UNDERSTANDING REFRIGERANT DETECTION SYSTEM REQUIREMENTS OF IEC 60335-2-40:2018 – ANNEX LL

NET Cyber Heads have been recently declared conform to Annex LL of IEC 60335-2-40:2018. This short article will explain in greater details the content of Annex LL and what are the requirements of refrigerant detection systems for flammable refrigerants for household and similar electrical appliances.

The IEC 60335-2-40 standard deals with the safety of electric heat pumps, sanitary hot water heat pumps and air conditioners, incorporating motor-compressors as well as hydronic fan coils units, dehumidifiers (with or without motor-compressors), thermoelectric heat pumps and partial units. Annex LL specifically defines requirements for refrigerant detection systems for use in such appliances, as well as testing methods to ensure the requirements are met.

Here’s a brief description of the outlined requirements:

1. The sensing system shall give an output signal in response to a pre-set concentration of refrigerant in the environment (25% LFL maximum) so that safety measures can be taken.
2. The standard precisely defines exposure and siting requirements for the installation of the sensor, while guaranteeing accessibility for inspection and replacement.
3. The refrigerant detection system shall be capable of detecting refrigerant over the full range of operating temperature and humidity as specified by the appliance manufacturer, within a defined range of tolerance.
4. The response time of the refrigerant detection system shall be within 30 seconds when exposed to a concentration of 25 % of LFL.
5. The refrigerant detector sensor set point shall be factory set and sealed with no field adjustment.
6. The refrigerant detector sensor shall not respond to substances other than the target refrigerant (selectivity requirement) to avoid false alarms and shall not be subject to poisoning.
7. When exposed to the refrigerant mixed with oil, the refrigerant detector shall not by damaged and its ability of detecting refrigerant shall not be compromised.
8. The standard defines long term stability requirements for the refrigerant detection system, within a defined range of tolerance.
9. The refrigerant sensors shall be able to withstand vibration without damage or loss of ability of detecting refrigerant.
10. The refrigerant sensors shall not represent a source of ignition for the refrigerant gas.
11. Self-test protocols run every hour to ensure proper operation and function and notify the user in case of malfunctions or sensor end-of-life.

NET Cyber Heads, both in their stainless steel and plastic versions, have been tested according to the methods defined in the standard and a conformity statement has been released accordingly.