Details:

The DG-4 relative humidity controller and dewpoint controller allows you to control the water vapor content of an air stream in several versatile ways. It can be operated in either a locally controlled mode, or a computer-controlled mode that allows the generation of complex water vapor ramps and steps.

 In relative humidity controller mode, the DG-4 relative humidity controller reads the temperature of the area in which relative humidity control is required, using a supplied thermistor probe. Using a saturated air stream as its input (saturator supplied with unit), the DG-4 then adjusts the water vapor content of the air stream to yield the precise set relative humidity. It does so by calculating the saturated water vapor pressure at the regulated air, using the measured temperature at that point. Then, it calculates the target water vapor pressure corresponding to the desired relative humidity entered by the user. Finally, it calculates the dew point corresponding to the target water vapor pressure and regulates its internal condensing unit at that temperature, using a space-age solid-state heat pump.

The result is accurate, consistent relative humidity control even in the face of fluctuating environmental temperatures. This is a unique capability of the DG-4 that is invaluable for many kinds of biological experimentation, product testing, protein crystallography, and so on.

Alternatively, the DG-4 can be used as a dewpoint regulator (range 1 - 45 C) or as a water vapor partial pressure regulator. Air flow rates ranging from about 25 ml/minute to 5 liters/minute can be used without affecting the system's regulation efficiency. Condensed water is evacuated from the condenser by a miniature diaphragm pump at user-settable intervals. Alternatively, a simple plumbing change allows the user to remove condensate slowly and continuously with a user-supplied peristataltic pump. 

All of the instrument's functions are accessed via high quality rotary encoders. We have paid particular attention to making their operation as intuitive and flexible as possible. The DG-4 is extremely easy to operate. All adjustments and settings are permanently retained in the absence of power. Analog and serial data outputs are standard.

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