Gas detectors according to DGUV: organizing use, operation, bump testing and calibration correctly

→ Gas detectors

Gas detectors are an important part of occupational safety when employees may be exposed to flammable gases, toxic gases, vapors or oxygen deficiency. In practice, this is not only about selecting the right device, but also about safe use, regular checks, calibration, alarm handling and traceable documentation.

Anyone searching for gas detectors DGUV usually wants to know which requirements must be observed when operating portable or fixed gas detectors. Particularly relevant are DGUV Information 213-056 for toxic gases, vapors and oxygen, and DGUV Information 213-057 for gas detection devices used in explosion protection.

This article explains what operators, safety specialists, maintenance teams and users should pay attention to: from risk assessment and selection of target gases to bump testing, calibration, maintenance, alarm thresholds, documentation and suitable portable or fixed gas detectors.

You can find suitable devices in our category
Gas measuring instruments / gas detectors.
For mobile applications, for example,
portable gas detectors
are relevant. For plants, machine rooms, process areas or continuous monitoring,
fixed gas detectors
can be used. Depending on the application, products such as
Gas-Pro multi-gas detector,
Gasman single-gas detector,
Tetra 3 portable multi-gas detector
or fixed SMART gas detectors can be used.

What are gas detectors?

Gas detectors are measuring and warning devices that detect hazardous gas concentrations or oxygen deviations in the air. They warn users or plant operators before a dangerous situation develops or before limit values are reached.

Depending on the application, portable gas detectors, fixed gas detectors or complete gas detection systems are used. Portable devices protect individual persons during mobile work. Fixed systems continuously monitor specific areas, rooms, plants or process zones.

Device type	Description	Typical application
Portable gas detector	Carried by a person and provides a warning directly at the workplace.	Tank entry, sewer, shaft, wastewater treatment plant, maintenance.
Single-gas detector	Monitors one specific target gas.	CO, H₂S, O₂ or flammable gases.
Multi-gas detector	Monitors several gases simultaneously.	O₂, CO, H₂S and flammable gases in one device.
Fixed gas detector	Continuously monitors a fixed measuring point.	Machine room, storage area, process plant, gas cylinder storage.
Gas detection system	Consists of several detectors, an evaluation unit and alarm signaling.	Continuous room or plant monitoring.

DGUV reference: which information is important?

Two DGUV information documents are particularly relevant for gas detectors. DGUV Information 213-056 covers gas detection systems and devices for toxic gases, vapors and oxygen. DGUV Information 213-057 covers gas detection systems and devices for explosion protection.

These documents provide important guidance for design, use, operation, initial commissioning, maintenance, checks and repair. However, they do not replace the specific risk assessment of the company or the review of the respective manufacturer’s instructions.

Source	Topic	Link
DGUV Information 213-056	Gas detectors for toxic gases, vapors and oxygen.	Open DGUV 213-056
DGUV Information 213-057	Gas detectors for explosion protection.	Open DGUV 213-057
BAuA / TRGS	Technical Rules for Hazardous Substances as an important basis for occupational safety.	Open BAuA TRGS overview

Risk assessment as the basis

The selection of a gas detector does not begin with the device, but with the risk assessment. This determines which gases can occur, where they can occur, at which concentration they become hazardous, how quickly the situation can change and which protective measures are required.

Only then can a meaningful decision be made as to whether a portable gas detector, a fixed detector or a complete gas detection system is required. Alarm thresholds, sensor type, test intervals and documentation also depend on this assessment.

Question	Why important?	Example
Which gases can occur?	Sensors must match the target gas.	CH₄, H₂S, CO, O₂, CO₂, VOC or refrigerants.
Where can gases occur?	Measuring point and device use depend on the location.	Shaft, tank, machine room, laboratory, hazardous area.
What hazard exists?	Explosion hazard, poisoning or oxygen deficiency differ.	LEL monitoring, occupational exposure limit reference, O₂ deficiency.
How quickly does the hazard develop?	Response time and alarm signaling must be suitable.	Leakage, gas release, process disturbance.
Who needs to be warned?	Personal protection and plant alarm differ.	Portable personal detector or fixed alarm system.

