Modern Refrigeration and

1
Modern Refrigeration and Air Conditioning
Althouse Turnquist Bracciano
PowerPoint Presentation by Associated
Technical Authors
PublisherThe Goodheart-Willcox Company,
Inc.Tinley Park, Illinois
2
Chapter 14
Commercial Systems Applications
3
Learning Objectives

• Discuss the various types of commercial
  refrigeration systems and their applications.
• Explain the differences between commercial and
  industrial refrigeration applications.
• List various types of commercial and industrial
  applications.
• Follow approved safety procedures.

4
Industrial Refrigeration

• Uses refrigerating machines that require an
  attendant constantly on the job.
• Attendant usually a licensed refrigeration
  engineer.
• Industrial plants usually have manually-operated
  refrigeration machines.
• Examples include large cold-storage warehouses,
  packing houses, industrial plants, ice cream
  manufacturing operations, frozen food processing
  plants, and ice-making.

5
Commercial Refrigeration

• Typically includes high-capacity systems with
  aluminum and stainless steel cabinets for greater
  durability and ease of maintenance.
• May use multiple compressors, condensing units,
  and evaporators.
• Examples include supermarket refrigeration units,
  food display cases, refrigerated beverage and ice
  cream dispensers, and ice-making machines.

6
CommercialCabinet Construction
14.1

• Surfaces either metal or plastic.
• Finishes easily cleaned.
• Structural members are steel.
• Insulation usually polystyrene or urethane in
  slabs or foamed in place.
• Refrigeration should be possible under most
  severe service conditions.
• May have resistance heating strips around
  surfaces to prevent moisture condensing on
  cabinet.

7
CommercialCabinet Constructioncontinued
14.1

• May be designed for use with a remote condensing
  unit.
• Units may be connected to several cabinets of
  varying temperatures.
• Most condensing units are air-cooled. Units may
  be water-cooled.

8
Supermarkets
14.2

• Layout and location of units vary with each
  installation.
• Larger installations use multiple condensing
  units located in a back servicing area or on top
  of supermarket roof.

9
Commercial Mechanical Rack
14.2

• Provides common discharge line and liquid
  receiver.
• Each display case has own evaporator and
  refrigerant control.
• Microprocessor control system delivers maximum
  efficiency.
• Compressors may all run at same time for high
  load condition or cycled for low load conditions.

10
Commercial Mechanical Rack
14.2
11
Multiplexed ScrollCompressor System
14.2

• Places refrigeration equipment as close as
  practical to merchandisers being refrigerated.
• Provides a 65 to 75 reduction in refrigerant
  charge.
• Four to six scroll compressors may be used.
• Compressors operate in a multiplexed manner
  (common discharge and common suction line) to
  refrigerate a line-up of merchandisers containing
  a variety of products (dairy, frozen food, and
  produce).

12
Multiplexed ScrollCompressor System continued
14.2
Compressor or compressors cycle off to match the
capacity of the refrigeration system to the
merchandisers.
13
Multiplexed ScrollCompressor System continued
14.2
Machine room may have multiple condensing units
prewired and piped to various food display and
walk-in coolers located inside the supermarket.
14
Grocery Cabinet(Reach-In Cabinet)
14.3

• Maintain perishable products at satisfactory
  temperatures.
• Range in size from 20 ft3 to 100 ft3 net capacity
  (inside volume).
• Contains one to three doors with magnetic
  gaskets.
• Door widths vary from 30" to 85" (0.76m to 2.2m).
• Height of cabinet from 5 1/2' to 6 1/2' (1.7m to
  2.0m).
• Reach-in refrigerator cabinet may have a
  top-mounted condensing unit and evaporator.

15
Grocery Cabinet(Reach-In Cabinet) continued
14.3

• Cooled air is distributed through a vertical
  duct. The space holding the evaporator is called
  the bunker.
• Temperatures are approximately the same as in
  domestic cabinets, with a minimum of 35ºF (1.7ºC)
  and a maximum of 45ºF (7.2ºC).
• Relative humidity of about 80 is necessary for
  salads, desserts, and fresh foods.

