09A - Introduction to Refrigerants Flashcards by garrett packer (2024)

What were the three CFC refrigerants originally developed and used in the 90s?

R12, R22, and R502.

What does CFC stand for?

Chlorofluorocarbons

What does HCFC stand for?

Hydrochlorofluorocarbons

What does HFC stand for?

Hydrofluorocarbons

What was the Montreal Protocol? When was it signed?

The Montreal Protocol was a document which went into effect on January 1, 1989. This was designed to ban the production of CFCs in all large, developed countries. This required countries to stop producing CFC refrigerants by January 1, 1996.

What is the EPA?

The Environmental Protection Agency is a US governmental agency charged with enforcing the regulations for working with refrigerants.

What is the Clear Air Act?

The Clean Air Act is a federal law that includes guidelines, restrictions, and penalties for releasing refrigerants into the atmosphere. Fines are assessed up to $37,500 per day, for failure to comply with the Clean Air Act.

What are some of the Clean Air Act violations subject to legal action?

What is refrigerant ODP?

Ozone depletion potential is the measurement of the ability of a refrigerant to destroy the ozone layer. The base unit of measurement is the refrigerant R11, which has an ODP of 1.0. The more harmful the refrigerant is to the ozone layer, the higher its ODP.

What is GWP?

Global warming potential is a measure of the ability of a gas to contribute to global warming over time. The baseline gas is carbon dioxide, which has a GWP of 1.0 is commonly measured over a 100 year time period. The higher the GW is, the greater the risk of environmental damage.

What are the refrigerant chemical classifications?

What is a CFC?

Chlorofluorocarbons were the first halogen-based refrigerants developed over eighty years ago. CFCs are composed of chlorine, fluorine, and carbon. They are considered to be fully halogenated because all the hydrogen atoms in the original methane or ethane molecule have been replaced by halogens, such as chlorine and fluorine. Two popular CFC refrigerants include R-11, and R-12. They were phased out of production since 1995, but can still be found in some equipment produced before 1995.

How many ozone molecules can be broken apart by one molecule of chlorine?

100,000

What is an HCFC?

Hydrochlorofluorocarbons are refrigerants whose molecules are composed of hydrogen, chlorine, fluorine, and carbon. HCFC molecules include halogens combined with either methane or ethane. Examples of HCFC refrigerants are R-22 and R-123. They have less impact on the ozone layer than fully halogenated CFCs. HCFCs are considered to be partially halogenated because not all the hydrogen atoms have been replaced by chlorine and fluorine. As a result, HCFCs tend to break down in the lower atmosphere and cause less ozone depletion than CFCs. They do however still linger in the atmosphere for a long time and have a high GWP. The EPA requires the complete phaseout of HCFCs by the year 2030.

What is an HFC?

Hydrofluorocarbons are refrigerants that contain hydrogen, fluorine, and carbon. They differ from CFCs and HCFCs in that they contain no chlorine atoms. HCFs have zero ODP. Like HCFCs, HFCs are partially halogenated, but they have a lower ODP than HCFCs because they do not contain chlorine atoms. This makes HFC refrigerants well suited to replace ozone depleting refrigerants. Examples of HFC refrigerants are R-123a, R-152a, and R-404a.

What is a refrigerant blend?

Refrigerant blends are mixtures of two or more established refrigerants. Based on their thermodynamic properties, they are split into the following groups: azeotropes, zeotropes, and near-zeotropes.

What are Azeotropes?

Azeotropes are refrigerant blends that respond to changes in pressure and temperature like a single refrigerant, having fixed boiling and condensing points. An azeotrope maintains constant properties during all operating conditions. At atmospheric pressure, the individual refrigerants will not separate as the blend evaporates or condenses.
Azeotropes can be identified by their ASHRAE classification number series of 500. (Ex: R502, R500)

What are Zeotropes?

Zeotropes are refrigerant blends in which each individual refrigerant that makes up the blend responds differently to conditions based on its individual characteristics. Therefore, a zeotropic blend operates under a range of boiling and condensing points that correspond to the range of its individual refrigerants and the percentage of the blend that each refrigerant makes up.
Zeotropes can be identified by their ASHRAE classification number series of 400. (Ex: R407C, R409A)

What is Fractionation?

Fractionation is the phenomenon where zeotropic blend’s individual refrigerants will separate during phase change. Fractionation can be thought of as the refrigerant splitting up or “fracturing” into its base components. This occurs because the different refrigerants in a zeotropic blend have different boiling points.

What is bubble point?

Bubble point is the temperature at which a liquid zoetrope first begins to boil. The refrigerant with the lowest boiling point boils first.

What is dew point?

Dew point is the temperature at which a vapor zoetrope first begins to condense. The refrigerant with the highest condensing point condenses first.

What is temperature glide?

