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Get to know LPG bobtail trucks: Chapter #2: Relief Valves

Jul 20, 2018

Cavagna Group S.p.A. | Get to know LPG bobtail trucks: Chapter #2: Relief Valves

In our blog last week, we covered the various internal valves available for bobtails. Link
This week we are going to share with you some interesting information about Relief Valves for LPG delivery trucks.
Let us briefly recap, the set of components for Bobtail trucks includes: internal valves, pressure relief valves, float gauges, double check filler valves, hose-end valves, swivels, back checks, excess flow valves and ball valves.
The main function of the Relief Valve, also known as Pressure Relief Valve, is to protect the tank from being over-pressurized.
Relief valves are available in 2 different configurations, flanged or threaded. The flanged relief valve is available with a 3-inch 300-pound connection and the threaded relief valve is available with either a 2 or 3-inch male NPT thread.
Similar to the internal valve, the relief valves internal mechanism is located inside of the tank allowing it to remain fully operational should damage occur to the outside of the tank.

How does a Pressure Relief Valve work?

When the tank pressure exceeds the designated set value of the relief valve, the valve will open and release LPG into the atmosphere reducing the pressure inside the tank. When the pressure inside the tank returns to the set pressure value of the relief valve it will automatically close.

Relief valves are equipped with weather caps, which protect the valve from rain, snow, ice and dirt. These caps will then be ejected from the relief valve when pressure is released, so it is important to always ensure the relief valve has its weather cap in place.

Should anyone require any clarification on any of the technical information that we have discussed here, please contact info@cavagnagroup.com

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