Glossary
Refrigeration terms, explained.
154 terms you'll meet on spec sheets, quotes and service reports — what they mean and why they matter.
2
A
- Air curtainA sheet of cold air blown across an open display front or doorway that limits warm, humid room air entering the cold zone.
- Ambient temperatureThe temperature of the air around the refrigeration equipment, especially at the condenser intake, which strongly affects capacity, efficiency and reliability.
- AMCAn annual maintenance contract: a yearly agreement in which a service provider maintains and repairs equipment for a fixed fee, with defined visits, response times and coverage.
- Anti-sweat heaterA low-power heater around door frames, mullions or glass that keeps these surfaces above the dew point so condensation and ice do not form.
B
- Back-bar coolerA low, counter-height refrigerator with glass or solid doors, built to sit behind or under a bar counter and keep bottles, cans and mixers cold within reach of the bartender.
- BEE star ratingThe energy label issued under India's Bureau of Energy Efficiency programme; more stars mean lower energy use than other models in the same category.
- BIS markA conformity mark issued under the Bureau of Indian Standards, India's national standards body, showing a product meets the applicable Indian Standard under a BIS certification scheme.
- Blast chillerA cabinet that uses high-velocity cold air to cool hot, freshly cooked food to chilled temperature quickly, moving it through the danger zone far faster than a normal refrigerator.
- BTU (British thermal unit)A unit of heat: the energy needed to raise one pound of water by one degree Fahrenheit. Cooling capacity is often quoted in BTU per hour.
C
- Cam lockA hook-and-pin locking mechanism foamed into the edges of cold-room panels that pulls adjacent panels tightly together when turned with a key.
- Capillary tubeA long, very thin copper tube that acts as a fixed restriction, dropping the refrigerant's pressure between the condenser and the evaporator.
- CastorsWheels fitted to the base of a commercial cabinet, usually swivelling and lockable, that let staff move the unit for cleaning, servicing and layout changes.
- CE markingA marking that shows a product's manufacturer declares it conforms to the applicable European Union requirements, allowing it to be sold in the European Economic Area.
- Chef baseA low refrigerated drawer unit with a reinforced, heat-tolerant top built to carry cooking equipment such as a griddle, char-grill or fryer directly above the cold storage.
- Chest freezerA box-shaped freezer with a lid on top, widely called a deep freezer in India, used for bulk frozen storage in shops, kitchens and ice cream outlets.
- Climate classA rating that states the range of room temperatures, and for some standards humidity, in which a refrigeration appliance is designed and tested to perform.
- Coefficient of performance (COP)The ratio of cooling delivered to electrical power consumed; a COP of 2 means two units of heat are removed for each unit of electricity used.
- Cold chainThe unbroken series of refrigerated storage and transport steps that keeps a temperature-sensitive product within its required range from production to final use.
- Cold holdingKeeping prepared cold food at or below a safe chilled temperature, commonly around 5 °C, while it waits to be served on a line, counter, buffet or display.
- Cold wellA refrigerated recessed well, often dropped into a counter, that holds GN pans of cold food for buffet, salad bar or service line use.
- CommissioningThe process of installing, starting and testing new refrigeration equipment on site to confirm it works as specified before it is handed over for use.
- Comprehensive AMCAn annual maintenance contract that covers labour, routine maintenance and most replacement parts, so repairs within its scope cost nothing extra during the contract year.
- CompressorThe motor-driven pump that draws low-pressure refrigerant vapour from the evaporator and raises it to high pressure so it can reject heat in the condenser.
- Compressor overload and relayTwo small parts on the side of a hermetic compressor: the relay brings in the start winding at start-up; the overload cuts power if the motor overheats or draws too much current.
- Condensate panThe tray, usually near the compressor, that collects defrost water from the cabinet and evaporates it into the room so no floor drain is needed.
- CondenserThe heat exchanger, usually a finned coil with a fan, where hot high-pressure refrigerant releases heat to the surrounding air and turns back into liquid.
- Conditioned ice packA frozen ice pack that has been left at room temperature until it begins to melt, so it keeps vaccines cold without risking freezing them.
- Convertible cabinetA commercial cabinet that can be set to run either as a refrigerator or as a freezer, letting an operator change its role as menus or seasons change.
- Cooling capacityThe rate at which a refrigeration system removes heat, usually stated in watts, kilowatts or BTU per hour at defined operating conditions.
- Cross-contaminationThe transfer of harmful bacteria, allergens or other contaminants from one food, surface or person to another, most often from raw food to ready-to-eat food.
