Inhibited Glycol: Properties and Manufacturing Process

General Information:

Inhibited glycol or propylene glycol is an organic double alcohol with a chemical formula of C3H8O2 and a CAS number of 57-55-6. Its official IUPAC name is propane-1,2-diol. It is a thick, clear, and nearly odorless substance with a faintly sweet taste. Propylene glycol shares similarities with glycerin - hygroscopic, soluble with water, acetone, and chloroform.

Physical Properties:

Molecular mass:                                76.10 g/mol
Melting point:                                   -59° C
Boiling point:                                    187.6° C
Vapor pressure:                                 0.2 (23° C)
Vapor density:                                   2.62 (air=1)
Viscosity:                                         91.41 cp (10.45° C)
Surface tension:                                40.1 g/s2 (25° C)
Refractive index:                                1.4324 (20° C)
Heat of vaporization:                          66.27 kJ/mol
Heat of combustion:                           -1828 kJ/mol

Manufacturing Process:

Propylene glycol is usually sourced from propylene oxide or glycerol. Manufacturing is done by either catalytic (150°-180°C) or non-catalytic high-temperature process (200°-220°C), with an ion exchange resin or a small amount of sulfuric acid or alkali. Final products include 20% propylene glycol, 1.5% dipropylene glycol, and other polypropylene glycols. Then, resulting glycols are further distilled to be purified prior to storage and distribution. To assure high quality and compliance with the FDA standards, a track-and-trace system is used to monitor the start of the process up to the delivery point.

References:

Wikipedia - http://en.wikipedia.org/wiki/Propylene_glycol

University of Akron Chemical Database - http://ull.chemistry.uakron.edu/erd/Chemicals/8000/
7709.html

Cefic - http://www.propylene-glycol.com/production.html

Monograph of Inhibited Glycol

General Information:

Inhibited glycol or propylene glycol is an organic double alcohol with a chemical formula of C3H8O2 and a CAS number of 57-55-6. Its official IUPAC name is propane-1,2-diol. It is a thick, clear, and nearly odorless substance with a faintly sweet taste. Propylene glycol shares similarities with glycerin - hygroscopic, soluble with water, acetone, and chloroform.

Physical Properties:

Molecular mass:                            76.10 g/mol
Melting point:                                -59° C
Boiling point:                                187.6° C
Vapor pressure:                             0.2 (23° C)
Vapor density:                               2.62 (air=1)
Viscosity:                                    91.41 cp (10.45° C)
Surface tension:                           40.1 g/s2 (25° C)
Refractive index:                            1.4324 (20° C)
Heat of vaporization:                    66.27 kJ/mol
Heat of combustion:                     -1828 kJ/mol

Production:

Propylene glycol is usually sourced from either propylene oxide through hydrolysis, or glycerol. Production is more or less similar with glycerin, using either catalytic (150°-180°C) or non-catalytic high-temperature process (200°-220°C). Propylene glycol is manufactured using ion exchange resin or a
small amount of sulfuric acid or alkali. Final products include 20% propylene glycol, 1.5% dipropylene glycol, and other polypropylene glycols. Then, resulting glycols are further distilled to be purified prior to storage and distribution. To assure high quality and compliance with hygienic standards, production is monitored and controlled through a track-and-trace system from the start of process up to delivery point.

References:

Wikipedia - http://en.wikipedia.org/wiki/Propylene_glycol

University of Akron Chemical Database - http://ull.chemistry.uakron.edu/erd/Chemicals/8000/
7709.html

Cefic - http://www.propylene-glycol.com/production.html

First Aid Treatment for Inhibited Glycol Exposure

Inhibited glycol is a non-poisonous substance and is considered safe by the US FDA standards for industrial use. However, exposure to large amounts and improper handling can pose serious health risks. Following precautions and application of proper first aid treatment are of paramount importance to ensure safety.

