Gas Alarm GX-D500P

The professional CO₂ detector for thermally demanding rooms: safely monitor CO₂ from cold stores, dry ice storage and technical rooms from the outside

The Schabus Profi CO₂ Detector GX-D500P is a carbon dioxide warning device with an integrated NDIR sensor for thermally demanding or heavily dust-laden rooms. It is permanently installed on the wall and connected to the room to be monitored via a silicone hose, for example to a cold store. Room air is drawn to the sensor in the device via the hose. This keeps the sensor and control unit protected, while the hose bridges cold, heat, humidity and dust from the monitored room. A plain-text display continuously shows the operating status and the current CO₂ concentration in the monitored room.

Alarming takes place in two stages and is based on the technical guidelines for beverage dispensing systems according to DIN 6653-2: a pre-alarm at 1.5 % CO₂ and a main alarm at 3.0 % CO₂. The thresholds are designed for technical CO₂ releases, not for room air monitoring. False alarms caused by the breath of people are therefore not to be expected; a leaking valve, a broken hose or a defective tank, on the other hand, are reported in stages. The detector warns optically and acoustically and at the same time switches a potential-free relay that can, for example, activate forced ventilation or close solenoid shut-off valves. A second relay reports faults to the building management system.

The GX-D500P is ideal for detecting faults in technical CO₂ systems under pressure in indoor areas before the room is entered. It is also ideally suited for monitoring ventilation in rooms with dry ice processing. Installation next to the access door to the monitored room is recommended: anyone wishing to enter the room can see the current CO₂ value beforehand and is warned in good time in the event of danger.

Extract, measure, warn, switch

The GX-D500P combines an internal NDIR sensor with an extraction hose, two alarm stages adapted to technical leaks and two potential-free relay outputs.

What is included in the box

The device is supplied with hose, dust filter and mounting material. It has no options and no additional variants.

• GX-D500P CO₂ warning device
• 2 metres of silicone hose (re-orderable under Art. No. 21002)
• 1 dust filter (re-orderable under Art. No. 300259)
• 2 large and 1 small PG cable glands
• Mounting material: 4 screws with wall plugs, 2 cable ties, 2 screwdrivers
• Operating and installation instructions

Optionally available is the USB calibration adapter cable (Art. No. 200340), see Accessories section.

How the GX-D500P is constructed

The control unit sits in a surface-mounted housing on the wall. The silicone hose guides the air from the monitored room to the sensor in the device. The microcontroller evaluates the measuring signal and controls the display, LEDs, alarm generator and the two relays.

Two stages, two signals

The technical guidelines for beverage dispensing systems stipulate that a pre-alarm is triggered from 1.5 % CO₂ in the ambient air. The main alarm follows at 3 % CO₂.

You acknowledge the acoustic alarm with the TEST/RESET button. This only mutes the alarm tone; the alarm mode remains active. If the ventilation measures initiated immediately have not significantly reduced the CO₂ concentration, at least below 3.0 %, the alarm cannot be switched off. If the CO₂ concentration falls below the alarm threshold, the device resets itself.

Alarm delay times are not defined by the software. A natural delay results from the length of the hose and the response time of the NDIR sensor. To ensure a reaction within 3 to 4 minutes, the hose should not be longer than 4 metres; shorter is always better.

The fixed alarm limits can only be adjusted at the factory. Even a re-calibration by the operator does not change the spacing of the warning stages.

Mount correctly, route the hose and put into operation

The GX-D500P may only be installed in dry indoor areas on a wall. The mounting position “at medium height” is chosen so that the display is easy to read when standing. This also ensures proper function of the warning device.

Wall mounting

1. Loosen the four housing screws of the front panel.
2. Remove the front panel and, if necessary, unplug the ribbon cable from the connector.
3. Fasten the base shell of the housing to the wall with the enclosed mounting material (4 screws with wall plugs).
4. After installation, fit the front panel, plug the ribbon cable firmly into its socket and screw the front panel back on.

