Dielectric gasket for gas stove. Dielectric inserts for gas: application and function

Dielectric gas coupling provides safety in residential areas, and saves people's lives.

Equipment running on natural gas is connected to electricity sources. To prevent an accident when electric current enters the gas pipeline network, a protective insert should be mounted on gas appliances.

The purpose of the dielectric coupling for gas

Boilers and boilers are used to heat the water in the heating system. For cooking, stoves, ovens and hobs are placed in the kitchen. In the listed devices there is a system of control sensors, electric ignition, oven lighting. Therefore, the gas type of the device requires connection to the electrical network.

So that the current does not flow through the gas pipe inside the room, polyamide insulators are used - couplings. For the dielectric coupling for gas, yellow polyamide is used due to the low content of conductive impurities.

Dielectric insulating inserts, when current enters the gas network, will maintain the performance of gas devices and gas meters.

How does a breakdown occur in the gas network

Natural gas is supplied to homes and other premises through metal pipes laid underground in urban areas or above its surface in the private sector. Metal corrodes when exposed to moisture. Applying a positive electrical potential helps to reduce the degree of corrosion.

According to the safety regulations, a dielectric coupling is installed on the pipe at the entrance to the house. In this way, the indoor gas riser is protected, provided that the coupling is installed correctly and in good condition. But the deaf grounding of the pipe in the basement of the house can break due to corrosion.

Further, in a house or apartment, suppose the stove is connected to the riser through a rubber hose with a metal braid. If suddenly the insulation of the electrical wire in the plate is broken, the current will go through the hose braid. Depending on the strength of the current, the time for heating up and breakdown of the hose will be short or long, but a breakdown will definitely occur.

Sometimes residents of the house arrange grounding on the gas pipe.

Possible fire due to a gas leak in the apartment. Everything can do without victims, but with material losses. After such an event, the question of why a dielectric coupling for gas is needed will no longer be hypothetical for residents.

How the clutch works

Details of the gas network are produced in several types according to the type of fastening: "fitting - fitting", "nut - fitting". The product is one-piece, non-separable, and therefore safe to use. Any excess connection is a source of gas leakage.

High-quality couplings are made of brass, the thickness of the tube is not less than 4.5 millimeters. The insulating part is made of yellow polyamide, which includes a "flame retardant".

The choice of eyeliner and coupling

It is better to choose a bellows eyeliner coated with a yellow insulator. It is easier for housewives to wash such an eyeliner from dust and kitchen soot. At the same time, the insulator will protect against the flow of current when touching the bare terminals of live devices or the conductive body of the device.

Of course, an inexpensive rubber hose could be supplied. But rubber tends to age, lose elasticity, microcracks appear on the rubber hose - places of gas leakage.

Dielectric couplings for gas will protect against the flow of current through any hose. These parts are tested for breakdown with a current of 50 Hertz and a voltage of 3.75 kV for 6 seconds or more. When a voltage of one kilovolt is applied, the electrical resistance is 5 megaohms. Inserts withstand temperature differences from -60 to +100 degrees. Insulator manufacturers guarantee a service life of at least 20 years.

By installing a dielectric coupling for gas, leaving the house on business or taking a bath, the reader will be confident in the safety of home, loved ones and neighbors. Dielectric insulator - protection against burning of the eyeliner, subsequent gas leakage and inevitable explosion.

>Why do I need a dielectric coupling for gas and how to install it?

Dielectric coupling- this is a cut-off fitting that protects the "brains" of gas-consuming devices from the destructive effects of stray currents. That is, we have a very useful node, the effectiveness of which is proven by the definition itself. However, many owners of gas stoves, columns and boilers, as well as employees of gas services, are not aware of the existence of such an insert. And in this article we will try to fill this gap in knowledge by talking about the benefits dielectric fitting, its varieties and installation methods.

Stray current - where does it come from in the gas pipeline

Such currents appear in the ground due to an accidental breakdown of a household or industrial power line. The source of stray voltage can be either a ground loop or an electrified railway or tram line. Such a current enters the gas pipeline due to the difference between the resistivity of the earth and the metal parts of the gas supply line. In fact, all the electricity discharged into the ground does not go into the ground (it has too much resistance), but into bare cables or metal structures. And since most of the main and household gas pipelines are made of metal, the appearance of a stray current in the system is only a matter of time.

The main pipe can become a source of stray voltage in a household gas pipeline. To protect the gas supply pipeline from corrosion, the line is loaded with an electric potential of insignificant strength, which suppresses the natural process of electrochemical splitting in the structural material. And if in the common insulator separating the main from the household branch, a breakdown of the dielectric insert for gas occurs, then the useful protective potential will turn into an unwanted stray current.

