Gas Detector / Gas Detection Instrument

Correctly used gas detectors save lives by alerting in case of dangerous gas concentrations that cannot be detected without technical assistance. They also protect material assets and the environment, and thus our living space, by warning against flammable and explosive mixtures, by monitoring the required gas concentration in production processes or by detecting leaks in pipes and equipment. The gas warning device can be equipped with optical, acoustic or vibration alarms or a combination of these. Stationary gas detectors for production monitoring often also have standard signal or switching outputs. If the limit values are exceeded or undercut, such a gas warning device can be used to automatically control adjustments in the production process or measures for ventilation.

At first it may be irritating that some gas detectors should not be used near flammable gases or in explosive atmospheres. However, it is essential that you observe this warning in the operating instructions and use gas detectors only with special equipment for potentially explosive atmospheres. An unprotected gas detector can ignite existing flammable gas mixtures by sparking or by the heating of the sensor required for the measuring process. In the following European standards you will find important binding specifications regarding requirements for the devices that may be used in hazardous areas:

• Directive 2014/34/EU
for equipment and protective systems for intended use in potentially explosive atmospheres (ATEX Directive)
• EN 60079-0 / IEC 60079-0 / VDE 0170-1
Explosion endangered areas
Part 0: Equipment - General requirements
• EN ISO 80079-36
Explosion endangered areas
- Part 36: Non-electrical equipment for use in potentially explosive atmospheres – Basic concepts and requirements

Before selecting gas detectors for hazardous areas, you should read the relevant regulations and seek advice from a competent person.

Measurable gases – single gas and multi-gas devices
One of the most basic guidelines when looking for a gas detector is to know about the gas or gases to be measured. Depending on the type of danger posed by the gas to be monitored, a distinction is made between gas detectors for toxic gases, for combustible gases or for climate-damaging fluorinated hydrocarbons, which are grouped together under the designation F-gases. Many gas detectors are designed to detect a single special gas. If, for example, firefighters or persons with gas heaters or fireplaces need to be protected from excessive carbon monoxide concentrations, a gas detector specifically for carbon monoxide is used. For the process control of industrial manufacturing processes, it is also advisable to select a gas warning device specifically for the process gas to be monitored – i.e. a single gas measuring device, in order to be able to take targeted countermeasures in the event of deviations. If, however, it is necessary to stay in the areas where several potentially hazardous gases may be present or to search for leaks in gas installations and coolant circuits, then gas detectors that can detect several gases are recommended. There are gas detectors for personal protection which can be equipped with up to four different sensors. These gas detectors for several gases are called multi-gas devices. Fitters, mechanics, miners or rescue workers can be warned of dangerous concentrations of hydrogen sulfide, methane, carbon monoxide and oxygen with such a gas detector. A gas warning device is also frequently used to monitor the quality of indoor air. It can continuously measure and display not only the carbon dioxide content, but also formaldehyde and volatile organic compounds or other additional values such as temperature, humidity or particle content.

Stationary or mobile gas detector
For most applications it is relatively easy to determine whether a stationary or a mobile gas detector is more suitable. The stationary gas detectors are mostly used indoors. If a stationary gas detector is to be used in recreation rooms to monitor the indoor air quality by means of the key variable, such as carbon dioxide concentration, gas detectors with traffic light displays are well suited for indicating the measured values. These green, yellow or red signal lamps or notifications on the displays can be easily recognized in offices and classrooms, even from a longer distance. If the indoor air quality deteriorates, additional ventilation can be provided. For the rooms in which urgent ventilation on is not possible or not desired by the user, the stationary gas detectors with analog or switching outputs can automatically trigger mechanical window openers and increase the air exchange rate of the ventilation systems. Alternatively, persons who are in the endangered area can be warned via connected signal lights or acoustic alarm devices. Stationary gas detectors with interfaces to other devices are also used to monitor and control industrial processes. In addition to the analog and switching outputs, the stationary devices can also be equipped with RS485 or USB connection.

