Water Flow Indicators & Switches

Indicators

Kurt J. Lesker recommend installing a visual flow indicator on every water circuit to give the operator confirmation, usually by a spinning rotor, that water is flowing.

Use flow indicators without switches when an interrupted supply will not cause damage or when the component has its own coolant alarm.  For water-cooled components critical to the vacuum (diffusion pump, turbo pump) or those possibly damaged by flow failure (e-beam source, sputter gun), use a water switch with the indicator.  Switch should connect to an alarm or process “kill” button.

Switches

In a flow switch, a rotating magnet induces a current in an external coil.  The current is sensed and compared to a variable set-point value.  If the water flow decreases to a value below the set-point, a relay is de-energized.  This arrangement ensures that a stuck rotor carrying the magnet cannot give a false positive flow indication.

Lesker Water Flow Indicators & Switches