with the motor.  
> Hank
> 
> On Saturday, September 16, 2017, 12:21:01 PM MDT, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> I wasn't suggesting regulated air compensation, but rather fixed-volume
> oil compensation, with regulated air to provide the positive pressure on
> the compensator rather than a spring.  In that case, a failure of the
> air system just leaves you with compensation at ambient pressure.
> 
> Sean
> 
> 
> On 2017-09-16 10:06, Alan via Personal_Submersibles wrote:
> > Thanks,
> > yes if the sub were on an angle the weight could get lodged in position
> > temporarily, or lose some of it's force on the rolling diaphragm. 
> > But in the worst case this would leave the oil compensated at ambient.
> > I looked seriously at Hugh / Cliff's system with the regulated air supply
> > giving an over-pressure on my oil filled thrusters, but you would probably
> > need a dedicated air tank in case of a major leak, or more valves &
> > through
> > hulls to be able to turn the air off. Also the stainless regulator was
> > more than 
> > what I wanted to pay. 
> 
> > Cheers Alan
> >
> > Sent from my iPad
> 
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