Mobile gas detectors with a memory for measurement data often also have an interface that allows the data to be transferred to a PC. Often the USB interface on the mobile gas detector can be used not only to transfer the data but also to charge the internal battery. Since mobile gas detectors are often used for personal protection in hazardous areas, some of the devices have special functions. For example, one of these special functions in the gas detector can record the total exposure of the carrier for the entire shift. This data can be used to evaluate the total concentration of hazardous substances to which the employee was exposed on that day. To enable the person to be protected to concentrate on his or her task and the environment, the devices can be attached to the clothes and also alert by vibration. To ensure reliable operation even under tough operating conditions with mechanical stress, some of these mobile gas detectors are also tested in special drop tests.

Measuring range for gas detectors
It is essential that the measuring range is selected in consideration of the intended use, i.e. in relation to the purpose of the measurement. For example, a gas warning device for carbon dioxide with a measuring range of up to 500 ppm or up to 60,000 ppm can be selected. But not only the upper limit value, but also the lower value must be considered. Not every gas detector can measure from a concentration of 0 ppm. Some sensors for CO2 are designed in such a way that they can only measure and display values above 400 ppm – which corresponds approximately to the natural concentration of carbon dioxide in the outside air. For many applications this limitation is irrelevant. If, however, the lower values are required for special measurements, care must be taken to select a gas detector that can detect these values.

Measuring and display accuracy of a gas detector
Also the requirements regarding the measuring and display accuracy of the gas detector depend on the application. For the gas detectors for leak detection, which react already far below dangerous concentrations, displays without numerical values are often sufficient. The presence and the intensity of the gas leakage is visually signaled by several indicator bars or LEDs as well as acoustically and haptically. With higher concentrations of the gas, the number of the bars and the frequency of signal tones and vibrations also increase. In indoor areas where the user can react to too high measured values with ventilation, the gas detectors should have both a numerical value display and a clearly recognizable assignment of the value – for example via the traffic light system. In other monitored areas, the gas detectors should be able to store the measured data as a numerical value and, when the threshold values are reached, to control via interfaces the other devices that either ventilate mechanically or sound an alarm. A gas detector for personal protection or for the control of industrial processes must be able to be set with sufficient accuracy to the critical values for the respective gas.

Alarm types and alarm thresholds for a gas warning device
In addition to the visual display of the measured value as a numerical value, gas detectors can have additional visual, acoustic or haptic alarms. A mobile gas detector for personal protection is often equipped with all three types of alarm. Fire departments and rescue services have defined the criteria after several carbon monoxide poisonings during rescue operations in order to protect the emergency services with reasonably used gas detectors. Often such a gas detector used for personal protection is used with two alarm values. The pre-alarm can be set, for example, to allow a stay of 30 minutes without health damage. The main alarm can then signal that the rescuers are only allowed to stay in the affected area for up to 15 minutes or that the area must be left immediately. Some gas detectors have fixed alarm thresholds, while others can be adjusted to the specific conditions of use.

IP degree of protection
Depending on the environment in which the gas detector is to be used, the appropriate IP classification must be ensured. The IP degree of protection indicates the degree to which an electrical device is protected against water and ingress of foreign bodies or dust due the construction of the housing. The higher the IP classification, the better the gas detector is protected against these influences.

Gas detector for flammable gases – explosion protection
The prerequisite for a fire is the presence of the three conditions: combustible material, oxygen and ignition source. If flammable material and oxygen already form an ignitable mixture, even single ignition sparks can lead to explosions. According to the evaluations of the Gesamtverband der Deutschen Versicherungswirtschaft e. V. (Association of the German Insurance Industry registered association), fire caused 50 percent of the damage among the commercial companies and even 70 percent of the damage – among the industrial ones. For residential buildings, the share was only about 20 percent of the total regulatory expenditure.

