Liquid Withdrawal Valve

Figure 1 7590U with Cap

The liquid withdrawal valve is often known by manufacturer names such as Chek-Lok or Checkmate. However, the proper name is "actuated liquid withdrawal excess flow valve". The service of this device is essential to the propane tank liquid evacuation. They are also used in other applications requiring the use of liquid propane.

Note: Do not attempt to extract liquid from a propane tank through this valve. Contact your propane company concerning the operation of the propane tank liquid withdrawal valve.

To operate this valve, another valve is required overlapping the other (angle valve) with the handwheel pushing the stem to open the valve, of course, the thread male/female must be the same. Figure 2 - 3 below shows as it should be.

Operation Chek-Lok®

• Loosen cap to vent any accumulated LP-Gas from the Chek-Lok. After venting stops, remove the cap. If venting does not stop, retighten the cap and use other approved means to withdraw liquid from the container.

NOTE: Use a suitable size wrench when removing the cap and adapter from the Chek-Lok. Do not allow the Chek-Lok to un-thread from the tank during removal. When necessary, use a second wrench to secure the Chek-Lok in position

• Before beginning withdrawal, securely connect a RegO 7550P angle valve or a suitable shut-off valve to the adapter. Fully open the shut-off valve – the valve’s handwheel must be fully opened before connecting the adapter to the tank.
• Completely thread the adapter and shut-off valve assembly onto the Chek-Lok by turning the adapter’s coupling nut clockwise until it is tight. Immediately close the shut-off valve. Listen for an audible click to signal that the Chek-Lok has opened and is actuated for liquid withdrawal. The flow can now be controlled by the transfer valve
• Check the coupling nut and adapter assembly for leaks using a suitable leak detection solution. If the Chek-Lok fails to open after following this procedure, the pressure downstream of the shut-off valve should be increased to equalize pressure in the Chek-Lok. It is simple to equalize pressures using vapor from either the vapor return valve or service valve, or from a hose end valve connected to the delivery truck.

Propane Liquid Withdrawal Valve Operation

The liquid withdrawal valve functions only with additional specialized fittings supplied by a propane company for liquid evacuation. Without these required fittings, the liquid withdrawal valve is unusable. The liquid withdrawal valve is attached to the tank and itself is in the vapor space. The dip tube that reaches the bottom of the tank is in direct communication with the propane tank's liquid space, which allows it to be used for liquid propane service or liquid withdrawal. The valve consists of a powerful spring holding a seat disc in a firmly closed position. The seat disc (left) is opened by attaching a second valve to the exterior of the liquid withdrawal valve outside the tank. This secondary valve is available only through a licensed propane company. Once the liquid withdrawal valve has been successfully opened, propane liquid can be withdrawn by attaching the second valve to the exterior portion of the liquid withdrawal connection. The liquid withdrawal valve has a safety mechanism built-in called an excess flow valve. If the liquid flow reaches a rate in excess of its design, the valve will close, hence the name "excess flow valve". Figures 3 - 4 shows the valve open and close.

Liquid Withdrawal Valve Uses

Figure 5

Used primarily by propane companies, the liquid withdrawal valve allows the tanks to be emptied of liquid propane before they are transported or moved. They are also used in consumer applications for portable refuelling cylinders. In this regard, the valve attached to the liquid withdrawal valve is used as a service valve. The hose-end fittings allow propane liquid to be transferred into smaller tanks and cylinders for use on forklifts, gas grills or other appliances utilizing propane cylinders as an energy source. This makes a domestic ASME container more of a distribution supply source.

Order information

You can buy the valve directly here on our website including our advice, or directly  to REGO or FISHER website..

Application

Chek-Lok® Excess Flow Valves are designed to provide a convenient means of withdrawing liquid from stationary containers prior to moving the container. The Chek-Lok® permits one transfer shut-off valve with an adapter to be used interchangeably on a number of tanks.

The 7590U and 7591U Chek-Loks® are also designed for use on permanent installations provided the excess flow valve is sized properly for the system and piping. NOTE: In some cases, it may be necessary to use an in-line excess flow valve to protect the downstream piping. This valve is not recommended for use as a liquid source for pumps.