Valves and Flowsheets

The instruments usually provided for cooling towers and circulating pumps include  

Valves are used to control the water flow through the water lines of the cooling tower distribution system. Valves used for this type application include stop valves, flow control valves and float control valves. The types of valves, quantity required and complexity of design are dictated by the type and size of tower. 

Stop valves are used on both counterflow and crossflow towers to regulate the water flow, particularly between cells on multicell towers, and to shut off the water for maintenance or other purposes. In regions in which freezing temperatures are not encountered, conventional stop valves may be replaced on crossflow towers with flow control valves that 

Flow control valves are used on crossflow towers to equalize water flow between tower cells and cell basins. Flow control valves, if properly designed, may also be used as stop valves under certain climatic conditions. 

The specifier must have a good understanding of instrumentation and support machinery. Any process instrumentation book will acquaint the newcomer to this area with the criteria for proper instrumentation selection. To illustrate the process involved in specifying the entire cooling tower system package, the following example has been prepared. 

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