CO2-based gas fire extinguishing systems have been used since the early 1930s. It was welcomed at the time for the lack of alternative solutions. However, over time, problems with its use challenged the technology, and inventors sought to introduce new technology to improve the performance of firefighting systems and solve their problems. Some of the disadvantages of using CO2 gas are as follows:

1. Impact on fire by reducing the concentration of oxygen in the place: With the help of CO2 injection during a fire, the volume of oxygen gas is greatly reduced and as a result, the fire is extinguished. However, this has an immediate effect on people’s health, which in the saturated state will lead to immediate death and in the local state will lead to severe brain damage on the people present at the site. It should be noted that the minimum concentration required for fire extinguishing (Minimum design concentration) with the help of Co2 gas is 34% of the volume of the environment, while the maximum level of concentration for survival of people is 5% of the volume of the environment.

(German Safety and Health standards BGR 134)

Therefore, the ideal fire extinguishing system is a system that does not reduce the amount of oxygen in the environment and does not endanger people’s health if activated.

2. Due to the fact that CO2 gas is under pressure in the capsules, so when leaving and facing the ambient pressure, carbon dioxide will be required to take the temperature of the environment in order to increase the distance between the molecules. Therefore, during unloading, the ambient temperature will decrease significantly, which will damage the equipment located in the environment.The CO2 fire extinguishing scenario is plotted in such a way that the fire has occurred and in the interval between the detection of the fire by the sensors and the passage of the delay time for people to leave, the equipment located near the fire is heated and then immediately cooled by CO2. . This rapid temperature change changes the appearance of metal objects and deforms them. In many cases, it is necessary to replace the mentioned parts. Therefore, the ideal fire extinguishing system is a system that does not cause a sudden change in ambient temperature.

3. CO2 gas is considered as a greenhouse gas and causes the depletion of the ozone layer and increase the Earth’s temperature. (ODP = 1, GWP = 1) It should be noted that CO2 gas is a measure of the rate of ozone depletion and global warming, so ODP and GWP consider it one. Therefore, the ideal fire extinguishing system is a system that has the least degradation on the ozone layer and the Earth and has a minimum durability in its environment, because with its production and consumption in the world, its concentration in the atmosphere will continuously increase.

4. The use of pressurized cylinders is itself a threat to the environment in which it is installed. On a daily basis, we see the explosion of such capsules in all parts of the world. The cause of their explosion is due to various reasons such as the occurrence of an earthquake, direct exposure to the flame, damage to the valves and its body by accidental manpower and so on. However, there are very strict rules regarding the production of such tanks in various standardsTherefore, in the by-laws approved by the country’s passive defense committee, laws have been passed regarding the non-installation of pressurized tanks near facilities that have a security category. This threat applies not only to places with a security rating, but also to all public places and expensive equipment. Therefore, the ideal fire extinguishing system is a system that does not use such tanks as much as possible. 

5. The number of required tanks and related piping occupies one part of the environment and makes another part unusable. This will be more pronounced in places where space is limited, which will cause other problems that may not have seemed so at first. Therefore, the ideal fire extinguishing system will be a system that occupies the least possible space.

6. Due to the fact that CO2 gas has a small molecular mass (its molecular mass is 44) gas is very volatile and its use as a local application in places that have pores is faced with a high risk. If the firebox is not located exactly .next to the nozzle, it is very possible to reduce the accuracy of the systemThis possibility may lead to the system failing to extinguish the fire, so alternative systems such as the FM-200 (with a molecular mass of 172) have tried to use heavier molecular weight materials to reduce the risk of gas leakage. Find. However, the ideal fire extinguishing system is a system that reduces the risks of gas leakage and leakage to the outside environment to a minimum, or the mechanism of firefighting is changed in such a way that there is no need to prevent oxygen exposure to the fire.

In view of the above, during the last century, the community of engineers and inventors have always sought to find new solutions to increase efficiency and reduce injuries. The result of these efforts has been the emergence of various solutions and the introduction of various technologies over time, some of which are mentioned below.

– Using a combination of other gases such as N2 with CO2 gas to reduce the harmful effects of CO2 gas, which has resulted in the production of gases such as IG-54

– The use of inert gas to reduce the destructive effects of CO2

– Use of halo carbon gases such as Halon 1301 and FM-200

Although halocarbons shone brightly and were much more successful in practice than CO2, their devastating impact on the environment prevented the engineering community from working to reduce the damage. The following is a table comparing the impact of these gases on the environment.

Inert Gases

PFC-3-1-10

HFC-125

HFC-227ea (FM-200)

Halon 1301

 

0

15

0

0

12

ODP

n.a

9000

3400

3500

6900

GWP

n.a

130

29

33

65

ALT(years)

Quoted from IPCC2001

As it seems, the first place in the least environmental damage belongs to neutral gases, but the impact of this type of gas on fire is very weak, and therefore first Halon 1301 gas and then in the decade 80 AD was selected as the most suitable replacement for the FM-200 gas extinguishing system and was widely used. However, this type of extinguishing system was still a long way from the ideal fire extinguishing system. The reasons for this are as follows.