In addition, stray voltage may appear in the internal gas supply line due to poor grounding of the circulation pump or other electrical appliances that come into contact with the heating system wiring or the home branch of the gas pipeline. Another reason for the appearance of such currents may be an error when installing a boiler, column or gas stove connected to the mains. As you can see, stray current is not a myth, but a real problem. And the metal structure that fell under its action turns into a serious threat to the safety of all residents of the house connected to the gas pipeline.

What happens if there is no shut-off fitting in the system

To cut off stray currents in pipelines, a special dielectric insert. It cuts into the area between the tap and the connection to the gas-consuming device. Or in the area between the gearbox and the gas meter. What happens if there is no such insertion? Believe me, no good.

  • Firstly, your or a neighbor's stove, column or boiler may suffer from a stray current or turn into a source of one. As a result, there is a risk of losing their performance, due to the defeat of the "smart" filling, assembled on the basis of capricious chips, reacting even to minor power surges.
  • Secondly, a spark can occur in the pipeline - a source of fire. Moreover, cases of spontaneous combustion of the eyeliner are not so rare. And if this fact is not discovered in time, the case may end in a big catastrophe. The detonation of the gas-air mixture can destroy even an apartment building.
  • Thirdly, the user may be electrocuted. If the potential of the stray charge is significant, and this happens during a thunderstorm or a power failure, then we can not talk about an unpleasant "bite", but about a full-fledged injury with difficult to predict consequences.

Varieties of dielectric cut-offs - couplings and bushings

The product range of stray current cutters for gas distribution systems is usually divided into two groups, which include:

Dielectric couplings (MD)- special fittings with threaded ends, mounted between the gas pipeline and the device consuming blue fuel.

Dielectric bushings (VD)- non-conductive inserts installed in the place of collapsible interface of gas pipeline elements.

In turn, the nomenclature of couplings is divided into four sizes, based on the diameters of the threaded part: ½, ¾, 1, 1 ¼. Such a set allows you to cover all types of pipe fittings used in gas pipelines, since diameters less than ½ inch and more than an inch and a quarter are not used in such systems. In addition, the range of couplings can be divided according to the design features of this fitting, distinguishing three groups: MD thread/thread, MD thread/nut, MD nut/nut. After all, the thread of this fitting can be cut both outside and inside the end part.

The nomenclature of dielectric bushings is divided only on the basis of their geometric dimensions - according to the diameter of the liner. In this case, we are dealing with 11 standard sizes and diameters from 8 to 27 millimeters. At the same time, both couplings and bushings have the same margin of safety. The working pressure of both types of cutters is 0.6 MPa (about 6 atmospheres), and the limit is 50 MPa (493 atmospheres). In both cases, a practically incombustible polymer is used as a dielectric - polyamide, which has an enormous resistance (about 5 million ohms).

How to install the clutch - act carefully

Dielectric coupling must be mounted between the gas distribution valve and the consumer device, therefore, when installing dielectric cut-offs, the following sequence of actions is used:

  • We close the valve on the metal pipe supplying gas to the stove, boiler or column. At the same time, it is better to leave the burners of the devices open so that the gas in the supply burns out.
  • Holding the valve body with the first wrench, carefully twist the supply nut with the second wrench - a flexible pipeline (hose) connecting the shut-off assembly with the gas inlet pipe of the boiler, stove or column. The use of a pair of keys in this case is mandatory, since the supply nut can “stick” to the valve fitting or pipe and transfer torque to it, after which gas will pour into the room, and it will be possible to shut off its supply only with a street reducer valve.
  • We screw the FUM coupling (polymer sealant) onto the free ends and screw it into the gas pipeline valve with our hands. Next, we take the same two keys and, holding the valve body, screw in the coupling until it stops. Try not to overdo it at this stage, as excessive force will deform the valve body and leak gas.
  • We screw on the free end of the coupling the nut for supplying to the device that consumes gas, controlling our effort and holding the fitting with one of the adjustable wrenches.
  • Next, you need to check the tightness of the resulting connection. To do this, you need to purchase a shaving brush and, after carefully lathering it, process all the joints of the valve, coupling and supply. After that, you open the valve and observe the foam at the joints. If you don't see any bubbles, the joints are hermetically sealed and your gas pipeline is ready for safe operation.

If soap bubbles are found at the joints, turn off the gas supply valve and carefully tighten the coupling or supply nut. If this does not help, you will have to disassemble the entire connection and add a few turns of the FUM to the ends of the coupling.

Attention: the use of matches or lighters instead of soap suds when testing the tightness of the joints is strictly prohibited. You may not have time to react and turn off the gas, causing a serious fire.

