[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PSUBS-MAILIST] No Machining Hatch Sealing Concept



Ja Alan
We did not want to embarrass them in front of there families,
Thanks for info
Glen SA
----- Original Message -----
From: Alan James
Sent: Sunday, September 06, 2009 12:45 AM
Subject: Re: [PSUBS-MAILIST] No Machining Hatch Sealing Concept

Hi Glen,
Didn't the Aussies play well.
Below is a link to a good article on seals.
 
Alan
----- Original Message -----
From: glen brown
Sent: Sunday, September 06, 2009 8:20 AM
Subject: Re: [PSUBS-MAILIST] No Machining Hatch Sealing Concept

Hi Frank D
I understand the theory but keeping the ''hatch'' o ring from falling out of the groove surely the mouth of the groove cant be larger than the diameter of the material of the o ring or does one simply use an o ring with a slightly smaller ID which holds against the inner tapered wall of the groove .
All the best
Glen SA 
----- Original Message -----
Sent: Saturday, September 05, 2009 7:23 PM
Subject: Re: [PSUBS-MAILIST] No Machining Hatch Sealing Concept

Hi Brent. The groove for an "O" ring is quite a bit wider than the "O" ring itself, leaving a space inside the groove for water to get into. The "taper" in the groove is on the inside face and it's only a tiny bit, under 5 degrees out of plumb. The bottom corners of the groove are supposed to be rounded slightly. The Parker "O" ring "design book" explains the function and has charts for sizes and many different types of applications depending on what the "O" ring is trying to accomplish. There's quite a few different types of groove shapes with some designs based on a rotating shaft, sliding shaft, and a bunch of other applications. The common function of all of them is to apply pressure against the rubber and force it into a TINY crack.
The "O" ring gets pushed up against the inside groove wall  as the water pressure is applied. The "O" ring doesn't really deform into a slightly rectangular shape until the pressure builds up enough to squash the hatch down.
The groove needs to be wide enough to accommodate the "squared" "O" ring and still leave enough space for the water to get in there so the water is applying pressure to the "O" ring, forcing it up against the crack between the two metal surfaces. It's a real simple design and can withstand a LOT of pressure.
Your rendering shows the taper on the outside groove wall and the rubber "O" ring is filling the groove. That won't seal because there's no where for the water to get in there so it's actually acting like a flat gasket.
The water would slip under the squared "O" ring because the pressure is being applied to the gap and not "behind" the "O" ring.
Frank D.
 
                                                      
                                                               



No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.409 / Virus Database: 270.13.77/2346 - Release Date: 09/04/09 17:51:00



No virus found in this incoming message.
Checked by AVG - www.avg.com
Version: 8.5.409 / Virus Database: 270.13.77/2346 - Release Date: 09/04/09 17:51:00