Hydrostatic Testing
Start Tracking NowHydrostatic testing is a pressure test for cylinders and extinguisher shells. The cylinder is filled with water and pressurized beyond its normal working pressure to confirm it can still hold pressure safely, without leaking, permanently expanding, or rupturing. Water is used because it barely compresses, so if the cylinder does fail, it doesn't release the stored energy a gas would.
Over years of service, corrosion, dents, and repeated pressurizing can weaken a cylinder in ways a visual inspection can't detect. Periodic hydrostatic testing catches that before the cylinder fails in use.
What Needs Hydrostatic Testing
- Portable fire extinguishers, under OSHA 1910.157 and NFPA 10
- SCBA and breathing air cylinders, at intervals set by DOT and the cylinder's special permit
- Compressed gas cylinders, such as welding and industrial gas cylinders, under DOT rules
- Fire hose, which has its own service testing under NFPA standards
Fire Extinguisher Test Intervals
| Extinguisher type | Interval |
|---|---|
| Water, antifreeze, and wetting agent | 5 years |
| Foam and AFFF | 5 years |
| Wet chemical | 5 years |
| Carbon dioxide | 5 years |
| Dry chemical with stainless steel shell | 5 years |
| Stored-pressure dry chemical with mild steel, brazed brass, or aluminum shell | 12 years |
| Halon | 12 years |
This is a summary of OSHA's Table L-1. Check the standard and the extinguisher's label for your specific units. Stored-pressure dry chemical extinguishers on the 12-year cycle also need a 6-year internal examination.
Records
OSHA requires a hydrostatic test record with the test date, the signature of the person who performed it, and the extinguisher's serial number or other identifier. Keep it until the extinguisher is tested again or taken out of service. Test facilities also mark the cylinder or attach a label showing the test date.
Tracking Hydrostatic Test Dates in ToolWorks
The ToolWorks Portable Fire Extinguisher Inspection checklist preset includes a check that the hydrostatic test and 6-year internal examination dates are within their intervals, so an overdue test is caught at the monthly inspection, not by an auditor. An extinguisher that fails goes out of service automatically.
Learn more in OSHA fire extinguisher inspection requirements, or start your free trial.
Frequently Asked Questions
What is a hydrostatic test?
A pressure test that fills a cylinder or extinguisher shell with water and pressurizes it beyond its normal working pressure, to confirm it can still safely hold pressure without leaking, bulging, or failing.
How often do fire extinguishers need hydrostatic testing?
Every 5 years for most water-based, foam, wet chemical, and carbon dioxide extinguishers, and every 12 years for most stored-pressure dry chemical extinguishers. OSHA Table L-1 in 1910.157 lists the interval for each type.
Who can perform a hydrostatic test?
Trained people with suitable test equipment and facilities, usually a fire protection service company or cylinder test facility. It is not something a facility inspector does during a monthly check.
What records are required for hydrostatic testing?
OSHA requires a record of the test date, the signature of the person who performed the test, and the extinguisher serial number or other identifier, kept until the next test or until the extinguisher is taken out of service.