Gas pollution control system: device, installation and maintenance

Gas Contamination Control System: Design, Installation and Maintenance

A leak of natural or carbon monoxide gas is one of the main threats in residential and industrial premises. In order to detect a dangerous concentration in time and automatically shut off the fuel supply, special complexes have been developed – gas contamination control systems. In this article we will examine what a GCCS consists of, how sensors and valves work, which models are produced under the brands MK, SGK, BSU, and how to correctly perform installation while complying with technical requirements. You can view the equipment in the catalogue gas contamination control system.

1. What Is a Gas Contamination Control System and Why Is It Needed

GCCS, or a gas alarm, is an automatic complex that continuously measures the concentration of combustible and toxic gases in the air. When threshold values are reached, an audible and visual alarm is generated, and a command is also issued to close a solenoid valve that cuts off the gas supply. In gas supply, such protection is mandatory for boiler houses, kitchens with gas cookers, and rooms with heating boilers. The abbreviation SAKZ stands for “automatic gas contamination control system”. In everyday life, people often say “gas control” or “gas detector”, implying the entire set of devices.

Household models such as SGK, BSU, MK, “Intellect”, “Kristall Mini”, “Carbon”, “Eco” differ in the number of sensors and the type of shut-off valve. Some are designed only for methane (natural gas), others – for methane and carbon monoxide CO. Combined CO/CH4 versions provide protection against both explosion and poisoning. During installation, it is important to take into account that methane accumulates near the ceiling, and carbon monoxide – at breathing level, therefore the sensors are placed at different heights. The connection of MK 2 and similar models must be carried out according to the diagram from the passport so that the valve correctly responds to the alarm signal.

2. Regulatory Framework and Design

The installation of a gas contamination control system is regulated by SP 60.13330.2016 “Heating, ventilation and air conditioning”, SP 41‑108‑2004, as well as safety rules for the use of gas in the home. The technical requirements prescribe the installation of an alarm in every room where gas equipment with a power of more than 50 kW operates, as well as in basements and ground floors with gas appliances. For apartments with gas cookers, mandatory installation does not yet exist, but the recommendations of the Ministry of Emergency Situations and gas services strongly advise equipping dwellings with such devices.

Design includes the choice of sensor type, placement location, calculation of wire cross‑sections and selection of a solenoid valve by diameter – DN20, DN25, DN32, DN50. The valve must correspond to the working pressure and gas flow rate. When drawing up a project, the ceiling height, ventilation, and the location of windows and doors are taken into account. An incorrectly chosen valve diameter can lead to insufficient shut‑off or too slow actuation. The connection diagram of MK and other units is mandatorily agreed with the design organisation.

3. Main Components of a GCCS

Any gas contamination control system consists of three key parts:

• gas sensors (gas analysers) that respond to the concentration of methane CH4 and/or carbon monoxide CO;
• a solenoid valve that shuts off the gas pipeline;
• a control and alarm panel that processes the sensor signals and controls the valve.

In some models, for example MK‑2, MK‑3, the sensors and the panel are combined in one housing, and the valve is connected with an external cable. In autonomous versions, such as the household alarm SGK‑B, power is supplied from a 220 V network, and the valve is powered directly from the control board. The panel acts as a relay and power source, and also contains an indication of modes: “Normal”, “Alarm”, “Fault”. The MK gas analyser, depending on the modification, can monitor one or two gases.

4. Classification and Popular Models

Manufacturers offer several equipment lines. The most well‑known series:

• MK – gas control MK, includes models MK‑1, MK‑2, MK‑3 and their modifications (MK‑2 1Ai, MK‑2 CIT, MK‑1A, MK‑2 DN25, MK‑2 DN20, MK‑2 1Ai DN 25, etc.).
• SGK – gas alarm of the SGK series: SGK‑2, SGK‑B, autonomous type SGK‑B, as well as modification SGK‑2 1.
• BSU – universal household alarm, often with the index “Kristall Mini”, as well as versions BSU‑2, BSU‑ECO.
• Intellect, Carbon, Eco – separate trade marks with their own algorithms.

All the listed devices perform one function, but differ in algorithms, the possibility of connecting additional sensors, and the type of shut‑off valve. For example, the MK‑2 household system is equipped with a valve with a nominal diameter of DN20 or DN25, while MK‑3 allows DN32, DN50. The MK 2 DN25 ND valve is normally closed, opening only when power is supplied. Upon loss of power, the valve automatically shuts off the main, which complies with the safety principle. The MK 2 gas alarm has two channels and can be connected to two independent valves.

Current modifications are regularly supplemented. For example, MK‑2 1Ai DN 25 is a version with a normally closed valve of 25 mm diameter. The MK 2 instruction contains the connection diagram, testing procedure and technical characteristics. When choosing a model, one is guided by the type of gas, the diameter of the supply pipe and the need to connect additional sensors. It is worth separately noting the MK‑2 1Ai sensor, which is compatible with most valves of the KZEM series.

5. Operating Principle of the Automatic System

The automatic gas contamination system operates according to a clear algorithm. The methane CH4 sensor is set to a threshold of 10% of the lower flammability limit, which is about 0.5% by volume in air. For carbon monoxide CO, the threshold is 20 mg/m³. When the concentration is exceeded, the alarm emits an intermittent audible signal and flashes a red indicator. After 10–15 seconds, a pulse is generated to close the valve. In normally closed valves of the KZEM type, gas supply is possible only when the stem is cocked and voltage is applied; upon loss of power, the valve automatically shuts off the main. After actuation, it is necessary to ventilate the room, find the cause of the leak and manually open the valve, only after making sure there is no dangerous concentration.