D
- Defrost cycleA period when cooling pauses and the evaporator is warmed, passively or with heat, to melt frost so air can flow and the coil can absorb heat again.
- Defrost terminationThe condition that ends a defrost cycle: either the evaporator reaching a set temperature, a maximum time elapsing, or both.
- Deli caseA serve-over refrigerated display for cold meats, cheeses, salads, marinated items and prepared foods sold by weight or portion across the counter.
- Digital temperature controllerAn electronic controller that reads one or more temperature probes, shows the cabinet temperature, and manages the compressor, fans, defrost and alarms.
- Dipping cabinetA display freezer that holds open tubs or pans of ice cream at scooping temperature, with glass for customers to see the flavours and access for staff to serve.
- Door gasketThe flexible seal around a cabinet door, usually PVC with a magnetic strip inside, that closes the gap between door and cabinet to keep warm air out.
- Drain line heaterA small electric heater along a freezer's defrost drain tray or pipe that keeps meltwater from refreezing before it leaves the cabinet.
- Drawer refrigeratorAn undercounter refrigerator or freezer fitted with pull-out drawers instead of doors, so the full contents can be seen and reached without bending into a cabinet.
- Dual-temperature cabinetA single commercial cabinet split into a refrigerated section and a frozen section, each with its own door and usually its own temperature control.
- Duty cycleThe percentage of time the compressor runs to hold the set temperature; a measure of how hard the system is working against its load.
E
- EarthingA low-resistance connection from the metal body of equipment to the ground, so that a fault current flows safely away and protective devices can trip.
- Electric defrostA defrost method in which electric heater elements on or near the evaporator coil melt frost, used mainly in freezers where cabinet air is below 0 °C.
- Electronic expansion valveAn expansion valve driven by a stepper motor and controlled by a microprocessor that reads pressure and temperature sensors to meter refrigerant precisely.
- Energy consumption (kWh/24h)The electricity a cabinet uses over one day under defined test conditions, stated in kilowatt-hours; the practical figure for estimating running cost.
- EPS insulationExpanded polystyrene: a lightweight bead foam, familiar as thermocol, used in some low-cost panels and packaging, but a weaker insulator than PUF.
- EvaporatorThe cold coil or plate inside the cabinet where liquid refrigerant boils at low pressure and absorbs heat from the air and the stored product.
- eVINIndia's digital system for tracking vaccine stocks and monitoring cold chain temperatures across immunisation cold chain points, run by the health ministry with UNDP support.
F
- Fan-forced coolingCooling in which a fan blows air across the evaporator and around the cabinet, giving fast recovery and even temperature from top to bottom.
- FEFOA stock rotation rule: the item with the earliest expiry or use-by date is used or dispatched first, regardless of when it arrived.
- FIFOA stock rotation rule: the stock that arrived first is used or sold first, so older items do not get pushed to the back and forgotten until they spoil.
- Filter drierA small canister in the liquid line packed with desiccant that traps moisture, acid and debris before they block the metering device or damage the compressor.
- FootprintThe floor area a piece of equipment occupies, including the clearances it needs for ventilation, door swing and service access, not just its external dimensions.
- Freezer burnDry, discoloured, leathery patches on frozen food caused by moisture escaping from the surface, usually because of poor wrapping, long storage or temperature swings.
- FSSAIIndia's national food regulator, set up under the Food Safety and Standards Act, 2006, which licenses or registers food businesses and sets food safety and hygiene requirements.
- FSSAI Hygiene RatingAn FSSAI scheme under which food outlets such as restaurants, sweet shops and bakeries are audited by an empanelled agency and given a hygiene rating to display to customers.
G
- Glass-top freezerA chest freezer with sliding glass lids, flat or curved, that lets shoppers see frozen products before opening it. Used for ice cream, frozen snacks and impulse sales.
- Global warming potentialA measure of how much heat a gas traps in the atmosphere over a set period, usually 100 years, compared with the same mass of carbon dioxide.
- GN panA standard-sized food pan based on the Gastronorm system, whose fractional sizes (1/1, 1/2, 1/3 and so on) fit interchangeably in ovens, refrigerators, prep tables and serving counters.
H
- HACCPA systematic food safety approach that identifies hazards in each step of food handling and sets critical control points, limits, monitoring and corrective actions to manage them.
- Hard-top freezerA chest freezer with a solid, insulated lid, built for back-of-house bulk storage where holding temperature and efficiency matter more than display.
- Heat loadThe total amount of heat a refrigeration system must remove to hold the set temperature, from product, air infiltration, the walls and internal equipment.
