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cylinder colorcode for R 409A?
medium brown
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Blowout discs on all tanks prevent what?
hydrostatic expansion
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Cylinder colorcode for R 22?
Light Green
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What is a 400 series refrigerant?
Zeotrope
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Cylinder colorcode for R 12?
White
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What is the benefit to charging vapor on the low side of the system?
technician does not have to worry about liquid slighting or waiting for the system to stabilize
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Cylinder colorcode for R 404 a?
Orange
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Why can you not charged liquid into the high side of a running system?
Pressure on the high side of the system is greater than that of the cylinder
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You must charge the low side as a vapor, charging as a vapor is slower and the pressure will be lower in the cylinder due to?
Cooling of the cylinder and releasing of pressure into the system from charging
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Cylinder colorcode for R 410 a?
Rose
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What is the most accurate way of charging a refrigerant?
Weighing in refrigerant in liquid form to the high side
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What is the safest way for recharging system for both the technician and the equipment?
Charging vapor into the low side of the system while it is running
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Cylinder colorcode for R 134A?
Light Blue
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Ruptured disc blowout at what temperature?
130°
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Cylinder colorcode for R 502?
Purple
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To prevent lower pressures in the cylinder wall charging on the low side of the system, What must you do?
Warm the cylinder while it is charging the system by using a tub of hot water or a warming blanket
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What is a 500 series refrigerant?
Azeotrope
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When there is a problem with temperature glide on a small system with a single fan, what will you see as a technician?
An average temperature over the evaporator coil
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In bigger systems with multiple evaporator fans, what does temperature glide cause?
Temperature glide will cause warm and cold spots throughout the conditioned space
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First bubble of vapor appears in liquid occurs in the evaporator (used for sub cooling)?
Bubble Point
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All zeotrope's must be charged as?
As a liquid from the cylinder
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Temperature glide has a range of what?
1° to 16°F, depending on the refrigerant used
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Temperature glide varies between?
1° and 60°F, depending on the blend of the refrigerant
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What causes temperature glide?
The different boiling points and condensing points of The mixture of refrigerant
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When there is a problem with the temperature guide on large systems with multiple fans, The technician will see?
Warm and cool spots throughout the conditioned space
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When does temperature happen and where does it happen?
it happens in the evaporator when the system is operating
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once in the system, The only place you can get fractionation is?
whenever there is a leak in the condenser or evaporator or wherever the refrigerant is saturated
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the first drop of liquid that condenses from paper, occurs in the condenser (used to determine superheat)?
dewpoint
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when dealing with a 400 series zeotrope, the PT chartshows one pressure for vapor and one pressure for liquid, what would these be called?
the bubble point and the dewpoint
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pressuring the system is at a constant level but individual refrigerants in the blend have different what when talking about temperature glide
boiling points and condensing points
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what are interim replacement refrigerants, 400 series zeotrope's, designed to do?
to get the life out of equipment that used are 12
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when the refrigerant is saturated, there is a boiling range because the liquid begins to boil at one temperature and the vapor condenses at a different temperature?
temperature glide
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when using a 400 series zeotrope what must you do to prevent fractionation while you charge a system?
zeotrope scan only be charged as a liquid to prevent them from separating, While in saturation
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if you lose more than 50% to 80% of the charge when using a zeotrope you must do what?
remove the remaining refrigerant and recharge as a new refrigerant
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the components of a zeotropic blendwith the highest pressure leave the cylinder first when charging as a vapor thus, composition of the mixture changes?
fractionation
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what is an interim replacement refrigerant?
HCFCs and they were used to get the life out of newer equipment
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in smaller systems with single fans, what will happen when temperature glide is a problem?
you would get an average temperature across the evaporator coil and it is not really an issue
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what is a throttling valve used for?
it acts like a metering device that flashes off the refrigerant as it leaves the cylinder. It is the safest way and fastest method for charging liquid into the low side
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production to stop in 2030. No longer used in new equipment. Contains chlorine. Is less stable so they break up before they reached the ozone layer
HCFCs, hydrochlorofluorocarbons,
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when is fractionation a problem?
only when charging a system or if there's a leak in the system
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refrigerant vapor is heavier than air. Can displace oxygen when inhaled and cause unconsciousness,heart irregularities and death by asphyxiation. Refrigerants at high temperature form hydrochloric acid, hydrofluoric acid and phosgene gas?
hazards of refrigerants
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what refrigerators used in the air-conditioning's? HFC
R410A
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how can you use the manifold gauge set to throttle liquid refrigerant into the low side of the system?
open enclose rapidly the low side gauge and valves, there's no way to determine the amount of liquid going into the compressor
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when topping off a running system, you must do what?
you cannot charge on the high side must charge vapor into the low side While it is running
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contains chlorine, fluorine, and carbon. Production was stopped January 1, 1996. Depletes the ozone.
