Features of a Sherlock Refrigerant Monitor

A good Sherlock refrigerant monitor has a range of features that are critical to ensuring the correct refrigerant concentration. The control module and sensing point are key components and must be installed in a rigidly mounted location indoors. They should be mounted where the display is visible from most parts of the room and service is easy. The best location for the sensor/sampling point is approximately 18 inches above the floor and in an area where refrigerant vapors are most likely to accumulate.


When using a refrigerant monitor, selectivity is the ability to differentiate between a variety of refrigerants. Selectivity may not be a critical factor when only one or two refrigerants are present. However, sensitivity is more crucial in cases where multiple refrigerants, such as halocarbons and volatile hydrocarbons, are present. Furthermore, in many cases, a facility will have a physical separation of the potential leak sources, and sensitivity will be a consideration.

The sensitivity of a refrigerant monitor is typically measured in parts per million volume. CMOS and Photoacoustic Infrared technologies can provide adequate sensitivity. As long as a monitor is capable of meeting safety standards, it should be installed in a location where both the controller and sensor can be easily accessed. The controller should be installed so that the display can be viewed from various parts of the room. Ideally, the sensor/sampling point should be located at least 18 inches above floor level in an area where refrigerant vapors can collect.

Operation in two environments

The Sherlock refrigerant monitor is capable of operation in two environments. A sensor in one environment is required for monitoring refrigerant concentration in the other environment. Its performance depends on the location of the sensor and controller. Ideally, the sensor and controller should be mounted indoors and rigidly mounted, and the controller should be located in an area where calibration and service can be performed easily. In the monitored environment, the sensor/sampling point should be positioned at a height of about eighteen inches off the floor, where the most refrigerant vapors are likely to accumulate.

Control module monitoring

The SHERLOCK refrigerant control module monitoring systems are permanently installed electronic control panels. The system monitors the analog output signal from up to two Sherlock sensors and activates four Form C SPDT relay contacts (K1, K2, K3, and K4). The monitor has optional zone isolation alarm relays and can be installed outside the monitored room. The unit is ETL/CSA approved and meets the requirements of various codes and standards.

The Sherlock 202 monitors the sensors in real time to ensure that the temperature is controlled properly. If a sensor is disconnected or cut, an alarm will appear on the display. If a sensor fails to operate, the unit switches to the second set of parameters. A sensor can also be disabled or silenced, so that the unit can continue to function. When a sensor is disconnected or cut, the 202 will activate the K1 and K2 relays and the corresponding logic will be notified.

Sensor/sampling point location

The location of the sensor/sampling point on a Sherlock refrigerant monitor is crucial for accurate measurement of the concentration of refrigerant. Sensors should be located near possible sources of leaks and low-lying areas. Additionally, the sensor/sampling point should be 18 inches off the floor and preferably in an area where refrigerant vapors are most likely to accumulate.

If the room is large, one sensor per 20,000-30,000 cubic feet is sufficient. For smaller rooms, a single sensor may not be necessary. For larger rooms, more sensors can be installed to cover more space. If you’re installing a Sherlock refrigerant monitor, you can choose a sensor/sampling point combination that works well with your room layout. The Sherlock 4-Series has additional features to make it more flexible. For example, you can install an Audio / Visual alarm appliance within the sensor/sampling point location.