Most fuel-gas appliance manufacturers require the installation of a sediment trap. Sediment traps prevent debris from entering the gas controls and causing hazardous malfunctions.
A sediment trap should be installed downstream of the equipment's shut-off valve as close to the inlet of the equipment/appliance as possible. Sediment traps cause the gas flow to change direction 90 degrees at the sediment-collection point. The solids and contaminants in the fuel will drop out of the gas flow at the collection point. The sediment trap could be constructed as a T-fitting with a capped nipple at the bottom of the opening of the run of the tee. Thank you InterNachi @ www.nachi.org