- Heated glassInsulated glass for cabinet doors and display fronts that uses coatings, gas fill and sometimes a heated film to stop condensation and reduce heat gain.
- HFC refrigerantSynthetic refrigerants containing hydrogen, fluorine and carbon but no chlorine; safe for the ozone layer but often with high GWP, so now being phased down.
- HFO refrigerantSynthetic refrigerants with a carbon double bond that breaks down quickly in the atmosphere, giving very low GWP; often mildly flammable.
- Hold-over timeHow long a cabinet keeps its contents within a safe temperature range after power is lost, with doors or lids kept closed.
- Hot-gas defrostA defrost method that diverts hot refrigerant vapour from the compressor through the evaporator, melting frost from the inside of the coil.
- Hydrocarbon refrigerantRefrigerants made from purified hydrocarbons such as propane (R290) and isobutane (R600a), with near-zero GWP, zero ODP and good efficiency, but flammable.
I
- Ice-lined refrigeratorA top-opening vaccine refrigerator with a lining of water or ice packs around the storage space that keeps vaccines between +2 and +8 °C through power cuts.
- Insulation densityThe mass per cubic metre of foam insulation; for cabinet and cold-room PUF, a moderate density gives the best balance of insulation, strength and cost.
- Inverter compressorA compressor driven by an electronic inverter that varies motor speed to match cooling demand, instead of simply switching fully on and off.
- IQ / OQ / PQThree documented stages of qualifying equipment in regulated settings: installed correctly (IQ), operates as specified (OQ) and performs reliably in real use (PQ).
- Island freezerA long, low freezer cabinet placed in the middle of a store aisle so shoppers can browse frozen products from both sides, usually with sliding glass lids.
K
L
- Labour-only AMCAn annual maintenance contract that covers scheduled maintenance visits and repair labour, but charges separately for any parts that need replacement.
- Latent heatHeat absorbed or released when a substance changes state, such as water freezing or vapour condensing, without any change in its temperature.
- Load lineA marked limit inside a display case or chest freezer showing how high product can be stacked without blocking the cold airflow that keeps it at temperature.
- Locked-rotor amps (LRA)The current a compressor motor draws when power is applied but the rotor cannot turn; a rating used to size wiring, breakers and backup supplies.
M
- MCB (miniature circuit breaker)A resettable switch in the distribution board that trips automatically on overload or short circuit, protecting the wiring feeding the equipment.
- Mithai counterA refrigerated display counter used by Indian sweet shops to show and serve mithai, often combining chilled sections for milk sweets with ambient sections for dry sweets.
- Monoblock unitA single, factory-built refrigeration unit for a cold room that mounts through the wall or on the roof, with all its working parts in one package.
- Multideck chillerAn open-fronted refrigerated display with several shelves, kept cold by a curtain of chilled air, used in supermarkets for dairy, produce, drinks and packaged foods.
N
- Net vs gross litresGross litres is the total volume inside the cabinet's liner; net litres is the space actually usable for storing product after deducting fittings, coils and airflow space.
- NSF certificationCertification by NSF, a US-based standards and testing organisation, that equipment meets its food equipment standards; NSF/ANSI 7 covers commercial refrigerators and freezers.
O
- Off-cycle defrostA defrost method used in chillers where the compressor stops and cabinet air above 0 °C melts the light frost on the evaporator, with no added heat.
- Ozone depletion potentialA measure of how much a substance damages the stratospheric ozone layer compared with the reference chemical CFC-11, which is given a value of 1.
P
- Pass-through refrigeratorAn upright refrigerated cabinet with doors on both the front and back, so one team loads it from one side and another team unloads from the other.
- Pastry showcaseA refrigerated glass cabinet designed to display cakes, pastries and desserts at chilled temperature while limiting the drying and condensation that damage their finish.
- Pharmacy refrigeratorA refrigerator built specifically to store medicines, vaccines or lab reagents within a narrow range, typically +2 to +8 °C, with tighter control, alarms and monitoring.
- Pizza prep tableA refrigerated prep counter with a deep, often marble or composite worktop for stretching dough and a raised rail of chilled topping pans along the back.
- Preventive maintenanceRegular planned servicing, such as cleaning condensers, checking gaskets, fans, drains and controls, done to prevent breakdowns rather than waiting for equipment to fail.
- Probe thermometerA handheld digital thermometer with a metal probe that is inserted into food to measure its core temperature, used for checking cooking, cooling, holding and deliveries.
- PUF insulationRigid polyurethane foam injected or laminated into cabinet walls and panels; the standard insulation for commercial refrigeration because it insulates well and adds strength.