During many fires, toxic gases are produced, which are the main cause of death and health damage caused by fire events. In addition to the carbon monoxide released in all incomplete combustions, additional toxic gases are often produced and spread in the surrounding area. For this reason, ABC-reconnaissance vehicles are used in large fires and in fires at commercial and industrial plants. For example, the gas detectors of such a vehicle measured increased levels of ammonia, chlorine and carbon monoxide during a major fire in Hagen in an adjacent street.

A gas detector for flammable gases often does not indicate the concentration of the gas, but how many percent of the lower explosion limit LEL has already been reached. This makes it easier for the user to assess the danger. The lower explosion limit LEL is the minimum concentration above which the flammable gases are ignitable or even self-ignite in the presence of oxygen. Combustion continues automatically from this concentration and leads to an increase in pressure and temperature. There is a particular danger if flammable gases in explosive concentrations are supplied with additional oxygen. This can happen unconsciously, for example by opening a window or door. This can lead to large-area ignition and a sudden increase in pressure. Gas detectors for flammable gases are used to measure in potentially hazardous areas whether an ignitable concentration is present.

Gas detector for F-gases
The term F-gases stands for fluorine-containing gases, which contribute significantly to global warming. The contribution of these industrially produced gases, which are mostly used as refrigerants or in manufacturing processes, to global warming is much higher than that of carbon dioxide. In order to be able to compare the effects, for each F-gas the global warming potential is given as GWP value – Global Warming Potential. The GWP value indicates as a factor how much more the F-Gas contributes to the greenhouse effect than carbon dioxide. For carbon dioxide the GWP is therefore 1, ammonia has no greenhouse effect, and for propane the GWP is 3. However, for the refrigerant pentafluoroethane (R125) the GWP is 3,500. One kilogram of the released R125 therefore has the same effect on the global warming as 3,500 kg of carbon dioxide. Both the climate-damaging F-gases and the refrigerants or technical gases that can be used as substitutes can be flammable or toxic. If the gas detector is used, attention should be paid to all three hazard possibilities in terms of measuring range and warning threshold.

In January 2015, the European F-Gas Regulation 517/2014 came into force. Its aim is to restrict further emissions of fluorinated greenhouse gases. In addition to bans on use, restrictions on placing on the market and refilling bans for maintenance and repair, this regulation also covers leakage checks and systems for detecting leaks in equipment containing F-gases. A gas warning device with a sensor adapted to the refrigerant is required for leakage checks. Some gas detectors can also detect several groups of common refrigerants with their sensor. This makes them suitable for detecting leaks in the systems with unknown fillings. These gas detectors usually do not provide exact numerical values, but they do show leaks in refrigerant lines and containers even in already contaminated rooms.

A gas detector for personal protection is available for you. Our mini - gas detector detects e.g. the following gases: Methane, oxygen, hydrogen sulphide, carbon monoxide. The gas detector / gas test instrument offers an impressive protection on site for persons who are in gas endangered surroundings. If your life depends on it, then you want to have a reliable gas detection instrument available that warns you safely and reliably.

The gas detection instrument is mainly used in production, in tunnels and on construction sites and guarantees absolute personal safety. We also offer gas sensors for fixed installation (as a "stand-alone version" or in combination with a gas warning system). So you can not only protect individuals, but also monitor entire rooms or buildings. Of course, the gas detector complies with all currently valid specifications for intrinsic safety and device protection (ATEX). The purpose of the ATEX directive is to protect people working in potentially explosive atmospheres. More information on this can be found at the end of this page. Inaccessible areas, such as tanks or unventilated rooms, hold great dangers.

Gas detectors warn of gas hazards by means of optical and acoustic signals. The sensor and the evaluation unit are technologically and structurally very well matched to each other and ensure reliable measurement results of the pollutants. Gases such as methane, propane, pentane, butane etc. are hydrocarbon compounds which can only be ignited with oxygen in certain mixing ratios. The measuring ranges of the sensors for flammable gases are set to the lower explosion limit (LEL) of the respective gas in order to warn the people working there of the emerging danger of an explosion. Hydrogen sulphide, carbon monoxide, chlorine, ammonia, cyanide, etc. are toxic gases for humans and animals.

