Purpose-built for horizontal installation under RV chassis, in pass-through compartments, or in motorhome propane bays, the Flame King YSN301HZL gives you serious propane storage capacity without the vertical-tank footprint that many RV mounting positions simply cannot accommodate. The tank ships empty and ready to fill at any certified propane station.
Many Class A motorhomes, Class C rigs, and fifth wheels mount propane cylinders horizontally under the coach or inside a dedicated propane compartment. Standard vertical tanks are not approved for this orientation -- the liquid propane can block the vapor valve and create a dangerous delivery condition. The YSN301HZL is engineered and DOT-certified specifically for horizontal use, so the valve, dip tube, and OPD (Overfill Protection Device) all function correctly when the tank is lying on its side.
At 30 lbs of propane capacity (approximately 7.1 gallons), this cylinder keeps your furnace, water heater, cooktop, and refrigerator running significantly longer between fill-ups compared to a standard 20 lb grill tank. It is a popular upgrade or direct replacement for worn, expired, or undersized OEM cylinders on motorhomes and large travel trailers that use horizontal mounting systems.
DOT-approved valve and dip tube orientation ensures safe liquid-free vapor delivery when mounted on its side -- required for under-coach RV propane bays.
Integrated Overfill Protection Device valve meets current federal code. Required on all cylinders 4 to 40 lbs. Prevents dangerous overfilling at the pump.
Powder-coated exterior resists rust, road grime, and UV exposure common in under-chassis propane compartments. Built to handle the road environment.
Arrives empty and ready for your first certified fill. No waiting on hazmat processing and no compliance issues at checkout or at the fill station.
Propane tanks are pressure vessels designed with a specific internal geometry. A standard vertical cylinder has its dip tube and valve positioned so that vapor -- not liquid -- exits the tank during normal use. When you lay a vertical tank on its side, liquid propane can reach the valve, travel into the regulator and appliance lines, and cause appliance damage or a safety hazard.
The YSN301HZL is built from the start for horizontal service. The valve stem and dip tube are oriented so that in the mounted-horizontal position, only vapor exits the service valve. This is not a field modification -- it is a factory-engineered, DOT-certified configuration. Never attempt to use a standard vertical tank in a horizontal mount.
The YSN301HZL measures 23.7 inches long x 13.0 inches wide x 12.0 inches tall (as mounted horizontally). Before ordering, measure your RV propane compartment or under-chassis bracket clearance against these dimensions. Common compatible mounting applications include:
The service valve uses the industry-standard 1-3/4 inch ACME left-hand thread (Type 1 -- QCC1) connection found on virtually all RV propane regulators and pig-tail hoses. No adapter is needed if your existing regulator hose uses a standard QCC1 fitting.
DOT propane cylinders manufactured in the United States require requalification every 12 years from the manufacture date stamped on the collar. After the first requalification, the cylinder must be requalified every 5 years. The manufacture date (month and year) is stamped directly on the cylinder collar. Most certified propane fill stations will inspect and note the date before filling. Plan ahead -- expired cylinders will be refused at the pump.
Flame King is a well-established propane cylinder brand offering DOT-certified tanks ranging from 1 lb camping canisters up to 100 lb stationary cylinders. Their horizontal RV cylinder line -- including the YSN201HZL (20 lb) and this YSN301HZL (30 lb) -- is designed specifically for the RV aftermarket, where horizontal orientation and precise bay dimensions are critical. Flame King cylinders are manufactured to DOT 4BW240 specification, using welded steel construction with a powder-coat exterior finish.