When connecting accessories to the potential-free relays, the switching current of 5 amperes must never be exceeded.

Routing the hose to thermally demanding rooms

The following rules apply to all applications:

• The warning device must always be above the hose inlet
• Sagging must be excluded by careful routing
• Between the CO₂ warning device and the wall exit the hose must be at least 1000 mm long
• Vertical routing is optimal; horizontal routing must be avoided
• In the case of lateral offset the minimum gradient is 15°, preferably 20°
• The maximum hose length is 4 metres
• The bending radius is at least 70 mm
• The hose must neither be kinked nor crushed
• Check the hose regularly for damage and contamination
• A floor-level hose inlet is optimal for CO₂

Depending on the position of the hole for the hose and the location of the warning device, the hose can be shortened. The minimum length of 1000 mm between the exit (hole) and the outlet on the GX-D500P must be observed for hot and cold rooms. To shorten, add the thickness of the wall and an overhang of the hose of 5 to 10 mm at the inlet. For a wall with 35 mm insulation, for example, this is at least 1040 mm. In rooms with dust loading, “inside” significantly more hose is needed to connect the dust filter with the minimum bending radius.

Sagging must be avoided at all costs. Accumulations of condensation and other deposits that impair the diffusion of the medium to be monitored into the device cannot be detected by the warning device. They can lead to delayed alarm behaviour, in the worst case to failure of the monitoring. The user therefore regularly checks the cleanliness of the hose and, if necessary, carries out cleaning measures or replaces the hose with an equivalent one. Only thick-walled silicone hoses are recommended, for example Schabus Art. No. 21002. With other types or hoses with a total length of more than 4 metres the response time can be significantly delayed.

Hose routing and fastening

• Mounted vertically above the exit hole, fastening or guiding of the hose can be omitted, provided it is not a public area
• Where public traffic is to be expected, covering with a standard cable duct is recommended
• For mounting with lateral offset, empty conduits or plastic hose clamps are recommended
• Since the hose must neither be crushed nor kinked, loop formation cannot be avoided at the smallest bending radius of 70 mm

The specialist carrying out the installation is responsible for finding the fastening appropriate to the respective environment and thereby contributes to the intended function of the warning device.

Using the dust filter

In dry indoor areas with high dust loading, for example a woodworking shop or dry ice blasting, attach the enclosed dust filter (Art. No. 300259) to the hose inlet and secure it with a cable tie. The filter can be fastened to the wall with a screw and wall plug at the filter’s screw hole. Observe the smallest bending radius of 70 mm. If the warning device and dust filter are in the same room, the hose may also be significantly shorter than for thermally demanding rooms. Minimum lengths do not have to be observed in normally tempered rooms (10 °C to 40 °C).

• The dust filter must not be used in particularly warm or cold environments
• The combination of extraction and dust filter presupposes at least similarly tempered rooms in which people can stay permanently
• Like the device itself, the dust filter is permanently suitable only for temperatures of +10 °C to +50 °C
• Regularly free the filter of dust by blowing and avoid moisture or wetness on the filter
• After one year of operation the filter should be replaced

Commissioning

1. Apply mains voltage. The display greets you with the manufacturer’s name and the device type; an electrical function test runs for a few seconds.
2. The self-tests and the initialisation of software and sensor start. The display shows “Wait... Sensor Preparing” for around 3 minutes.
3. Then the main display with the measured CO₂ concentration appears. If the green LED lights alone, the warning system is in order and ready for operation. It now monitors the room immediately and can remain in continuous operation for years apart from the regular calibrations.

Even after a short power failure the function test is started again.

Display information and self-monitoring

With each press of the SERVICE button you go to the next display until the main display appears again. If you remain on a display, the device automatically returns to the main display after a few minutes, likewise if you hold the SERVICE button pressed a little longer.

