Regulators installed on an underground propane tank are subject to different precautionary measures for proper protection, safety and continuous operation. Concerning all propane tank installations, regulator safety and protection is of the utmost importance. But when dealing with underground installations, regulator installation takes on a new set of standards and additional safeguards. According to NFPA 58, "the discharge of the regulator vent shall be above the highest probable water level".
The term "underground regulator" may be a bit misleading as the regulator is not buried in the same manner as the propane tank. The regulator sits in an underground dome or shroud where it is protected from the surrounding earth and backfill. Under ordinary circumstances, the tank shroud (housing) and lid will provide adequate protection for the regulator. However, if the tank is buried in a location where water collects, added protection will be necessary. For instance, if the propane tank has been buried in a location where the water level may even temporarily rise above the level of the vent, additional regulator protection must be provided even if drainage seems sufficient. Tanks that are buried where drainage is sufficient do not always need additional regulator and vent protection but as previously mentioned, the regulator vent discharge must be above the highest probable water level. Any regulator that has been underwater for any length of time needs to be replaced as soon as possible.
The protection of underground propane tank regulators is essential for safe and continuous operation downstream of the tank. When additional protection is needed, such as in areas where the tank is subject to collecting water during heavy rains, a simple vent pipe can be attached to the regulator's vent inlet. The vent extension allows the propane regulator to properly "breathe" in the event it becomes submerged in water. Regulator vent extensions are installed by licensed propane companies and professionals and should be attached at the time the tank is installed. Propane customers should contact their propane company to have a vent extension installed on their underground propane tank regulator if one is not in place but is needed.
Also See Underground Propane Tanks