Light Aircraft Association

Guys,

I've been looking into brake seal materials to ensure compatibility with master and slave cylinders.
From what I can gather so far, EPR is suitable for Dot3 and Dot4 Glycol based fluids and Dot5 Silicon based, but not Mineral based oils.

Does anyone know the common materials used for the first group, Dot 3,4,5 and a different fluid for Mineral based oils?

Cheers

Gavin

Hi Gavin,

I was faced with this question when I needed to match some motorcycle master cylinders running DOT 3 and Dot 4 automotive brake fluid to some US made disc brakes designed to run on aircraft-type mineral hydraulic fluid, typically Mil-H-5606.

My research found that EPDM was appropriate for the glycol-based DOT 3 and 4, whereas Nitrile (Buna-N) was right for the mineral fluids and also Silicone oils. I subsequently found a firm who were able to make me some EPDM seals to fit the US disc brakes, at a very reasonable cost too.

http://www.efunda.com/designstandards/o ... emical.cfm is a helpful site for checking the compatibility of seal materials with different chemicals, as is http://www.pspglobal.com/fluid-compatibility/index.html.

Good luck!

John.

Hi John,

Thanks for the information and references.
I'm going completely with the mineral based oil with placard on the reservoir and note in the aircraft logbook.


Many thanks

Gavin