And with a strong leak, panic can seize you - the sight of a flaming valve unbalances even the most cold-blooded masters. Therefore, the best leak tester is soap suds.

Dielectric insert (insulating insert, dielectric insert for gas) -

This is a device that prevents the spread of so-called leakage currents (stray currents) through intra-apartment or intra-house gas pipelines. The dielectric insert not only eliminates possible heating and sparking of the supply line in the event of an accumulation of electrical potential, but also protects the electronics and internal electrical circuits of gas appliances and meters from failure due to exposure to harmful stray currents.
The main causes of leakage currents include the following:
- Common insulator damage at the inlet of the main pipe to an apartment building or an insulator at the outlet of a gas distribution point (node). To protect against corrosion, a small electric potential is specially applied to the main pipes. In the event of damage to the common insulator, this potential freely enters the intra-house and intra-apartment gas pipeline.
- Faulty or missing ground electrical wiring in the house. Modern gas-consuming equipment has its own electrical circuits (electronic control units, electric ignition systems, lighting, etc.), and, in the absence of electrical grounding, as well as in the event of a malfunction of the internal electrical circuits of gas-consuming equipment, these devices themselves become sources of stray currents.
- Unqualified connection electrical appliances and their illegal grounding your neighbors (or "craftsmen" hired by them) on hard gas pipes and risers.

Dielectric insert is an integral connection and is installed between the gas cock and the gas supply. The metal parts of the insert fused into the dielectric do not touch each other, which makes it impossible for leakage currents to pass through it (the insert). insulating insert has an inner surface completely covered with a dielectric, which excludes the contact of each of the metal parts of the insert with the gas passing inside the insulator.

Materials used:
- Metal parts: Sanitary brass LS59-1 according to GOST 15527;
- Electrical insulator: Polyamide according to GOST 14202-69 with fire resistance category PV-O according to GOST 28157-89.

Specifications:
- Nominal pressure PN 0.6 MPa, which is 200 times higher than the normal gas pressure in household gas networks (according to SNIP 2.04.08-87 and 3.05.02-88, gas pressure up to 0.03 atm is considered normal);
- Operating temperature: from -60 to +100 degrees Celsius, which makes it possible to install the insert in unheated rooms;
- Pipe thread, 1/2" or 3/4";
- Inner passage diameter: 10.0 mm (for 1/2") and 14.5 mm (for 3/4")
- Electrical resistance at a voltage of 1000V more than 5 MΩ;
- The insert does not require maintenance during operation.

Employees of gas services in some regions are already using a dielectric insert in in-house and in-house gas pipelines without fail. In particular, its use is regulated by the order of MOSGAZ of December 26, 2008 No. No. 01-21/425: "When replacing gas stoves and connecting them to a flexible supply, provide a dielectric insert."
"Small spool, but expensive" - ​​this expression is the best suited for inserting a dielectric. The cost of this product is negligible even compared to the cost of possible repairs of electronic and electrical components of modern gas equipment, not to mention the consequences of emergencies such as fire or explosion.

A dielectric coupling is a shut-off fitting that protects the "brains" of gas-consuming devices from the damaging effects of stray currents. That is, we have a very useful node, the effectiveness of which is proven by the definition itself. However, many owners of gas stoves, columns and boilers, as well as employees of gas services, are not aware of the existence of such an insert. And in this material we will try to eliminate this knowledge gap by talking about the benefits of a dielectric fitting, its varieties and installation methods.

Stray current - where does it come from in the gas pipeline

Such currents appear in the ground due to an accidental breakdown of a household or industrial power line. The source of stray voltage can be either a ground loop or an electrified railway or tram line. Such a current enters the gas pipeline due to the difference between the resistivity of the earth and the metal parts of the gas supply line. In fact, all the electricity discharged into the ground does not go into the ground (it has too much resistance), but into bare cables or metal structures. And since most of the main and domestic gas pipelines are made of metal, the appearance of a stray current in the system is only a matter of time.

The main pipe can become a source of stray voltage in a household gas pipeline. To protect the gas supply pipeline from corrosion, the line is loaded with an electric potential of insignificant strength, which suppresses the natural process of electrochemical splitting in the structural material. And if in the common insulator separating the main from the household branch, a breakdown of the dielectric insert for gas occurs, then the useful protective potential will turn into an unwanted stray current.

In addition, stray voltage may appear in the internal gas supply line due to poor grounding of the circulation pump or other electrical appliances that come into contact with the heating system wiring or the home branch of the gas pipeline. Another reason for the appearance of such currents may be an error when installing a boiler, column or gas stove connected to the mains. As you can see, stray current is not a myth, but a real problem. And the metal structure that fell under its action turns into a serious threat to the safety of all residents of the house connected to the gas pipeline.

