GX-CFC: HFC Leak Detection Sensor

The external refrigerant sensor for leakage monitoring – Accessory for the GX-A1+ and GX-HS gas warning devices

The Schabus GX-CFC is an external gas sensor for the detection of fluorinated refrigerants (HFC / HFO), for example R32, R410A, R454B and many others. It is used as an accessory for the GX-A1+ and GX-HS gas warning devices and is connected via an RJ plug connection.

The sensor detects refrigerants escaping from leaking fittings of refrigeration, air-conditioning and heat pump systems. It has high sensitivity to A2L and A3 refrigerants, improved selectivity and is energy-efficient.

The GX-CFC is not ATEX-certified and must not be used in potentially explosive areas.

Protects where refrigerants are indispensable

The GX-CFC reports escaping refrigerant at an early stage to the connected gas warning device.

Why refrigerant monitoring is important

Even small leaks have consequences. Early detection increases operational safety.

• Fluorinated refrigerants are greenhouse gases
• They partly have high GWP values (Global Warming Potential)
• They are subject to the EU F-Gas Regulation
• Refrigerants are highly flammable
• Even small leaks can cause energy losses
• Leaks can reduce the efficiency of the system
• Leaks can trigger documentation obligations
• The GX-CFC supports early leakage detection and increases operational safety

CFC or HFC?

The designation GX-CFC refers to the intended use for air-conditioning systems and refrigeration equipment and stands here for “Climate Fluoro Carbons”, in German FKW (fluorinated hydrocarbons). It is a pure type and trade designation and must not be confused with the designation for chlorine-containing CFC refrigerants.

How the sensor works

The GX-CFC supplies the gas warning device with a signal that changes with the gas concentration.

• The sensor is supplied by the connected GX gas warning device
• Evaluation is carried out via the resistance ratio Rs/Ro: Rs is the sensor resistance at gas concentration, Ro the reference value at 5,000 ppm R-32
• The method enables reproducible leakage detection in the ppm range
• The operating instructions contain a sensitivity diagram showing typical sensitivity characteristics of the refrigerants under standard test conditions
• A further diagram shows the typical temperature dependence of the sensor
• To avoid false alarms due to small concentration fluctuations, the GX warning device only triggers after the gas concentration has been permanently exceeded for approx. 30 seconds; in the case of a very rapidly rising concentration, earlier
• Frequent and high gas concentrations reduce the sensitivity over time and shorten the service life

Detectable refrigerants

The sensor covers both classic HFCs and modern HFO refrigerants with reduced GWP. It reacts among others to:

• R-32
• R-410A
• R-404A
• R-407C
• R-454B
• R-1234yf
• R-1234ze
• R-22
• R-290 (propane)
• H₂ (hydrogen)

What is included in the box

The sensor is supplied with sensor cable and mounting material.

• Gas sensor GX-CFC with 2.5 m sensor cable
• Mounting material (1 screw, 1 wall plug)
• Operating instructions

Only usable in conjunction with GX-A1+ or GX-HS.

How the GX-CFC is constructed

The GX-CFC is a compact external sensor with a permanently connected supply cable.

Mounting and connection

Installation must be carried out by a qualified specialist. Read the operating instructions thoroughly before mounting and commissioning and follow the safety instructions.

Positioning the sensor

1. Install the sensor only in dry indoor rooms and outside refrigeration systems and position it correctly according to the type of gas to ensure proper functioning.
2. Heavy refrigerants (gas heavier than air, escaping refrigerant sinks to the floor): Mount the sensor at a height of 15–30 cm above the floor, but not more than 4 m away from the air-conditioning unit.
3. Light refrigerants (gas lighter than air, escaping refrigerant rises upwards): Mount the sensor at a height of 15–30 cm below the ceiling, but not more than 4 m away from the air-conditioning unit.
4. The prescribed mounting height must be strictly observed.

Connecting the sensor

1. Connect the sensor to the GX-A1+ or GX-HS gas warning device via the RJ plug connection. Connection is described in the operating instructions of the GX gas warning device.

Extending the sensor cable

The sensor cables are 2.5 m long as standard. A 3-core cable must be used for extension. The following minimum cross-sections apply depending on the length of the cable:

• 3 × 0.75 mm²: maximum length 10 m
• 3 × 1.5 mm²: maximum length 20 m

Do not mount

The sensor must not be mounted in the following locations:

• Places that could prevent alarm activation in the event of a gas leak (e.g. behind curtains or in cupboards)
• Directly above a cooker or combustion appliance or above a sink
• Next to a door, windows, ventilation, fan, ovens, etc.
• In areas where dust or dirt can put the sensor out of operation
• In areas where a constantly high gas concentration is present as standard
• In potentially explosive areas

Warm-up time and display on the gas warning device

• After applying the mains voltage to the gas warning system, the sensor requires a warm-up time of approx. 15 minutes
• Once the sensor has reached the required operating temperature, the GX-A1+ displays “Operation”
• On the GX-HS the LED switches from flashing to continuously lit
• Even in the event of a power failure, the warm-up time is restarted
• The sensor voltage can be displayed on the GX-A1+ display
• The open-circuit voltage settles within 30 minutes after commissioning; in colder surroundings it decreases
• The sensor element should not become colder than permitted, as the increased heating current requirement also accelerates ageing
• If the sensor voltage is too low, GX gas warning devices detect a sensor failure and display a fault
• Also read the operating instructions of your GX gas warning device

