dead-end nipple before a gas appliance

amakarevic

some guy at home depot that looked like a total random told me that you are supposed to use a dead-end nipple before your gas line makes a 90 deg turn towards an appliance, by actually using a tee rather than an elbow with the nipple going into the tee socket opposite from the direction of flow. he said that is needed in case some completely foreign particles come through the gas line to prevent them from going into the appliance by trapping them into the nipple.

is this guy really onto something or had he been smoking stuff ? it does not sound like an effective way to trap foreign particles to me, why wouldn't they follow the line into the appliance rather than going straight into the dead-end nipple ? i thought that, if this were an issue, they would rather make some sort of filters that get mounted on the line to make sure there is no weird stuff.

nap

actually, he is correct. It allows larger particles of debris (rust, sand) to fall to the bottom of the nipple rather than making the turn and flowing into the appliace.

amakarevic

dude, why don't they make a filter box of some sort ?

how bad is it if you don't do it ? what percentage of applications have it ?

amakarevic

also, which length nipple should i use for this ?

DangerMouse

every gas furnace i've seen has it. there's probably code for this....

DM

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DangerMouse

for a pic of my furnace as example, see this thread. http://www.diychatroom.com/showthrea...517#post178517
post #3

DM

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skymaster

The term is a "drip Tee" it allows debris and condensation to fall out of the gas stream and not contaminate the feed into a device

Clutchcargo

3" drip leg is code in Massachusetts. YMMV

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Marvin Gardens

You should have one in every line. It doesn't have to be right at the appliance.

If you decide not to put one in then get ready to clean your appliances as they slowly fill up with crud.

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SD515

Drip-leg, drip-tee…we call them soot-traps. A 3 inch trap at the end of the run before the pipe enters the appliance is needed. Appliance gas valves have a screen in their inlets to block larger particles, and the soot-trap collects smaller particles that drop out of the gas stream.

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Kyle

Just because you can, doesn't always mean you should

DangerMouse

i think we should mention too that the end has a square-end plug to allow for easy cleaning. (when the gas is turned off, of course)
hi Kyle.

DM

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skymaster

Gas off?? DM you take all the fun outta it!!!!!!!!!!!!
Of course OFF MUST BE Just in case somebody took me serious

Marvin Gardens

I've pulled traps out that were 50 years old and there was hardly anything at the bottom. I can see about 1000 years from now that they might need a cleaning.

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fireguy

In Oregon the drip leg is code. I have opened a number of gas lines over the years, not as many at Marvin Garden. I can only think of one job where I found galvanized flakes, and that pipe was at least 25 years old. Those flakes had not made it to the drip leg. And I have never seen a screen in the appliance regulator, but then I do not do residential, just commercial.

nap

I guess that is testimony as to why you are not supposed to use galvanized pipe for gas systems.