QOD For W/E 09-11-11 #1

Here is one more old exam question on heating/plumbing, with a twist …

The section of gas pipe close to equipment that collects sediment and other debris before the gas enters the equipment is called a:

Sediment Trap not listed, so dirt leg would have to suffice. :slight_smile:

a.k.a. :mrgreen:

See attached to stir things up a bit

Gas Piping.gif

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From the ASHI Reporter;
http://www.nachi.org/forum/newreply.php?do=newreply&noquote=1&p=821130

Drips (also called drip legs and drip tees) and sediment traps are components in a fuel gas system that help remove impurities from fuel gas. They look similar and are installed in the same place, but they serve different functions.
A drip helps remove moisture from fuel gas, whereas a sediment trap helps remove particulate impurities from fuel gas.
Both drips and sediment traps begin with a tee fitting into which a short-capped pipe (about 3 inches long and called a nipple) is inserted and turned toward the ground.
The difference between these components is where the gas connector enters the tee fitting. With a drip, the gas connector enters the tee fitting at a 90-degree angle to the nipple and in line with the gas line entering the appliance.
With a sediment trap, the gas connector enters the tee fitting in line with the nipple and at a 90-degree angle to the gas line entering the appliance.

The theory is that particulate impurities will more easily fall into the nipple if the gas flow is in line with the nipple and must change direction to enter the appliance.
IRC G2419.2 requires drips only if the gas supplier advises that wet gas exists.
This condition is rare in modern gas systems.
IRC G2419.4 requires independent sediment traps unless one is incorporated as part of the appliance.
Exceptions are gaslights, ranges, clothes dryers and outdoor grills.
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The correct answer is … dirt leg

A “sediment trap” is required just before the gas enters the equipment to catch sediment and other debris. It is also called a “dirt leg” or “dirt pocket”

A “drip” or “drip leg” is required at a low point in gas piping to collect moisture or condensate when the gas has water vapor, or is consider “wet” gas … very unusual these days.

Sometimes the short section of capped gas pipe in a basement just before the gas enters the equipment can serve both functions, but the question only related to “sediment and other debris” … that was the twist … :wink: