Air Switch / Pneumatic Switch- Manufactured by Techmark TBS132A - This is a pressure switch to detect sufficient flow safe enough for the heater to operate and also used to prevent a pump from running dry. Fits hole size:15mm Height: 48mm Width: 25mm (at widest point) Depth: 48mm (from front to rear spade)
Up to 250vac. 16A resistive (meaning use with a heater for example), 4A inductive (meaning use with a 1HP pump for example. EPDM is the material of the diaphragm, it has been preset to work specifically with a bath heater. Basic operation is to switch either directly an appliance or a relay.
This switch is commonly used in a bath or jetted tub application in conjunction with a TBS133 mom / alt air control switch. Once the switch has detected enough pressure it will complete the circuit with the TBS133 until either the alternate switch is switched off or the pressure in the pipe work drops causing a low flow situation.
Instead of running a dry air pipe connected to an air transmitter the pipe would be connected to a pressurised outlet of the pump or heater. The water pressure will then lift the EPDM diaphragm to make contact.