CFCs, chlorofluorocarbons
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when charging refrigerant into the new equipment you must do what?
- leak check the system.
- evacuate the system.
- charge system, way in liquid refrigerant into the high side of the system is the most accurate way
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what refrigerant is used in automobiles?HFC
R 134 a
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what are the two problems when dealing with a 400 series zeotrope?
fractionation and temperature glide
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what refrigerant is used in commercial refrigeration? HFC
R 134 A
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the ozone protects us from what?
UV rays
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one Chlorine atom can kill 100,000 What?
ozone molecules
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50.0 water capacity of the cylinder at 100% would allow you to put how much into it at 80%
50.0 x 0.80 = 40
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contains no chlorine, zero ozone depletion potential, you still must recover it?
- HFC, hydrofluorocarbons, R134a, R401a ,R507, R410
- R 134 Most Common
- R410a Newest
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components of a zeotropic blend boil and condenser at different rates. Therefore, they separate during boiling?
fractionation
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what does recycle mean?
to clean the refrigerant with a filter and reuse in a system
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what is the difference between A and B in a refrigerants name?
both are the same refrigerants, but have a different amount of the same course
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refillable and recovery cylinders have a pressure relief device that opens at what temperature?
165°Fto relieve pressure
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what are the R#'s for azeotrope's
R500, R502, R507
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what is the R# series for inorganic refrigerants?
R 700 Series, ammonia, CO2, and helium
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recovery cylinders
DOT regulated, yellow top gray bottom, they have two valves and can only be filled at 80% maximum fill rate
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what are the pure refrigerants?
R 22, R12, R134a
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what are the two type's of blend refrigerants?
azeotrope and zeotrope
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what is the R# series for azeotrope?
500 series
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what does a reclaim mean?
to turn the refrigerant into a facility where the refrigerant will be taken back to a near virgin state. This is an EPA standard
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if the conditioned space of an icebox cooler is 40° the evaporator must run at what temperature to soak up the heat
20° lower than the design temperature, which would make the evaporator run at 20°
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the lower The design temperature the more capacity required for the compressor?
the larger the horsepower
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disposable cylinders
cannot be reused because they have thin walls and will corrode, have a check valve in them, recover any remaining refrigerant in the tank and puncture, 30 pound cylinders are the most common
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refrigerant characteristics
- low ozone depletion potential.
- Low boiling point
- High latent heat value
- safe, non-toxic, and nonflammable
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evaporator operation temperature when the conditioned space is at its required temperature?
design temperature of the system
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cylinder labels must have what information on them?
- test date.
- Gross weight: cylinder and contents.
- Tare weight: cylinder only.
- Water capacity: liquid capacity of the cylinder 100%
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for recovery cylinders, there is 80% maximum fill of the cylinder. Why?
- 20% of the tank for recovery cylinders allows for expansion.
- 15% for refillable cylinders
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what does recovery mean?
removing refrigerant and storing in a cylinder
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on disposable cylinders, there is a ruptured disc, at what temperature does the structure?
130°F
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refillable cylinders
- DOT regulated,
- heavy duty.
- Must be tested every five years.
- All cylinders are color-coded and have R# to identify them more clearly
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rule of thumb for design temperature/evaporator temperature.
High temperature system, subtract 20° from the?
desired conditioned space
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compressor application categories.
High
20° to 55°
AC systems and walk-in coolers
compressor application categories.
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single component, one molecule and does not change composition When boiling or condensing?
pure refrigerants
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rule of thumb for design temperature/evaporator temperature.
Medium temperature systems subtract 10° to 12° from the desired?
conditioned space temperature
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rule of thumb for design temperature/evaporator temperature.
Low-temperature system subtract 6° to 8° from?
the desired conditioned space temperature
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rule of thumb for design temperature/evaporator temperature.
For high temperatures, 50°F conditioned space should equal?
30°F design temperature
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rule of thumb for design temperature/evaporator temperature.
For low temperatures 5°F for conditioned space should equal question
-1° two. -3° design temperature
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What are the R #'s for Zeotropes?
R409a, R401a, R402a, R410a, R404a
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What is the R# series for Zeotropes?
R400 Series
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Cylinder Color code for R 401a?
Coral
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Cylinder color code for R 500?
Yellow
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Cylinder Color code for R 402a?
Whitish Green
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