Valves may be operated manually, either by a hand wheel, lever or pedal. Valves may also be automatic, driven by changes in pressure, temperature or flow. These changes may act upon a diaphragm or a piston which in turn activates the valve, examples of this type of valve found commonly are safety valves fitted to hot water systems or steam boilers.
Syed Ajmal Ahmed
P.O. Box: 62981, Dubai, , United Arab Emirates