The rules that apply on location
OSHA 1910.157 covers the placement, use, maintenance, and testing of portable fire extinguishers. NFPA 10 is the standard the industry follows for inspection and servicing. On an oilfield location, every unit you carry answers to both. The rule of thumb for placement is travel distance. For Class A fires, an employee must reach an extinguisher within 75 feet. For Class B fires, the distance is 50 feet. Units must be mounted so they are readily accessible without putting anyone at risk.
Monthly visual checks
Every extinguisher gets a visual inspection every month. Check the pressure gauge, the safety pin, and the seal. Look for corrosion, dents, leaks, or a missing tag. OSHA also requires every unit to stay fully charged and operable, and to stay in its designated place except when in use. A unit that shows damage, or one that has been used, comes out of service until it is recharged or replaced.
Annual maintenance and hydrostatic testing
Once a year, every extinguisher gets a maintenance check. Stored pressure units do not need an internal examination. Record the annual maintenance date and keep the record for at least one year. Stored pressure dry chemical units that require the 12-year hydrostatic test must be emptied and serviced every 6 years. Hydrostatic testing follows the intervals in Table L-1: stored pressure dry chemical with mild steel shells every 12 years, carbon dioxide every 5 years. Certification records must include the test date, the tester's signature, and the serial number of the unit. When an extinguisher leaves service for maintenance, put alternate protection in its place.
A dead gauge or a broken seal turns protection into decoration. Wire the monthly check into your routine the same way you plan hot work and welding safety. Treat extinguisher placement like the hazard mapping behind electrical safety in classified locations, and keep the documentation as tight as your SPCC and secondary containment plans. If the tags are the only record of a check that never happened, book an operations audit.