16
Walk-In Cabinet
14.4

• Have large doors and windows and may be referred
  to as butcher boxes.
• Sizes vary. The 7'6" and 9'10" (2.3m and 3.0m)
  outside dimensions are considered standard.
• Boxes may be of knockdown type, meaning easily
  taken apart for moving.
• Cabinets made with metal linings and
  exteriorsusually galvanized steel or aluminum.
• Doors have a gasket to make the box airtight.

17
Walk-In Cabinet
14.4
18
Walk-In Cabinet continued
14.4

• Door latches must be accessible from inside for
  safety.
• Doors may have heating wires along the edge to
  eliminate sweating and freezing.
• May be dual-temperature unit with both a regular
  temperature compartment and a frozen foods
  compartment.
• Recently produced coolers use foamed-in-place
  insulation of rigid polyurethane foamed between
  the inner and outer walls. Insulation is usually
  4" (10cm) thick.

19
Walk-In Cabinet continued
14.4

• Forced convection evaporators are popular.
• Temperature dependent on use. Meat or fresh
  produce storage requires temperature between 35ºF
  and 40ºF (1.7ºC and 4.4ºC). Relative humidity
  should be about 80. Air movement is required.
• Ultraviolet lamps may be used to control bacteria
  and mold growth.

20
Walk-In Cabinet continued
14.4

• Caution Overexposure to ultraviolet rays is
  dangerous. Lamps may be turned off when anyone is
  in the cabinet. People working near these lamps
  must be protected from the rays.
• A drain is recommended.
• In systems where dehydration is not a concern,
  such as milk storage and beverage cooling, colder
  temperatures may be used. Blower evaporators may
  be used.

21
Florist Cabinet
14.4.1

• Vary in size and construction.
• May be self-contained or walk-in.
• Differ from grocery cabinet in three ways
• Cabinet temperature may be kept higher.
  Temperatures between 38ºF and 40ºF (3.3ºC and
  4.4ºC) are common.
• Insulation is generally only 1" to 2" (2.5cm to
  5cm) thick due to smaller temperature difference.
• Cabinet usually has large window surfaces,
  permitting viewing of contents.

22
Florist Cabinet continued
14.4.1

• Humidity should be kept at 90 to 95, with a
  minimum of 80 acceptable.
• Large cooling surfaces maintain high humidity
  levels.
• Natural convection evaporators used in most
  cases.
• Motor controls allow little variation in cabinet
  temperature.
• Odor-removing devices, such as activated carbon
  may be used. These reduce mold growth and
  neutralize ethylene. Use of these filters
  requires good airflow across the filter and a
  dedicated circulating fan.

23
Display Cases
14.5

• Used to provide ease of shopping and allow easy
  viewing by purchaser while maintaining safe
  refrigeration.
• Temperature in case is determined by its use.
• Display case lighting installed outside glass
  case to prevent increasing refrigerant load.

24
Display Cases continued
14.5

• Cases vary in design, length, and height. Three
  common types
• Glass-enclosed display case only.
• Glass-enclosed display case and enclosed storage
  cabinet.
• Open display case used for fresh produce, frozen
  foods, meats, or dairy products.
• Display case may be classified by location of
  evaporator overhead, end, or base.

25
Single-Duty Case
14.5.1

• Popular display case using an overhead
  evaporator.
• Main evaporators mounted in upper portion of
  display space under shelf that forms the top.
• Provides good refrigerating temperatures all
  through the display space.
• May contain a shelf evaporator called auxiliary
  evaporator located under the shelves. These are
  placed so that each shelf is individually cooled.

