A dirt leg is created by putting a T on a short nipple into the gas control. One uses the center port of the T and then one turns the T so that it faces up and down. On the down side, one installs a 5- or 6-inch-long nipple with a cap on the end. On the up side, one installs the gas flex line adapter. The ideas is for the gas to make a turn into the control and drop any debris into the capped pipe.