Manually operated valves are installed on water circuits associated with refrigeration systems—either on cooling towers or in secondary brine circuits. They are installed for convenience in servicing and for flexibility in operating conditions. These valves make it possible to recircuit, bypass, or shut off water flow as desired (see Fig. 11-54).
These manually operated shutoff or flow-control valves are available in a wide variety of styles and sizes. Valve stems and body seats are accurately machined to close tolerances, ensuring easy and positive shutoff.
They are made of nonporous cast bronze.
There are three main types (see Fig. 11-54):
? Stop valves
? Globe valves
? Gate valves