26
Double-Duty Case
14.5.2

• Additional refrigerated storage space located
  beneath the display section of the counter.
• Cases usually serve as a temporary container for
  food or produce. Contents are transferred to a
  walk-in storage cabinet overnight.
• Temperatures may be kept at 40ºF to 45ºF (4.4ºC
  to 7.2ºC) in both compartments.
• Evaporators must be narrow made with fins as
  small as 1 1/4" (32mm) wide.

27
Double-Duty Case continued
14.5.2

• Some evaporators are plain tubing type.
  Evaporators are usually connected in series.
• May use blower evaporators for cooling to provide
  even refrigeration temperatures throughout the
  case.

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Open Display Case
14.5.3

• Commonly used in supermarkets due to easy
  accessibility of contents by customer.
• May have storage space in base of unit.
• Space at top is open.
• Walls or upper portion of walls may be enclosed
  in three to four layers of glass.
• Higher temperature case used for fresh meats and
  dairy products. Blower evaporators are used.
• Ducts carry the cold air through grilles located
  at rear of case. Warm air returns down the front
  of the case.

29
Open Display Case
14.5.3
30
Open Display Case continued
14.5.3
Often used for produce and kept at about 40ºF
(4.4ºC) and at high humidity.
31
Open Display Case continued
14.5.3

• Air curtains prevent dry air to circulate over
  contents, spoiling the appearance of the
  contents.
• Airflow patterns can be monitored. An airflow
  meter of chemical smoke may be used.
• Airflow curtain should not touch the shelves or
  products.
• Electrical wiring system of display case is
  designed to handle lighting, heating elements,
  and fans.

32
Open Frozen Food Display Case
14.5.4
Constructed in both chest and upright cabinet
styles.
33
Open Frozen Food Display Case continued
14.5.4

• Temperatures are very low in these cases.
  Openings are fitted with gaskets or seals.
  Insulation is thick and carefully hermetically
  sealed.
• Chest types are popular since top openings
  prevent cold air spillage when case is opened.
• Must be protected from drafts produced by
  grilles, unit heaters, and fans since drafts will
  interfere with the air curtain of the case,
  causing higher operating cost and defrosting
  problems.
• Supermarkets usually connect several cases
  end-to-end. Total electrical load must be
  carefully checked.

34
Open Frozen Food Display Case continued
14.5.4

• Evaporator must quickly be defrosted at least
  once per day.
• Defrosting is done automatically. A timer
  operates a hot gas defrosting system or an
  electric heater defroster device.
• Cabinets may use two or three air curtains.

35
Open Frozen Food Display Case continued
14.5.4
Construction of a three-air curtain open frozen
foods case.
36
Frozen Food Storage Cabinet
14.6

• May be chest or upright type insulated with 4" to
  6" (10cm to 15cm) of polyurethane.
• Stainless steel often used for inner liner.
• Outer liner usually aluminum or stainless steel.
• Doors and access openings heavily insulated.
  Double gaskets usually provided for better
  sealing.
• Cabinets that use temperatures below dew point of
  the room require heaters to prevent moisture from
  forming on glass.
• Electrical resistance strip heaters used around
  door frames and parts that sweat.

37
Frozen Food Storage Cabinet continued
14.6

• Used for storage purposes only. Food is moved to
  display cases as needed.
• Operate at 0ºF (17.8ºC) or lower.
• Refrigerating mechanism usually installed on top
  of cabinet.

38
Fast-Freezing Case
14.7

• Similar to storage cases.
• Temperatures are maintained at about 20ºF
  (29ºC).
• Food is placed as close to freezing plates as
  possible.
• May use refrigerated shelves to provide more
  heat-transfer surface.

39
Ice Cream Cabinet
14.8

• Consists of steel framework with a sheet metal
  exterior with 3" (75mm) of polyurethane
  insulation.
• Size of sleeve (ice cream holder) is standard.
  Therefore, construction of cabinets is similar.
• Cabinet sizes range from one to twelve ice cream
  holders.
• Cabinet should be maintained at approximately 0ºF
  (17.8ºC). If temperature is too cold, scooping
  is difficult and crystallization of ice cream
  will occur.
• Use dry-type evaporators with a capillary tube, a
  thermostatic expansion valve, or an automatic
  expansion valve refrigerant control.