Portable or fixed gas detectors?

Portable gas detectors and fixed gas detectors fulfill different tasks. Portable devices accompany people directly during work. Fixed systems continuously monitor fixed areas and can trigger alarms, ventilation, shutdowns or control functions.

Version	Advantage	Typical application
Portable gas detector	Direct personal protection at the place of use.	Maintenance, entry, clearance measurement, service.
Portable device with pump	Sampling before entry is possible.	Pre-entry test in tanks, shafts or sewers.
Fixed gas detector	Continuous monitoring of a fixed area.	Machine room, storage area, gas supply, process plant.
Gas detection system	Several measuring points and central alarm signaling.	Industrial plant, laboratory area, refrigeration system, hazardous area.

In many companies, both solutions are combined: fixed gas detectors for continuous area monitoring and portable gas detectors for maintenance, entry and work at changing locations.

Target gases: flammable gases, toxic gases and oxygen

Gas detectors must be matched to the target gases. A device for oxygen deficiency is not automatically suitable for flammable gases. A CO detector does not automatically detect H₂S. An Ex measuring range in percent LEL has a different meaning than a toxic measuring range in ppm.

Hazardous substance group	Typical gases	Measuring objective
Flammable gases	Methane, propane, butane, hydrogen, solvent vapors.	Warning of explosive atmosphere.
Toxic gases	CO, H₂S, NO₂, SO₂, NH₃, Cl₂.	Warning of concentration hazardous to health.
Oxygen	O₂ deficiency or O₂ enrichment.	Detection of suffocation hazard or fire-promoting conditions.
Carbon dioxide	CO₂ in basements, breweries, laboratories or refrigeration systems.	Monitoring of breathing air and process hazards.
VOC	Volatile organic compounds.	Detection of solvent vapors or organic vapors.

Gas detectors for explosion protection

For flammable gases and vapors, explosion protection is often the main focus. Gas detectors monitor the concentration in relation to the lower explosion limit. The aim is to detect hazardous concentrations early and trigger suitable measures.

In hazardous areas, not only the measuring range and sensor must be suitable. Device approval, ATEX version, type of ignition protection, temperature range, mechanical robustness and operating environment are also relevant.

Selection point	Why important?	Practical recommendation
LEL measuring range	Required for evaluating flammable gas-air mixtures.	Check measuring range and target gas.
ATEX approval	Device must match the hazardous zone.	Compare Ex marking with place of use.
Sensor principle	Catalytic, IR or MPS sensors react differently.	Select sensor according to gas type and environment.
Cross-sensitivities	Other gases can influence the indication.	Evaluate application and gas mixture.
Alarm signaling	Warning must be timely and clear.	Provide optical, acoustic, vibration or plant alarm.

Detecting oxygen deficiency and oxygen enrichment

Oxygen measurements are important when oxygen can be displaced or enriched. Oxygen deficiency can occur, for example, due to nitrogen, carbon dioxide, argon or other inerting gases. Oxygen enrichment can significantly increase the risk of fire.

Especially for tank entry, confined spaces, laboratories, refrigeration systems, gas cylinder storage or inerting processes, oxygen monitoring is a central part of the safety assessment.

Situation	Hazard	Gas detector
Inerting with nitrogen	Oxygen is displaced.	O₂ detector or multi-gas device with O₂ sensor.
CO₂ release	Oxygen deficiency and CO₂ hazard possible.	Check CO₂ and O₂ monitoring.
Confined spaces	Unknown atmosphere before entry.	Pre-entry test with portable gas detector.
Oxygen enrichment	Increased fire and reaction hazard.	O₂ monitoring with suitable alarm thresholds.

Safely monitoring toxic gases

Toxic gases can be dangerous even in small concentrations. Target gas, measuring range, sensor type and alarm thresholds must therefore be selected carefully. Typical toxic gases include carbon monoxide, hydrogen sulfide, nitrogen dioxide, sulfur dioxide, ammonia or chlorine.

For toxic gases, it is especially important whether a short-term peak exposure or a time-weighted exposure is to be evaluated. Many portable gas detectors can display instantaneous values, peak values and time-weighted values.

