' I was working on a static tightness (for air conditioning), so our criteria was about sustaining pressure et limiting gaseous loss through a quick-coupling device... Thightness was maintained with few compression ratio (let says roughly diameter/compression between two flat surface), with only 5% compression, the o-ring being pushed against a third surface when under gas pressure. This low "compression" ratio was needed for ease of assembly of the coupling in an industrial way. Several material were tested keeping in mind the cost and functional application, such as HNBR, NBR, VITON, etc..
By the way it is noticeable that the Shore range is important of course. (we tested from 50, 60 to 80 Shore A). As much harder is the material, as much harder was the coupling difficult to assemble.
So, we used most of the time optical magnifier to measure micro-meter (or at least 1/100e millimeter), looking for 1% deformation.
(this percent, was to be considered for us as assembly effort on our coupling device).
Airy
To:
fairchildclub@yahoogroups.com
From:
fairchildclub@yahoogroups.com
Date: Mon, 16 Mar 2015 11:41:58 -0500
Subject: Re: [fairchildclub] Re: DOT 5 and Cleveland O-rings
So Airy – After the one-week absorption/swelling test, what was deemed acceptable – some percentage of original dimension, I suppose. Were there also any strength tests conducted that were relevant to the function of the elastomeric piece – O-ring or whatever. Thanks.
From: fairchildclub@yahoogroups.com Sent: Monday, March 16, 2015 10:32 AM
To: fairchildclub@yahoogroups.com Subject: RE: [fairchildclub] Re: DOT 5 and Cleveland O-rings
if you can have very sensitive micrometer (or visual magnifier to mesure tiny things), it is best to measure the o-ring diameter "dry", and measure again at 48hours, and at one week oil immersion. (use several pieces to be measured statistically). That's what I did when I was working professionnaly for a rubber company, years ago...
Airy
To:
fairchildclub@yahoogroups.com
From:
fairchildclub@yahoogroups.com
Date: Mon, 16 Mar 2015 08:23:15 -0700
Subject: [fairchildclub] Re: DOT 5 and Cleveland O-rings
I bought the Cleveland conversion kit many years ago, just didn’t install it during the rebuild. Back then it cost $1700, if I recall correctly. Costs 4,250 bucks these days at Aircraft Spruce. That $4k was a good guess!
I hadn’t heard of using 210 disks and brakes on the PT. Sounds like a good idea. Probably uses 2 pucks rather than the 3 as in the 310 setup. I assume that the attachment plate fits okay on the PT's strut brake attach flange. Is that true?
When I was working on the master cylinders (years ago) I found that the rubber Napa cups swelled up in 5606 hydraulic fluid, so I switched to the DOT5. Since the DOT5.1 and 5.2 are mineral based I’d guess they won’t work well with the master cylinder cups I have now. A friend is giving me some 310 O-rings this morning so I’ll give them a DOT5 soaking to see what happens. Charles
---In
fairchildclub@yahoogroups.com, wrote :
Are speaking about DOT5 (full silicon, color purple or blue)
Or about DOT 5.1 or DOT5.2 which are both still mineral oil based
???
Most of the time, on modern material, silicon doesn't have any appreciable effects.
Airy
To:
fairchildclub@yahoogroups.com
From:
fairchildclub@yahoogroups.com
Date: Sun, 15 Mar 2015 18:23:05 -0700
Subject: [fairchildclub] DOT 5 and Cleveland O-rings
I've been using DOT 5 with the Hayes expander tube brakes on my PT-26. I'm now converting to Cleveland brakes with the C-310 conversion kit.
Will the DOT-5 be compatible with the Cleveland O-ring material?
Any feedback will be helpful.
Charles
'
