McDonnel & Miller, now part of ITT Inc., has produced high-quality low-pressure steam boilers, boiler controls, liquid level controls, and flow switch products for almost a century. Their products are put to the test in demanding applications in the oil and gas industry, especially where high accuracy is required. Certified with ISO 9001 and ISO 14001, the McDonnel & Miller brand products are time-tested and reliable.
The McDonnell & Miller Series 69 switch is typically used as a low-level switch or low water cut-off for low pressure boilers (maximum 20 psi) or atmospheric feed tanks. A mechanical float-type level switch, model MMLSS69 is mounted directly onto the tank with a 2-1/2" NPT coupling. This switch includes two precision single pole single throw switches, one NO and one NC.
The MMLSS69 is generally used as a low-level switch for atmospheric-pressure feed tanks within boiler feed systems. The maximum operating pressure is 20 psi, so it is typically not used on deaerators. This switch can be affected by waves within the tank since it's mounted directly to the tank, and for this reason it is typically only used as a low-level switch.
This model is not recommended for use as a high-level switch or makeup level control switch.