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Properties of propylene glycol used as an RV or heating boiler antifreeze and in other applications.
This article series describes how to add anti-freeze to a heating boiler and to the hot water or hydronic heating system piping, baseboards, convectors, radiators, etc. to protect the system from freeze damage.
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Propylene Glycol Properties, Toxicity, Poisoning Symptoms, Detection in Water
Reader Question: How can you tell if the propylene glycol is leaking into the drinking water?
3 September 2015 AJ said:
How can you tell if the propylene glycol is leaking into the drinking water? What are the signs? Can it be seen, tasted or smelled?
First, if you're asking about leaks in a tankless coil in a heating boiler that has been treated with propylene glycol as an antifreeze solution, except when the building has lost water pressure, the leaks would tend to be in the opposite direction: from the tanklsess coil into the boiler, not the other way around.
See TANKLESS COIL / HOT WATER COIL LEAKS if that's your concern.
The U.S. ATSDR data on ingestion or respiration of propylene glycol at high levels enough to be discussed as toxic includes symptoms resembling inebreiation or "drunkeness" that we detail in a bulleted list below.
At very low concentrations you'd not know by taste (sweetness) that propylene glycol was in your drinking water. You'd need a water test lab assay test. The state of New Hampshire in the U.S. published comments including
There is no federal or state drinking water guideline for propylene glycol, and EPA has no
approved oral or inhalation toxicity values for it. However, DES has determined that 30,000 ppb
is an appropriate interim drinking water guideline for propylene glycol based on current toxicity
information and that there is also dietary exposure because of its use as a food additive. - retrieved 3 Sept 2015 original source des.nh.gov/organization/commissioner/pip/factsheets/ard/documents/ard-ehp-12.pdf
Various uses of propylene glycol as an antifreeze in RVs, building heating systems, and other applications are discussed
at ANTIFREEZE for BOILERS
Standardized test procedure for proplylene glycol
ASTM E202 - 12 Standard Test Methods for Analysis of Ethylene Glycols and Propylene Glycol - Quoting: These test methods measure certain chemical and physical properties of ethylene glycols and propylene glycols and may be used to determine compliance with specification in which limits are established for these properties. For those tests that use the procedure of another ASTM test method, that test method should be consulted for additional information on the significance and use of that test.
There are tests for propylene glycol both as medical tests (difficult as we cite below) and as a concentration in antifreeze solutions but I could not find an expert source citing a commonly-used test for low levels of propylene glycol in drinking water.
Indirectly and more crudely there are "antifreeze test strips" used in the automotive industry that will respond to both the toxic and the potable glycols. But I'm doubtful that such testing would be sufficiently sensitive to detect low levels of glycol in a building's water supply or well.
This ATSDR comment on proplyene glycol is helpful
Excerpt: Propylene glycol is generally considered to be a safe chemical, and is not routinely tested for, unless specific exposure, such as to a medicine or cosmetic, can be linked with the observed bad symptoms. Since propylene glycol breaks down very quickly in the body, it is very difficult to detect.
... According to the World Health Organization, the acceptable dietary intake of propylene glycol is 25 mg of propylene glycol for every kilogram (kg) of body weight. - www.atsdr.cdc.gov/phs/phs.asp?id=1120&tid=240
The following describes how to identify propylene glycol but NOT how to detect it in low concentrations
Identification (1) To 1 ml of Propylene Glycol, add 0.5 g of potassium hydrogen
sulfate, and heat. A fruity odor is evolved.
(2) With 2－3 drops of Propylene Glycol, mix 0.7 g triphenylchloromethane, add 1
ml of pyridine, heat with a reflux condenser on a water bath for an hour, and cool.
Dissolve in 20 ml of acetone while heating, add 0.02 g of active carbon, stir, and filter.
