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06 · Maintenance

Maintenance and inspection intervals

The single most useful thing to understand about hyperbaric maintenance: NFPA 99 requires that a routine maintenance program exist and be logged, but it does not codify a periodic PM interval for the chamber itself. The numbers come from four different places, and they are not interchangeable.

Bucket one

Intervals fixed in code or standard

Numeric intervals that are written down Codified
IntervalTaskSource
Before each pressurizationVisual inspection of acrylic viewports (first pressurization of the day if pressurized more than once daily).ASME PVHO-2-2019
Before each pressurizationVisual inspection of electrical switches, valves and monitoring equipment associated with fire detection and extinguishment.NFPA 99, Ch. 14
WeeklyTesting of fire detection equipment trouble circuits and signals.NFPA 99, Ch. 14
Every 12 months (±30 days)Primary pressure gauges deadweight tested or calibrated against a master reference gauge — or whenever two equivalent gauges disagree by more than 2 percent of full scale.ASME PVHO-2-2019
SemiannuallyFunctional test of deluge and handline fire suppression systems (Class A).NFPA 99, Ch. 14
AnnuallyFull test of fire detection and extinguishing equipment, including discharge of extinguishing media.NFPA 99, Ch. 14
AnnuallyDocumented hyperbaric-specific emergency and fire drill by all hyperbaric personnel, with evacuation time measured.NFPA 99, Ch. 14
18 / 24 / 36 monthsMaintenance Viewport Inspection, with the applicable interval set by service environment and service life.ASME PVHO-2-2019
Every 10 yearsComplete viewport refurbishment for cylindrical-window chambers, regardless of usage.ASME PVHO-2-2019

Sources: UpCodes Chapter 14 and the ASME PVHO-2-2019 free ANSI preview. Edition caution: the PVHO-2 rows above are drawn from the free ANSI preview of the 2019 edition. ASME publishes a newer edition, and these intervals should be re-verified against the edition you are held to before you build a program around them (ASME PVHO-2 product page).

Bucket two

Duties the code defers

These are Chapter 14 requirements with no numeric interval attached. The code requires that the task be part of the facility’s routine maintenance program, and that it be logged — the cadence comes from your manufacturer’s manual and your own program.

  • The safety director ensures all valves, regulators, meters and similar equipment are proper, safe, compensated for hyperbaric use, and tested per the facility’s routine maintenance program. No interval stated
  • Pressure relief valves are tested and calibrated as part of that program. No interval stated
  • All electrical, monitoring, life support, protection and ventilating arrangements are inspected and tested per the routine maintenance program. No interval stated
  • All chamber electrical circuits are tested per the program, including a ground-fault check confirming no conductors are grounded to the chamber, and a test of normal functioning. No interval stated
  • Materials containing rubber are inspected regularly for cracking and degradation. “Regularly”
  • All replacement parts and components conform to the original design specification.
  • Installation, repair or modification receives an engineering evaluation, is tested under pressure, and is approved in writing by the safety director.
  • The safety director maintains a log of all maintenance and tests on chamber equipment and systems, and operating equipment logs are signed before the chamber returns to service.
  • A regular housekeeping program keeps the facility free of grease, lint, dirt and dust, with housekeeping staff training documented.

Sources: UpCodes Chapter 14 and the itemised cross-reference in the UHMS accreditation manual.

What this means in practice

“No codified interval” is not the same as “no obligation.” The obligation is to have a program, run it, and be able to show the log. That is exactly the gap a documented service visit fills — and it is why FDA’s 2025 letter tells facilities to ensure manufacturer-recommended maintenance intervals and safety checks are followed for each device (FDA Letter to Health Care Providers).

