[PSUBS-MAILIST] Brushless Thruster

Tue Oct 4 23:25:09 EDT 2016

Banging my head against a wall as usual.
No the local seal expert doesn't have a balanced seal that fits a 10mm shaft.
Nearest is 18mm. This will cost around N.Z. $200-. The motor only cost $60-.
The standard unbalanced mechanical seal ($60-) he doesn't recommend for
the pressure at 500ft, even though the thruster is oil compensated.
I may stick with my 2 lip seals.
The upside is It made me think about attaching an 18mm stainless shaft over
the motors 10mm shaft, which may be an easier option than replacing the shaft
right through the motor.  
Alan

Sent from my iPad

> On 5/10/2016, at 2:02 am, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> Hank,
> I did a bit more Googling on their site, & apart from more complicated systems
> for large pumps, they use a balanced mechanical seal for submersible fluid
> compensated pumps. I have sent an email off to a local agent, so I could come 
> up with a more specific answer.
> Surely they will have one for a 10mm shaft??
> Alan
> 
> Sent from my iPad
> 
>> On 5/10/2016, at 1:16 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Alan,
>> There is a picture of the mechanical seal  if you scroll down on the site you provided us.  It looks like a typical ceramic spring seal, same as what was in my Perry thrusters.  I think the K subs used the same thing.
>> It might be a trick finding a 10 mm though.
>> Hank
>> 
>> 
>> On Tuesday, October 4, 2016 2:04 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> 
>> I am not sure Brian.
>> I am thinking that a balanced mechanical seal would be necessary if I went
>> with a mechanical seal. Even though the motor is compensated it would
>> have more pressure pushing the faces together at depth. 
>> Every ROV  & submarine thruster seems to have a different seal.
>> I might try & contact this submersible pump manufacturer & see what they use.
>> https://www.flowserve.com/sites/default/files/2016-07/fpd-1362-ea4.pdf
>> They have been in the business of manufacturing submersible pumps for 50
>> years.
>> Their headquarters are in Hamburg. Carsten, if you know them I am wanting advice
>> for a mechanical seal for a pressure compensated thruster with a 10mm shaft 
>> rotating at 1500 rpm when under load.
>> Thanks
>> Regards Alan
>> 
>> 
>> Sent from my iPad
>> 
>>> On 4/10/2016, at 2:38 pm, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> I thought the ceramic seals were the way to go on those motors.
>>>  
>>> Brian
>>> 
>>> --- personal_submersibles at psubs.org wrote:
>>> 
>>> From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>> Subject: Re: [PSUBS-MAILIST] Brushless Thruster
>>> Date: Mon, 3 Oct 2016 22:44:10 +0000 (UTC)
>>> 
>>> Alan,
>>> You are right, the mechanical seal is the easiest way to go.  My Perry thrusters had simple spring loaded seals with a sealed cavity behind the mechanical seal.   You will be oil filled, so the seal will have the back up oil.
>>> Hank
>>> 
>>> 
>>> On Monday, October 3, 2016 1:27 PM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Hank,
>>> yes I like the idea of going straight to the penetrator with the clear tube attaching
>>> on to a barbed fitting. I want to put a 4psi overpressure in the system & are
>>> intending to do this with compressed air; so need to tee in an air line. I also
>>> need an oil filling point, however the air connection point could double for this.
>>> I like the clear tube as it is a visual indication of the oil level.
>>> I have 2 lip seals at the moment. Hugh wasn't too impressed with that idea
>>> & thought I should go with a mechanical seal. From what I have read, the shaft
>>> the lip seal runs on needs to be plunge ground to a certain finish, & a mechanical
>>> seal would eliminate that precision process.
>>> Also I look at what other large manufacturers have done & figure they have
>>> done the research on seals & have the experience.
>>> Cheers Alan
>>> 
>>> Sent from my iPad
>>> 
>>> On 4/10/2016, at 12:37 am, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> Alan,
>>> You can make up a pretty simple penetrator for the wires, or why not leave the wires the way they are in the clear tube and run the tube to a penetrator on the sub that is made from a barbed fitting.  The clear tube can be oil filled and act as your compensator.  I know you already though of this.  I think the DW's work like that.
>>> If you are oil filled, why the mechanical seal.  Just go with a higher pressure rated lip seal.
>>> Hank
>>> 
>>> 
>>> On Monday, October 3, 2016 3:40 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Hi Hank, thanks.
>>> yes am intending on getting that type of seal, but I will try & get some advice
>>> on an appropriate seal for the viscosity & type of oil I am using (Morlina S2 Bl 10).
>>> Must be a bit barmy because I was getting quite excited about the new 
>>> compensating oil I bought. 
>>> I haven't quite decided how I am going to terminate the wires coming out of the 
>>> motor. At present I have the wires running through a clear hose up to a manifold.
>>> I say manifold but it is a modified brass T plumbing fitting. The hose is hose clamped
>>> to one end & the wires are silicone sealed coming out the other end. On the T I have
>>> a plug that I can remove to fill the tube & thruster with oil. This is okay for experimental
>>> purposes but will need to add pressure to the system & a through hull fitting
>>> when I mount it on the sub.
>>> Alan
>>> 
>>> 
>>> Sent from my iPad
>>> 
>>> On 3/10/2016, at 9:28 pm, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> Alan,
>>> That is great! well done..  What type of mechanical seal will you use?  Are you planning a spring loaded pump seal?  
>>> Hank 
>>> 
>>> 
>>> On Monday, October 3, 2016 2:07 AM, Alan via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> 
>>> 
>>> Just did a pool test of my latest brushless thruster.
>>> This thruster uses a 60kv (revs per Volt) 6374 (dimensions in mm) brushless
>>> sensored outrunner motor. The propeller was a 3 bladed 7&1/4" x 4" with no kort nozzle.
>>> I was getting 30kg (66lb) thrust from 30 amps off 52 volts (1560W) with the thruster
>>> oil filled. This seems comparable to what Cliff was getting from his Minnkota 101.
>>> The difference is this is a much smaller unit. I have been keeping a file on
>>> performance statistics of commercial thrusters & trolling motors & this is slightly 
>>> above average.
>>> The manufacturer told me not to run the motor more than 40 amps continuosly,
>>> so I am being conservative with the 30 amp draw. I could bump it up by putting
>>> on a bigger prop.
>>> Next step is to use it as a boat motor & notch up 100 or so hours, then build
>>> another housing with a mechanical seal.
>>> Added a couple of photos to the project page, but they loaded upside down for
>>> some reason. Couldn't change them. 
>>> http://www.psubs.org/projects/1235435392/brushlessthruster/
>>> Alan
>>> 
>>> Sent from my iPad
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