Gas	Typical hazard	Typical application
CO	Carbon monoxide poisoning.	Combustion processes, boiler rooms, fire service operations, industry.
H₂S	Highly toxic gas, often found in wastewater and process areas.	Wastewater treatment plants, shafts, sewer systems, oil and gas industry.
NH₃	Irritant gas and hazardous substance.	Refrigeration systems, chemical industry, fertilizers, food industry.
NO₂ / SO₂	Irritating and harmful gases.	Combustion, exhaust gases, process areas.
Cl₂	Highly reactive and toxic gas.	Water treatment, chemical industry, disinfection.

Bump test / function test before use

A gas detector must function reliably before use. A bump test or function test checks whether the device reacts to a suitable test gas and whether alarm signaling, indication and sensor response are basically functioning.

The bump test does not automatically replace full calibration. It is a quick function check before use. The exact frequency and procedure must be defined based on the risk assessment, DGUV guidance, manufacturer’s instructions and company specifications.

Check	What is checked?	Why important?
Visual inspection	Housing, display, filter, sensor opening, accessories.	Detect mechanical damage or blockages.
Battery status	State of charge and readiness for operation.	Device must function for the duration of use.
Bump test	Reaction to test gas and alarm signaling.	Sensor and alarm function are checked quickly.
Alarm test	Acoustic, optical and vibration alarm.	Warning must be perceptible during use.
Documentation	Proof of function check.	Important for operational safety and traceability.

Calibration and adjustment of gas detectors

Gas detectors are measuring instruments. Sensors can age, drift or be affected by environmental conditions. Gas detectors must therefore be checked and calibrated regularly. During calibration, the indication is compared with a known test gas. During adjustment, the device is set so that the indication again matches the test gas correctly.

Calibration intervals depend, among other things, on sensor type, gas type, frequency of use, environmental conditions, manufacturer’s instructions and company specifications. In critical applications, calibration and function checks should be organized and documented particularly carefully.

Term	Meaning	Practical benefit
Bump test	Quick function check with test gas.	Shows whether the device generally reacts and alarms.
Calibration	Comparison with known test gas.	Shows the measurement deviation of the device.
Adjustment	Setting the device to correct indication.	Reduces measurement deviation.
Zero check	Checking the indication in clean air or zero gas.	Important before span calibration.
Span check	Check with defined test gas concentration.	Evaluation of the sensor in the relevant measuring range.

Maintenance, sensor replacement and servicing

Gas detectors must remain functional throughout their entire period of use. This includes visual inspection, cleaning, filter replacement, sensor check, calibration, battery check, software or device settings and, if necessary, sensor replacement.

Sensors have a limited service life. Some sensor types react sensitively to certain substances, poisoning, humidity, temperature or overload. Devices should therefore be evaluated not only according to calendar intervals, but also according to operating conditions.

Maintenance point	Why important?	Practical recommendation
Sensor opening / filter	Blockage prevents gas access.	Check and clean regularly.
Sensor ageing	Measured value can drift.	Monitor calibration history.
Battery / rechargeable battery	Device must be reliably ready for use.	Check charge level and battery condition.
Alarm indicators	Alarm must be perceptible.	Test acoustic alarm, LED and vibration.
Software / settings	Alarm thresholds and gas type must be correct.	Document and approve configuration.

Alarm thresholds, pre-alarm and main alarm

Alarm thresholds must match the hazard and the company’s protection strategy. For flammable gases, values are often based on the lower explosion limit. For toxic gases, occupational exposure limits, short-term values, peak values and company specifications play a role. For oxygen, the focus is on oxygen deficiency or oxygen enrichment.

Many gas detectors work with several alarm levels. A pre-alarm can provide an early warning, while a main alarm should trigger clear protective measures. Fixed systems can also activate ventilation, shutdown, signal lights or control systems.

