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Parker Brakes Nitrile or Viton

ExtraKatana

Well Known Member
I have the 30-9 Parker single puck. Needing to replace the O-Ring. I have read in the parts manual for the 30-9 that the 101-02300 (23mm) is the replacement O-Ring but not sure if a similar Nitrile or Viton 23MM will work. I pulled a 23MM from the Parker assortment of O-Rings I have at home and that lasted about 60 hours. Might be the 8606 Hydraulic fluid working on the regular rubber. When I picked the O-Ring out of the puck it was square like it might not have been the right composition or it would have retained its shape. Some swear by Viton O-Rings. Others say they don't do well in cold. The replacement ring is $20 per O-Ring at Spruce for the original part number. Anyone that has gone down this path with the Parker 23mm O-Ring?
 
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There's wide-temperature Viton materials available too, Parker has them as GLT and GFLT.
I've looked into these for my calipers but none of the distributors I've talked to keep stock. With a minimum special order of around 150pcs, I haven't gone anywhere with it.
 
Parker Brakes Nitrile or Viton Reload this Page Reply to Thread

Nitrile 75 durometer has worked for me, granted a different size. Buy from McMasterCarr, they have tons of sizes in stock, in small affordable quantities. This part of the world of aviation has always driven me nuts - that horrible red turns sticky, is flammable MS brake fluid, O-rings that can't handle the heat (that's why yours turned square). I Changed all my caliper O-rings to Viton and fluid to DOT5 silicone a long time ago after the first time my caliper rings turned flat and the plane greeted me with fluid puddles on the ground. Worked perfectly ever since.
 
Nitrile 75 durometer has worked for me, granted a different size. Buy from McMasterCarr, they have tons of sizes in stock, in small affordable quantities. This part of the world of aviation has always driven me nuts - that horrible red turns sticky, is flammable MS brake fluid, O-rings that can't handle the heat (that's why yours turned square). I Changed all my caliper O-rings to Viton and fluid to DOT5 silicone a long time ago after the first time my caliper rings turned flat and the plane greeted me with fluid puddles on the ground. Worked perfectly ever since.

I do see the 23mm ID in the 75 durometer. $16.50 for 25
The thickness I'm not sure of. The orig. Parker part number is 101-02300. Where 02300 is 23MM, the thickness of the groove is just shy of 4 MM. Gonna go with 4.
 
Aircraft Spruce and McMaster are inexpensive sources

I have the 30-9 Parker single puck. Needing to replace the O-Ring. I have read in the parts manual for the 30-9 that the 101-02300 (23mm) is the replacement O-Ring but not sure if a similar Nitrile or Viton 23MM will work. I pulled a 23MM from the Parker assortment of O-Rings I have at home and that lasted about 60 hours. Might be the 8606 Hydraulic fluid working on the regular rubber. When I picked the O-Ring out of the puck it was square like it might not have been the right composition or it would have retained its shape. Some swear by Viton O-Rings. Others say they don't do well in cold. The replacement ring is $20 per O-Ring at Spruce for the original part number. Anyone that has gone down this path with the Parker 23mm O-Ring?

A chain of specifications:
  • Cleveland Parker o-ring PN 101-02300 cross-references to MS28775-218 where dimensions are given. (Ref Aircraft Spruce here. If that link is broken you can google "CLEVELAND 30-9 500 X 5 COMPLETE BRAKE ASSEMBLY" hopefully you'll find the Aircraft Spruce page.)
  • MS28775 points to MIL-P-25732 for material. (Ref MS28775 title block, lower left, "Procurement Specification".)
  • MIL-P-25732 requires the material to be:
    • Good for use in MIL-H-5606 and MIL-H-83282 hydraulic fluids, -65 to 275F
    • Shore A hardness 68 minimum.
    • Butadiene acrylonitrile material (aka: nitrile rubber, nitrile butadiene rubber, NBR, buna nitrile, Buna-N, acrylonitrile butadiene rubber).

MS28775 and MIL-P-25732 are available for free on everyspec.com

MS28775 sizes:
  • -218 is often listed as 1-1/4" id and 1/8" width but it's actually 1.234 x .139.
  • Catalogs often refer to AS568 "Aerospace Size Standard for O-Rings" which gives dimensions without calling on a material spec.

Search Aircraft Spruce for PN AN6227B-23 or MS28775-218 and it's $1.05. (AN6227 was cancelled in 1985) I see the > $20 Cleveland Parker 101-02300 o-ring also... maybe that one comes in a Cleveland Parker bag LOL.

If you look on McMaster-Carr, size -218 is available in various materials.

