The McDonnell & Miller Model 64level switch is a mechanical float-type level switch. The switch is piped into an external water column via 1” NPT equalizing pipes. This switch is typically used as a low-level switch, high-level switch, or low water cut-off and is typically installed on boilers (50 psi maximum), feedwater tanks, and deaerators. The switch includes two precision single-pole single-throw switches (one NO and one NC). The McDonnell & Miller 64 is commonly used for three different applications within boiler feed systems:

• Low level alarm: A single Model 64 level switch can be used to detect a low-level condition. This is common on tanks of all sizes.

• High level alarm: A single Model 64 level switch can be sued to detect a high-level condition. This is common on tanks of all sizes.

• On/Off makeup valve control: Two Model 64 level switches can be used in conjunction to control an electronic two position makeup control valve.

The lower of the two switches controls when the valve opens. The higher of the two switches controls when the valve closes. This type of control is common for applications where maintaining a steady flow into the tank is not required, for example, medium sized atmospheric feed tanks (100 to 750 gallons). This design is very robust and provides more flexibility compared to a single level controller.

• Maximum Operating Pressure: 50 PSI
• Connects to tank via 1” NPT equalizing pipes
• Includes cast iron float housing
• 2 precision switches.
• 1 Normally Open (NO) and 1 Normally Closed (NO) set of contacts
• Switches rated for 7.4 amps at 120 VAC (3.7 amps at 240 VAC)