OSHA does not require employers to equip forklifts with portable fire extinguishers. However, depending on the hazards present in an area where forklifts travel, OSHA may have requirements for fire protection in that specific hazardous location which would include mounting extinguishers on forklifts. Again, it depends upon the area where the forklift operates.
Also, if the truck manufacturer equips the forklifts with fire extinguishers, the employer must maintain the extinguishers according to the requirements of 1910.157. If the truck comes so equipped, the extinguisher cannot be removed permanently from the forklift without written permission from the manufacturer.
Local or state fire codes may also apply, so employers must check with local authorities or the Fire Marshal.