What happens if there is no shut-off fitting in the system

To cut off stray currents in pipelines, a special dielectric insert is used. It cuts into the area between the tap and the connection to the gas-consuming device. Or in the area between the gearbox and the gas meter. What happens if there is no such insertion? Believe me, no good. Firstly, your or a neighbor's stove, column or boiler may suffer from a stray current or turn into a source of one. As a result, there is a risk of losing their performance, due to the defeat of the "smart" filling, assembled on the basis of capricious chips, reacting even to minor power surges.

Secondly, a spark can occur in the pipeline - a source of fire. Moreover, cases of spontaneous combustion of the eyeliner are not so rare. And if this fact is not discovered in time, the case may end in a big catastrophe. The detonation of the gas-air mixture can destroy even an apartment building. Thirdly, the user may be electrocuted. If the potential of the stray charge is significant, and this happens during a thunderstorm or a power failure, then we can not talk about an unpleasant "bite", but about a full-fledged injury with difficult to predict consequences.

Therefore, in the set of rules SP 42-101-2003, regulating the construction of gas distribution systems, there is a special clause (6.4), stipulating the mandatory presence of a dielectric insert, used even in polyethylene pipelines. And modern industry produces several types of such cutters.

Varieties of dielectric cut-offs - couplings and bushings

The product range of stray current cutters for gas distribution systems is usually divided into two groups, which include:

  • Dielectric couplings (MD) are special fittings with threaded ends, mounted between the gas pipeline and the device consuming blue fuel.
  • Dielectric bushings (VD) - non-conductive liners installed at the place of collapsible interface of gas pipeline elements.

In turn, the nomenclature of couplings is divided into four sizes, based on the diameters of the threaded part: ½, ¾, 1, 1 ¼. Such a set allows you to cover all types of pipe fittings used in gas pipelines, since diameters less than ½ inch and more than an inch and a quarter are not used in such systems. In addition, the range of couplings can be divided according to the design features of this fitting, distinguishing three groups: MD thread/thread, MD thread/nut, MD nut/nut. After all, the thread of this fitting can be cut both outside and inside the end part.

The nomenclature of dielectric bushings is divided only on the basis of their geometric dimensions - according to the diameter of the liner. In this case, we are dealing with 11 standard sizes and diameters from 8 to 27 millimeters. At the same time, both couplings and bushings have the same margin of safety. The working pressure of both types of cut-offs is 0.6 MPa (about 6 atmospheres), and the limit is 50 MPa (493 atmospheres). As a dielectric in both cases, a practically non-combustible polymer is used - polyamide, which has an enormous resistance (about 5 million ohms).

How to install the clutch - act carefully

Item 6. 4 of the set of rules SP 42-101-2003 indicates that MD and HP must be mounted between the gas distribution valve and the consumer device, therefore, when installing dielectric cut-offs, the following sequence of actions is used:

  • We close the valve on the metal pipe supplying gas to the stove, boiler or column. At the same time, it is better to leave the burners of the devices open so that the gas in the supply burns out.
  • Holding the valve body with the first wrench, carefully twist the supply nut with the second wrench - a flexible pipeline (hose) connecting the shut-off assembly with the gas inlet pipe of the boiler, stove or column. The use of a pair of keys in this case is mandatory, since the supply nut can “stick” to the valve fitting or pipe and transfer torque to it, after which gas will pour into the room, and it will be possible to shut off its supply only with a street reducer valve.
  • We screw the FUM coupling (polymer sealant) onto the free ends and screw it into the gas pipeline valve with our hands. Next, we take the same two keys and, holding the valve body, screw in the coupling until it stops. Try not to overdo it at this stage, as excessive force will deform the valve body and leak gas.
  • We screw on the free end of the coupling the nut for supplying to the device that consumes gas, controlling our effort and holding the fitting with one of the adjustable wrenches.
  • Next, you need to check the tightness of the resulting connection. To do this, you need to purchase a shaving brush and, after carefully lathering it, process all the joints of the valve, coupling and supply. After that, you open the valve and observe the foam at the joints. If you don't see any bubbles, the joints are hermetically sealed and your gas pipeline is ready for safe operation.

If soap bubbles are found at the joints, turn off the gas supply valve and carefully tighten the coupling or supply nut. If this does not help, you will have to disassemble the entire connection and add a few turns of the FUM to the ends of the coupling.

Attention: the use of matches or lighters instead of soap suds when testing the tightness of the joints is strictly prohibited. You may not have time to react and turn off the gas, causing a serious fire. And with a strong leak, panic can seize you - the sight of a flaming valve unbalances even the most cold-blooded masters. Therefore, the best leak tester is soap suds.

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