The Marshall Excelsior MER401-20 is a 20-inch flexible LP gas pigtail hose designed to connect a propane cylinder valve to a regulator or distribution system. The excess flow feature helps shut off gas flow automatically if a downstream line ruptures or separates -- a critical safety layer for any RV or outdoor LP installation. Built in the USA with crimped brass ferrules and UL/CGA-listed thermoplastic hose, this pigtail is a direct, code-compliant replacement for worn or aging hoses on single- or dual-stage regulator setups.
Propane pigtail hoses take more abuse than most RV owners realize -- constant connect/disconnect cycles, UV exposure, road vibration, and occasional kinks all degrade hose integrity over time. Marshall Excelsior has specialized in LP gas components since 1954, and the MER401-20 reflects that focus: the thermoplastic inner core is formulated specifically for liquid and vapor LP service, and the fully crimped brass ferrules eliminate the leak points that compression-only fittings can develop.
The 7/8-inch POL (Prest-O-Lite) left-hand-thread nut seats securely into a standard ASME/DOT propane cylinder service valve -- the same valve found on 20 lb, 30 lb, and most portable cylinders. The opposite end terminates in a 1/4-inch male inverted flare, which connects directly to most two-stage RV regulators, manifold blocks, and automatic changeover regulators without an adapter.
Internal excess flow mechanism restricts gas flow if a line breaks or separates downstream, reducing fire and explosion risk at the cylinder connection.
Both ends are factory-crimped -- not clamped -- for a leak-free, pull-resistant seal rated to 400 lbs. of tensile force.
Meets UL and CGA standards for LP gas service. Accepted by NFPA 58 compliant installations and required for many campground and RV park hookups.
Integrated thermal protection helps the hose withstand elevated temperatures -- useful when routed near engine compartments, generators, or enclosed battery areas.
Getting the threads right is the most common pigtail selection mistake. This hose uses two distinct connection standards:
If your regulator uses a 3/8-inch inverted flare inlet or a POL female inlet, you will need a separate fitting adapter -- this hose will not connect directly in those cases.
Marshall Excelsior manufactures this hose domestically and backs it with a 5-year limited manufacturer warranty against defects in materials and workmanship. Replace every 5 years regardless of appearance, or immediately if cracking, stiffness, or odor of propane is detected near the hose body.
A standard pigtail hose passes gas freely regardless of downstream conditions. An excess flow hose (like this MER401-20) contains a spring-loaded check mechanism that senses abnormal flow rates and restricts flow automatically. For full-timers, boondockers, and anyone running long propane lines through the chassis, the excess flow version is the preferred choice and may be required by local codes.