Thanks Dan Cliff and Hugo,
Firstly what a great resource this community is! The information
available from the members of this site will in my case allow me to turn ideas
into reality.
I think the Double Mechanical Cartridge Seal sound like the
best option. Having a Technical Diving Background I’m very big on redundant
systems. I am more than prepared to have higher costs if it means a safer
system.
In the case of a Sub like Euronaut what system would be used
to support the end of the shaft protruding from the rear cone? Some sort of sealed
bearings or again a Mechanical Cartridge Seal?
Regards
Stephen Pearce
-----Original
Message-----
From:
owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of Cliff Redus
Sent: Wednesday,
1 February 2006
1:26
AM
To:
personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] Propeller
Shafts
A single or double mechanical
cartridge seal used on pumps are the way to go especially for higher shaft
rpm. These seals will normally handle 200+ psi differential pressure with
ease. Use a single mechanical cartridge seal for a low speed
shaft and a double mechanical seal for high speed. With a double
mechanical seal, there are two sets of carbide mechanical seals separated by a
barrier fluid that is typically held at 20-30 psi above ambient pressure.
This makes any leaks (drops) go outboard rather than inboard.
Utex http://utexind.com/main.asp makes
a nice line of single and double mechanical seals that are similar to the John
Crane seals mentioned by Hugo except they are about half the cost and use the
same bolt arrangement. For my boat I went with a Utex Liberator II ,
double mechanical seal for a 1" diameter shaft. I use a marine
propylene glycol / water 50-50 mixture (v:v) as seal barrier fluid. The
propylene glycol is used rather than ethyl glycol (antifreeze) because it
is non toxic with the same cooling capability as ethyl
glycol. If I were selecting a seal for low speed shaft, I would go
with a single mechanical cartridge seal because heat generation is not an
issue. If you speak with any of the seal manufactures, they will walk you
through ordering the correct seal materials for the faces. They will also give
you the dimensions of the cavity that needs to be machined in the inboard
side of the stern tube. One other argument for the double mechanical
is seal is safety. If one seal fails for any reason, you still have the
other seal.
----- Original Message -----
Sent: Tuesday, January 31, 2006 4:35 AM
Subject:
[PSUBS-MAILIST] Propeller Shafts
Hi everyone
Can anyone advise me on the best system of
sealing Propeller Shafts?
I will be running a Diesel Electric setup using
the Electric Motor propulsion as well as generation (I’m told you can do
this).
Are there several options available?
Stephen Pearce
Brisbane Queensland Australia