Comparison of clean Pyro technology
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:
- Effect on fire by reducing the concentration of oxygen in the area: By injecting CO2 during a fire, the volume of oxygen gas is greatly reduced and 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.
- 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 to increase the distance between the molecules. Therefore, during discharge, 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.
- CO2 is a greenhouse gas that destroys the ozone layer and raises 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.
- 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 standards.
- Therefore, 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.
- 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.
- Due to the fact that CO2 gas has a small molecular mass (its molecular mass is 44), the gas is very volatile and its use as a local application in places that have pores is facing a high risk. If the firebox is not located exactly next to the nozzle, it is very possible to reduce the accuracy of the system.
- This 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 to reduce the destructive effects of CO2 resulting in the production of gases such as IG-54.
- 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|
|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 in the old technology
- The detrimental effect on the environment, although less than previous technologies, has not yet 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.
- Reducing the risk of other threats such as earthquakes, floods and hurricanes: Although fire extinguishing systems are designed to deal with fire, many of them themselves have become a threat to natural causes. The use of pressurized tanks acts as a bomb against the destruction of their places and earthquakes, and the possibility of bursting of tanks arises. . The following is a comparison of the internal pressure of some materials:
|Internal pressure of tanks||300 times||250 times||55 times||24.8 times||Ambient air pressure|
|Table comparing the concentration required in the design and its impact on people’s health|
|Extinguisher||Concentration required design||NOAEL||LOAEL|
|NOVEC||5.2%||10%||Less than 10%|
|FE-13||18%||50%||Less than 50%|
|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 the depletion of the ozone layer, has been taken very seriously. Therefore, two indicators called ODP (Ozone Depletion Potential) and GWP (Global Warning Potential) are defined, the criterion of which is the impact and degradation of carbon dioxide. There is also a standard called ALT (atmospheric life time). ALT is when materials remain in the environment
- Efforts are being made to use materials that have the least environmental damage. Below is a comparison table of these parameters for several types of extinguishing agents.
|Comparison table of the impact of several common extinguishers on the environment and their lifespan|
|Novec||1||1000||3 to 5 years|
|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|
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 detrimental effect on people’s health
- Environmentally friendly (with ODP = 0, GWP = 0, Alt = 0) No emissions of abnormal substances in the environment
- No effect on ambient temperature during evacuation (This system allows the increase in temperature caused by the fire to naturally decrease and will not damage the 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 over 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.