[PSUBS-MAILIST] air compensation

[Jon Wallace via Personal_Submersibles]

 I don’t think we should lose sight of the logistical issues surrounding air comp including regulators and hoses which open potential failure points, and the potential of additional tanks and getting them filled in a location that does not have good SCUBA support.  Just the fact that oil comp reduces the number of components to achieve the intended result makes it an attractive option in my eyes. 
Cliff, the photos appear to show a lot of sludge…do you attribute this to the brushes only?  How badly were the brushes worn and are they still solid or has the oil penetrated them to the point that they are soft and decaying?   Are all four motors in the same condition with score marks on the shaft and commutator?
Jon

    On Sunday, July 30, 2023 at 03:20:17 PM EDT, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
  Hank, I did a calculation yesterday as to how much air it would take for the four Minn Kota 101s for a round trip to 300 fsw and back.  The answer was 1.5 SCF for the total (37 fluid oz internal volume in each thruster).  This was less than I expected so I am not feeling so concerned about the R300 HP air supply if I switch back to air compensation.  I have not made this decision yet, but I don't have high hopes that I am going to be able to find an oil that will not be affected by the arcing for these 101s.
Gas leak detection with soapy water works.  Can you send me the make and model of the first stage scuba regulator you are using and the part number for the pressure relief valve you are using?  If I switch back to air compensation, I cannot use the first stage I have because I have need for it at 50 psig above ambient for BIBS and MBT blowing.  I found the previous pressure regulator I used was just too small to handle four thrusters which was how it was plumbed.  It sounds like your regulator might work better.  
I will be interested in your next dive with all four thrusters under air compensation.  Hopefully it will be deeper to give the air compensation system a good test.
Cliff
    On Sunday, July 30, 2023 at 09:36:09 AM CDT, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
 Cliff, I am wondering if you can reduce the volume of air inside the motor to reduce air consumption?  Maybe some form fitted plastic inserts between the magnets etc. I have just discovered a nice feature while connecting my rear thrusters to the air compensation  system this morning.  You can pressure test for leaks with your soapy water sprayer. Hank_______________________________________________
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