• Main display: current CO₂ concentration, with “Pre-alarm” in the event of a pre-alarm, with “Alarm!” in the event of a main alarm
• Product Type: device family
• Software Version: installed version
• On Time: time since switch-on
• Last Error: error code of the last fault
• CO2 Sensor: current ppm value
• CO2 at alarm: CO₂ value at the last alarm
• Alarm Counter: CO₂ alarms to date
• Error Counter: faults detected to date
• Starts Counter: counter for restarts
• System Temp: internal system temperature
• Chip Temp: current temperature of the microcontroller
• Last Error at: time since the last error
• Max. Chip Temp: highest temperature of the microcontroller
• Sensor Range: installed sensor

Self-tests in the background

The built-in 32-bit microcontroller continuously monitors the system at around 300 points in hardware and software. Several temperatures, voltages and currents are measured and compensated, some of the results are stored for internal long-term tests, calculated with one another and some of them displayed on the display. In addition the system performs regular tests on the sensor element. If the test result is “good”, you notice nothing of the self-tests. If it is rated “not good”, the system performs up to three restarts, repeats the measurements and then decides whether a fault message is issued.

Test the alarm generator regularly

For your safety the manufacturer recommends regularly checking the acoustic alarm generator with the test button for proper function.

How to check the GX-D500P

1. Press the TEST/RESET button.
2. All three LEDs light up, the alarm generator sounds and both relays Re1 and Re2 drop out.
3. Also check whether connected devices such as forced ventilation or the building management system react as intended.

Behaviour in the event of an alarm

• Ventilate the room and ensure by switching off or shutting off the CO₂ source that no further carbon dioxide can escape
• Inform other persons and ask them to leave the room
• Remain calm, open all doors and windows, take all combustion appliances out of operation and provide fresh air
• If the alarm continues or occurs again: evacuate the building, leave all windows and doors open and ensure that all persons in the building are warned
• Seek medical help for anyone showing symptoms of carbon dioxide poisoning and point out that inhalation of carbon dioxide is suspected
• If necessary call the emergency number so that the source of the CO₂ release can be identified and eliminated
• Only put the CO₂ system back into operation when a competent person has checked it and released it for use

Faults, cleaning and zero-point adjustment

Recognising a fault

• Fault relay Re2 always drops out so that the building management system or home automation is informed
• The yellow LED flashes or lights up
• A short beep sounds every 10 to 30 seconds
• Press the SERVICE button repeatedly until the display shows the type of fault: “error” and a number appear. Quote this number to the technical support of Elektrotechnik Schabus, who will find a solution together with you

Faults can have many causes and different effects. Only a few affect the measurement and prevent alarming in the event of danger. Some merely indicate adverse ambient conditions with accelerated ageing or mains voltage fluctuations. The flash rhythms of the yellow LED come directly from the microcontroller. If the yellow LED only lights continuously, the microcontroller itself has a fault. A controller problem can only be remedied at the manufacturer’s works.

Remedying simple faults

• Press the TEST/RESET button so that fault relay Re2 is energised again. Alarm relay Re1 remains energised even if a fault is present
• Only in the event of a new fault of the same or a different type does Re2 drop out again
• Most faults remedy themselves or when the device is disconnected from the power supply, allowed to cool for about 15 minutes and then restarted, if possible in fresh air
• If there is no improvement, contact technical support

Maintenance

The GX-D500P operates with essentially low maintenance. Free it of dust from time to time and use only dry cloths for this purpose. Please do not blow into the hose and do not suck on it. Check the hose regularly for cleanliness and damage and replace the dust filter after one year of operation.

Every sensor is subject to natural drift. The zero point shifts upwards, the sensor becomes more sensitive and goes into alarm more and more often and earlier. This is intrinsically safe, because the spacing of the prescribed alarm thresholds is retained. Therefore reset the zero point regularly or as required. “Regularly” means approximately every six months to annually; with increased requirements up to once a month. The less frequently the sensor receives fresh or low-load air, for example below 800 ppm CO₂, the more frequently a zero-point adjustment is necessary. The service life of the sensor is more than 8 years; a factory inspection after 5 years is recommended.