– Use of pressure vessels as old technology

– The destructive impact on the environment, although less than previous technologies, but still has not reached the ideal level

– Impossibility of use in Local application projects and insisting on using the total flooding method

– Can be used only in fire classes A, B, C

Production of HF (halogen acid) during molecular decomposition in the face of temperatures above 500 ° C, which will have a very dangerous and deadly effect.

Reduce hazards in the face of other threats such as earthquakes, floods and hurricanes: Although fire extinguishing systems are designed to deal with fires, many of them have become a threat to natural causes. The use of pressure vessels acts as a bomb against the destruction of their places and earthquakes, and there is a possibility of bursting tanks. Therefore, in the development and progress of this industry, an attempt was made to reduce the internal pressure of the tanks as much as possible. . The following is a comparison of the internal pressure of some materials:

Extinguisher

IG-55

CO2

Halon-1301

FM-200

Aerosol

Internal pressure of tanks

300 times

250 times

55 times

24.8 times

Ambient air pressure

Comparison table of the concentration required in the design and its effect on people’s health
Extinguisher

Concentration required design

NOAEL

LOAEL

IG-55

40%

43%

52%

FM-200

7.5%

9%

10.5%

NOVEC

5.2%

10%

Less than 10%

FE-13

18%

50%

Less than 50%

HALON 1301

5%5%

0%

CO2

35 – 50%

Less than 5%

fatal

Reducing threats and damage to the environment: In recent decades, the impact of greenhouse gas emissions on
Global warming and climate change, as well as ozone depletion, have been taken very seriously
Is. Hence two indicators called ODP

(Ozone Depletion Potential) and GWP (Global Warning Potential) are defined as the measure of the impact and degradation of carbon dioxide. also

A criterion called ALT (atmospheric life

time) is also considered. ALT is when

Materials remain in the environment

        
Efforts are being made to use materials that have the least damage to the environment
To be. Below is a comparison table of these parameters for several types of extinguishing agents
Is.

Comparison table of the impact of several extinguishers
Common on the environment and their longevity

Extinguisher

GWP

ODP

ATL

Inergen

00

n/a

IG-55

00

n/a

FM-200

38001200
36.5 years

ECARO

38002100

32.6 years

Novec

11000

3 to 5 years

FE-13

11700

1100

250 years

Aerosol

000

CO2

11

n/a

Halon 1301

6900

3200

65 years

– Making the materials used in the fire extinguishing system more efficient, which in turn reduces the storage space of the materials. According to the standards of each extinguishing material, the amount of required materials is as described in the table below.

Type of extinguishing agent

CO2

Inert gases

HFC-125

FM-200

Halon-1301

Aerosol

Required concentration

35-50%

38-40%

8-11.5%

7.2-8.7%

5%

1%

 

Aerosol

As can be seen, the most effective extinguishing agent is aerosol, which is the latest generation of extinguishing agents. It should be noted that the aerosol effectively remains in the environment for up to 45 minutes and prevents the fire from returning. However, none of the previous materials are able to provide this level of protection. It should be noted that the standard prepared for Aerosol is NFPA2010, which confirms the accuracy of this document.

Therefore, after that, the effort to find the ideal fire extinguishing system continued, which led to the invention and production of a new generation of fire extinguishing systems called aerosol, which was codified under the NFPA-2010 standard.

Aerosol has the following specifications:

– No need for pressure vessels

– No need for plumbing and occupy the least possible space compared to previous generations of fire extinguishing systems

– No destructive effect on people’s health

– Environmentally friendly (with ODP = 0, GWP = 0, Alt = 0) No emissions of unnatural substances in the environment

– No effect on the ambient temperature during evacuation (this system allows the increase in temperature caused by the fire to naturally decrease and will not cause damage to equipment and devices in the environment.

– No need to cut off the oxygen connection with the fire bin and no reduction of oxygen in the environment

– No need for an annual charge

– Shelf life of more than 25 years

In addition, in the standard and in theory, it will not have any detrimental effect on human health, the environment and equipment. So far, there have been no reports of damage in practice.

Therefore, this company, with its laboratory capacity and product production in its factory, has provided the possibility for the consulting community of the country to be closely acquainted with this type of technology and to put the products of this company to the testing plant. Hopefully, an effective and useful step will be taken to keep the national tools and equipment of this country healthy.

It should also be noted that according to the NFPA standard, the volume of the environment is calculated and at least one tenth of the calculated volume of aerosol active ingredients is considered for extinguishing

All sources and references are reserved and if you wish to provide more content, calculation methods and system design based on this type of products.