The purpose of a flow switch is to go on/off with the flow of water from a pump or in circulation and to give you an indication/alarm on flow on/flow off which can also be used to switch on/off any pump/etc.Go to sites of McDonnel & Miller ITT & Ayvaz and download their broucher.You can then decide how and where to install and what to indicate/control.
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I not only use all the brains that I have, but all that I can borrow. Woodrow Wilson