GX-H₂ – external gas sensor for the detection of hydrogen (H₂)

The external hydrogen sensor for leakage detection – accessory for the gas warning devices GX-A1+ and GX-HS

The Schabus GX-H₂ is an external gas sensor for the detection of hydrogen (H₂, hydrogen) in dry indoor rooms. It is used as an accessory for the gas warning devices GX-A1+ and GX-HS and is connected via an RJ plug connection.

The sensor detects H₂ leaks, for example in air-conditioning and heat-pump systems, with high selectivity for hydrogen. It is small, has low power consumption and can be quickly integrated into Schabus gas warning systems.

The GX-H₂ is not EX-certified and must not be used in potentially explosive atmospheres.

Invisible gas – visible safety

The GX-H₂ reports escaping hydrogen at an early stage to the connected gas warning device.

Why hydrogen monitoring is important

Hydrogen is invisible. Early detection helps to recognise safety-critical conditions in time.

• Hydrogen is highly flammable
• Hydrogen has a very small molecule size
• Hydrogen is significantly lighter than air, according to the manufacturer 14 times lighter
• Escaping hydrogen therefore preferentially collects in the ceiling area
• Early detection recognises technical defects, leaks and safety-critical conditions in time

How the sensor works

The GX-H₂ supplies the gas warning device with a voltage signal that rises with the hydrogen concentration.

• The sensor is supplied with 5 V DC by the gas warning device
• After the supply voltage is applied, the sensor requires a warm-up time
• The sensor output supplies a signal of 0.4 to 4.5 V DC
• At 10 % LEL the gas warning device triggers
• The sensor shows no cross-sensitivity in normal room air and hardly any cross-sensitivity to ethanols
• The sensor shows an exceptionally high sensitivity to hydrogen
• The sensitivity diagram in the operating instructions compares the sensor resistance (Rs/Ro) in air, ethanol and hydrogen, related to 100 ppm hydrogen
• Frequent and high gas concentrations reduce the sensitivity over time and shorten the service life

What is included in the box

The sensor is supplied with sensor cable and the material for mounting.

• Gas sensor GX-H2 with 2.5 m sensor cable
• Mounting material (screw & wall plug)
• Operating instructions

How the GX-H₂ is constructed

The GX-H₂ is a compact external sensor with permanently connected supply cable.

Mounting and connection

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

Positioning the sensor

1. Mount the sensor at a height of 15–30 cm below the ceiling (in the upper third of the room), as hydrogen is significantly lighter than air.
2. According to the manufacturer, the distance to the gas heater or boiler must not exceed 4 m.
3. The prescribed mounting height must be strictly observed.
4. Use only in dry indoor rooms.

Connecting the sensor

1. Connect the sensor via the RJ plug connection to the gas warning device GX-A1+ or GX-HS. Connection is described in the operating instructions of the GX gas warning device.
2. After the supply voltage is applied to the gas warning system, the sensor requires a warm-up time.

Extending the sensor cable

The sensor cables are 2.5 m long as standard. For extension a 3-core cable must be used. The following minimum cross-sections apply:

• 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 at the following locations:

• Places that could prevent the alarm from being triggered in the event of a gas leak (e.g. behind curtains or in cupboards)
• Next to a door, windows, ventilation, fan, stoves, 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

Function test, replacement and behaviour in the event of an alarm

Function test and care

• Carry out a function test with a safe H₂ test gas source (test spray) in accordance with the manufacturer’s instructions
• Hold the gas source 10–20 cm above the sensor and allow the gas to act briefly
• Never direct pure hydrogen gas from pressure cylinders or cartridges directly onto the sensor
• The manufacturer recommends carrying out the test every 6 months
• Remove dust regularly by blowing it off the sensor
• Protect the sensor from moisture, pressure and draughts
• Observe the test date (month/year) indicated on the sensor and return the sensor to Elektrotechnik Schabus for factory testing or replacement
• Replace the sensor for safety reasons after a maximum of 5 years (service life approx. 5 years)

Behaviour in the event of an alarm

• Do not unplug the warning device
• Do not switch on any further electrical devices
• Do not light any open flame 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 recurs, evacuate the building and leave all windows and doors open. Ensure that all persons in the house are warned
• Inspect the room or house for any sources of fire
• Eliminate the cause of the gas leak. In case of doubt, contact the energy supply specialist
• The Ordinance on Hazardous Substances (GefStoffV) also applies when handling hydrogen

Manufacturer’s notes

• Read the operating instructions carefully before mounting and commissioning and keep them
• The sensor is not EX-certified and is not suitable for potentially explosive areas
• The sensor operates in dry rooms (air humidity non-condensing)
• Never expose the sensor to pure refrigerant gas
• Do not permanently expose the sensor to high gas concentrations: this reduces sensitivity and shortens the service life
• Do not open the device; it contains no parts that can be serviced by the user
• Packaging material is not a toy and must be kept away from children
• Intended for residential, commercial and industrial areas as well as small businesses connected to the public low-voltage network
• Avoid moisture (splash or rain water), dust and direct sunlight on the device. Storage temperature −20 °C to +60 °C
• Clean only with a dry linen cloth; if heavily soiled, slightly dampened; no solvent-containing cleaning agents
• The manufacturer accepts no liability for damage or losses resulting from the failure of the gas detector to emit an alarm signal despite elevated gas concentration
• The CE declaration is available for download on the manufacturer’s website

Warranty, guarantee 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. Repair and spare parts are available directly from the manufacturer.

In the event of a defect please contact the manufacturer and provide your complete address as well as the reason for return. Within Germany you will receive a free returns label by e-mail. Unpaid packages will not be accepted; unjustified returns will be charged subsequently. In the case of statutory warranty the device must be sent in with a description of the fault, proof of purchase as well as address and delivery address.

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).

Why the GX-H₂ is suitable

Areas of application

• H₂ leaks in air-conditioning systems
• H₂ leaks in heat-pump systems
• Battery rooms
• Charging areas for lead-acid batteries
• Hydrogen storage
• Research and test facilities, laboratories
• Industrial plants with H₂ technology
• Technical installations in dry indoor rooms

The Schabus GX-H₂ detects escaping hydrogen in the ceiling area – where it preferentially collects.

Gas warning devices with which the GX-H₂ is operated

• GX-A1+ – gas warning device from Schabus
• GX-HS – gas warning device from Schabus

Frequently asked questions