CH265 pH / Free Chlorine Analyzer

Chlorine Analysis Made Simple

CHEMTROL® CH265 PPM/pH Digital Controller introduces the new PPM Sensor for Free Chlorine control. A microprocessor-based digital controller, designed to maintain both free chlorine (PPM) and water pH in Municipal Water, Well Water, Waste water and Industrial applications.

  • No Reagents.
  • No Maintenance.
  • No Pressure Regulator.
  • Free CL Range 0.00 to 10.0 PPM.
  • pH Range 0.0 – 14.0.
  • Programmable 4-20 mA output to PID and/or Chart Recorder.
  • Programmable 4-20 mA Output Control with Adjustable Setpoint.
  • Dry Contact Remote Alarm.

Standard Features

  • Easy to install
  • Simple to use
  • All Control Functions on Front Panel
  • Separate Adjustable Setpoints
  • Separate Adjustable Alarms
  • Acid/Base Selector
  • Proportional Feed with Adjustable Bandwidth
  • Separate Adjustable Overfeed Safety Timers
  • Rain and Splash Proof Cabinet
  • 5-year Electronics Warranty

Precise and Reliable PPM Reading

The new Free Chlorine Sensor is a solid state sensor with a selective membrane that provides direct readings of Free Chlorine in water at concentrations ranging from 0.1 to 10 ppm (parts per million) or mg/l (milligrams per litter). These are true readings of Free Chlorine corresponding to the DPD #1 test.

A significant advantage of this PPM sensor is that it’s not affected by cyanuric acid (CYA) stabilizer and/or oxidizers, thereby assuring constant Free Chlorine levels at all times. Unlike other chlorine sensors on the market, this new sensor is easy to install and maintain and gives the operator precise and reliable control of Free Chlorine under the most difficult conditions. The PPM sensor is covered by a full 2-year warranty.

CH265 Specifications

Free Chlorine ControlAdjustable from 0.1 to 10.0 ppm (mg/l)
pH ControlAdjustable from 0.0 to 14.0
Free Chlorine SensorSolid state electrode with 3 m cable
pH SensorGlass electrode with 3 m cable
ReadoutsPPM (3 digits) and pH (2 digits) LEDs
Feed ModeManual, automatic, proportional
AdjustmentsSet-point, calibration, limits, feed rate
IndicatorsLEDs for feed mode, feed status, alarms
SafetyAudio, visual and remote alarms,
out-of-range limits and overfeed safety timers
CabinetPolystyrene 22 x 18 x 10 cm
Electrical230V or 24 VAC (specify)
Warranty5 years on electronic module

CH265 Installation

Unlike conventional amperometric or colorimetric sensors, the new PPM sensor is easy to install and maintain. It does not require a pressurized cell for the sensor and/or expensive and expendable chemical reagents. And best of all, it’s maintenance free.

Installation of the CHEMTROL® CH265: For best operation, it is recommended to install the sensors on a bypass line with a Flow Cell Assembly (FCA) as shown on the schematic.


The Flow Cell Assembly (FCA) includes a see-through cell with a plastic cover that regulates the flow of water and allows the operator to see the tip of the sensors.

The cell includes the following:

  1. two 1/2″ FPT fittings for the connections to the bypass line,
  2. two 1/2″ FPT fittings for mounting the sensors,
  3. a spigot for water testing,
  4. a bleed line to prevent air lock in the cell,

In addition it is also recommended to install a safety switch on the bypass line to prevent accidental feeding of chemicals.

CH265 Operation

The CHEMTROL® CH265 Free Chlorine Analyzer automatically maintains both Free Chlorine concentration and pH of the water.

All operating functions are clearly labelled and accessible from the front panel, with safety and easy-reset features not found on other controllers.

The Free Chlorine concentration can be adjusted from 0.0 to 10 ppm (or mg/l) based on local Health Department regulations for prevention of germs and bacteria (or from 0.01 to 3.00 for low chlorine level applications).

The pH control level can be adjusted from 6.0 to 8.0. Below 6.0, the water is too acidic and causes corrosion. Above 8.0, it is too alkaline and causes scaling, stains and reduced sanitizer efficiency.