What is a gas holder?
The general principle of a domestic gas storage system is the same as that of a bottled gas system: somewhere outside the house there is a metal container with liquefied gas, from which fuel in a gaseous state is supplied to the house through a gas pipeline. The difference in size: if the capacity of household gas cylinders is usually measured in liters or tens of liters, then the volume of household storage is several cubic meters (thousand liters), liquefied gas under pressure of 6 atm. The most popular volume of a household gas tank (it’s not entirely correct to call the tank that way, but the name has taken root) is five cubic meters (4.85 m³).
Gas from the gas tank is supplied to the house according to the same rules as from the gas main — underground. Photo: Terrikom
This volume allows for year-round heating (as well as hot water and cooking) for a house of approximately 150 m². For small houses (less than 100 m²), gas tanks with a volume of 2-3 m³ are used, and for large mansions, respectively, models of a larger volume, up to 20 m³, several gas tanks or LPG (liquefied hydrocarbon gas) evaporation plants.
The underground option for placing gas tanks seems to many to be not only safer, but also aesthetically attractive: the gas tank will not clutter up your site. Photo: Russian Gas
Tanks/reservoirs (gas holders) are made of steel sheet with a thickness of at least 5.5 mm (according to the requirements of GOST) and are covered outside and inside with protective coatings. All this ensures the service life of the devices for at least 20 years, and all models of gas tanks approved for sale in Russia must comply with this requirement. The quality (grade) of steel, a special protective coating are the main differences between Russian and European tanks. At domestic plants, due to the high cost of equipment and sometimes the impossibility of acquiring imported special coatings, rarely anyone uses the latest compositions and technologies for their application, which reduces the life of the tank if additional elements are not installed.
Gas holders with a horizontal arrangement of the tank, a variant with a high neck. Photo: Gas Region Invest
How to install a gas tank?
Gas tanks are buried in the ground at a certain distance from the house (SNIP requires 10 m, but in some cases it is allowed to reduce the distance to 5 m). In Europe, ground-mounted gas tanks are more commonly used. This design turns out to be cheaper (no need to pay for earthworks), but it has not received distribution in Russia.
First, due to more stringent regulations. So, in Europe, ground-based gas tanks are placed almost close to houses and cottages, while in Russia this is prohibited. In our country, the distance to the ground gas tank, according to SNIP, should be 20 m, the minimum distance to trees is 10 m, not 5 m, etc. As a result of such restrictions, there is simply no place for a ground tank in a small area.
Secondly, in Europe, pure propane is used as a fuel, while in our country it is a propane-butane mixture of LPG (70/30, 50/50), which at low temperatures (and under pressure) will not evaporate and pass into the gaseous phase. Therefore, in order to work in winter, such a gas tank will have to be equipped with a special evaporative unit. It is not always possible to find a place suitable according to GOST, but this does not stop the most ardent supporters of autonomous gasification, and sometimes the gas tank is installed with violations. So far, such violators have been able to avoid responsibility; at present, there is no such strict supervision over the state of the autonomous gas economy, which, for example, is carried out over the main gas pipelines. But the situation may one day
change dramatically, and then violators will have serious problems.
The cost of the equipment and its turnkey installation depends on the size of the tank, the volume of excavation, additional options and, as usual in a market economy, on the implementation of your additional wishes. As for the differences in equipment brands, there is now no such price difference between domestic and imported products as, say, between gas boilers. On average, owners will have to pay 200–250 thousand rubles for autonomous gasification with a tank of 4.8 m³.
Photo: ShutterStock/Fotodom.ru; «Russian gas»
Are gasholders safe?
For many of our citizens, the proximity to a gas reservoir seems dangerous. But the danger is actually exaggerated. The gas is stored in the tank without access to air at a pressure of 5–6 atm, and air cannot get there in any way. And if depressurization occurs, the explosion will still not happen, since the gas will be released into the atmosphere, where it will dissipate to a safe concentration. That is why the gas tank should not be placed indoors — so that the gas does not accumulate in the event of a leak. In addition, a safety valve is installed in the gas tank, which relieves excess pressure if, for one reason or another, the tank is heated.
Visualization: Igor Smiryagin/Burda Media
Which gas tanks to choose: horizontal or vertical?
Structurally, all household gas tanks can be divided into models of a horizontal or vertical arrangement of the tank. Horizontal ones are easier to install (in terms of earthworks), but take up more space in area, which can be critical for small areas. Vertical in this regard is more convenient. In addition, they are deeper, so the liquefied gas is less cooled, which is necessary for its normal supply (the temperature must be above zero). Otherwise, the intensity of evaporation of liquid gas inside the tank is sharply reduced, and the fuel begins to flow into the heating system in insufficient quantities.
