Neoprene coated valve seats

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haaken
Posts: 20
Joined: Thu Mar 11, 2004 4:25 pm

Neoprene coated valve seats

Post by haaken » Tue May 11, 2004 6:41 pm

I have just read a document by Bureau of Aeronatics, they coated a the valve grid/seats on a 22 inch pulsejet. They extended the valve life to 164 minutes of operating time!

Surely beats 30 minutes!

The valve grid vas coated with neoprene by the means of a process developed by the B. F. Goodridge company of Akron Ohoi.

The process is as follows:

The grid sections are degreased, painted with a primer and brushed with a neoprene cement, dipped in a coagulant and then in Neoprene latex, washed with water and dryed with the trailing edge up.

I attaced the pdf file here

http://naca.larc.nasa.gov/reports/1945/naca-wr-e-270/
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naca-wr-e-270.pdf
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larry cottrill
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Post by larry cottrill » Tue May 11, 2004 7:42 pm

Haaken -

I think actually there is a better and easier-to-use material at the local hardware store, for anyone who wants to try this. It is Black Silicone Caulk, a material that air dries overnight and is extremely stable under a wide range of temperature conditions. I'm sure it wouldn't stand running red hot -- but your valve plate doesn't get anywhere near that hot, anyway. It is exremely tough and long-lasting, and never gets brittle in 'normal' use. I have no idea how intermittent flame exposure would affect it.

Be sure to get the 100% silicone stuff; the paintable 'siliconized' caulk will not have the stability and high-temp properties of pure silicone. Interestingly, although this material is a good electrical insulator, it is fairly good at conducting heat.

I recently repaired the valve pad on an air regulator with this stuff, and it worked great [the old rubber pad had gotten brittle and cracked -- the regulator is ancient]. You could use this in almost any situation where a permanent, flexible seal is needed. It does give off an unpleasant amount of acetic acid fumes while curing, but by the next day it is essentially odorless. You would want to form a 'seat' of some kind all around your valve port to support it, and make sure the surface is clean and de-greased. Then, just lay it in with a toothpick or other small tool -- you have plenty of time to puddle it around and smooth it out before it starts to set up. Use water for cleanup, until it starts to set.

L Cottrill

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