Bucket three

Voluntary accreditation cadences

UHMS accreditation criteria put dates on several things the code leaves open. For an accredited facility these are real obligations; for everyone else they are a well-considered benchmark, not law. Examples include daily documented visual inspection of all acrylic viewports and cylindrical tubes per PVHO-2, recorded by individual viewport or chamber serial number — a daily framing of the standard’s “prior to each pressurization” rule — and ground-integrity verification at least weekly for Class A chambers or before each patient treatment for Class B chambers (UHMS accreditation manual). Voluntary

Bucket four

The published military schedule

NAVFAC MO-406, the U.S. Navy’s Hyperbaric Facilities Maintenance Manual, is a freely readable federal document with an explicit periodicity table. It is not a commercial code requirement and it was written for Navy facilities — but it is the most concrete public example of a complete hyperbaric preventive-maintenance schedule, and it is a useful benchmark when you are building a program from nothing. Its periodicity codes run weekly, monthly, quarterly, semiannual and annual, plus 24-, 36-, 60- and 72-month items. Military guidance

Selected NAVFAC MO-406 recompression chamber and support-system items Military guidance, not commercial code
PeriodicityChamberAir system and compressors
Weekly—Compressor oil check.
MonthlyVisually inspect and lubricate doors; clean and inspect the chamber; test communications; inspect and clean the circuit breaker and fuse panel; clean, inspect and sterilise BIBS masks (also after every use); operate chamber valves through a complete turn; test emergency lighting and inspect or replace batteries.Valve operation; cooler cleaning; discharge filter renewal; manual relief valve lift.
QuarterlyLubricate door hinges, door dogs and the spider worm gear.Piping and valve inspection and leak test; filter element and air purifier cartridge renewal; strength test of hoses 5 to 9 years old; corrosion inspection and foundation bolt tightening.
SemiannuallyAir analysis sample; comparison check of gauges; inspect electrical wiring and lighting.Air analysis; gauge calibration; oil change and intake filter cleaning (or per manufacturer hours).
AnnuallyInspect and test chamber relief valves.Relief valve testing; reducer testing; piping pressure test at maximum operating pressure; piping-system gauge calibration; full-working-pressure test operation and relief valve lift-pressure testing.
24 months—Support pressure vessels inspected; compressed gas flasks inspected.
72 months—Piping-system pressure vessels larger than 3 in. inside diameter inspected and strength tested; compressed gas flasks strength tested.

The same manual specifies hydrostatic testing of installed systems to 150 percent of maximum design working pressure, relief valves set at 110 percent of design pressure, and records retention of cycle and quarterly schedules for a minimum of five years with weekly schedules and check-off sheets retained for a minimum of one year (NAVFAC MO-406). A companion Department of Defense design document, UFC 4-159-01, Design: Hyperbaric Facilities, is also publicly readable, though it is marked inactive (UFC 4-159-01).

The gap nobody wants to find during an inspection

What is not codified anywhere

No codified numeric hydrostatic or pressure-retest interval for clinical hyperbaric chambers was found. ASME PVHO-2-2019 explicitly leaves periodicity to the user, the manufacturer and the jurisdiction. The only concrete retest numbers located in public documents are the Navy’s 24-month chamber pressure test and 72-month piping-vessel strength test, which are not commercial code (ASME PVHO-2-2019 preview, NAVFAC MO-406).

Similarly, no periodic monthly, quarterly or annual PM interval for the chamber itself appears in the reviewed Chapter 14 text; the chapter defers to the routine maintenance program of the facility (UpCodes Chapter 14).

So when someone tells you your chamber is “due” for a code-required annual, the correct follow-up is: due under whose document? If the answer is your manufacturer’s manual, that is a legitimate and enforceable answer under both the code’s maintenance-program provisions and FDA’s recommendation to follow manufacturer intervals. If the answer is vague, you are being sold something. Our service and maintenance work is built around whichever of those documents actually applies to your equipment, and around leaving you the records.

Scope of this information

Hyperbaric Service Pros installs, services, and maintains hyperbaric equipment. We are not a medical facility and do not provide medical advice or treatment. Technical information on this site is general reference only — always follow your chamber manufacturer's documentation and the codes enforced in your jurisdiction.

Sources

Every claim on this page, traced to its source

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