A backwater valve has a hollow valve body with an inlet and an outlet and a valve member pivotally movable about a pivot axis disposed above the inlet. The valve member is movable between a closed position covering the inlet and an open position. The valve member has a specific gravity that is greater than water and has a basin that causes the valve member to be buoyant when the basin is filled with air. A releasable latch holds the valve member in the open position and releases the valve member when the valve member pivots to a release position. A rotational stop engages the valve member at a fill position permitting water to overflow into the basin.

A fluid valve has a valve plug configured as follows. In order to control a flow rate of a fluid between a first pressure chamber and a second pressure chamber, the valve plug is provided so as to be openable and closable in accordance with a difference between forces generated by pressures in the pressure chambers and resilience of an elastic member. The fluid valve includes an opening motion promoting portion. The opening motion promoting portion promotes an increase in degree of opening of the valve plug after the valve plug has been opened.

A backwater valve has a hollow valve body with an inlet and an outlet and a valve member pivotally movable about a pivot axis disposed above the inlet. The valve member is movable between a closed position covering the inlet and an open position. The valve member has a specific gravity that is greater than water and has a basin that causes the valve member to be buoyant when the basin is filled with air. A releasable latch holds the valve member in the open position and releases the valve member when the valve member pivots to a release position. A rotational stop engages the valve member at a fill position permitting water to overflow into the basin.

A fluid valve has a valve plug configured as follows. In order to control a flow rate of a fluid between a first pressure chamber and a second pressure chamber, the valve plug is provided so as to be openable and closable in accordance with a difference between forces generated by pressures in the pressure chambers and resilience of an elastic member. The fluid valve includes an opening motion promoting portion. The opening motion promoting portion promotes an increase in degree of opening of the valve plug after the valve plug has been opened.

A handheld device according to an exemplary embodiment of this disclosure, among other possible things, includes an emergency stop valve including an inlet, at least one outlet, an exhaust, a main passage, and a stem passage. Air flows from the inlet to the outlet and from the outlet to the exhaust during normal operation of the handheld device, and the inlet is blocked and the air is exhausted through the exhaust during emergency operation of the handheld device. The handheld device includes a valve stem assembly received in the main passage, and the valve stem assembly includes a button and a cavity having a pocket. The handheld device also includes a locking stem including an end portion, and the locking stem is received in the stem passage and the end portion of the locking stem is received in the cavity of the valve stem assembly. The end portion of the locking stem is located in the cavity during normal operation of the handheld device when the valve stem assembly is in a first position to direct air to the inlet of the pendant valve, and the end portion of the locking stem is located in the pocket of the cavity of the valve stem assembly during emergency operation of the handheld device to retain the valve stem assembly in a second position when the emergency button is activated to direct air to the exhaust.