Electrical systems generally require either Halon or CO2 suppression. Both are also suitable for human contact (briefly). CO2 remains possibly the BEST overall fire suppression/extinguishing mechanisms available.

The total required volumes and storage cylinder pressures will depend on the volume/surface of the potential fire consumables.

Your statement about the pressure measurement is not understood. All CO2 delivery systems should have simple pressure measurement gauges installed.

The title speak about fire suppression in transportation vehicle where power source appears to be electrical possibly involving either overhead cables or batteries.The FSS here is understood to take care of electrical fire and not the fires originating at other places in the vehicle (luggage area, passenger area etc).

The choice of fire suppression agent is dependent upon factors like, if the area being protected is manned or unmanned, enclosed, semi-open or open and/or if the power source can be isolated after detection of fire.

In this context, other than CO2, the suppression can be achieved using halon alternatives or inert gases. Halon alternative such as HFC227ea is a better choice, when compared to CO2 and inert gases, as its quantity requirement is significantly less. In addition aerosol (gas generating or condensed) based FSS are also being offered for electrical fires. There may be some concerns with all of these options when employed in manned area.

The question regarding measurement of pressure is not understood clearly. Measurement of CO2 pressure in pipe is easily through gauges or transducers. The designed FSS shall have sufficient quantity of the gas to achieve desired extinguishing concentration of CO2 after release. You may refer relevant NFPA standards to cross check the design and quantities.

Satya Dobhal Mr. Satya thank you for your answer. But as you know Halon gases are forbidden because of their toxicity and air pollution, regardless to that concentration of CO2 is %100 and as you understood FSS that we are talking about is in battery and engine cabin. Thank you for your advice about NFPA standarts I'll check the designs. I have another question for you is there a posibilty to calculate required amount of CO2(g) related to volume of engine cabin. Thank you for your co operation.

Steven Cooke First of all thank you for your answer. If we are going to talk about 1L of CO2(g) at 50bar how much heat does it can draw in an isolated engine cabin or do you have an advice source for this research.

Canberk Usta please send your email to me at [email protected] for detailed discussion. I worked exclusively with CO2 and its many applications for over 15 years of my professional career.

https://drwhocooke.wixsite.com/safe-business

Canberk Usta : "If we are going to talk about 1L of CO2(g) at 50bar how much heat does it can draw in an isolated engine cabin or do you have an advice source for this research."

At 50 bar and 20’C carbon dioxide has an enthalpy of -70kJ/kg and a density of 125 kg/m3from the Mollier diagram. Releasing that to atmospheric pressure of 1 bar changes the enthalpy to -500kJ/kg for a net “cooling” effect to the environment of -430 kJ/kg.

1L is 0.001m3, so your example would “draw” 125kg/m3 x 0.001m3 x 430 kJ/kg = 53.75 kJ of ‘heat’.

Steven Cooke thank you for all of your effort. I appreciate your knowledge about EFS. Your answers are really helpful for our project. In advance I'll be contact you via email.

Steven Cooke Mr. Cooke we were using -47'C I corrected the calculations for that temprature but i can not find out how much heat can be generated in an EV fire do you have an idea about that ?

The temperatures and profiles of different types of fires are much more complex. Battery combustion, materials, and temperatures will be quite different from combustible materials like fabrics or wood. Even "common" fire sources have widely different temperature profiles depending on the specific material and configurations.

If the batteries are a source, then they may contain their own oxidation source. Normally, CO2 fire suppression is very good at both temperature and oxidation source removal. Of the two, removal of the oxidation source (usually air) is really the primary and most effective use of CO2. The temperature cooling capacity is really less than water, which is THE best cooling agent known, and only avoided in situations in which it could cause further problems - like power circuits.