Alarm type	Function	Typical measure
Pre-alarm	Early warning when concentration rises.	Observe area, check cause, prepare measures.
Main alarm	Hazardous concentration or critical condition.	Leave area, stop process, activate ventilation or emergency plan.
STEL / short-term value	Evaluation of short-term exposures.	Important for toxic gases.
TWA / time-weighted average	Evaluation over a longer period.	Relevant for occupational safety and exposure assessment.
Fault alarm	Device or sensor not ready for operation.	Lock device, check, service or replace.

Documentation and record keeping

The safe operation of gas detectors must be organized in a traceable manner. This includes device assignment, serial number, target gases, alarm thresholds, bump tests, calibrations, maintenance, sensor replacement, repairs and release for use.

Especially with several devices, changing locations or safety-critical applications, structured documentation is important. Docking stations, calibration software or digital device management systems can significantly reduce the workload.

Documentation	Why important?	Example
Device data	Assignment and traceability.	Serial number, device type, sensors, target gases.
Alarm thresholds	Settings must be traceable.	Pre-alarm, main alarm, TWA, STEL.
Bump test	Proof of readiness for use.	Date, result, test gas, user.
Calibration	Proof of measurement accuracy.	Test gas, measured value, deviation, adjustment.
Maintenance / repair	Device history.	Sensor replacement, battery replacement, cleaning, troubleshooting.

Product comparison: suitable gas detectors

The right device selection depends on whether persons need mobile protection, whether measurements must be taken before entry, or whether an area needs to be monitored continuously.

Product / category	Suitable for	Typical application
Gas measuring instruments / gas detectors	Overview of portable and fixed gas measuring technology.	Preselection of suitable devices for occupational safety and plant monitoring.
Portable gas detectors	Personal protection and mobile measuring tasks.	Maintenance, tank entry, sewer, shaft, hazardous area.
Gas-Pro multi-gas detector	Monitoring of up to several gases, optionally with pump.	Pre-entry tests, industry, hazardous areas, maintenance.
Tetra 3 portable multi-gas detector	Personal multi-gas monitoring.	Work in hazardous areas and confined spaces.
Gasman single-gas detector	Personal monitoring of one target gas.	CO, H₂S, O₂ or flammable gases depending on version.
Fixed gas detectors	Continuous area and plant monitoring.	Machine rooms, refrigeration systems, gas storage, process areas.
SMART S-MS fixed gas detector	Refinery, petrochemical and industrial hazardous-area applications.	Fixed monitoring of flammable and toxic gases.
SMART 3G-C2 fixed gas detector	Fixed detection of toxic, flammable and refrigerant gases.	Industry, process plants, gas detection systems.

Practical examples from industry, wastewater treatment, laboratory and hazardous areas

Example 1: Tank entry with portable multi-gas detector

Before entering a tank, the atmosphere is checked. A portable multi-gas detector with pump measures oxygen, flammable gases, carbon monoxide and hydrogen sulfide. The area may only be entered once the measured values are non-critical and the company approvals are available.

Example 2: Wastewater treatment plant with H₂S and oxygen hazard

Hydrogen sulfide and oxygen deficiency can occur in shafts and sewers. Employees carry a portable gas detector that warns of H₂S and O₂ deviations. Before use, a function test is carried out and documented.

Example 3: Solvent storage with fixed Ex monitoring

A fixed gas detection system is used in a storage area for flammable solvents. Detectors monitor possible gas or vapor concentrations. In the event of an alarm, optical and acoustic warnings as well as technical measures are triggered.

Example 4: Refrigeration system with ammonia or CO₂

In machine rooms of refrigeration systems, ammonia or carbon dioxide can reach hazardous concentrations. Fixed gas detectors continuously monitor the area and can activate ventilation or alarm signaling.

Example 5: Laboratory area with changing hazardous substances

Different gases and vapors can occur in laboratories. The selection of the gas detector must therefore be adapted to the actual substances, quantities, ventilation situation and work processes. For VOCs, a PID sensor can be useful.

Checklist: using gas detectors safely according to DGUV

This checklist helps to better prepare and organize the use of gas detectors.

