McDonnell & Miller 150S (171702) Level Controller

The McDonnell & Miller Model 150Sis a mechanical float-type ON/OFF level controller and low water cut-off. The controller is piped into an external water column via 1” NPT equalizing pipes. The 150S is typically used to control a two-position makeup valve. When used on a boiler, the controller also includes a single pole double throw (SPDT) switch for low water cutoff and alarm. The 150S is rated for a maximum pressure of 150 PSI. A single McDonnell & Miller 150S is commonly paired with an electronictwo position makeup valve for ON/OFF operation. The snap action switches have a 3/4" fixed control range. That is, the makeup valve will open when the level is 5/8” above the “Cut-off line” and the valve will close when level is 1-3/8” above the “Cut-off line”. This type of control is common for applications where maintaining a steady flow into the tanks is not required, for example, small atmospheric feed tanks (less than 500 gallons). For larger atmospheric tanks and deaerators, a modulation makeup valve is t...