You are legally required to provide functioning fire extinguishers in your building to help protect your employees and the public. Fire extinguisher servicing guarantees that the fire equipment in your building is in peak condition for its intended use.
BS5306 Part 3 2017 is the code of practice, pretty much like the highway code, (Fire extinguishing installations and equipment on premises. Commissioning and maintenance of portable fire extinguishers. Code of practice)
The Regulatory Reform (Fire Safety) Order 2005 states that the responsible person must take such general fire precautions as will ensure, so far as is reasonably practicable, the safety of any of his employees in relation to relevant persons who are not his employees, take such general fire precautions as may reasonably be required in the circumstances of the case to ensure that the premises are safe. Not adhering to this Order is a criminal offence.
CO2 is stored at 55 bar in a fire extinguisher while the pressure in stored pressure fire extinguishers are around 12 bar (the exact figure is printed on the side of each extinguisher and varies depending on the size and contents).
No, the strong jet from a CO2 can carry the burning fat into the room and make the situation worse. Also, while CO2 extinguishers are rated for flammable liquids, deep fat fryers have their own class (F) because the burning fat is so hot that conventional class B extinguishers cannot cool them down to below the auto-ignition temperature.