40
Ice Cream Cabinet continued
14.8

• Evaporators may have tinned tubing wrapped around
  and soldered directly to sleeves or sheet metal
  with refrigerant passages formed in them.
• Sleeve openings are at the top, so no spilling of
  cold air occurs when cabinet is opened.
• Some cabinets are self-contained with condensing
  unit built into one end of the cabinet.
• Cabinets may be made with condensing unit
  separate (remote type).
• Upright and open display types may also be used
  for ice cream storage. Packaged ice cream should
  be kept at about 10ºF (23ºC) to retain firmness.

41
Soda Fountain
14.9

• Provides a means to store and dispense ice cream,
  cold water, beverages, and syrup. May also store
  ice.
• Compact design may make service difficult.
• Design makes serving easy. A built-in ice cream
  cabinet and a water cooling mechanism usually
  located in cabinet.
• Evaporator outlet tubing from ice cream cabinet
  and drinking water cooler pass around beverage
  syrup containers keeping them the same
  temperature as the water.

42
Soda Fountain continued
14.9

• Syrups should be kept at about 45ºF (7.2ºC).
  Water temperature should be between 32ºF and 50ºF
  (0ºC to 10.0ºC). Ice cream should be kept between
  0ºF and 10ºF (17.8ºC and 12.2ºC).
• A typical soda fountain uses a thermostatic
  expansion valve. The ice cream evaporator has a
  check valve in the suction line. The
  two-temperature valve controls the syrup and
  bottom compartment evaporator temperature. The
  beverage cooler has a solenoid liquid line
  shutoff valve. Note sight glass, heat exchanger,
  and drier mounted in refrigerant lines near
  condensing unit.
• Drink dispensers for ice and beverages are
  commonly used.

43
Dispensing Freezers
14.10

• Soft ice cream making machines are also known as
  dispensing freezers.
• Temperatures vary depending on product
• Frozen carbonated beverages 25ºF (3.9ºC).
• Slushes 28ºF (2.2ºC).
• Fruit or water ices 10ºF to 20ºF (12.2ºC to
  6.7ºC).
• Soft-serve ice creams 21ºF (6.1ºC).
• Milkshakes 27ºF (2.8ºC).
• Sherbets 20ºF (6.7ºC).

44
Dispensing Freezers continued
14.10

• Uses a large refrigerating machine to cool or
  fast-freeze the mix. It then is fed to the
  freezing cylinder. The same or a separate motor
  drives the stirring mechanism or dasher.
• Units may operate continuously because mix must
  be kept within a narrow temperature range. Unit
  must be kept within 1ºF to 2ºF (0.5ºC to 1ºC) of
  correct temperature. Thermostatic expansion
  valves are used as refrigerant control.
• Quality of mix is important.

45
Dispensing Freezers continued
14.10

• Frozen carbonated beverage is one part syrup and
  four parts carbonated water. Serving temperature
  is 22ºF to 26ºF (5.6ºC to 3.3ºC).
• Health codes require keeping mix containers and
  freezing cylinder sanitary.

46
Shake Maker
14.10

• Controls its temperature with a thermostat.
  Temperature control is based on consistency of
  mix.
• As mix is frozen, the belt tightens and moves the
  consistency control idler, eventually opening the
  motor circuit.

47
Modular Refrigeration Systems
14.11

• Flexible refrigeration systems in which glass
  door storage components can be used in various
  combinations with refrigeration units.
• System has forced air circulation, automatic
  defrost, adjustable temperature control, and
  automatic condensate evaporator.