McMaster 4198T255 is Buna Nitrile, size 218, meets the MIL-P-25732 material spec, Shore A 70 durometer, McMaster calls it -65 to 275F, $15.05 for 25.,

Viton fluorocarbon:
  • Viton fluorocarbon is good for higher temperatures compared to Buna Nitrile but gets amazingly stiff at cold temperatures (like 30F). I don't know how much better Viton GFLT is at low temperature... Good For Low Temperature LOL.
  • If you want to try Viton, 1288N178 might be a good choice, McMaster calls it “super-resilient”, rated to -15 to 400F, 75A durometer, I wouldn’t go harder than that.
  • When I worked in automotive gasoline fuel injector design in the ‘90s, we used Viton GFLT sometimes for its high temperature capability, 400F. Those o-rings had a tendency to weep at -40F where the engine was required to start but sealed as the engine warmed and were un-damaged.
 
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Cleveland Parker o-ring PN 101-02300 is MS28775-218. MS28775 calls for it to meet MIL-P 25732 which says it's good for use in 5606 hydraulic fluid up to 275F, also Shore A hardness 68 minimum.

MS28775-218 is often listed as 1-1/4" id and 1/8" width but it's actually 1.234 x .139.

Search Aircraft Spruce for PN AN6227B-23 or MS28775-218 and it's $1.05. (AN6227 was cancelled in 1985)

If you look on McMaster-Carr, size 218 is available in varoius materials.

One commercial site I looked at says MS28775 o-rings are Buna Nitrile.

Viton flurocarbon is good for higher temperatures compared to Buna Nitrile but gets amazingly stiff at cold temperatures (like 30F). I don't know how much better Viton GFLT is at low temperature... Good For Low Temperature LOL.

THANK YOU!!!
 
If you look in McMaster, the -218 O-ring is available in several Viton grades. I use the brown Viton grade which is good down to -15 degrees Fahrenheit. Good enough for me.
 
Have you tried "the o-ring store"? I have found them to meet my needs so far. # 218, Buna-N $.32. (15 minimum)- -Viton 75 Durometer, #218 mils spec - $1.00 no minimum.
 
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Viton will leak at cold temps. Buna Nitrile is softer and will wear faster. So it depends if you want to have brakes and stop when it's cold and replace them from time to time, or have a leaker when it is cold.
 
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McMaster 4198T255 is Buna Nitrile, size 218, meets the MIL-P-25732 material spec, Shore A 70 durometer, McMaster calls it -65 to 275F, $15.05 for 25.

If you want to try Viton, 1288N178 might be a good choice, McMaster calls it “super-resilient”, rated to -15 to 400F, 75A durometer, I wouldn’t go harder than that. When I worked in automotive fuel injector design in the ‘90s, we used Viton GFLT sometimes for its high temperature capability, 400F. They had a tendency to weep at -40F where the engine was required to start but sealed as the engine warmed and were un-damaged.

I ordered from McMaster C the Buna Nitrile that meets the MilSpec. 25 for $15 I couldn't pass up although I'll have O-Rings for life in this application. I needed to order some Torx screws also.
 
Viton will leak at cold temps. Buna Nitrile is softer and will wear faster. So it depends if you want to have brakes and stop when it's cold and replace them from time to time, or have a leaker when it is cold.

I disagree. It depends on the durometer of Viton you use. Mine are 75, and you can get even softer as cited in a previous post. You just don't want to use 90. I live in Chicago and routinely fly down to 10 degrees F, and have never had a leak. Five years now with Viton 75 rings and DOT 5 silicone fluid.

Especially if your wheels are tightly cowled, I would state the trade off as brakes that always work v.s. one day finding your brake fluid leaked out due to heat set damage to Buna N caliper O-rings.
 
I disagree. It depends on the durometer of Viton you use. Mine are 75, and you can get even softer as cited in a previous post. You just don't want to use 90. I live in Chicago and routinely fly down to 10 degrees F, and have never had a leak. Five years now with Viton 75 rings and DOT 5 silicone fluid.

Especially if your wheels are tightly cowled, I would state the trade off as brakes that always work v.s. one day finding your brake fluid leaked out due to heat set damage to Buna N caliper O-rings.

yep, it depends on the Viton hardness. the coldest I ever operated on the ground is -20C but colder in flight. 8 yrs on the original seals.

initial cold weather testing in Wisconsin in 2013. -20C in-flight at less than 3000 ft but warmer higher. ah, those were the days. fly to some place really cold and determine if everything works. also, let it soak overnight in the cold temps. you may learn something. I'm sure the guys in Alaska could teach us a thing or two.

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