- Pull-down timeThe time a cabinet takes to cool from room temperature to its operating temperature, measured empty or with a defined load under stated conditions.
R
- R134aA single-component HFC refrigerant, non-flammable and long used in refrigerators, bottle coolers and car air conditioners, with a GWP of about 1,430.
- R290 (propane)Refrigerant-grade propane: a natural hydrocarbon refrigerant with very low GWP and excellent efficiency, widely used in modern plug-in commercial cabinets.
- R404AA non-flammable HFC blend once standard for commercial freezers and low-temperature display, now being phased down because of its very high GWP.
- R600a (isobutane)Refrigerant-grade isobutane: a hydrocarbon refrigerant with very low GWP, common in household refrigerators and some small commercial and display units.
- R744 (carbon dioxide)Carbon dioxide used as a natural refrigerant: non-flammable, non-toxic in normal concentrations, GWP of 1, but working at very high pressures.
- RCCB (residual current circuit breaker)A safety device that trips when it detects current leaking to earth, such as through a person or damaged insulation, protecting against electric shock.
- Reach-in refrigeratorA tall, self-contained commercial cabinet with one, two or three doors that staff open and reach into, used for bulk chilled or frozen storage near the cooking line.
- Reciprocating compressorA compressor that uses a piston moving up and down in a cylinder, with reed valves, to compress refrigerant vapour; the most common type in small commercial cabinets.
- Refrigerant chargeThe exact quantity of refrigerant, by weight, that a sealed system is designed to hold; usually printed in grams on the unit's rating plate.
- Refrigerated display caseA glass-fronted refrigerated counter or cabinet that shows chilled food to customers while keeping it at safe temperature, used for deli, sweets, cakes, sushi and seafood.
- Refrigerated prep tableAn undercounter refrigerated base with chilled pan wells on top and a cutting board in front, used to assemble dishes from cold ingredients held within arm's reach.
- Refrigeration cycleThe closed loop in which a refrigerant evaporates to absorb heat inside the cabinet and condenses to reject that heat outside, driven by a compressor.
- Remote refrigeration systemA refrigeration setup in which the cabinet or cold room holds only the cooling coil, while the heat-rejecting condensing unit is installed elsewhere, connected by refrigerant piping.
- RFQA request for quotation: a document or message asking suppliers to price specific equipment and services against your requirements, so quotes can be compared fairly.
- Rotary compressorA compact compressor that compresses refrigerant with a rolling piston turning inside a cylinder, giving smooth, quiet running with few moving parts.
S
- Safe thawingBringing frozen food up to a workable temperature in a controlled way, most safely in a refrigerator, so the outside does not sit warm while the centre is still frozen.
- SaladetteA compact refrigerated counter with a row of chilled GN pans on top, often under a hinged lid or sneeze guard, used for salads, toppings and cold garnishes.
- Saturation temperatureThe temperature at which a refrigerant boils or condenses at a given pressure; every refrigerant has its own fixed pressure-temperature relationship.
- Scroll compressorA compressor that squeezes refrigerant between one fixed and one orbiting spiral, giving high efficiency and smooth running at larger capacities.
- Self-contained unitA refrigerator, freezer or display case with its complete refrigeration system built into the cabinet, so it only needs a power socket to run.
- Sensible heatHeat that changes the temperature of a substance without changing its state; the heat you can measure with a thermometer.
- SetpointThe temperature the controller is told to hold; the compressor starts and stops around this value according to the differential.
- Shock freezerA freezer that drives food from hot or chilled down to deep-frozen temperature very quickly using intense cold airflow, forming small ice crystals that preserve texture.
- Sight glassA small window in the liquid line that lets a technician see whether the refrigerant is a full liquid stream and, on many types, whether moisture is present.
- Site surveyA check of the installation location before buying or delivering equipment, covering space, access, ventilation, power supply, drainage and ambient conditions.
- Spec sheetA manufacturer's document listing a model's dimensions, capacity, temperature range, electrical requirements, refrigerant, ambient rating and other technical details.
- Start capacitorAn electrical component that boosts the starting torque of a single-phase compressor motor so it starts quickly, even against some pressure.
- Starting currentThe brief, high current a compressor motor draws in the first moments of starting, several times higher than its normal running current.
- Static coolingCooling without an evaporator fan: cold plates or tubes in the cabinet chill the air, which circulates naturally as cold air sinks and warm air rises.
- Strip curtainA curtain of overlapping flexible PVC strips hung in a cold room doorway that limits the warm air entering whenever the main door is open.
