Specifications

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3.2 Microprocessor Humidity Controller Operation
3.2.1 Set-Point Adjust
1. Press and hold the “∗” button. The letters “rh” will appear, followed by the
current set-point value. While holding the “∗” button, the current set point
value and ‘rh’ will alternately appear in the microprocessor display.
2. To adjust the set point higher, press the “t” button. To adjust the set point
lower, press the “u” button.
3. Release the “∗” button.
3.2.2 Humidification System
To operate the Model 518 Humidification System:
1. Read the Humidifier operating instructions.
2. Plug the Humidifier into the ‘HUMIDIFY’ outlet on the ‘Side Interface Panel’.
3. Adjust the RH set-point to a value above the ambient RH conditions.
4. Turn on the “RH” STANDBY switch on the Model 518 Front Panel.
This will not automatically apply power to the Humidifier. Turning on the “RH”
STANDBY switch only makes the ‘HUMIDIFY’ outlet available to the
microprocessor controller.
When the controller activates the outlet, the small green LED in the upper left
corner of the RH display will illuminate. The humidifier will activate and begin
pushing a fine water mist into the chamber.
5. The controller will determine the amount of humidification needed to maintain
the desired set-point in the chamber.
If less than the full output capacity of the humidifier is needed, the controller
will provide pulses of power to the unit to limit the output. The humidifier will
be turned on and off cyclically to obtain an average humidity output lower
than the full capacity of the humidifier, appropriate to maintain the desired set-
point in the enclosure.
For best results, the Cycle Time (CyC.t) should be set as short as possible.
Refer to the Humidification System instructions for minimum cycle time
recommendations.