A measurement method for a steam valve according to at least one embodiment of the present disclosure, includes: a step of measuring acceleration of a valve stem when a slave valve is opened by driving the valve stem with an actuator from a fully closed state of a master valve and the slave valve; a step of detecting a timing at which the slave valve is fully opened, based on the measured acceleration of the valve stem; and a step of calculating an amount of movement of the valve stem from a reference position to a position where the slave valve is fully opened.

A water tank for operation in an aircraft includes a rigid tank shell, and a pressure compensation mechanism to equalize a pressure inside of the rigid tank shell with an environment. The pressure compensation mechanism includes a shutoff member to move between a closed position, a first open position allowing air to enter the rigid tank shell and a second open position allowing air to leave the rigid tank shell.

A steam valve according to at least one embodiment of the present disclosure, includes: a valve body that includes a steam flow path through which steam flows, and a valve seat disposed in the middle of the steam flow path and having an opening portion; and a stop valve that includes a valve stem which extends in an axial direction, where an axis extends, and is movable back and forth in the axial direction, and a first valve disc which is fixed to a distal end part of the valve stem and is abutted against the valve seat to close the steam flow path. The valve stem is partitioned into a first valve stem to which the first valve disc is fixed and a second valve stem different from the first valve stem.

An on-off valve that operates between an open position and a closed position, particularly with high-pressure working fluids, has a valve body that defines a valve cavity having a first chamber and a second chamber. A valve poppet is slidably mounted within the valve cavity. The valve poppet has a larger first end positioned within the first chamber and a smaller second end positioned within the second chamber. The valve poppet has a fluid seal around the first end and a second fluid seal around the second end. Each fluid seal is isolated in the space between the seals and the space is connected to the atmosphere. A pilot control valve is fluidly connected to the first chamber of the valve body and sends a control fluid or working fluid in and out of the first chamber and moves the valve poppet between the open position and the closed position. The pilot valve has a control tube or control rod having fluid passages made on or inside the control rod. The control rod is positioned inside a cylindrical cavity and the cavity has rod seals and bushings that define 3 separate fluid chambers, including an inlet chamber, an exit chamber and a cocking chamber. The inlet chamber is fluidly connected to the source of the control fluid. The exit chamber is fluidly connected to the exterior of the pilot valve. The cocking chamber of the control rod cavity is fluidly connected to the first chamber of the main valve. The control rod can be moved with an outside force to a first position and to a second position such that the main valve will be open when the control rod is at its first position and the main valve will be closed when the control rod is at its second position. The pilot valve can be mounted inside or outside of the main valve. The pilot valve can also be integrated into the valve poppet to form a valve cartridge for a simplified valve construction.