Refrigerants: How They Are Named?

Hi Everyone!

To those aspiring mechanical engineering students or refrigeration/air conditioning technicians or mechanical engineers who wondered how refrigerants are being commercially named, well, I experience the same too. It was during the time when I am about to start my early grind for the upcoming mechanical engineering licensure examinations (that licensure examination was scheduled 28^th and 29^th day of September 2016) when I got interested and felt intrigued about the naming of refrigerants since during the past two board examinations (September of 2015 and March of 2016) my friends especially those quizzers from different universities told me that indeed the naming convention for the refrigerants came out in the board examination and also the review director of the review center that I am having my review confirmed that it had been luckily included to the 100 item question which as far as I can remember it was being inserted in the subject of Mathematics and Power and Industrial Plant Engineering subjects (PIPE). I was a happy to know that news because I still have my stock knowledge from the advance chemistry subject that I had way back on my 4^th year in high school wherein we were taught about hydrocarbons, its derivatives and also the aromatic hydrocarbons. And most refrigerants are hydrocarbons like alkanes wherein methane and propane both belong, and because of that I felt confident because if I am given the IUPAC (International Union of Pure and Applied Chemistry) or old names of those alkanes I can generate chemical formula or if I am given the chemical formula and I’m ask to give its IUPAC name I can easily generate the name during that time. All the while, I did missed something in the naming conventions of refrigerants and that is the refrigerant designation number which was a standard being developed by ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) for global and commercial use. I have to be honest, I did neglect it during my time as a mechanical engineering students especially during my 4^th and 5^th year stay wherein refrigeration and air conditioning are being taught to us by our dear professor.

Since I was renting a boarding house during my entire review and it is very far away from my alma mater (University of Cebu Lapu – Lapu and Mandaue) I need to schedule a visit on it so I can review in my alma mater’s library. I search lots of books relating to Refrigeration and Air Conditioning and was so happy to find a book wherein it explains how these refrigerants are being commercially named for global use, and unfortunately I forgot the name of that book and the thing that I remember from that informative book is the units that are being used in all of its problems and that units are based on the English System of Units.

So with that allow me to explain and discuss the naming conventions for refrigerants.

Image Source

So let us now proceed to the general naming convention for refrigerants.

In the above photo it shows the general formula for the naming convention of hydrocarbon refrigerants, wherein:

Because of the general formula for the naming convention of hydrocarbon refrigerants, series for hydrocarbon refrigerants had been established such as:

• 000 Series
  This series of saturated hydrocarbon refrigerants are based on the simplest form of alkane and that is methane. Methane is having a chemical formula of CH₄. And based on the naming convention found in the above photo, we will be expecting “zero” right after the “R” for refrigerant since the number of Carbon atoms in a methane compound is 1 and from the above formula (m-1), we will be having R-050, since from the formula (n+1), methane has 4 hydrogen atoms and therefore we will be having 5, and then since methane doesn’t have any fluorine atom, we simply place 0 after 5. And therefore, for methane it has R-50, since 0 is removable. Additionally, since R-11 and R-12 are very well-known, I’ll show how they obtained that commercial and standard name.
  For Trichloromonofluoromethane (CCl₃F) or R-11 or Freon-11, since it has one carbon atom, therefore, it starts with “0”, and then, since it doesn’t have hydrogen atoms left, therefore it is followed with “1” from the formula (n+1), and since it has 1 fluorine atom, then, it is followed with “1”. Therefore, R-11 is the naming convention for Trichloromonofluoromethane. So the same thing goes for the Dichlorodifluoromethane (CCl₂F₂), since it has one carbon, therefore we will be starting at “0”, then since it has no hydrogen atom, then it is automatic to have 1 from the formula for hydrogen atoms and then since it has 2 fluorine atoms therefore it has 2. And thus, Dichlorodifluoromethane is commercially and given a standard name of R-12 or Freon-12. And if you’ve noticed why R is replaced Freon for this case, since these hydrocarbons with chlorine and fluorine atoms otherwise known as chlorofluorohydrocarbons (CFHC) and that makes them exceptional to be applied only to halocarbon or halogenated products such as refrigerants. Additionally, “Freon” is a registered trademark of The Chemours Company.^[1]

• 100 Series
  For this series of saturated hydrocarbon refrigerants it is based on the second simplest form of alkane and its derivatives and that alkane is ethane wherein it has 2 carbon atoms. By the way for alkanes, their chemical formula is based on this formula C_nH_2n+2. And additionally, ethane has a chemical formula of C₂H₆. And based on the formula for the naming convention ethane refrigerant is having refrigerant designation number of 170 (R-170), due to the fact that it is two Carbon items wherein it is subtracted by 1 which makes it have “1” based on the formula (m-1), then since it has 6 Hydrogen atoms and that is why it is followed with “7” based on the formula (n+1) and finally it has zero Fluorine atom, automatically “0” follows.

• 200 Series
  For this series of saturated hydrocarbon refrigerants it is solely based on the third simplest form of alkane and its being named as “propane” wherein it has a chemical formula of C₃H₈. And the refrigerant designation number for propane is R-290, since it has having 3 Carbon atoms which makes it to start with “2”, and since it has 8 Hydrogen atoms, “9” follows to “2” and lastly, since it doesn’t have any Flourine atom, automatically it will be placed with “0”. So that makes it R-290 for propane.