Eyes:

Liquid and/or vaporized inhibited glycol may cause mild eye irritation. If  exposure causes redness and stinging sensation, wash eyes with cold, running water for at least 15 minutes to soothe. Occasionally lift both eyelids to wash thoroughly.

Skin:

Glycol may be absorbed through damaged skin. Remove any tainted clothing and wash exposed skin areas with plenty of soap and water until irritation subsides. Apply an antibacterial cream if exposed areas develop rashes. Wash clothing well before reuse.

Ingestion:

Consumption of small amounts poses no grave danger, but intake of greater than 3-4 oz. (or approximately 100 ml.) can cause stomach pain, nausea, or even vomiting. Medical assessment may reveal hemoglobinuric nephrosis and surface changes in EEG, especially for people with kidney problems. Long-term ingestion can cause lactic acidosis and seizures.

In case of ingestion, give two to four glasses of water or milk to dilute the substance (but do not give anything by mouth to an unconscious person). It is very important NOT to induce vomiting. Instead, call the local poison control center to mitigate the problem and to get proper guidance. Victim should be monitored constantly for signs of acidosis and central nervous system  dysfunction.

Inhalation:
Inhibited glycol poses low respiratory hazards but can cause breathing difficulties and respiratory tract irritation if used in areas with poor ventilation. Because of its low vapor pressure at room temperature, vapor exposure is unlikely to happen. If inhaled, transfer victim immediately in areas with fresh, circulating air. Supplement with artificial oxygen if symptoms persist. Seek medical help immediately.

References:

Material Safety Data Sheet (MSDS) of Biopropylene Glycol. (2008, July 7). BioPG MSDS. Retrieved June 20, 2011, from www.globalbiochemna.com/uploads/BioPG_MSDS.pdf

Propylene Glycol. (2010, September 24). HordeNet at The University of Akron. Retrieved June 20, 2011, from http://ull.chemistry.uakron.edu/erd/Chemicals/8000/7709.html

Inhibited Glycol Common Applications

Inhibited glycol is a fluid widely utilized for controlling several industrial functions like secondary cooling and heating applications, protection of pipes from freezing and bursting during colder months, and for various defrosting, de-icing, and dehumidifying purposes. 

Different glycol fluids are employed for the same functions because of their similarity in physical characteristics. Propylene glycol is one of the most safe to use. It has a slightly better freeze and burst protection with minimal environmental contamination or toxicity.

Common Applications:

• Chillers
• Cold room dehumidifiers
• Heat recovery
• Boilers
• Refrigeration coil defrosting
• Sidewalk snow-melt systems
• Refrigeration warehouse floor heating
• Liquid food chillers
• Outdoor wood boilers
• Freeze/burst/corrosion protection for HVAC system
• Thermal energy storage (TES) systems
• Air preheating
• Immersion freezing or chilling for solid, wrapped foods
• Ground source heat pumps
• Process heating and chilling
• Moderate temperature batch processing
• Conveyor roller defrosting
• Fermentation and indirect food cooling
• Solar heating
• Ice skating rinks
• Beverage processing for wines and beers
• Radiant floor heating
• Hydronic heating systems

Propylene glycol is an organic alcohol, also known as propane-1,2-diol in IUPAC nomenclature. Pure propylene glycol is synthesized through the hydration of propylene oxide. Its single atom has three carbon atoms, eight hydrogen atoms, and two oxygen atoms represented by C₃H₈O₂. For non-industrial applications, propylene glycol is usually added to foods, toiletries, and cosmetic products as a humectant and preservative.

Inhibited Glycol

95% Inhibited Propylene Glycol is commonly used as a Boiler Antifreeze. It is low hazard, propylene glycol based heat transfer fluid concentrate for use in closed water systems. The corrosion inhibitor package provides an effective combination of inhibitors for steel, cast iron, copper, cupric alloys, and aluminum. 95% Inhibited Propylene Glycol is designed to be used in systems requiring freeze protection. Dilute with water to meet your specifications. Comes clear or with a pink fluorescence.