Function test, false alarms and behaviour in the event of an alarm

Function test and care

• Hold a lighter (without flame) at least 10–20 cm above the sensor and allow the escaping gas to sink onto the sensor for a short moment
• GX-A1+: If a voltage increase is displayed in the 2nd line of the display, the sensor is functioning correctly
• GX-HS: Carry out the test at least until the GX-HS switches to pre-alarm in order to recognise a reaction
• Do not overdo the test: Every contact with gas contributes to wear and shortens the service life. Never “bathe” the sensor in gas; it could be destroyed
• The manufacturer recommends carrying out the test every 6 months
• Regularly remove dust from the sensor by blowing
• Protect the sensor against moisture, pressure and draughts
• Observe the date (month/year) indicated on the sensor for the next sensor inspection and return the sensor to Elektrotechnik Schabus for factory inspection or replacement
• For safety reasons, replace the sensor after a maximum of 5 years (service life approx. 5 years)
• Further information can be found in the operating instructions of the GX gas warning device

False alarms and cross-sensitivity

• Due to the close chemical relationship with combustible gases (CGs) such as methane, butane, propane and ethanols, the sensor shows pronounced cross-sensitivities to these compounds
• This must be taken into account when assessing false alarms

Behaviour in the event of an alarm

• Do not unplug the warning device
• Do not switch on any further electrical appliances
• Do not light any open flames or extinguish open fires
• Ensure fresh air: remain calm, open all doors and windows and thoroughly ventilate the room or house
• If the alarm continues or occurs again, evacuate the building and leave all windows and doors open. Ensure that all persons in the house are warned
• Investigate the room or house for possible sources of fire
• Refrigerants are highly flammable. Important: All persons must leave the house
• Eliminate the cause of the gas leak. In case of uncertainty, contact the energy supply specialist
• In the event of a persistent or repeated alarm, contact the energy supply specialist or the fire brigade
• Provide medical help for everyone
• Observe the reaction notes of the R and S phrases issued with the safety data sheet for the respective refrigerant

Manufacturer’s notes

• Read the operating instructions thoroughly before mounting and commissioning and keep them; they form part of the product
• The sensor is not ATEX-certified and is not suitable for potentially explosive areas (EX zones)
• The sensor operates in dry rooms and is operated outside refrigeration systems
• Never expose the sensor to pure refrigerant gas
• Do not permanently expose the sensor to high gas concentrations: This reduces sensitivity and service life
• Do not open the device; it contains no parts that can be maintained by the user
• Packaging material is not a toy and must be kept away from children
• The device is not approved for any use other than that described
• Intended for residential areas (houses, flats, rooms), commercial and business premises (shops, hypermarkets), small businesses (workshops, service centres) with connection to the public low-voltage network
• Avoid moisture (splash or rain water), dust and direct sunlight on the device
• Clean only with a dry linen cloth; if heavily soiled, slightly dampened; no solvent-based cleaning agents
• The manufacturer is not liable for damage or losses of any kind, e.g. individual or consequential damage, resulting from the fact that no alarm signal is given by the gas detector despite elevated gas concentration
• The CE declaration is available for download on the manufacturer’s website

Use in EX areas

The GX-CFC is an electronic device that is not designed in such a way that it reliably excludes an ignition source. In potentially explosive atmospheres, special safety regulations apply and devices must be certified there according to the ATEX Directive. This does not apply to the GX-CFC. However, a gas leak does not automatically lead to an explosive atmosphere. In many areas of application (e.g. technical rooms, heat pumps), no EX zone classification is necessary; the GX-CFC can be used there. If you do not know whether your place of use is classified as an EX area, speak to your occupational safety specialist, the responsible electrical planner or the manufacturer of the system.

Warranty, guarantee, return and disposal

The device is covered by the statutory warranty of at least 2 years in the EU. The manufacturer Elektrotechnik Schabus additionally offers a 5-year guarantee that can be registered online. There is a right of withdrawal of 14 days. Repair and spare parts are available directly from the manufacturer, even beyond the statutory warranty.

The manufacturer repairs or replaces the device free of charge in the event of a warranty claim if the following is fulfilled: The device is sent in with a description of the fault, proof of purchase and address and delivery address (name, telephone number, street, house number, postcode, city, country), adequately packed (the manufacturer accepts no liability for damage or loss during shipping) and used in accordance with the operating instructions. No liability is accepted for damage caused by accident, misuse, modification or negligence.

In the event of a defect, please contact the manufacturer and provide your complete address and the reason for return. Within Germany you will receive a free return label by e-mail. Carriage forward packages will not be accepted; unjustified returns that do not constitute a complaint will be charged subsequently.

The device does not belong in household waste. The crossed-out wheeled bin symbol reminds you to use the take-back systems for waste electrical and electronic equipment (WEEE No. DE91394868). The product may contain substances that are hazardous to health and the environment. Information on collection, reuse and recycling systems can be obtained from your local waste advisory service or from the manufacturer.

Why the GX-CFC is suitable

Areas of application

• Heat pumps
• Air-conditioning systems
• Cold stores
• Refrigeration systems
• Technical rooms

The Schabus GX-CFC monitors systems for refrigerant leaks, for the protection of people and systems as well as against consequential damage.

Gas warning devices with which the GX-CFC is operated

• GX-A1+ – Gas warning control unit from Schabus
• GX-HS – Gas control unit (signalling device) from Schabus

Frequently asked questions