What is the name of the odor for gas: what gives natural gas its characteristic odor + odorant hazard class

The human sense of smell is the most effective “device” for detecting gas leaks.And special additives with an unpleasant odor, which are mixed with “blue” fuel, are called upon to help. Agree, they are rarely remembered and even less known. Are you wondering what the smell of gas is called and why it needs to be added to the gas?

We will help you understand these issues - the article discusses the reasons for adding aroma to gas and the characteristics of these odorous substances. The standards according to which odor is added and safety measures when using odorants are given.

Requirements for odor additives for gas

The two most unpleasant characteristics of natural gas for consumers are the absence of color and odor. The reason is that its leakage is a direct path to explosion or fire. It is almost impossible to detect a leak of a colorless, odorless substance.

Therefore, the only way out is to use odorants. What these substances are is stated in TU 51-31323949-94-2002, developed by VNIIGAZ LLC, which is a division of Gazprom. Based on the provisions of these conditions, odorants are manufactured.

The paradox of the situation with substances that are supposed to give gas an odor and save people’s lives is that organic but toxic compounds are used for this purpose

And the specified technical specification states that odorants are intensely smelling substances or combinations thereof that are added to natural gas.Moreover, only in small concentrations in order to impart a specific (unpleasant) warning odor.

This is done to make it easier to detect gas leaks when the gas concentration level does not reach the lower explosive limit. This makes it possible for anyone to detect a fuel leak when its concentration is about 1% of the total volume of the room. This provides time to prevent negative consequences. Since an explosion can occur when the gas concentration reaches 5% of the total volume of the room.

We recommend checking out the best ways to check for gas leaks at home.

The use of odorants increases the cost of gas. Therefore, the mixing procedure is carried out in distribution networks before the energy is supplied to consumers

GOST 5542-2014 regulates what it should be domestic gaswhich is supplied to consumers. Actually, it can be considered the main profile document. Since in the Russian Federation the issue of what needs to be added to natural gas to give it a specific unpleasant odor is not completely regulated.

The only exception can be considered the document VRD 39-1.10-069-2002. This is an internal document of Gazprom. It describes in more detail the odorization procedure, what substances are used for this, as well as safety requirements when working with odorants.

Since the odorant has a pungent odor and is also poisonous (in a concentrated state), it is stored and transported in special tanks and barrels

In addition to the specific smell, odorants must have a number of characteristics:

• exhibit chemical and physical stability in a vapor state when mixed with gas and when transported through a pipeline;
• do not have a negative impact on the materials from which the pipes are made and any other structural elements of gas pipelines - this is necessary to prevent a decrease in the operational characteristics and service life of pipelines as a whole and its individual structural elements;
• be concentrated - this will make it possible to reduce the amount of substance used;
• have little toxicity — this requirement applies exclusively to working concentrations of odorants.

It should be noted that today not a single widely used chemical substance fully meets all of the listed requirements.

But the most suitable are the so-called natural mercaptans, and, to be precise, mixtures of them. The smell of which consumers feel every time they turn on gas equipment.

Features of a mixture of natural mercaptans

A mixture of natural mercaptans is an organic compound. Mercaptans have pronounced aromatic properties, so they emit an unpleasant and pungent odor even at low concentrations.

The odorant production method is based on alkaline extraction, that is, the separation of mercaptans from stable gas condensate, as well as its mixtures with oil. As a result, a primary product is obtained, which is called SMP - a mixture of natural mercaptans.

The photo shows a special vehicle designed to transport odorant. It belongs to a new generation and has increased safety. And Gazprom is investing in the development of such vehicles

The secondary product is SMP-1, which is drained SMP. Moreover, both types of odorant are suitable for mixing with gas. This is what is said in the above technical specifications.

Mercaptan mixtures are supplied in liquid form. It is transparent and has an extremely unpleasant and pungent odor. In addition, SMP, as well as its derivative SMP-1, is hazardous substances of hazard class 2. They are classified as flammable products. Therefore, premises for odorization and storage of the mixture must be equipped in accordance with the requirements for premises of category B-1a.

Mercaptans became the main odorant back in 1984. Currently, they are produced at the Orenburg Processing Plant (part of Gazprom).

Norms and restrictions when adding odorant

As mentioned above, mixtures of natural mercaptans are introduced in small quantities. In practice, this is true, since only 16 g of these chemicals for every 1000 m³ of natural gas supplied to consumers can provide the required level of odor.

Today, GOST 5542-2014 limits the density of mercaptan sulfur in the odorant to 0.0036 grams per cubic meter. Although this document states that in individual gas pipelines the amount of this substance in the composition of odorants may be somewhat greater. However, the exact figure is not given.

The reason for the limitation is that sulfur reacts with iron oxide formed as a result of corrosion of steel pipes of gas mains and a significant part of distribution pipelines. And this feature often leads to a significant reduction in the amount of odorant used, which makes their use practically useless.

