Introduction

Heldon flow switches are used in liquid flow lines carrying water, ethylene glycol or any other fluid that is non-harmful to brass or phosphor bronze. They are used to sense the flow of liquid for the purpose of alarming or activating a lockout circuit should the flow stop for any reason. Commonly used in chillers or water sourced heat pumps they are responsible for shutting down the plant should the flow rate fall below a predetermined value and there is a risk of the fluid freezing in the evaporator heat evacuator.

Heldon flow switches are manufactured to withstand the rigors of being mounted directly to the pipe work, they consists of a solid brass body, a stainless steel frame and a splash proof plastic cover. The Omron® micro switch is completely sealed and isolated from the liquid by a copper alloy bellows. The paddle consists of five different length stainless steel segments that can be removed and trimmed for use in 1’’ to 6’’ diameter pipe. The maximum operating pressure is 980Kpa at an ambient of 80°C and with a maximum liquid temperature of 90°C.