A valve device, in particular a double stop-check valve, preferably of the two-way valve type, has at least three fluid connections (1, 2, 3) provided in a valve housing (51). Two valve elements (65, 67) can slide in the valve housing (51). One control device (71) controls the valve elements (65, 67). At least one of the valve elements (65, 67) forms, together with parts (59/61) of the valve housing (51), a seat leak-tight closure part for the associated fluid connections (1, 2, 3).

The invention relates to an automatic cylinder changeover device (1), comprising two gas inlets for mounting gas cylinder banks, namely the left gas inlet and the right gas inlet, a gas outlet through which gas may be discharged and a valve suitable for connecting said left gas inlet or said right gas inlet with the gas outlet and configured for automatically reversible switching between these two connections, characterized in that the device (1) comprises an indicator, suitable for being manually set in one of two distinct positions, one of said positions indicating the left gas inlet and the other of said positions indicating the right gas inlet and comprises means for detecting the position of the indicator, including at least one sensor (5), preferably a pair of sensors (5). The invention also covers a method for monitoring a gas installation equipped with such automatic cylinder changeover device.

A spool switching valve device may include a columnar spool housing and spherical valve bodies. The spool housing includes first input port cavity portions, valve body movable portions and valve seat members. Each valve seat member has a through hole and includes a second input port portion. A second valve seat portion is provided to open and close the gap between valve body movable portion and the second input port portion. Each valve body movable portion includes an output port penetrating the side surface of the spool housing to communicate with the outside of the spool. Each valve seat mounting portion includes an engagement receiving portion suppressing the detachment of the valve seat members when the valve seat member is actually mounted. Each valve seat member includes an engagement portion fitted into the engagement receiving portion when the valve seat member is mounted to the valve seat mounting portion.

A gas-supply system includes a gas container filled with gas, a gas flow controller coupled to the gas container, and an operation device electrically connected to the gas flow controller. The gas-supply system further includes a buffer tank coupled to the gas flow controller and configured to receive the gas from the gas container via the gas flow controller. Furthermore, a pressure transducer disposed on the buffer tank and configured to generate a pressure signal to the operation device according to the pressure of the gas in the buffer tank. The operation device is configured to generate a control signal to the gas flow controller according the pressure signal, and the gas flow controller is configured to adjust the flow rate of the gas according to the control signal to keep the pressure of the gas in the buffer tank in a predetermined pressure range.

The invention relates to an automatic cylinder changeover device (1), comprising two gas inlets for mounting gas cylinder banks, namely the left gas inlet and the right gas inlet, a gas outlet through which gas may be discharged and a valve suitable for connecting said left gas inlet or said right gas inlet with the gas outlet and configured for automatically reversible switching between these two connections, characterized in that the device (1) comprises an indicator, suitable for being manually set in one of two distinct positions, one of said positions indicating the left gas inlet and the other of said positions indicating the right gas inlet and comprises means for detecting the position of the indicator, including at least one sensor (5), preferably a pair of sensors (5). The invention also covers a method for monitoring a gas installation equipped with such automatic cylinder changeover device.

A discharge vacuum relief valve kit to provide vacuum relief for a SVRS pump in a hydraulic system is provided. The discharge vacuum relief valve kit includes a vacuum vent tube including a first end and a second end, a discharge vacuum relief valve coupled to the first end of the vacuum vent tube, and a vacuum vent screen coupled to the second end of the vacuum vent tube. The discharge vacuum relief valve is coupled to a drain plug opening of the SVRS pump.