• 300 Series
  For this series of saturated hydrocarbon refrigerants it is solely based on cycloalkanes wherein its chemical formula is based on the naming convention of C_nH_2n wherein n is the number of carbon atoms in the compound. And the most popular cyclic hydrocarbon refrigerant is octafluorocyclobutane, wherein it has a chemical formula of C₄F₈; notice that it no longer have hydrogen atoms, it is because all the 4 carbon atoms are paired to Flourine atoms or in other words each Carbon in the octafluorocyclobutane otherwise known as perfluorocyclobutane^[2] is being paired to 2 Flourine atoms. Moving on for the refrigerant designation number for C₄F₈, since it has 4 Carbon atoms, therefore it would start with “3” from (m-1) formula; then followed by “1” since it has no Hydrogen atom which is based on the (n+1) formula; and finally, it is followed by “8” since it has 8 Fluorine atoms. Thus, octafluorocyclobutane’s refrigerant designation number is R-318.
  
  

And that ends my discussion on the naming convention for the saturated hydrocarbon refrigerants. So what about those zeotropic, azeotropic, other special purpose organic compound refrigerants, inorganic compound refrigerants and the unsaturated organic compound refrigerants and? Well, I will be tackling it for this blog post.

• 400 Series
  This series of refrigerants are based solely for zeotropic refrigerants like R-400 wherein it is a blend of R-12 and R-114. Next to R-400 is R-401A wherein it is a blend of R-22 and R-152a. For additional information, you may refer to ASHRAE’s Refrigerant Designations under the Refrigerant Blends group and Zeotrope zub-group. And you might notice that there is lower case letter after the third digit of a refrigerant well that means that there is an increasing unsymmetrical of the isomers of that refrigerant, whereas for those being followed by upper case letter it is an indication that it has a different molecular mass compared to the refrigerants other isomers.

• 500 Series
  This series of refrigerants are based solely for azeotropic refrigerants like R-500 wherein it is a blend of R-12 and R-152a. Next to R-500 is R-501 wherein it is a blend of R-22 and R-12. For additional information, you may refer to ASHRAE’s Refrigerant Designations under the Refrigerant Blends group and Azeotrope sub-group.

• 600 Series
  For this series of refrigerants it is solely dedicated to the other special purpose organic compound refrigerants such as butane and pentane wherein its isomers are also included. Like for butane wherein it has a refrigerant designation number of R-600 whereas it has a known isomer called isobutane that is being designated as R-600a. For additional information, you may refer to ASHRAE’s Refrigerant Designations under the Miscellaneous Organic Compounds group.

• 700 Series
  For this series of refrigerants it is solely dedicated to inorganic compounds that are being used as a refrigerant such as Ammonia (NH₃) and the increasing popularity of Carbon dioxide CO₂ as a refrigerant. The naming convention for this series goes in the form of R-(700+Molecular Weight of the Inorganic Compound). So for Ammonia since it has NH₃ as its chemical formula, we can easily obtain its molecular weight by simply summing up the product of the number of atoms of each element and the atomic mass of the element. So for Ammonia, atomic mass of nitrogen (N) is 14 and since it has only 1 nitrogen atom, we retain 14 and since ammonia contains three hydrogen (H) atoms, we will simply multiply it with 1 since the atomic mass of hydrogen is 1, and that makes it 3. And the sum is 17. Therefore the refrigerant designation number for ammonia (NH₃) is R-717. For additional information, you may refer to ASHRAE’s Refrigerant Designations under the Inorganic Compounds group.

• 1000 Series
  For this series of refrigerants it solely dedicated to the unsaturated hydrocarbons and their derivatives, wherein the naming convention goes like this:
  

  
  Wherein;
  
  As far as I can remember, hydrocarbons that are having double or triple bonding are those that belong to alkenes and alkynes. Alkenes are unsaturated carbons wherein it has at least one carbon-to-carbon double bond, for example ethylene wherein it has a chemical formula of C₂H₄ or for easier recognition, H₂C=CH₂, as you’ve notice that “=” indicates that is double bond between the two Carbon atoms which is composed of two lines. For this blog post we will tackle only the alkenes since based on ASHRAE’s Refrigerant Designations under the Unsaturated Organic Compounds group, most of the compounds being listed are alkenes. With that, I will obtain the refrigerant designation for ethylene which is also known as ethene; since it has “1” double bond, “R-“ is followed by “1” and then, since it has 2 Carbon atoms, it is followed by “1” from the formula of (m-1); then since it has “4” Hydrogen atoms thus it is followed by “5” based on the formula (n+1); and finally since it has no Fluorine atoms, it is automatically followed with “0”. So ethylene’s refrigerant designation number is R-1150.

I guess that would be all for my blog post regarding the naming convention for the refrigerants being used previously (I am talking about those HCFCs that are to be banned like Freon based refrigerants) and the ones that are still being used up to this day.

Thank you for spending your time reading this blog post of mine.

Much love and respect.

Joseph Ace Tigas | @josephace135
Registered Mechanical Engineer (RME)

References:

1. https://en.wikipedia.org/wiki/Freon
2. https://en.wikipedia.org/wiki/Octafluorocyclobutane
3. https://refrigeranthq.com/refrigerants-get-name/
4. https://www.quora.com/How-is-the-nomenclature-of-refrigerant-done
5. https://www.ashrae.org/technical-resources/standards-and-guidelines/ashrae-refrigerant-designations
6. Industrial Plant Engineering by Joel A. Mandawe and Roger S. Capote