Glossary of Wellness Equipment Terms

Short answer: This glossary defines the terms used across our hyperbaric, red light, cold plunge and cryotherapy guides, in plain English. It is educational and is not medical advice. See our disclaimer.

Last reviewed: September 2026.

Business and installation terms
Hyperbaric terms
Red light and PEMF terms
Cold plunge and cryotherapy terms
General terms

Hyperbaric terms

ATA (atmospheres absolute): A measure of total pressure. 1.0 ATA is normal air pressure at sea level. 1.3 ATA is about 4.4 PSI above room pressure. See pressure levels explained.
PSI: Pounds per square inch. Chamber gauges usually show the pressure above the surrounding air. PSI above room = (ATA − 1) × 14.7.
HBOT (hyperbaric oxygen therapy): Breathing oxygen-enriched air inside a chamber pressurized above normal atmospheric pressure. See what is HBOT.
Mild hyperbaric chamber: A soft-shell chamber that operates at a lower pressure, usually about 1.3 to 1.5 ATA, designed for home or studio use.
Soft-shell chamber: A flexible, zippered chamber on a frame. It is portable and runs at lower pressure than a hard-shell chamber.
Hard-shell chamber: A rigid vessel that generally reaches higher pressures, up to 2.0 ATA in models we carry. See soft-shell vs. hard-shell.
Multiplace chamber: A hard-shell chamber that holds several people at once, such as the Macy-Pan HE5000 series.
Oxygen generator (concentrator): A machine that separates most of the nitrogen from room air and delivers a higher oxygen concentration. Summit to Sea specifies a 10 LPM at 20 PSI unit for its chambers. See how the system works.
LPM: Liters per minute, a measure of gas flow.
Compressor: A pump that pushes filtered air into the chamber to raise its pressure. Redundant (dual) compressors mean a second one can keep running if the first stops.
Barotrauma: Injury caused by pressure changes, most often to the ears or sinuses.
Equalizing: Balancing the pressure in your ears and sinuses with the pressure around you, for example by swallowing, yawning or moving your jaw.
Class II device: A U.S. medical device classification. Per the manufacturer, Summit to Sea chambers are Class II devices and require a prescription to purchase. See regulatory status explained.
Contraindication: A condition that makes a treatment or device unsafe for a person. Only a healthcare professional can judge this for you.

Red light and PEMF terms

Photobiomodulation: The use of low-level red or near-infrared light to influence cellular activity. Another name for red light therapy. See what is red light therapy.
Nanometer (nm): The unit of a light wavelength. Red is roughly 620 to 700 nm and near-infrared roughly 700 to 1,100 nm.
Near-infrared (NIR): Invisible light just beyond red. It penetrates deeper than red light. Common devices use about 850 nm.
Irradiance (mW/cm²): The light power reaching each square centimeter of skin. To convert from W/m², divide by 10. See irradiance and dose.
Dose (J/cm²): Total light energy delivered in a session: irradiance (mW/cm²) × time (seconds) ÷ 1,000. Try the dose calculator.
LED: Light-emitting diode. LED count describes coverage and density, not power.
Pulsed vs. continuous mode: Whether a device emits light steadily or in rapid pulses. Some devices offer both.
PEMF: Pulsed electromagnetic field. A separate technology from light. See red light and PEMF.
Microtesla (µT): A unit of magnetic field strength. Some PEMF products list a maximum in µT.
Photosensitivity: Increased sensitivity of the skin or eyes to light, sometimes caused by medications or skin conditions.

Cold plunge and cryotherapy terms

Cold water immersion: Sitting or standing in cold water, commonly around 37 to 59°F, for a few minutes.
Cold shock response: The body's automatic reaction to sudden cold: a gasp, fast breathing and a jump in heart rate and blood pressure. See cold plunge safety.
After-drop: A continued fall in core body temperature for a few minutes after leaving cold water.
Chiller: A refrigeration unit that cools tub water and holds it at a set temperature. See chillers explained.
HP (horsepower): A rating of a chiller's compressor size. Higher HP generally cools larger volumes or cools faster.
UV filtration: Ultraviolet light in the water circuit that reduces microbes.
Ozone sanitation: Using ozone gas to sanitize water. Some tubs, such as the Solbasium Polar Elite One, include it.
Biofilm: A slimy layer of microbes that builds up on surfaces in untreated water.
GFCI: Ground-fault circuit interrupter, a safety device that cuts power if it detects a fault. Chillers and pumps near water should be GFCI protected.
Contrast therapy: Alternating heat (such as a sauna) with cold (such as a plunge). See contrast therapy guide.
Cryotherapy: Brief exposure to extreme cold, usually very cold air or vapor, across the body or on one area. See what is cryotherapy.
Whole-body cryotherapy (WBC): Standing or sitting in a chamber of extremely cold air for a few minutes, usually in a commercial setting.
Liquid nitrogen chamber: A cryotherapy chamber cooled with liquid nitrogen. Nitrogen can displace oxygen, so these need ventilation and oxygen monitoring.

General terms

Recovery stack: The combination of tools someone uses in a routine, such as heat, cold, light and pressure. See recovery stack order.
General wellness use: A product positioned for general wellbeing and not for diagnosing, treating, curing or preventing disease.
Prescription requirement: A manufacturer or regulator condition that a device be purchased with a healthcare professional's authorization.

Business and installation terms

Single-phase and three-phase power: Two ways electricity is delivered. Homes usually have single-phase service. Some commercial equipment, such as the XR Cryo Kiosk, lists 220 V three-phase power.
Amps (A), volts (V) and watts (W): Amps measure current, volts measure electrical pressure and watts measure power. Watts are roughly volts times amps. An electrician uses these to size a circuit for your equipment.
Dedicated circuit: An electrical circuit that serves only one appliance. Some beds and chamber machines list a dedicated circuit breaker.
Dewar: An insulated container that stores liquid nitrogen. Nitrogen cryotherapy chambers use one or more dewars supplied by a local vendor.
Pre-cooling: The time a cryotherapy chamber needs to reach its working temperature before the first session. Some listings state up to an hour.
Utilization: The share of your available session slots that are actually booked. It is one of the main inputs to payback. Try the ROI calculator.
Payback period: The time it takes for monthly results to cover the upfront cost of equipment and installation.
Lead time: The time from placing an order to receiving the equipment. Ranges vary by product; we confirm yours at quote.
Freight delivery: Delivery of large equipment on a pallet or crate by a freight carrier. Inspect it before signing and note any damage.
Letter of Medical Necessity (LMN): A letter from a licensed healthcare professional that some HSA and FSA plans ask for. See HSA and FSA information.