48
Water Cooler
14.12

• Sheet metal housing attached to steel framework.
• Condensing unit usually located near the floor.
  Above it is the water-cooling mechanism which is
  insulated with foamed plastic 1" to 2" (2cm to
  5cm) thick.
• Water cooler basin generally porcelain-coated
  cast iron, porcelain-coated steel, or stainless
  steel.
• May have a heater to provide hot water. May have
  a refrigerated compartment for storing items.
• Heat exchangers frequently used on water coolers,
  making use of the low temperature of wastewater
  to pre-cool the fresh water line to the
  evaporator.

49
Water Cooler continued
14.12

• Must be installed according to the National
  Plumbing Code and local codes.
• Hand shutoff valve should be installed in fresh
  water line.
• Drain pipe, at least 1 1/4" (32mm) in diameter
  should be provided.
• Bubbler opening must be above the drain to
  eliminate accidental siphoning of the drain water
  back into the fresh water system.

50
Water Cooler continued
14.12

• Water coolers must be designed for easy access
  and use by the disabled.
• Temperatures for a cooler in a heat-treating area
  of a factory should be 50ºF to 55ºF (10.0ºC to
  12.8ºC). For offices, temperature should be 50ºF
  (10.0ºC).

51
Water Cooler continued
14.12
52
Water Cooler continued
14.12
Water coolers may use a self-contained water
supply.
53
Automatic Ice Maker
14.13

• Several different types available.
• Automatically controls water feed and freezes the
  water.
• Empty ice into storage bins and shut down when
  storage space is full.
• Cloudy cubes caused by entrapped air.
• Floats and solenoids control water flow.
• Switches operate storing action when ice is made.
• Ice may be removed from freezing surfaces by use
  of electrical heating elements, hot water, hot
  gas defrosting, or mechanical devices.

54
Automatic Ice Maker continued
14.13

• Cabinet is insulated.
• The freezing surface and bin storage basin made
  of stainless steel.
• Some units are self-contained others use remote
  condensing units.
• Both supply and drain plumbing are required.
• Capacity varies from a few pounds to many tons
  per day.
• Capacities decrease as water temperature and/or
  ambient air temperature increase.
• Water circuits and ice-freezing parts should be
  cleaned yearly.

55
Vending Machines
14.14

• Automatically dispense cold drinks with ice and
  canned or bottled soft drinks.
• May dispense ice cream, cold food, cold milk, and
  frozen desserts.
• Most use capillary refrigerant controls, hermetic
  motor compressors, and defrosting devices.
  Electrical system generally part of overall
  system.
• Electrically transfers material and operates coin
  and currency devices.

56
Vending Machines continued
14.14

• May have a variety of components for dispensing
  including
• Coin and currency devices.
• Carbon dioxide systems.
• Cup dispensers.
• Heating systems.
• Refrigerating systems that are usually air-cooled
  using fan evaporators. Some have defrost systems.
• Transfer systems.

57
Milk Cooler
14.15

• Milk must be cooled within an hour after being
  taken from a cow. By law, it must be cooled to
  50ºF (10.0ºC), then stored at 40ºF (4.4ºC) or
  lower.
• Bacterial growth in milk is dramatically affected
  by temperature. During a 24-hour period, bacteria
  count will increase as follows
• 2400 at 32ºF (0.0ºC).
• 2500 at 39ºF (3.9ºC).
• 3100 at 46ºF (7.8ºC).
• 11,600 at 50ºF (10.0ºC).
• 180,000 at 60ºF (15.6ºC).
• 1,400,000,000 at 86ºF (30.0ºC).

58
Milk Cooler continued
14.15

• Stainless steel is often used for bulk coolers.
  The evaporator is located in the base. Coolers of
  this type have a 450-gallon to 6000-gallon (1700L
  to 23,000L) capacity.
• Condensing unit is mounted outside milk room and
  is usually air-cooled. It should not be put in
  the vacuum pump room.
• Caution Coolers should always be properly
  grounded. Use a separate safety ground wire the
  same size as the power wires or larger. These
  units typically have a crankcase heater.