Sensors can be semiconductor or thermocatalytic. Semiconductor sensors are sensitive to alcohol and ammonia vapours, therefore they are not placed near exhaust hoods and food preparation areas. Thermocatalytic ones are more accurate, but consume more energy and require periodic calibration. The MK‑2 1Ai model is equipped precisely with a thermocatalytic sensor, which reduces false alarms and increases reliability. The sensor warm‑up time after switching on is 3–5 minutes, during which the alarm is inactive. The control panel may have a built‑in battery, as in the MK‑2 CIT, ensuring operation during short‑term power outages.

6. Installation, Mounting and Requirements

It is necessary to install the gas alarm in accordance with the project. The main rules:

• the methane sensor is fixed near the ceiling, since methane is lighter than air; the distance from the ceiling is 10–30 cm, from the gas appliance – not more than 2 m horizontally;
• the carbon monoxide sensor is mounted at a height of 1.5–1.8 m from the floor, since CO is close to air in density; in boiler houses, an additional sensor is installed near the floor;
• installation close to windows, doors and ventilation openings is prohibited – the distance to them must be at least 1 m;
• the solenoid valve is cut into the gas pipe before the meter or boiler, guided by the flow direction arrow.

The MK connection diagram provides for a three‑core cable from the panel to the valve with a cross‑section of at least 0.5 mm². To power the panel, a separate line from the apartment switchboard is used, protected by a 6 A circuit breaker. It is forbidden to connect the alarm via an extension lead or a socket into which a powerful appliance can be plugged. Connection diagrams are given in the MK passport, where the pinout is also indicated. When installing a GCCS in a boiler house with powerful equipment, two sensors are installed: near the ceiling – for methane, on the wall – for CO. The valve is selected according to the diameter of the gas pipeline, for example DN20 or DN25. For cottages with a flow rate of more than 5 m³/h, a DN32 valve is used. The valve insertion work must be performed by a certified gas service specialist. The MK‑2 CIT Plus connection diagram has an additional contact for remote control.

7. Solenoid Valves in a GCCS

A solenoid valve is an actuator that shuts off the gas supply. In household systems, normally closed valves with manual cocking are used, such as KZEM‑20, KZEM‑25, KZEM‑32. They open when voltage is applied and remain open until an alarm signal or loss of power. The MK 2 DN25 ND valve is specially adapted for joint operation with MK alarms and is distinguished by reduced energy consumption. For large facilities, impulse valves with stem latching are used. The choice of valve by diameter depends on the supply pipe and the gas flow rate. The characteristics of common valves are given below.

The connection of the valve to the alarm must be carried out strictly according to the diagram: brown wire – phase, blue – neutral, yellow‑green – earth. Incorrect connection leads to failure during an emergency. Many models, for example MK‑2 1Ai, automatically test the integrity of the valve circuit upon switching on.

8. Maintenance and Verification

Maintenance of the gas contamination control system is carried out once a year. It includes cleaning the sensor from dust, testing actuation from a reference gas mixture, checking the valve stem travel. Verification is performed by a specialised laboratory with the issuance of a certificate. The inter‑verification interval for most models is 12 months. Some manufacturers, for example “Cit Plus”, allow an interval of up to 24 months provided annual self‑testing is performed.

Checking operability at home is possible with the help of a probe – a lighter without a flame (emits a small amount of methane) or a special aerosol. If the alarm beeps under a normal atmosphere, a sensor malfunction or contamination of the contacts is possible. In that case, one refers to the MK operating manual, where the error codes are described. The MK 2 instruction contains a detailed test algorithm and an explanation of the indication. Testing actuation by bringing a flame or open gas is not permitted – this creates an explosive concentration.

9. Operating Manual and Passport

Each device is supplied with a passport and an operating manual. The MK 2 passport includes technical characteristics, warranty obligations, verification marks. The manual contains the connection diagram, installation description, and first start‑up instructions. For example, the MK 2 instruction prescribes first cocking the valve, then supplying power, waiting for warm‑up for 3 minutes and making sure that the indicator is lit green. The MK‑2 CIT Plus operating manual highlights a separate section on replacing the built‑in battery, which ensures operation during short‑term power supply interruptions. The passport also indicates the warranty period and the date of manufacture.

10. Frequently Asked Questions

Users often ask what to do if the device “beeps”. The reasons can be different: actuation during a leak, a sensor fault, low supply voltage, sensor contamination. The algorithm of actions is described in the MK manual. Another common question is whether a separate circuit breaker is needed for the power supply. According to technical requirements, the power line must be dedicated so that when the protective circuit breaker of another circuit trips, the system remains operational. Another frequent question concerns the connection of MK‑2 1Ai to the DN25 valve: the diagram and terminals are indicated on the back of the housing and in the passport; it is important not to reverse the polarity, otherwise the valve will not open. Sometimes the alarm beeps in the absence of gas – in this case, check the reliability of the contacts and the absence of dust on the sensor. The question “how to connect MK 2 1Ai DN 25” is disclosed in the connection diagram: the valve is connected to the “Valve” terminals observing the phasing.

11. Conclusion

A gas contamination control system is a mandatory safety element for any gasified facility. The correct choice between MK, SGK or BSU models, proper installation with observance of heights and distances, as well as regular maintenance and verification guarantee reliable protection against methane and carbon monoxide leaks. The equipment is available from specialised organisations, and detailed consultations can be obtained by contacting official suppliers.