- SubcoolingHow many degrees the liquid refrigerant leaving the condenser has been cooled below its condensing (saturation) temperature.
- SuperheatHow many degrees the refrigerant vapour has been heated above its boiling (saturation) temperature after it has fully evaporated, measured on the suction line.
- Surge protectorA device that diverts brief high-voltage spikes away from connected equipment, protecting controllers, inverter boards and compressors from transient damage.
T
- Temperature alarmA warning from the controller or a separate monitor when cabinet temperature stays above or below set limits for longer than an allowed delay.
- Temperature danger zoneThe temperature range, commonly taken as roughly 5 °C to 60 °C, in which most harmful bacteria in food can multiply quickly. Food should spend as little time in it as possible.
- Temperature data loggerA small electronic device that records temperature automatically at set intervals, and often sends alerts, giving a continuous record of a refrigerator, freezer or shipment.
- Temperature differentialThe gap between the temperature at which the compressor stops and the temperature at which it restarts, which prevents rapid on-off cycling.
- Temperature excursionAny time a temperature-sensitive product is exposed to temperatures outside its approved storage range, whether too warm or too cold, for any length of time.
- Temperature logA written or digital record of storage temperatures taken at set times, with initials and any corrective action, used to prove refrigeration is working and food is safe.
- Temperature mappingA study that places many calibrated sensors throughout a cold room, refrigerator or store to measure how temperature varies by position and over time.
- Temperature probeThe sensor, usually a thermistor in a small sealed tip, that tells the controller the temperature of the cabinet air, the evaporator or the product.
- Thermal bridgeA path of higher-conductivity material, such as a metal bracket or frame, that crosses the insulation and lets heat leak into the cold space.
- ThermostatA device that switches the compressor on and off to keep a cabinet near its set temperature; in simpler units it is a mechanical dial with a gas-filled sensing tube.
- Thermostatic expansion valveA self-adjusting valve that meters refrigerant into the evaporator by sensing suction-line temperature, holding superheat roughly constant as the load changes.
- Ton of refrigeration (TR)A unit of cooling capacity equal to 12,000 BTU per hour, or about 3.5 kW; it comes from the heat needed to melt one short ton of ice in 24 hours.
- Total cost of ownershipThe full cost of owning a piece of equipment over its working life: purchase price plus installation, electricity, maintenance, repairs, downtime and spoiled stock, minus resale value.
- Two-stage coolingA method for cooling cooked food safely in two timed steps: first from hot to about 21 °C within two hours, then to 5 °C or below within the following four hours.
U
- U-value and R-valueTwo ways to describe insulation: U-value is how much heat flows through a wall per square metre per degree; R-value is its resistance to that flow.
- UL listingA mark showing that samples of a product have been tested by UL, a US-based safety certification organisation, and found to meet applicable safety standards, mainly for North American markets.
- Ultra-low temperature freezerA freezer built to hold far colder than a standard −18 °C freezer, commonly in the −40 to −86 °C range, for seafood, specialist foods, samples and lab materials.
- Undercounter refrigeratorA low commercial refrigerator or freezer, roughly counter height, that slides under a work surface or stands as a counter itself so chilled ingredients sit at the cook's knees.
- Upright freezerA tall, front-opening freezer cabinet with shelves, used where floor space is limited or stock needs to be organised and visible at eye level.
V
- Vaccine carrierA small insulated box, used with conditioned ice packs, that keeps vaccines within their required temperature range while they are carried from a health facility to an outreach session.
- Vapour barrierAn airtight, moisture-proof layer on the warm side of insulation that stops water vapour from migrating into the insulation and condensing or freezing there.
- Visi coolerAn upright refrigerator with a glass door and internal lighting, used in shops and outlets to display and sell chilled drinks, dairy and packaged food.
- Voltage stabiliserA device that corrects high or low incoming voltage to a steadier output, protecting compressors and electronics from damaging under- and over-voltage.
W
- Walk-in coolerAn insulated room, built from prefabricated panels, with a refrigeration system that keeps it chilled or frozen, used for bulk storage that is too large for cabinets.
- WarrantyThe manufacturer's written promise to repair or replace equipment that fails because of defects in materials or workmanship, for a stated period and on stated conditions.
- WHO PQSThe World Health Organization's system for setting specifications and prequalifying immunisation equipment, including vaccine refrigerators, freezers, cold boxes and carriers.
- Worktop refrigeratorAn undercounter-height refrigerator or freezer with a strong flat top that serves as a working counter, combining cold storage and prep space in one footprint.