Temperature glide is the temperature difference between the vapor and liquid state during evaporation or condensing at a constant pressure. Temperature glide is a result of the different boiling and condensing temperatures of a zoetrope’s individual components for a given pressure. This shows as a zoetrope changing its phase and temperature at the same time, and each zeotropic refrigerant blend has its own temperature glide. The common range for temperature glide is 0.3F to 10F.

What is a Near-Azeotrope?

Near-Azeotropes react similarly to zeotropes but respond over a smaller range of boiling and condensing points. Near-azeotropes are technically zeotropes, but allowing them their own category helps to differentiate them more precisely.

What are HFO refrigerants?

Hydrofluoro-olefins are composed of hydrogen, fluorine, and carbon, but they have at least one double bond between the carbon atoms. While HFOs are technically a group of HFCs, they are made from olefins, rather than alkanes. HFOs have zero ODP and very low GWP values. HFOs are miscible in POE lubricants and not soluble in mineral oils or alkylbenzene lubricants. Ex: HFO-1234yf, HFO-1234ze.

What are HCs?

Hydrocarbons are organic substances that contain carbon and hydrogen. These substances are the components in petroleum and natural gas. They are often known for their use as fuel and in the production of plastics, solvents, and industrial chemicals. Hydrocarbons can also be used as refrigerants. Pure hydrocarbons have 0 ODP and a low GWP compared to CFCs, HCFCs, and HFCs. HCs also have better energy efficiency than HFCs.

What is SNAP?

Significant New Alternatives Policy is the EPS’s program that evaluates and regulates substitutes for high ODP refrigerants. It helps to progress the phaseout of older refrigerants and meet the ozone protection provisions of the Clean Air Act. Ex: R-600a (Isobutane), R-290 (propane, R-441A (HC blend)

How are refrigerants identified?

By a standardized numbering system developed by the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE)

What is the significance of each number within a given refrigerant classification number?

The first digit indicates the refrigerant series to which a particular refrigerant belongs. The numbers that follow have a different significance depending on the refrigerant’s classification.

What is the defining characteristic of Methane, Ethane, and propane based refigerants?

They contain carbon as their main component.

What is the defining characteristic of cyclic organic refrigerants?

They are organic refrigerants that have double bonds between atoms.W

What is the defining characteristic of miscellaneous organic refrigerants?

They are carbon-based refrigerants that do not fall under any of the previous categories. Refrigerants in this category include butane and pentane.

What is the defining characteristic of Inorganic refrigerants?

They are refrigerants that typically do not contain carbon, such as hydrogen, oxygen, water, and ammonia.

What is the defining characteristic of unsaturated organic compounds?

They are used in the manufacture of plastics, such as vinyl chloride.

What is R-744?

Carbon dioxide.

How are 000 through 300 series refrigerant numbers classified when broken down?

What are the chemical classifications of each series of refrigerant?

000 - Methane based
100 - Ethane based
200 - Propane based
300 - Cyclic organic
400 - Zeotropes
500 - Azeotropes
600 - Miscellaneous Organic
700 - Inorganic
1000 - Unsaturated Organic

What do the lower case letters at the end of a refrigerant signify?

They are used to differentiate between isomers. Isomers are molecules that have an identical number of atoms, but the atoms are arranged differently in different isomers. As a result, isomers can have the same number of atoms but different properties and characteristics.

How are 400, 500, 600, and 1000 series refrigerant numbers classified when broken down?

How do you identify a recovery cylinder?

They are gray with yellow ends. These cylinders must be rated and approved for use by the Department of Transportation (DOT)

What is refrigerant toxicity?

Toxicity is the ability of a refrigerant to be harmful or lethal with acute or chronic exposure.

What is the difference between class A and class B refrigerants?

Class A refrigerants are those not known to be toxic at concentrations equal to or below 400 ppm.
Class B refrigerants are those that are known to be toxic at concentrations equal to or below 400 ppm.

What is refrigerant flammability and how is it classified?

Flammability is a substance’s capacity to ignite and burn. Classification is indicated by the following numbers:
1 - No flammability
2/2L - Low flammability
3 - High flammability
3L signifies a refrigerant that is hard to light and easy to extinguish.

What is a pressure-temperature curve?

This shows how a refrigerant’s temperature and pressure both rise and fall in relation to each other. These curves illustrate the combined gas law principle that temperature and pressure are directly related.

What is a PT chart?

A Pressure temperature chart may be used to determine if a unit is operating at the correct temperature or pressure. A technician can use a pressure gauge to measure the pressure in an evaporator and then use a pressure-temperature chart to find the boiling temperature of the refrigerant inside the component. It will only show the temperature at which the refrigerant is boiling/condensing under a certain pressure.

What is skin temperature in HVACR?

It is the temperature of the ACR tubing.

What is a pressure-enthalpy table?

