1. Start With the Pressure Boundary

Identify which component retains pressure: a welded metal vessel or a coated reinforced fabric assembly. Ask for the operating range, design pressure, cycle rating, thickness, joining method, and design basis.

A material name is incomplete. “Steel” omits the grade; “aluminum” omits the alloy and temper; “TPU” omits the reinforcing fabric, coating construction, and seam method.

2. Compare the Main Shell Material Systems

Q345R pressure-vessel steel

Q345R is a low-alloy pressure-vessel steel used in pressure equipment. It should not be described as stainless steel. Request its material certificate, thickness, weld documentation, nondestructive examination records, pressure test, and coating details.

Aluminum-alloy shells

Request the exact alloy, temper, thickness, joining process, finish, and repair procedure. “Aerospace-grade aluminum” is too broad unless linked to a specific grade and standard.

Flexible coated fabrics

A soft chamber may use polyester or nylon reinforcement with a TPU or urethane coating. Evaluate the finished construction, physical-property data, seam process, zipper design, leakage test, and pressure-cycle evidence.

3. Treat Acrylic Viewports as Engineered Components

Acrylic, or PMMA, is commonly used for pressure windows. Its specification should identify material, thickness, geometry, support method, design conditions, manufacturing date, inspection criteria, and replacement requirements.

Inspect for scratches, cracks, edge damage, clouding, chemical exposure, and fine crazing. Use approved cleaners because incompatible chemicals may damage acrylic.

4. Review Seals, Piping, and Oxygen Components

Request material information and part numbers for door seals, O-rings, gaskets, hoses, and zipper seals. Verify approved lubricants, inspection frequency, replacement criteria, and spare-parts availability.

In an air-pressurized chamber, oxygen may be delivered through a mask or Built-In Breathing System (BIBS), with exhaled gas routed outside. Review the oxygen source, piping, regulators, breathing stations, exhaust route, monitoring, and cleaning as one system.

5. Inspect Coatings and Interior Materials

For a painted shell, request coating data, surface preparation, cure requirements, cleaning compatibility, and repair procedures. “Fireproof” or “non-toxic” claims need a named test and defined scope.

Seats, mattresses, textiles, electronics, and user-carried items affect ignition risk, static control, and cleaning. Follow the chamber instructions and applicable requirements.

6. Documents to Request

Required records vary by chamber type, intended use, market, and local rules. A general factory certificate does not authorize every model.

7. Common Specification Red Flags

8. Commercial Buyer Checklist

• Identify the pressure-retaining material and construction.

• Verify grade, alloy, fabric, coating, thickness, and joining method.

• Confirm design pressure, operating range, and cycle rating.

• Review viewport, seal, hose, and oxygen-path specifications.

• Confirm cleaning, inspection, and repair procedures.

• Request traceable records for the exact model.

• Check warranty, spare parts, product training, and support.

References

U.S. FDA: Safe Use of HBOT Devices · ASME PVHO-1 · ASTM G63 · ASTM G94

Equipment procurement information only; not medical advice.