A variant of a gas tank with a horizontal tank and fittings placed on high tubes (covered with a protective casing). Photo: R-Gas
Household gas holders are tanks, in the upper part of which there is a platform (flange) with fittings placed on it (filling valve, liquid and vapor phase selection valves, reducer, safety valve). The site is closed on all sides by a protective cap, but it is not hermetically sealed. At the bottom there is a gap for ventilation, and it cannot be closed. The platform and the cap can be raised above the tank on the neck — part of the tank, made in the form of a cylinder located vertically.
Installation option for a horizontal gas tank
Visualization: Mavlyuda Melnikova/Burda Media
There are gas tanks with a high neck (the so-called Russian standard) and without it (European standard). The rejection of the neck reduces the cost of the structure by about 30–50 thousand rubles. But saving on it is not always necessary. The fact is that the presence of such a neck allows you to place a platform with reinforcement higher than in its absence. This allows you to better protect the reinforcement from soil moisture, especially at high groundwater levels or when perched. The ingress of water into the reducer will stop the gas supply. Of the latest technical innovations, gas tanks can be noted, in which there is no expensive assembly — the neck, instead of it all the fittings are placed on high tubes. Outside, the «forest» of them is closed with a metal cap. It turns out cheaper, but safety measures are observed, since the height of the tubes allows you to place all the fittings above the flood zone.
How to prevent gas freezing?
The tank is installed in a pit prepared for it. At the bottom, a sand and gravel cushion 30–50 cm thick is constructed, compacted and leveled. A concrete slab is placed on it, to which the gas tank is attached with metal cables, so that at a high level of groundwater, the tank does not float. The upper point of the tank must be at least 60 cm below ground level. The gas pipeline is connected through a reducer, which, like the filling valve, liquid and vapor phase selection valves, and a safety valve, is a necessary device for the operation of a gas tank. From the gas reservoir to the house, the gas pipeline is laid underground, the pipe is located at a depth below the ground freezing level. Devices that are desirable, but not required, include a separator for gas condensate. This device is placed on the gas pipeline before it is connected to the gas boiler at its lowest point in the ground.
Winter is the best time to install a gas tank: the workload of builders is reduced, and you don’t have to wait for a team of specialists to become free. Photo: ShutterStock/Fotodom.ru
Another optional device is a telemetry system that allows remote online monitoring of the state of the gas tank and the degree of filling of the tank. Telemetry, of course, increases the level of comfort, and it is not a pity to pay 10-15 thousand rubles for it, and in some cases it can be obtained at all for free. This service is provided by some gas tank installers. They do not lose money — the systems they offer duplicate information, so if a gas tank installer provides services for filling tanks, it turns out that he can always offer fuel to the owner in a timely manner. And given that the price of liquefied gas is 14-17 rubles. per liter, just a few refueling cycles are enough to fully recapture the cost of electronics.
Scheme of autonomous supply at home
Visualization: Igor Smiryagin/Burda Media
WHY DO YOU NEED A GAS SEPARATOR?
The gas separator, or condensate collector, serves to collect liquid gas condensate, which, under certain circumstances, can enter your home gas pipeline (the probability of this is small, but still not zero). If such condensate gets into the burner or on the burner of the stove, it will detonate. At best, there will be a loud bang, and at worst, equipment damage may occur.
How to avoid scandals with neighbors?
If the gas tank cannot be entered into the site without violations, experts advise, first of all, to monitor the observance of the interests of neighbors. So it’s easier to avoid scandals. You, after all, will not sue yourself if the gas tank is too close to your house or fence? But the neighbors are another matter.
For all my many years of activity, I have not come across new (factory-made) gas tanks certified according to GOST and at the same time unsuitable for use. Therefore, first of all, choose the one who will install your gas tank. In most cases, only real experience helps to correctly recommend the volume, type and manufacturer of a gas tank specifically for your situation, and the engineer will not hide the features of different manufacturers, because he will have to guarantee the operation of their products. As for the tanks themselves, I never recommend used and so-called refurbished gas tanks (they are often passed off as new, and this market was developed just a couple of years ago). Such tanks often go to resellers almost for nothing. But the state of these containers is unknown, no one seriously examines them. And in this case, it turns out not even a lottery, but a constant potential danger to yourself and others, then it is better to choose a completely different solution.
Commercial Director of the holding «Gaz Region Invest»
MINIMUM DISTANCES FROM UNDERGROUND GAS STORAGE TO UTILITY FACILITIES*
|Business entity type||Clear distance, m|
|Tank volume up to 10 m3||Tank volume 10–20 m3|
|Motorways of categories 4 and 5||5||5|
* When designing in cramped conditions, it is allowed to reduce these distances by 50%.
Source: Ideas for Your Home Magazine#221