Gas leak sensor with shut-off valve: device, classification + how to choose and install correctly

Even the most careful and careful use of gas can lead to an accident.Its leak is a serious problem, which is vital to know about before the gas concentration in the room reaches a critical level.

A good gas leak detector with a shut-off valve is an almost irreplaceable device that can prevent a tragedy. Such a device not only signals an emergency situation, but also prevents its development by cutting off the fuel supply. After its installation, every home owner will feel more confident and calm.

In this material we will talk about the design of a sensor with a shut-off valve, consider the structure and principle of operation, and give practical advice on selection and installation.

Features and types of household gas sensors

At its core, a gas leak sensor is a small, sometimes mobile device that responds to changes in the composition of the air in the room. A special shut-off element (valve), complementing the device, makes it possible to stop the fuel supply in time if its excess is detected in the air.

A gas leak detection device equipped with a shut-off valve can alert owners to a leak using sound or light signals. Some models can work in the "Smart House».

Gas analyzers that are integrated into a smart home system are able to inform the owner about a leak by sending messages. Additionally, installing a special application on your smartphone allows you to monitor the air condition in real time

The presence of a cut-off valve makes the gas analyzer extremely autonomous: the sensor will independently shut off the gas supply without human intervention, which is especially convenient if the homeowners are not at home. Additionally, modern devices can turn on forced ventilation in the room and transmit a signal about an emergency situation to the appropriate services.

The device itself consists of main functional units.

• primary converter — a sensor that detects gas in the surrounding air and records its concentration;
• measuring module — reads information from the primary converter and compares it with acceptable nominal values;
• executive unit — a valve that directly stops the supply of blue fuel;
• battery — network unit, battery or galvanic cell.

The sensor can respond to different types of gases, so detectors can be classified according to the type of fuel consumed.

Devices can be of the following types:

• natural gas content analyzers;
• carbon dioxide detectors;
• detection sensors carbon monoxide;
• combined devices that react to different gases.

The latter type is more popular, as it makes it possible to fully monitor the safety of the air composition.

Combined gas leak sensors usually detect the presence of methane and carbon monoxide in the air, signaling that the permissible concentration of these substances has been exceeded

Additionally, modern devices are divided according to the method of determining gas concentration:

1. Catalytic gas analyzers (or thermocatalytic) - in them the surface of the sensitive element is covered with a layer of catalyst (tin dioxide, platinum, palladium). The gas, the concentration of which increases during a leak, is oxidized by oxygen in the air, which causes heating. Which, in turn, is a signal for the sensor to operate.
2. Semiconductor detectors are triggered by a sharp decrease in the resistance of the sensitive element, made on the basis of tin oxide. Resistance decreases with increasing concentration of CO, which is further oxidized. To ensure the speed of the sensor, its design includes a heater - a resistive layer made of inert materials.
3. Electrochemical sensors with a solid or liquid electrolyte - the former use a solid electrolyte in conjunction with a heater, and the latter use an acid or alkaline solution as a sensitive element.
4. Infrared sensors establish the current fuel concentration by analyzing the environment that is within the infrared spectrum.

According to the method of feeding, gas analyzers are divided into wired And wireless. The first ones operate from the network and are dependent on the availability of electricity. Sensors of the second type operate using a battery and are more reliable due to their autonomy.

Equipping the device with a shut-off valve significantly expands the functionality of the device and makes its operation more rational. After all, just one timely activated shut-off valve can save dozens of lives. Therefore, it is worth dwelling in more detail on the operating principles of this unit.

Design and principle of operation of the valve

The most popular for domestic use remain electromagnetic shut-off valves and shut-off valves controlled by an electric pulse.

Locking mechanism solenoid valve allows you to quickly block the fuel supply when an emergency leak is detected. The unit is mounted at the entrance to the gas pipeline. As soon as the sensor detects the maximum gas concentration, the mechanism closes the electrical circuit, after which the valve closes.

The shut-off valve is a fairly small unit. Typically, once triggered, it must be manually re-cocked before it is ready for use again.

Gas analyzers with valves, intended for use in a house/apartment, which cut off gas due to the operation of an electrical impulse, work somewhat differently. The valve is in the open position thanks to a mechanical latch. If the sensor detects a leak, a short current pulse is transmitted to the electromagnet coil, after which the latch is activated and the valve itself moves to the closed position.

Valves of this type are conventionally divided into normally open (NA) and normally closed (NC). The device of the first type does not provide for supplying voltage to the coil; the gas is cut off when the sensor is triggered. In the second case, an impulse is required to open the valve itself, and the gas is cut off by the valve when the voltage in the coil disappears.