This is a chart listing actual operating temperatures and pressures for a specific unit that is provided by the manufacturer to help technicians compare readings to recommended cycle parameters.

What is a pressure-enthalpy diagram?

The numerical values displayed in PE table can be visually demonstrated in a diagram.

What is Coefficient of Performance?

This is the ratio of refrigeration effect to the heat of compression Refrigerants with higher coefficients of performance are more efficient than refrigerants with lower coefficients of performance.

What are the properties that are selected when choosing a refrigerant for a given application?

What are freezants?

Freezants are used in large food processing plants as a cryogenic fluid to rapidly freeze foods. Ex: Liquid nitrogen, carbon dioxide.

What is an expendable refrigeration system?

An expendable refrigeration system cools a substance or absorbs heat from an evaporator and then releases its refrigerant into the atmosphere. It uses an expendable refrigerant which evaporates only once in the system and is then vented. These are often referred to as chemical refrigeration systems or open-cycle refrigeration systems.

What is refrigeration lubricant?

This is lubricant charged into a refrigeration system in order to lubricate the contacts between moving parts. It circulates through the same tubes and components as the refrigerant, providing lubrication.

What is wax content?

Many refrigeration lubricants contain paraffin wax. When wax precipitates out of a lubricant at low temperatures, it is called wax separation. This can plug refrigerant control oraficices, therefor a refrigerant with a low wax content is desirable.

What is a floc test and how is it conducted?

A floc test is a test that determines how easily wax separates out of a mixture of refrigerant and lubricant. The test is conducted by mixing 10% refrigerant with 90% oil and placing it inside a sealed glass tube. It is then cooled slowly until a flocculent precipitate of wax appears. The highest temperature at which this occurs is recorded as the floc point. Synthetic lubricants do not contain wax and therefore have no floc point.

What is lubricant thermal stability?

Thermal stability is a lubricant’s ability to remain stable in high heat areas. Lubricants with lower thermal stability tend to form hard carbon deposits on hot spots in the compressor, such as discharge ports.

What is lubricant flash point?

The temperature at which vapors from a lubricant can surface ignite is the refrigerant’s flash point. In many hermetic units, refrigeration lubricants come in direct contact with the hot motor windings in the compressor, which makes having a high flash point important.

What is lubricant viscosity?

Viscosity is a measure of a liquid’s resistance to flow. A fluid with high viscosity resists flowing, while a fluid with low viscosity flows more easily. The viscosity of a lubricant will change with the temperature. Low temperature lubricant may not pour and can become a plastic solid.

What is lubricant pour point?

The lowest temperature at which a lubricant will flow is called the pour point.

What is lubricant dielectric strength?

The amount of moisture in a refrigeration lubricant can be measured by its resistance to the flow of a current of electricity through it without breaking down. This is known as its dielectric strength. A refrigeration lubricant with acceptable moisture content should have a minimum dielectric value of 25,000 volts.

What are the different varieties of refrigerant lubricants?

MO - Mineral Oils
POE - Polyol Ester Lubricants
AB - Alkylbenzene Lubricants
PAG - Polyalkylene Glycol

What are Mineral Oils used for?

Mineral Oils (MOs) are a type of refrigeration lubricant made from refined crude oil. Since mineral oils are not miscible with most HFC refrigerants, MOs are generally used only with CFCs and HCFCs.

What are Polyol Ester (POE) lubricants used for?

POE lubricants are a group of synthetic refrigeration lubricants that are compatible with CFCs, HCFCs, and HFCs. POE are miscible with mineral oil and alkylbenzene lubricants. There are numerous different grades, but may not be approved for use in certain compressors.

What are Alkylbenzene (AB) Lubricants?

AB lubricant’s are refrigeration lubricants manufactured from propylene and benzene. They are used with CFCs, HCFCs, and blends that include CFCs and HCFCs.

What are Polyalkylene Glycol (PAG) Lubricants?

PAG lubricants are refrigeration lubricants designed for use with HFCs. They tend to attract moisture and poorly lubricate aluminum on steel. Therefor, PAGs should not be used in compressors with aluminum pistons in steel cylinders. They are also not compatible with chlorine, so any R-12 retrofits must be thoroughly flushed before adding PAGs.

How should refrigeration lubricants be handled?

1- They must be kept in sealed containers
2 - They must be transferred in chemically cleaned containers and lines,
3 - They must not be exposed to air where it will absorb moisture.
4 - They should be purchased is small sealed containers, holding only enough for each separate service operation. Unused lubricant that is allowed to remain in the container may pick up some moisture and dirt.

What can too little/too much lubrication look like inside a refrigeration system?

What should be verified before adding lubricant to a system?

Make sure the lubricant is compatible with the refrigerant being used. Make sure to follow the manufacturer’s viscosity, pour point, and floc point recommendations. On a service call, add lubricant only if there is a sign of lubricant leakage.