[PSUBS-MAILIST] oil compensation

Sun Sep 17 01:13:36 EDT 2017

Thanks Cliff,
I am committed to filling my thrusters with oil because of the
thinness of the windings in my small BLDC motors. They require
the better heat transfer that you get with oil. Also the mechanical
seals & bearings require oil.
Thanks for the heads up on the cheap Ebay regulators, will
keep an eye out.
Alan

Sent from my iPad

> On 17/09/2017, at 9:44 AM, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Alan, I have been very happy with my simplified air compensation system for my thrusters.  Yes retail price is high for these Parker/Watts R364 SS pressure reducing/relieving regulators but they come up on Ebay all the time.  I purchased two of these regulators new on Ebay for less than $40.  Also I am using a single regulator and manifolding 1/4"  SS tubing to each of the thrusters rather than having dedicated regulators for each thruster in the spirit of KISS.   Yes you use more air than an oil compensated system but since I abandoned my VBT and use thrusters for depth control, I don't use any where near the air I did when I had the VBT system and used air to blow VBT at depth.  Having used both air and oil compensated system, I prefer an air system.  Oil system are messy and air systems are clean. 
> 
> Cliff
> 
> 
> 
>> On Sat, Sep 16, 2017 at 3:22 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 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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>> 
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