Zero-point adjustment step by step

1. Open the 4 housing screws of the front panel, fold the cover upwards and pull the ribbon cable plug out of the socket in the base.
2. Carefully lift the plug from the sensor module with a small screwdriver, changing sides several times so that it comes out as straight as possible. On no account pull on the wires.
3. Unscrew the two very small M2 screws in the opposite corners of the sensor module (they are easily lost) and remove the module.
4. Connect the USB calibration adapter cable to the sensor module and plug the USB connector into a 5-volt USB power source, for example a power supply unit, laptop or power bank, near a window or outdoors in fresh air.
5. Darken the membrane with your hand: the infrared LEDs underneath first light very weakly red and flash after up to one minute. This confirms that the power supply is present and the process has started correctly.
6. Take the sensor into genuine fresh air outdoors and leave it there for at least 30 minutes, ideally in a shady place, at least not in full sun, on an insulating surface. Move away from the sensor so that your breath does not falsify the values.
7. After more than 30 minutes of fresh air, hold the calibration button pressed for at least 7 seconds. A clock with a second display helps. The zero-point adjustment is then complete.
8. Reinstall the sensor module in reverse order: unplug the USB cable, fasten the module with the two M2 screws, connect it to the base, plug the ribbon cable firmly into its socket and screw the cover on. Then switch the operating voltage back on.
9. Document the calibration with date and time.

Cleaning and care

• Avoid the influence of moisture (splash or rainwater), dust and direct sunlight on the device
• Clean the device only with a dry linen cloth; in the case of heavy soiling it may be slightly dampened
• Do not use solvent-containing cleaning agents
• Do not blow into the hose and do not suck on it

Manufacturer’s notes

• Read the operating instructions carefully before installation and commissioning and keep them; they form part of the product
• Installation must be carried out by a qualified specialist
• Install only in dry indoor areas on a wall
• Do not use in potentially explosive areas
• The device is not approved for any use other than that described
• Intended for residential, commercial and industrial areas as well as small businesses; all places of use are connected to the public low-voltage network
• The connection cables must be permanently installed as surface-mounted cables
• Zero-point adjustment may only be carried out by authorised and competent specialist personnel
• Packaging material is not a children’s toy and does not belong in children’s hands
• Elektrotechnik Schabus is not liable for damage or loss of any kind resulting from the fact that no alarm signal is given despite an elevated gas concentration
• The CE declaration is available for download on the manufacturer’s website

Possible accessories

The device itself has no options. The following are available as accessories and spare parts:

Statutory warranty, guarantee, returns and disposal

The GX-D500P 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, even beyond the statutory warranty. A prerequisite is that the device has been used in accordance with the operating instructions. The manufacturer accepts no liability for damage caused by accident, misuse, modification or negligence.

The GX-D500P does not belong in household waste. The crossed-out wheeled bin symbol on the product reminds you to use the take-back systems for waste electrical and electronic equipment (WEEE Reg. No. DE91394868). In this way the materials can be reused in an environmentally friendly manner at the end of the service life. Information on collection, reuse and recycling systems is available from the waste advisory service of your city or from the manufacturer.

Why the GX-D500P is suitable

Areas of application

• Dry ice processing and storage, for example in vaccination centres
• Dry ice blasting and rooms with high dust loading, with dust filter
• Meat and sausage product cooling
• Cold stores, cold rooms and deep freezing
• Hot technical rooms and production areas
• Beverage dispensing systems, also in cellars with high air humidity
• Breweries with temperature fluctuations
• Greenhouses and plant production
• Automatic forced ventilation and ventilation systems with draughts
• Industry and food processing with dusty CO₂ processes

The Schabus Profi CO₂ Detector GX-D500P: Because good air knows no compromise.

Frequently asked questions