Calculating seal pressure
Calculating seal pressure
(OP)
I'm building an enclosure for some electronic equipment to take it underwater. Nothing complicated, a 6" cylinder with flat end caps bolted over a neoprene gasket. Is there any rule for calculating the the amount of clamping force needed on the enclosure seals to keep out the water? For example, If the end cap seals have 50 lbs of force on them, how much water pressure will that keep out?





RE: Calculating seal pressure
TTFN
RE: Calculating seal pressure
RE: Calculating seal pressure
TTFN
RE: Calculating seal pressure
The usual approach with this sort of seal is to use the force from the water pressure on the cylinder end-plate to force a seal profile against the cylinder (either radially or axially). If the seal/housing contact pressure exceeds the local water pressure then no water will come in - voila.
It is common in such circumstances to have a V type seal and angled abutment. The abutment angle on the seal works like a wedge or lever and dramatically increases the contact force between seal and cylinder, thus giving a higher seal/cylinder contact pressure for a given cylinder end-load.
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure
You should also select a good seal, probably off the net, suitable for such an application.
Also beware if you need to have any external switches or controls with wires coming out of the main enclosure. It is here that the water is most likely to get in and you would need a purpose-built (but probably still off the rack)switch interface to deal with this.
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure
OK, I did some basic calcs using some equations that I am not too familiar with - ie test what I suggest first without anything expensive inside. Also make sure that you bang the sides walls of the tube gently at depth to double check for buckling instability under rough use.
Assuming your pipe is made of some sort of Nylon and the end plates are lexan I predict that the plastic dran pipe walls will buckle with the pressure but the end plates will be OK (some comfort :-( )
I suggest using a minimum of 3/8" thickness pipe, preferably 1/2" to give you some margin for rough use.
Anybody else like to comment on my sizing suggestions?
Regards,
Gwolf.
RE: Calculating seal pressure
RE: Calculating seal pressure
TTFN
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure
p.s. O-Rings are "self Energizing" - don't need bolt force to establish initial seal
RE: Calculating seal pressure
But, I also don't want further compression of the seal from the water pressure to let the bolts get loose, since the bolts will also be used to attach handles, legs, lights etc. I think there's a way around that though if I add neoprene washers under the bolt heads, so they'll expand as the gasket is comoressed, keeping it all tight.
RE: Calculating seal pressure
TTFN
RE: Calculating seal pressure
RE: Calculating seal pressure
RE: Calculating seal pressure