| Popis: |
This chapter is divided into two parts. Part I describes the range of isolating, regulating and control valves installed in raw and potable water assets including gate, butterfly, globe, screwdown, ball, plug, diaphragm, pinch, needle sleeve and hollow-jet and non-return valves. Applications for each type of valve are given together with advice and information on valve closure speeds, cavitation, the equipment used to operate a valve, valve selection, air and washout valves. Part II describes flow measurement equipment used to control processes, for data acquisition and for billing customers. Permanently installed volumetric meters – electromagnetic, ultrasonic, turbine and propeller meters – are discussed together with temporary insertion and clamp-on devices. Separate sections describe revenue meters, their accuracy and future trends in automatic meter reading. |
