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minical iii

Minical Iii

NH3 detection for cooling circuits

Cooling systems with ammonia as coolant need to be continuously monitored for leaks for long-term security of investments as well as for open systems to comply with the environmental standards.  Ammonia is one of the most widely used refrigerants. However, it has a strong irritant and corrosive effect. In systems, ammonia reacts aggressively and this reaction quite often results in leaks for instance in copper lines. In order to avoid damage and not to endanger production processes, ammonia leaks must be detected early, hence, allowing time for elimination. For this purpose, devices for ammonia detection were integrated in the secondary cooling circuit. The MiniCal III system was specifically developed for this purpose. With the help of intensive cooperation with operators of refrigeration systems and due to extensive experiences, a powerful and user-oriented system could be designed which is fast and easy to install.

Selective measurement for early NH3 detection

To be able to detect ammonia leaks reliably, the selective measurement in the secondary circuit is essential. The MiniCal III system already detects at low concentrations selectively (0.2 ppm), whether in normal water, in cycles or in brine mixtures such as ethylene glycol, propylene glycol, TYFOXIT, Pekasol, etc.

A basic distinction between the detection in water cycles and water/brine cycles is made. In both cases, electrodes with selective membranes are used. Through the reaction of ammonia with the cooling medium, however, the ammonia detection is performed with either an ion-selective or a gas-sensitive ammonia electrode depending on the medium and pH thus resulting in an absolutely reliable statement on the ammonia leak.
Refrigeration systems with freons, R22, R134a, R404a, R407c etc. HFCs, HCFCs can also be monitored reliably with other specific sensors (electronic measuring elements) in the circuit.

Advantages of selective measurement technology

  • Reliable ammonia detection
  • Quick response of electrodes
  • 1 ppm resolution

Powerful measuring amplifier

The heart of the system is the sensitive amplifier which is simultaneously designed as a controller. It is programmed exactly for the required application and can immediately be used for numerous functions. The measuring amplifier is very flat and can be built into existing cabinets or wall casings.
At any time, the system provides information on the measured concentration, the limits when exceeding them or falling below and on the respective operating conditions. The individual system settings and the service settings are password-protected against unauthorized access.


To avoid interference between measurement chain and controller, the controller is directly mounted on the respective fitting. Here, the controller provides a local display and transmits the measurement signal to a control unit or a control centre.

Measurement procedure

The selective measurement method offers significant advantages compared to the ammonia detection by pH measurement. Ammonia leaks are detected early and safety measures can immediately be initiated. Damage to people, equipment and the environment are prevented. For more information on this measurement method please refer to the PDF file.


The fittings shown are suitable for a variety of applications. They are flexible to use, easy to install and have a compact design.

Various parameters are crucial for a possible Minical III quotation. Therefore, please use the check list for coolant monitoring for enabling us to prepare a detailed quotation under consideration of your respective requirements. The check list is available as PDF file.

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