A fire extinguisher is a pressure vessel. The shell fatigues, corrodes and thins over time, and a cylinder that fails under pressure is dangerous in its own right. Hydrostatic testing fills the cylinder with water and pressurises it well beyond its working pressure to prove it is still sound — and the standard says it has to happen on a fixed schedule whether the unit looks fine or not.
The interval depends on what is inside the cylinder, and the clock runs from the date stamped on the shell or from the last test — not from when you bought the building.
These two get confused constantly, and the confusion is expensive because a property can be told it is compliant when it is not. They are separate requirements on separate clocks.
The six-year internal maintenance empties a stored-pressure dry chemical unit, opens it up, inspects the inside of the shell and the valve, and recharges it. No pressure test is involved.
Hydrostatic testing is a pressure test carried out at a licensed facility, at twelve years for those same dry chemical units. A unit needs both, at different times, for its whole service life.
A failed cylinder is condemned. It cannot be repaired, repainted or returned to service — the standard requires it to be permanently taken out of use so it cannot end up back on a wall somewhere. We tell you which units failed and why, and quote replacements against what the building actually needs rather than a like-for-like swap of whatever happened to be there.
A tested cylinder is stamped or labelled with the test date and the facility's identification, and that marking is what an inspector or an insurer looks for. We record the manufacture date, last internal and last hydrostatic date for every unit on the property, so the next one coming due is known months ahead instead of being found during an inspection.
Stored-pressure dry chemical extinguishers — the standard ABC units — are tested every 12 years. CO2, water, water mist and wet chemical Class K units are tested every 5 years. Any cylinder with visible corrosion or damage, or that has been through a fire, needs testing straight away regardless of date.
Look for a stamp or label on the shell showing the test date and the testing facility, and check the manufacture date stamped on the cylinder or printed on the nameplate. If neither is legible the unit has to be treated as due. We survey and log this for every unit when we take on a property.
Yes. Cylinders due for testing come with us and loaner units go up in their place, so the property is never left without coverage and you are never out of compliance during the work. We schedule around your trading hours.
The cylinder is emptied, filled with water and pressurised to a test pressure well above its normal working pressure, then measured for permanent expansion, leaks and distortion. Water is used rather than air because water barely compresses — if the vessel does fail, it splits rather than exploding.
Hydrostatic Testing across Chicago and the surrounding Cook County suburbs. See all areas →
Call 312-877-2355 during business hours, or send the details and we'll come back with a quote and a service window.
1840 N Clybourn Ave · Chicago, IL 60614
