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    Updated: 10 May 2020


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Startpage > Products > Gas Detection > Refrigerants, Freon

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BHEP, Fieldbus detector - Duct
Modbus, BacNet, etc.





Underst. Art &  




RS485 Science  
    Environm. Duct  
    declaration Kit  



Gas monitoring and ventilatuion control in cold stores.
Gas monitoring in cold stores
should meet two main requirements:

  • To warn if the amount of harmful CFCs (environmentally and ecologically) reaches an unhealthy level.

  • To minimize the emission of expensive freon gases

Freon is a heavy and suffocating gas which in case of combustion can cause the formation of the highly toxic gas phosgene. Since the gas does not warn you of its presence through its smell it is advisable to monitor the gas as a safety precaution.

According to norms, cold stores containing more than 25 kg of Freon must be equipped with a gas monotoring system. In cases of system fillings, other relevant areas must also be monitored.

When considering freon from a monitoring point of view, it is appropriate to have two alarm levels, where the first gives an alarm at around 300-500ppm and the second at about 500-1500ppm. The recommendation differs from the hygienic threshold levels.

If you require a higher sensitivity, alert level 1 can be set at a lower level so that the plant gives an alarm for very small leakages. In this way, the gas monitoring facility can save on the very expensive freon.

The recommendation is a sensor density of about 1 sensor/100m2 or more if a higher leakage warning capability is required.

In some cases, you can supplement these facilities with an asphyxia warning system. Since the hygienic limits for hazardous atmosphere is much lower for freon, this measuring method is normally sufficient.

Ventilation control
The ventilation in the cold stores is generally temperature controlled since refrigeration compressors produce a great deal of heat.

This means that fans in cold stores run at full speed during summer.

Irrespective of how the ventilation control system is solved, it is important to "override" the temperature control so that at level 1 the fans at least run at half speed and at level 2 at the 1/1 power alternative, analog with a frequency converter.

Choice of instrument
Given the importance of providing the staff with a concentration reading ability prior to entering the monitored space, it is recommended that the facility be e
quipped with with a central instrument and display (the display can also be affixed to the sensor).
The instrument can be a single controller or one designed for several sensors.

The instrument should be located so that the alarm and any readings can be easily read. It should also be located in a frequented and meaningful place (outside the cold store).

To manage the monitoring- and control data, the instrument should have two alarm levels (with associated relays) and concentration readings.

The instrument must furthermore be able to identify faults in sensors, cables and instruments.

AFRE, Analog detector - Wall















 AFRE, Analog detector - Duct









Protection Manual



BFRE, Field Bus detector - Wall
Modbus, BacNet, etc.



to do   BFRE  








Electrical products in an explosive environment
A small amount of energy - a flame, spark, high surface temperature or similar is required to ignite an explosive gas mixture.

Products installed in an area with a potential explosion hazard must of course in themselves  not be a potential explosion hazard.

For this reason, the products are manufactured in such a way that this cannot occur.
The equipment must also be labeled and tested - ATEX classified - by the approved testing authority.

The Ex-class information is available in "Swedish Standard"
The choice of which Ex-classification is required is determined by factors such as type of gas, permissible maximum surface temperature and potential explosive hazards in the area where the products are to be installed.

The potential explosion hazard in the different areas is determined by the zone classification according to "Swedish Standard".

More about ATEX-products can be found in the following link

ATEX explosionproof detectors

CFRE, Combi detector - Wall
ModBus, Analog, Relay Output




Underst. CFRE  

deklaration RS485 RS485 Datasheet  





CFRE, Combi detector - Duct
 ModBus, Analog, Relay Output




CE missing  











Warning lights for freon detectors



Gas alarm plate for freon detector



Warning Siren for freon sensors

Combined warning siren and flash light for
freon sensors


E-mail: lars@fjellcom.se     

Phone: +46(0)31-287202

Mobile: +46(0)706-755561



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