In order not to be afraid of gas leaks and the disastrous consequences they can lead to, experts recommend installing leakage sensor with shut-off valve - such a device will not only detect a leak in a timely manner, but will also immediately cut off the gas supply to an apartment or house.

How does the process of adding scent work?

The specified substance, which serves to impart a specific odor to the gas supplied to consumers, is mixed with it using special installations. They are equipped with gas distribution stations.

The photo shows an odorization unit used at one of the Russian gas distribution points. And not a single cubic meter of gas supplied to the population passes by it

There are 2 methods of odorization:

• gas vapor saturation natural mercaptans;
• drip input the required amount of odorant into the gas stream.

Both types of installations are successfully used at domestic gas distribution stations. But the most popular equipment is the one used for drip injection of mercaptans. The reason is its simplicity and cheapness.

The odorant supply procedure is carried out using a dropper. And the method is based on the constant value of one drop of liquid. So, in the case of mercaptans, the indicated volume is always 0.002 g.

To prevent malfunctions in the operation of odorizing installations, the consumption of a substance that gives a specific odor to the gas is constantly monitored.

On the territory of the Russian Federation, 2 large factories are engaged in the development and production of odorizing installations. Since the country needs a large amount of such equipment, reliable and safe

The only automated way of mixing mercaptans and energy carriers is the use of bubbling units.

Despite the active use of odorants, methods for introducing them into the gas flow are considered obsolete. As a result, experts predict the emergence in the coming years of fundamentally new mixing methods based on methods of precise, express analysis of the situation.

Safety precautions when working with mercaptans

All types of odorants belong to Hazard class 2. The main component of the odorant is ethyl mercaptan - contains a large amount of sulfur. Usually it is not less than 37%, as indicated by TU 51-31323949-94-2002. And this feature can lead to negative consequences for the human body, even death (if the substance enters the body).

Therefore, when interacting, storing, transporting this substance, it is necessary to observe safety measures, which is dedicated to clause 5.5 VRD 39-1.10-069-2002.

It is necessary to know safety measures when handling mercaptans, if only because it happens as shown in the photo, where in the foreground you can see the barrels in which the odorant was stored abandoned by careless gas workers. And they are a danger. For example, soil on which a mixture of natural mercaptans has been spilled must be treated twice with special solutions

According to these requirements, when contacting a concentrated odorant, you should use special clothing, personal protective equipment - a gas mask, rubber boots and mittens, rubberized aprons.

In this case, exhaust ventilation must be turned on in the room with the odorant.If a toxic liquid or its vapor gets on the skin, the residue must be washed off with a significant amount of warm water, if possible with soap.

If mercaptans cause irritation of the mucous membranes, the affected areas should be washed:

• warm water;
• 2% soda if you have it nearby.

If the respiratory system is affected, then the victim should be evacuated from the room. And his well-being will be improved by fresh air and peace. And if the respiratory system is affected, it is imperative to call a doctor.

The photo shows a landfill located near the Tomsk railway station, where containers with the remains of mercaptans were inadvertently thrown away. As a result, for a long time, their smell frightened residents of the surrounding areas.

Although many experts criticize certain points and provisions contained in Gazprom’s departmental instructions on safety measures during storage, transportation, and use of odorants, consumers should be prepared for various situations.

The fact is that various incidents and incidents with odorants occur quite often. For example, in 2012, their smell led to a big commotion in Penza. A few years ago, incidents occurred in the Leningrad region, and just a couple of years ago, Emergency Situations Ministry specialists had to urgently evacuate a tank with mercaptans from the Northern capital itself.

In 2017, panic arose in the small Ukrainian city of Lisichansk when gas workers slightly exceeded the norm established for mixing odorant and gas. And at the end of 2018, Rospotrebnadzor detected the presence of a mixture of mercaptans in the atmosphere of Nizhnevartovsk. Moreover, in the very center of the city.As it turned out later, someone buried a barrel with this substance, and during excavation work it was damaged.

But the average gas consumer should not be afraid - in practice it is difficult to suffer from the effects of the odorant, because its concentration in the supplied fuel is negligible to cause a visible reaction during domestic use.

Still, it should be remembered that if the smell of SPM has become more acute, then you need to turn off all gas appliances, open the windows, leave the room and report the incident to the city gas service on duty.

If a pungent aroma penetrates from the outside, then you need to close the windows tightly and try not to go outside. In addition, you need to call the Ministry of Emergency Situations or Gorgaz.

We recommend that you familiarize yourself with the algorithm of actions when a leak is detected in apartment or entrance.

Conclusions and useful videos on the topic

The video attached below talks about the incident with mercaptans in Penza.

Odorants give gas an odor, which significantly reduces the likelihood of accidents. But organic substances used as hazard indicators are potentially hazardous to health and are used due to the fact that there is no alternative today.

As a result, consumers should have knowledge not only of whether the supplied gas has an odor, but also the skills to mitigate the consequences of poisoning with these substances.

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