Check question	Why important?	Practical recommendation
Is a risk assessment available?	Safe device selection is not possible without a risk assessment.	Define gases, locations, hazard and protective measures.
Which target gases must be monitored?	Sensors must match the specific hazard.	Check flammable gases, toxic gases, O₂, CO₂ or VOC.
Is personal protection or plant monitoring required?	Portable and fixed devices fulfill different tasks.	Select device type based on the use case.
Is the area of use hazardous?	Device must match the Ex zone.	Check ATEX marking and device approval.
Are bump tests organized?	Functionality must be ensured before use.	Define test gas, docking station or test procedure.
Are calibration intervals defined?	Sensors can drift or age.	Observe manufacturer’s instructions, DGUV guidance and company specifications.
Are alarm thresholds set correctly?	Incorrect alarm thresholds can lead to unsafe operation.	Define and document limit values professionally.
Are users instructed?	Warnings must be understood and evaluated correctly.	Train operation, alarm behavior and emergency measures.
Is everything documented?	Traceability is important for safe operation.	Record bump test, calibration, maintenance and repair.
Is there an emergency plan?	An alarm must lead to clear measures.	Define evacuation, ventilation, shutdown and release procedures.

Conclusion: operating gas detectors safely according to DGUV means more than just buying a device

Gas detectors are important protective systems for working areas where flammable gases, toxic gases, vapors or oxygen deficiency may occur. Safe use begins with a risk assessment and continues with suitable device selection, correct alarm thresholds, regular function checks, calibration, maintenance and documentation.

DGUV Information 213-056 and 213-057 provide important guidance for the use and operation of gas detectors. In addition, manufacturer’s instructions, TRGS, company specifications and the specific operating conditions should be considered.

For mobile work,
portable gas detectors
such as the
Gas-Pro multi-gas detector,
the
Tetra 3 multi-gas detector
or the
Gasman single-gas detector
are suitable.
For continuous monitoring of rooms, plants or process areas,
fixed gas detectors
and complete gas detection systems are the right solution. You can find an overview in the category
Gas measuring instruments / gas detectors.

FAQ: frequently asked questions about gas detectors and DGUV

Which DGUV information documents are important for gas detectors?

For gas detectors, DGUV Information 213-056 for toxic gases, vapors and oxygen and DGUV Information 213-057 for explosion protection are particularly relevant.

What is a gas detector?

A gas detector detects hazardous gas concentrations or oxygen deviations in the air and warns users or plant operators by optical, acoustic or vibrating alarms.

What is the difference between portable and fixed gas detectors?

Portable gas detectors are carried by people and provide mobile personal protection. Fixed gas detectors continuously monitor fixed areas and can trigger alarms or technical measures.

What is a bump test for gas detectors?

A bump test is a quick function check with test gas. It checks whether the gas detector reacts to the gas and whether the alarm function basically works.

Why do gas detectors need to be calibrated?

Sensors can age, drift or be affected by environmental conditions. Calibration shows whether the device indicates correctly when exposed to a known test gas.

What is the difference between calibration and adjustment?

During calibration, the indication is compared with a reference gas. During adjustment, the device is set so that the indication again matches the test gas as accurately as possible.

When do you need an oxygen gas detector?

An oxygen gas detector is required when oxygen deficiency or oxygen enrichment can occur, for example during inerting, in confined spaces, during CO₂ release or gas storage.

When do you need a gas detector for explosion protection?

A gas detector for explosion protection is required when flammable gases or vapors may occur and an explosive atmosphere is possible. The device must match the Ex zone and the application.

Which gases can be monitored with gas detectors?

Typical target gases are flammable gases such as methane or propane, toxic gases such as CO or H₂S, oxygen, carbon dioxide, ammonia, chlorine, nitrogen dioxide, sulfur dioxide or VOC.

What should be documented for gas detectors?

Device data, sensors, target gases, alarm thresholds, bump tests, calibrations, maintenance, sensor replacements, repairs and release for use should be documented.

Which products are suitable as gas detectors?

Depending on the application, portable devices such as the
Gas-Pro multi-gas detector,
the
Tetra 3 multi-gas detector
or the
Gasman single-gas detector
are suitable.
For continuous area monitoring,
fixed gas detectors
or complete gas detection systems can be used.