In a gas supply line, what is the primary function of a drip leg?

• A. Filters gas before it enters the appliance
• B. Collects condensate
• C. Reduces gas pressure to the appliance
• D. Acts as a gas trap for odorization

Answer: (B)

In gas supply lines, the main purpose of a drip leg is to collect condensate. As gas cools or moves through the piping, moisture and any entrained liquids can condense and settle out. The drip leg provides a vertical pocket where liquids and sediments can drop away from the moving gas, and it includes a drain to remove those liquids before the gas continues on to appliances. This helps protect regulators, burners, and control components from moisture and contaminants.

It isn’t a filter, so it doesn’t remove particulates like a dedicated gas filter would. It doesn’t reduce pressure—that’s done by a regulator. It isn’t used for odorization—that process adds odorant separately.