o-ring grease question

snip:

"I just happen to hate petro jelly due to non-rocketry reasons, and refuse to use it."

I'm not sure I should even ask...

Plain white lithium grease has a temperature range of about 0°F to

300°F. It should be fine for o-rings, and maybe for liners and threads with some reloads.

NFPA 1127 specifies that a case is to not get hotter than 200 degrees C, which is just under 400 degrees F (392 degrees F). (I believe that spec has been moved to 1125 in the latest versions of 1127 and 1125.) Therefore a propellant liner and closure grease should be able to stand up to 400 degree F.

Not all motor cases get up to 200C. I have no idea how hot the average case gets. But I do know that a stuck phenolic liner isn't fun. The more costly the case the less the fun. I've also seen closures refuse to unscrew until a large wrench was applied.

Synthetic grease with Teflon (such as Radio Shack's "Gel Lube") has a working temp of about -45F to +450F, which means you'll still be able to use it on a cold day. Some are rated at -65F to 500F.

Dow 111 is rated for -40F - 400F.

Dow 112 is rated for -40F - 450F.

Dow 111 and 112 will work with AeroTech motors, but cost more and are harder to find.

If you want to go all out, how about a nuclear grade, nickel-based antisieze grease with a working temp of -65F to 2600F? A 4 ounce can is about $22.00.

Or

"This environmentally friendly antiseize lubricant is made of graphite blended with high-temperature lubricating solids, extreme-pressure additives, and corrosion preventatives. Meets MIL-PRF-907E. Temperature range is -297° to +2400° F. Color is black."

Dean

That's for Hy-Brids Iz

Way too exspensive for RMS motors, $29 for 2oz. Use white lithium wheel bearing grease or super lube at the auto store for $2 a butter tub.

I use it fine. Others take their grease hypos and refill them out of my huge "butter" tub of it I got at home depot or the parts store.

Don't over do any grease. you really don't need grease if everythings perfect.

Art

That still works for for reloads. you are greasing the o-rings so they don't get bent out of shape on installation.

you grease the threads to keep them from galling on asembly. you should not be reling on the grease to provide a flame redardant shield of any sort.

my 2 cents, and have been using it for years, since late 91 ?

these comments are ment for 38 and 29 mm reloads.

not 54 and up.

Art

thanks for being kind in your correction (as have others)

:)

- iz

Yep, that's what I use, just toss it in the range box. I use enough to just shine up the o-rings. Greasing the motorliner and everything else in sight is not necessary, IMO.

-- Joe Michel NAR 82797 L1

Apparently you've never had a stuck liner then. Very common especially in the larger motors, or long burn motors. Especially the phenolic EX liners. I once forgot to grease one, and spent the better part of a week soaking it in WD-40 and pounding the heck out of it.

Mike Fisher

Doesn't Aerotech specificly say not to use petroleum based products?

This is directly from an Aerotech instruction pdf.

"Apply a light coat of grease to the 3 O-rings and all threaded surfaces. This will facilitate assembly and prevent the threads from siezing. NOTE: When all the grease that comes with the motor has been consumed, use petroleum jelly or similar grease."

Stones

"stones" wrote in news:lGdUb.29867$M81.13515 @twister.rdc-kc.rr.com:

The only argument I've heard against using vaseline is that most people buy it in tubs, and it tends to get grit in it when it's open at the field. Grit could cause an o-ring to fail, which is obviously bad for the motor. My solution is to buy vaseline in tubes, so contamination isn't a problem.

Such tiny ammounts of lube are used in a motor that I don't think the composition really matters, as long as it doesn't react with the motor materials or combustion byproducts. You would not want to use a petroleum based lube in a motor that used pure O2, but that's not an issue with solid motors.

Such concern, however, is the reason that a noncombustible fluorocarbon grease such as "Krytox" is recommended for N2O hybrids.

-dave w