NA valves are more suitable for use at home, since even an unexpected power outage will not lead to gas shutoff.Additionally, gas analyzers with such valves are considered more economical: if to maintain the operation of the NC cut-off valve, a constant voltage in the coil is required, then for the operation of the NA type valve in the open state, no electricity is needed.

Subtleties of choosing a gas analyzer

Selection and purchase of a gas analyzer with a shut-off valve requires a responsible approach. You should not skimp on the sensor, because such equipment should last for years. Therefore, searching for the cheapest device is not always justified.

Inexpensive models often use sensors that lose sensitivity too quickly and become unusable. This happens especially often with models ordered on the popular AliExpress website.

For domestic conditions, users most often choose sensors that respond to the leakage of natural gas, which arrives in apartments along the highway or located in liquefied state in cylinders.

In addition to the type absorbed by the device type of gas The user should pay attention to the following important characteristics inherent in a high-quality analyzer:

• limit value gas concentration, in which the device signals an accident;
• ability to analyze gas content in volume and mass fraction in the air;
• opportunity recording the current air condition at several points in the room;
• work autonomy and her time;
• opportunity tracking increases in concentration various types of gas.

An equally important role is played manufacturer's reputation And reviews real users. Detailed reviews of gas analyzers will help you choose the optimal model for specific conditions.

Warranty service – an equally important component of the service. It is worth paying attention and cost of spare parts, their availability in stores.

Since the gas leak sensor is almost always in sight, its appearance. In addition to the aesthetic component, it is worth considering such characteristics of the case as moisture and dust protection.

Additional functions will also be useful for a modern gas analyzer, for example, automatically turning on a forced ventilation system or sending an emergency notification about a gas leak to the homeowner’s phone

An acceptable glazing valve is selected based on its key characteristics:

• valve type – NA. or NС.;
• nominal diameter;
• type of food;
• threshold of permissible gas pressure.

All necessary information about the valve is indicated in its passport and on the label.

As stated above, normally open valves are more ergonomic to operate. However, when paired with a sensor that, when turned on, will automatically check its own outputs by sending a pulse, unplanned fuel shutoff may occur without causing a leak. Therefore, before purchasing a gas analyzer, it is necessary to study the sequence of its operation.

Installation of a gas leak sensor

The shut-off valve can only be installed by a certified gas service technician. And in case of unauthorized installation of a valve on a gas pipe, the consumer faces fine for interfering with the gas supply system.

But you can install a sensor that signals a gas leak yourself. When placing the device, you must rely on the recommendations from the data sheet for the device.This document contains all the information necessary for connection and describes the connection diagrams for additional devices.

Traditionally, the device is fixed on the wall in the place where fuel leakage is most likely. This may be an area near a gas water heater or boiler, stove, meter, in the fastening points of which leaky areas can often form. In this case, the distance from the gas equipment sensor should be no more than 1.5 m.

The sensors are mounted quite easily: usually, to mount the device using dowels, disassembling the analyzer body is not even required

The height at which the sensor is mounted depends on the type of gas being analyzed, since different types of fuel have their own weight and concentrate in the air at different levels. You should also follow the recommendations given in the instructions for the specific gas analyzer model. For example, for methane, the installation distance is set within 0.3-1 m from the ceiling.

The sensor for propane and other gases that are heavier than air is mounted at a height of 0.3-1 m from the floor. For combined devices that measure the concentration of methane and carbon monoxide, a suitable location would be 0.3-0.5 m from the ceiling.

It is strictly not recommended to install the sensor in the following places:

• near a window or ventilation system opening;
• near an oven or gas burners (distance up to 1 m);
• in an area subject to the accumulation of dust, fumes, grease or ash produced during the cooking process;
• in rooms used for storing paints and varnishes, gasoline, and all kinds of solvents.

In addition, you can find out about the location of the alarm sensor in the project documentation for gasification and other regulatory documents of the gas service.

Conclusions and useful video on the topic

An example of how a gas leak sensor is triggered and the fuel supply is cut off is shown in the video below:

Installing a reliable and high-quality gas analyzer, complemented by a shut-off valve, can be a key point in preventing gas leaks. After all, timely detected fuel leakage can not only reduce material damage in the event of explosion, but also to save someone’s life. Therefore, in the realities of the state of the modern gas supply system and given the increasingly common malfunctions in the gas equipment itself, users of conventional fuel should seriously think about their safety.

Do you use a gas leak detector? If yes, then please share with our readers your experience and impressions of using it, tell us whether you are satisfied with its work, and how often false positives occur. Write your recommendations, add a photo of your gas analyzer, ask any questions you are interested in - the feedback form is located just below.