Weather Cover/Chinese Hat
Weather Cover/Chinese Hat
(OP)
I've researched everything I can find to no avail concerning deltaP related to the effect of a weather cover on a vertical relief line. I think at one point in the past I had seen an estimation based of % free flow height (above pipe exit) as related to diameter.
Does anyone have a reference, or could point me to one?
Don
Does anyone have a reference, or could point me to one?
Don





RE: Weather Cover/Chinese Hat
I have only seen "chinese hat" rain covers on flue gas vents (stacks)from boilers, never on safety or relief valve discharges.
Addtionally, unless you have a very large amount of rain and/or no means to drain the flue gas vent, I would recommend against these.
If you have a safety/relief valve dischrge, put a drain on an elbow inside the building and you are done.
-MJC
RE: Weather Cover/Chinese Hat
in addiction to the drain suggested, your vent may be covered with a light, loose lid ( attached by a string, to avoid beeing thrown away ). If the line doesn1t have constant flow, this will avoid any unexpected clogging.
RE: Weather Cover/Chinese Hat
Typically, I use two 90's to make a "goose-neck vent", but this question arose, thus my enquiry.
RE: Weather Cover/Chinese Hat
Chinese hats are to be avoided.
RE: Weather Cover/Chinese Hat
RE: Weather Cover/Chinese Hat
There seem to be pleanty of uncovered vents around with a 1/4 inch hole at the bottom of the ell coming off the PSV outlet for draining any accumulated condensation or rainwater.
http://virtualpipeline.spaces.msn.com
"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein
RE: Weather Cover/Chinese Hat
psafety, the latter reference ACGIH manual does provide in several places the estimated loss due to 'weather caps' along with a warning in each place 'not reccommended' or 'wrong'.
I used very successfully a few years ago a 'rain tripper' and drain arrangement shown in the offset stack of Fig. 6-24. Looks to me like there are a couple of good concepts there in that figure to deal with your problem.
Probably the cheapest solution is dcasto's suggestion. Unfortunately, it would never, ever fly in our operation.