Armstrong Model C-1801 pneumatic operators are frequently used for humidifiers under modulating control. They have adjustable start points and various air-pressure ranges.
Standard Honeywell Model MP953D pneumatic operators are commonly used for humidifiers under modulating control. For operating spring ranges and start points, see the PDF download on this page. Operational start-point adjustment is available in the form of a pilot positioner where required.
Belimo models NVF24 (24V 60 Hz standard) and AF24SR (24V 60 Hz), and the Honeywell M9182A (24V 60Hz) are standard electric operators for humidifiers under modulating control. Transformers for other voltages are available for all electric operators.
The ASCO electric solenoid operator is standard for humidifiers under on/off control. Caution: On/off operation of humidifiers in air-handling systems is advisable only for very limited, specialized applications. Consult your Armstrong Representative.