MiniCal III

Ion selective measurement of cooling circuits

Ammonia is one of the most commonly used refrigerants. But it has a strong irritant and corrosive effect. Ammonia's very aggressivel reactions in industrial plants often result in damages, like leaks in copper pipes. Cooling water circuits with this refrigerant must be monitored continuously for leaks in order to ensure the long-term safety of the systems and, in the case of open systems, to comply with environmental protection regulations.

Ammonia leaks must be detected and repaired as quickly as possible, so as to avoid consequential damage and not endanger production processes. For this purpose, measuring devices for ammonia detection are integrated into the secondary cooling circuit. The MiniCal III system was developed specifically for this purpose. Intensive cooperation with operators of cooling systems and our extensive experience have resulted in a powerful and user-oriented system that is quick and easy to install.

Selective measurement for early warning
The selective measuring method has proven itself reliable for detecting ammonia leaks in direct secondary circuit testing. The MiniCal III system measures leaks selectively (0.2 ppm) even in the smallest concentrations, whether in normal water basins, in circuits or in brine mixtures such as ethylene glycol, propylene glycol, Tyfoxit, Pekasol, etc.

We differentiate between detection in water circuits and water/brine circuits. In both cases, electrodes with selective membranes are used. Due to the reaction of ammonia with the cooling medium, ammonia detection is carried out either with an ion-selective ammonium electrode or a gas-sensitive ammonia electrode, depending on the medium and the pH value. This allows for an absolutely reliable statement to be made about ammonia leakage.

Measurement method
The ion-selective measuring method of the MiniCal III system measures an effective concentration in the cooling circuit in ppm (parts per million). This is very important in order to avoid damage to the cooling system. Only ion-selective measurements allow for effective detection at the smallest unit of 1 ppm. Safety measures must be initiated at limit values as small as 3 ppm in open systems (cooling medium from lakes or rivers) and 20 ppm in closed systems.

With selective measuring electrodes, ammonia leaks can be detected reliably and at an early stage. As the diagrams show, detecting ammonia through the pH value is only possible above 100 ppm or 1000 ppm ammonia, depending on the medium. Using the selective measurement method of the MiniCal III system makes an earlier warning possible, allowing you to initiate appropriate actions faster.

PH measurement is not suitable for brine or glycol circuits, since added substances with a basic or acidic effect are buffered. The pH value will thus remain constant until the buffer capacity is exhausted. Any changes in the pH value can therefore only be measured at higher ammonia concentrations.

This measuring technique also has a higher sensitivity in water circuits, so that even smaller leaks can be detected at an early stage.

Signal amplifier
The Mini Cal III system's measuring signal is connected to a measuring amplifier/controller. This forwards the alarms to a higher-level control center. The system will give constant information on the measured concentration and correlating operating states, if the limit values are exceeded and about flow disturbances. If the alarm limit value is exceeded, appropriate actions are initiated.

There is also an additional signal pre-amplifier, which is mounted directly on the respective fitting. It provides an on-site display and reduces interferences between the measuring chain and the controller.

Fittings and installation locations
The selection of MiniCal III fittings depends on the installation location. The medium is tapped either from pipelines (with recirculation back into the pipelines), in basins or with a free outlet. They can be used flexibly, are easy to install and are characterized by a compact design. You will find a selection at the bottom of this page.