摘要 |
A no tie down valve or device for the actuation of hazardous machinery. The device comprises a spool moving within a cylindrical cavity having capped ends; input ports, an output port, and an exhaust port are located at suitable positions on the cylindrical cavity wall such that a pressurized output can only be obtained if both inputs are pressurized, and subsequently held, within a small time interval determined by design parameters of the device. An equivalent construction in terms of poppet or diaphragm-type seals, which is inherently more reliable and maintainance-free than spool construction, is also described.
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