GENERAL INFORMATION
3L.P.GAS excess flow valves have been designed, developped, and manufactured for a wide variety of industry needs for more than three decades.
Throughout the years, those concerned with installing and operating bulk plant facilities have looked to 3L.P.GAS products with confidence for reliable, longlasting valves as required by the National Fire Protection Association (NFPA) Standards 58 and 59, as well as any state, provincial, and local regulations.

It is a responsability we have not taken lightly.
3L.P.GAS products continue to not only assess the most effective designs, but anticipate and meet the industry's changing requirements.
Towards that goal, 3L.P.GAS products include different types and sizes of excess flow and check valves, to meet the needs of the LP gas and anhydrous ammonia industries.

HOW THEY WORK
Excess flow valves permit the flow of liquid or vapour in either direction.
This flow is controlled in only one direction (the direction of the arrow stamped on the valve).
If the flow in that direction exceeds a predetermined rate, the valve automatically closes.
The valve disc is held in the open position by a spring. When flow creates a pressure drop across the valve disc that overcomes the preset load on the spring, the valve disc moves to the closed position.

It remains closed until the force on both sides of the valve disc are approximately equal (a small bleed hole in the disc of each valve permits equalization), then the spring automatically reopens the valve.
When a line is completely broken, the pressure cannot equalize and the excess flow valve remains closed until the line is repaired.
Because the bleed hole in each valve disc permits equalization of pressure, excess flow valves do not provide a 100 percent type shut-off.
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