59
Milk Dispensers
14.15.1

• Dispense milk from bulk containers.
• Cans or plastic bags holding 3 gallons to 5
  gallons (10L to 20L) are installed in dispensers.
• Units must meet all health and sanitation codes.
• Milk is kept at 36ºF (2.2ºC) by a hermetic
  refrigerating system.

60
Bakeries
14.16

• Must refrigerate
• Perishable raw materials.
• Perishables during interrupted processing.
• Finished products. Both normal and
  low-temperature refrigeration is used.
• Normal refrigeration used to store ingredients
  and for dough retardation.
• Low-temperature systems used to freeze baked
  goods that are sold frozen.
• Controlled temperature and humidity are
  important, so air conditioning using
  refrigerating equipment is found in bakeries.

61
Refrigerant-to-WaterHeat Recovery System
14.17

• Produces and stores hot water.
• Transfers heat from the condenser to cold water.
• Adaptable to most refrigeration systems.
• Tanks are constructed of vertical plates that
  allow refrigerant to flow through them.
• Rapid transmission of heat to water is provided.
• Often used as a supplement to existing hot water
  systems.

62
LaboratoryRefrigerated Incubators
14.18

• Incubator can maintain constant temperatures.
• Refrigerating system used for cooling and
  electric elements for heating.
• Unit can maintain any constant temperature
  between 36ºF (2.2ºC) and 158ºF (70.0ºC).

63
Industrial Applications
14.19

• Common uses include
• Cooling of water that, in turn, cools electrodes
  on resistance welders.
• Cooling of quenching liquids used to cool metals
  in heat-treating applications.
• Cooling compressed air.
• Compressed air must be dry. Air is cooled to keep
  its dew point above the coldest spot in the air
  system. This prevents moisture in the lines.

64
Industrial Applications continued
14.19

• A refrigerating system cools air to bring it
  below its critical pressure dew point. It is then
  reheated.
• Pressure dew points are about 50ºF (28ºC) above
  atmospheric dew points at 100 psi (690 kPa) air
  pressure. The compressed air is cooled to about
  35ºF to 50ºF (1.7ºC to 10.0ºC).
• A 3000 cfm (1.42m3/s) air compressor will need
  about a 20 ton (55.2 kW) capacity refrigerating
  machine.

65
Industrial Applications continued
14.19

• Caution A refrigerating system located near
  flammable or explosive materials must be
  explosion proof. Sealed lights and sealed contact
  points are required.
• Low-temperature units capable of maintaining
  140ºF (95.6º C) are available. Such systems
  usually use 5" (12.5cm) of insulation and a
  cascade of systems.

66
Industrial Freezing of Foods
14.19.1

• Performed in two principal types of
  establishments
• Processing plants.
• Locker plants.
• Locker plants use a variety of equipment
  however, plan for freezing the food is similar.
• Food is weighed and checked for purity and
  suitability for freezing. It then moves to the
  processing room where it is prepared for
  freezing. Finally the packed food is sent to the
  freezing section where the freezing and storage
  process is completed.

67
Industrial Freezing of Foods continued
14.19.1

• Humidity in rooms where food is cured and stores
  should be near 100. Temperature should be near
  39ºF (3.9ºC).
• Cryogenic food freezing obtains temperatures of
  320º F (195.6º C) and freezing is
  instantaneous, causing little or no damage to the
  food.

68
Industrial Storage of Refrigerated Foods
14.19.2

• US Department of Agriculture (USDA) has issued
  guidelines on food preparation and storage.
• Hot foods must be cooled to 70ºF (21.1ºC) within
  two hours, and then to 41ºF (5.0ºC) within the
  next four hours.
• Cooling food too slowly allows growth of
  bacteria. Food cooled too rapidly losses flavor.
• A microprocessor system to control chilling
  process and defrosting to maintain food
  temperature may use a built-in printer to record
  operations.

