Here are the general requirements for competition vehicles under the current FIA fire extinguisher regulations, some series enforce requirements specific to that championship so it is always worth thoroughly reading the technical regulations of the series that you are competing in just to check compliance.
If you are competing in the UK then from 01/01/2019 all new vehicles will require an FIA Homologated system meeting the FIA's technical list 16 or 52 and from 01/01/2022 all vehicles are required to be fitted with an FIA system.
For Circuit Vehicles - FIA Technical List 16
The minimum requirement for a circuit vehicle is one plumbed in fire extinguisher homologated to FIA technical list 16 a full list can be found here (just scroll down to Technical list 16).
If the homologation number on the main serial label of the bottle matches one on the list then as long as it is not over ten years old, has been serviced within the past two years and is fitted as per the manufactures instruction then it is eligible for circuit racing.
For Rally - FIA Technical List 16
As rally cars are potentially further away from marshal aid there are a few extra requirements in place for rally cars, one plumbed in and one hand held extinguisher are required. Both must meet the requirements of FIA Technical list 16 a full list of plumed in systems can be found here can be found here (just scroll down to Technical list 16) there is a note stating which systems are eligible for rally as a minimum of 3.0kgs of suppressant is required.
If the homologation number on the bottle matches one on the list then as long as it is not over 10 years old, has been serviced within the past 2 years and is fitted as per the manufactures instruction then it is eligible. For the Hand held to be eligible then it must have a minimum amount of suppressant for AFFF foam it is 2.4 ltrs and for Novec 1230 Gas it is 2.0kg, the same service requirements apply.
For FIA Categories WRC, R5, RGT, T1, GT3, WRX – Technical List 52 8865-2015 Standard
The FIA introduced a new standard of fire suppression that came into force for some categories of motorsport, one plumbed in fire extinguisher homologated to technical list 52 is required, again if it is competing in an FIA rally event then a hand held (2.4 ltrs of AFFF foam or 2.0kg of Novec 1230) must be carried. Check the homologation number on your bottle and check it on the list here.
If the homologation number on the bottle matches one on the list then as long as it is not over 10 years old, has been serviced within the past 2 years and is fitted as per the manufactures instruction then it is eligible.
