Flow switch Specifications Efs series flow switch is an automatic element of protecting and controlling flow in the line of the system; Medium: water, ethylene glycol and other liquid which is not classified as hazardous; Liquid temperature:+5~-+120f¦; Max. Working pressure: 1.0mpa; The rate of the flow can be adjustable and it is stable. Eflow switch can not be used where the liquid in the pipes will drop below the liquid's freezing point.