This compact stand-alone pH controller was designed to precisely regulate the pH level of liquid biological solutions. It can be used in a number of biological experiments requiring regulated pH, such as: isolated organs (heart, lung, kidney, etc.) or isolated tissues, see section K in our full-line Bioscience Catalog.

Maintaining the pH is accomplished by either ‘bubbling’ CO2 gas through the solution or flowing the CO2 gas over the surface of the solution or medium.

To maintain the desired pH level, the ‘set-point’ of the controller is adjusted to the desired level. When the pH level exceeds the programmed set point, the flow of acidifying CO2 gas is started. Adjusting the controller’s flow rate regulator will determine at what rate the pH will decrease, the higher the flow rate the faster the drop in pH. The controller’s flow rate regulator will allow the end user to adjust the CO2 gas between 0 to 2.0 liters per minute. Once the pH reaches the set point, the gas flow automatically stops. Should the pH increase the process is repeated.

A three-position (manual override) switch on the front panel provides several ways to control the CO2 gas delivery.

By-Pass Mode: (up) the flow of CO2 gas is continuous and the flow rate will be controlled by adjusting the regulator.

Momentary Mode: (down) the flow of CO2 gas is allowed as long as the switch is depressed. The switch is spring loaded and will return to the Auto Mode when released.

Auto Mode: (center) the controller will use the set-point to activate the on/off flow of CO2 gas automatically. When used with the Harvard Apparatus series of heating/cooling micro-incubators, this controller provides a complete pH/temperature controlled environment, ideal for long term cell or tissue studies. The pH controller has a 4-digit LCD display capable of displaying the full pH range from 0 to 14 pH. The microminiature combination glass pH electrode that is supplied with the system is ideal for application involving placement of the pH electrode in a small area such as in our line of temperature controlled micro incubators, see pages M96 to M98. The system is also compatible with any standard type of
combination pH electrode.

A BNC connector on the rear of the unit provides a pH output (0 to 5 V) signal. This connection can be used to continuously log the pH values to a chart recorder, data acquisition system or other recording device. The unit is powered by 18 VDC universal power supply for benchtop use. The pH controller is shipped with: controller, power supply, AC/DC adaptor, combination pH electrode and quick disconnect fittings matching front panel connectors for input and output hoses.