69
Industrial Storage of Refrigerated Foods
continued
14.19.2

• Process
• Probes are inserted in the food, providing
  accurate measurement of each tray of food.
• Quick chilling is achieved by system of air ducts
  that evenly distribute cold air across the food.

70
Questions

• When using a multiplexed scroll compressor
  system, how is the capacity matched with the
  systems heat load?

By cycling compressors as needed.

• Which temperature and relative humidity must a
  cooler maintain that stores meats and fresh
  produce?

35ºF to 40ºF (4.4ºC to 1.7ºC) at 80 RH.

• A florist cabinet must maintain temperatures
  between ___________ and ___________ with a
  relative humidity of ______ to _______.

38ºF (3.3ºC)
40ºF (4.4ºC)
90
95
71
Questions continued

• What is the purpose of an air curtain used on an
  open display case?

Air curtains prevent dry air from circulating
over contents which will spoil its appearance.

• Name two types of defrost systems used on open
  frozen food display cases.

Electric and hot gas.

• Name two styles of frozen food storage cabinets.

Upright and chest types.
72
Questions continued

• What is used to prevent condensation on cabinet
  doors that operate below dewpoint temperatures?

Electrical resistance strip heaters around door
frames.

• At what temperatures are fast-freezing cases
  maintained?

Approximately 29ºF (33.9ºC).

• To retain firmness, packaged ice cream should be
  kept at about _________________.

10ºF (23.3ºC)

• Syrups from soda fountains should be kept at
  about ___________.

45ºF (7.2ºC)
73
Questions continued

• Temperatures vary depending on product at which
  temperature must the following items be
  maintained?
• Frozen carbonated beverages

25º F (3.9ºC)

• Slushes

28ºF (2.2ºC)

• Soft-serve ice creams

21ºF (6.1ºC)

• Milkshakes

27ºF (2.8ºC)

• Sherbets

20ºF (6.7ºC)

• Water cooler temperatures are usually maintained
  at

50ºF to 55ºF (10.0ºC to 12.8ºC).
74
Questions continued

• Cryogenic food freezing commonly uses liquid
  __________ or _______________ .

nitrogen
carbon dioxide

• Which temperatures are obtained by cryogenic food
  freezing?

320ºF (195.6ºC).
75
Safety
14.21

• Always check a unit prior to working on it to
  protect you and the public.
• Be certain mechanism and cabinet installed to
  local and national codes including fire,
  electrical, plumbing, building, and safety codes.
• Code violations must be reported to the
  appropriate authorities. Violations may result in
  serious damage to the physical structure or
  personnel.
• Move cabinets on rollers to avoid pinching hands
  or feet. Wear steel-toed shoes.

76
Safety
14.21

• Use handling equipment to move large commercial
  cabinets.
• Floor load limits should be checked before heavy
  commercial equipment is installed.
• Wiring and plumbing must be adequate, securely
  mounted, and made of correct materials.
• Health Department regulations apply to all
  equipment used around food and beverages.

77
Glossary

• airtight
• Sealed to prevent passage of gas.
• auxiliary evaporator
• Small evaporator consisting of coils of tinned
  tubing below the shelves in a display case.
• bunker
• Space where ice or cooling element is placed in
  commercial installations.
• cascade
• Two or more systems connected in a series.
• critical pressure
• Pressure at which vapor and liquid have same
  properties.

78
Glossary

• cryogenic food freezing
• Use of liquid nitrogen or carbon dioxide to
  process foods.
• dew point
• The water condensing temperature.
• locker plants
• Small unit designed to prepare, freeze, and
  store various products.
• polyurethane
• Any synthetic rubber polymers produced from the
  polymerization of a HO and NCO group from two
  different compounds.
• ultraviolet lamps
• Invisible radiation waves with frequencies
  shorter than wavelengths of visible light and
  longer than X rays.