A low concentration of hydrogen sulphide or carbon monoxide is sufficient to cause life threatening damage or death. Carbon monoxide, for example, is a colourless and odourless gas that cannot be taken seriously by the human sense organs. In the lungs, carbon monoxide binds to the red blood cells in place of oxygen and thus prevents the transport of oxygen into the cells. But not only the poisonous gases are dangerous, too much oxygen can also be dangerous.

An increased oxygen content in the air increases the fire risk considerably due to its fire-promoting effect. An oxygen content of more than 24 vol. % can cause oil-soaked cloths to ignite spontaneously, cause a fire and its spread is considerably accelerated by its fire-promoting effect. At PCE Deutschland GmbH you will find a wide range of gas detectors and gas warning devices for various applications. All gas detection instruments are tested and correspond to all current standards and regulations and can be used without any problems in safety relevant applications.

The main area of application for portable and stationary gas detection instruments is in personal protection and the safeguarding of plant capital in oil and gas production or supply and storage, steel production, water and wastewater treatment, the beverage industry and the maritime sector. However, even outside these core areas there are always interesting and challenging tasks that our technicians and engineers successfully handle. For example, the control of fumigation systems to produce fruit ripeness.

Consulting, project planning, commissioning planning, sales, installation, start-up, maintenance, calibration, service, emergency support - a long list - but it is not just empty words - PCE Instruments supports the customer from A-Z.

Consulting / Project Engineering / Commissioning Planning
In the foreground of these first planning steps are the needs of the customer as well as the technical feasibility (compliance with current guidelines and laws). Our technicians and engineers are familiar with most of the hazards caused by toxic or flammable gases, lack of oxygen or excess oxygen in the machining processes of the various industries and can propose adequate solutions for the detection of these gases or vapours. The project planning of the gas warning system is based on plans and information provided or, if necessary, on an on-site visit to the object in question.

Installation / Commissioning
Service technicians of PCE Instruments install the components, carry out the cabling and test runs with test gas.

The commissioning of the stationary gas detection instrument is carried out according to the manufacturers' guidelines and the relevant regulations of the professional associations (leaflets T021 and T023). The calibration gases used by PCE for commissioning and adjustment of the gas warning instruments are adjusted in concentration to the measuring ranges as well as to the individual requirements and are provided with a calibration certificate.

Maintenance / Calibration
Cleaning, maintenance and regular re-calibration of the gas detection instrument is carried out by PCE Instruments at the Freienohl factory or, in case of permanently installed systems, directly on site at the customer. The gas detection instrumentsare calibrated by PCE have test seals, which give the customer the information, when the device was calibrated / maintained and when it has to be recalibrated. The calibration or recalibration is carried out with certified calibration gases whose concentration is adjusted to the respective measuring range of the sensors.

In addition, PCE Instruments sends a reminder to the respective customer 6 weeks before the end of the calibration period. Thus, in advance, appointments, possibly provision of loaned devices for the calibration period or, in case of stationary gas warning technology, maintenance and calibration dates can be arranged with our field service.

Emergency support
Gas warning instruments / gas detection instruments must be available at any time. No matter whether it is a hand-held measuring device or a stationary gas warning system. A defective device has no use. In some companies, the failure or defect of the gas warning technology leads to the shutdown of machines and systems.

This loss of production sometimes costs enormous sums of money. In these cases PCE Instruments always advises to use a portable gas detection instrument or a redundant gas warning system during design and planning.

Because also the point of economic efficiency in many cases does not allow a redundant design of the systems, PCE Instruments offers a service, which allows the customer to get a replacement device within a few hours (depending on the location in Europe), which will be put into operation by a PCE service technician directly on site. This special offer requires an additional service contract with the customer.