Concentrate the filtrate to about 10 ml, and cool. Collect the diposited crystals by
filtration and dry for 4 hours in a desiccater. The melting point of the crystals so
obtained is 174－178℃. - (2008). Health effects of ethylene glycol and propylene glycol. Retrieved from www.eoearth.org/view/article/153380
Symptoms of Polypropylene Glycol Poisoning
Neurological Effects of Propylene Glycol if Consumed at Toxic Levels
Neurologic effects: The initial phase of ethylene glycol poisoning is characterized by inebriation caused by unmetabolized ethylene glycol. In acute poisoning cases, the following symptoms are common (Parry and Wallach 1974; Buell, Sterling et al. 1998)
The ATSDR article continues:
Possible sequelae of severe poisonings (Walder and Tyler 1994; Hantson, Vanbinst et al. 2002) include
Cerebral edema and deposition of calcium oxalate crystals in the walls of small blood vessels in the brain contribute to this CNS toxicity (Jobard, Harry et al. 1996; Bey, Walter et al. 2002; Tobe, Braam et al. 2002). Some studies also documented brain dysfunction with corresponding cranial computed tomography findings after ethylene glycol ingestion (Chung and Tuso 1989; Zeiss, Velasco et al. 1989; Morgan, Ford et al. 2000).
The ATSDR document (cited below, includes discussion of cranial nerve damage and respiratory effects, renal effects, and other effects.
Reader Question: use of the Propylend Glycol that is put in RV's,Cabin systems,etc. (Uni-Gard-50) sold in Home Depot,
(Nov 16, 2012) Ron said:
Why can't the use of the Propylend Glycol that is put in RV's,Cabin systems,etc.(Uni-Gard-50) sold in Home Depot, be used in the Hot Water system of a home.
In the article above that is exactly what experts recommended.
Reader Question: oily look in boiler water after installing antifreeze
(Jan 23, 2014) Marni Olsen said:
My plumber recently drained my Weil McLain Boiler & I have a Sid Harvery McDonnell & Miller cut-off. He put in what I believe is anti-freeze the water color is a light green & when I drain the water its slightly oily looking. I need to know if this is toxic since I toss the water outside into the ground. Also is this the right anti freeze to use? THe plumber will not return calls & will not speak to me of what he did.
Marni, there are two different types of antifreeze used in heating systems, one toxic and the other using food-grade products is non-toxic. You will need to ask the installer what product was used.
Installers may use either propylene glycol (non-toxic food-grade antifreeze, recommended where a tankless coil is used on a heating boiler and in some other cases), or ethylene glycol (automotive type and highly toxic antifreeze).
Leave a polite message for your plumber noting that you just want to know the brand and product of antifreeze installed.
About your comment "when I drain the water" - I'm unclear why you would ever be draining water from your heating system - that's not a normal step except for steam boilers which surely is not your case. What's going on ?
Let us know what you are told and I can comment further.
Reader Question: other uses are there for boiler glycol
(Oct 5, 2014) Fred said:
What other uses are there for boiler glycol. I just changed boilers and have about 15 gallons left over
Food grade antifreeze products are also used in winterizing RVs and plumbing.
Propylene Glycol Toxicity Research
ATSDR: - retrieved 3 Sept 2015, original source: www.atsdr.cdc.gov/phs/phs.asp?id=1120&tid=240
"Propylene Glycol, Properties" , [PDF] Japan Food Chemical Research Foundation, retrieved 3 Sept 2015, original source: http://www.ffcr.or.jp/zaidan/ffcrhome.nsf/
Toxicological Profile for Ethylene Glycol and Propylene Glycol. Agency for Toxic Substances and Disease Registry (ATSDR). Atlanta, Ga. September, 1997.
Toxicological information on ethylene glycol Integrated Risk Information System (IRIS). U.S.
EPA, Office of Health and Environmental Assessment. Last significant revision: September,
Health Advisory for Ethylene Glycol. U.S. EPA. Office of Drinking Water. Washington, D.C.,
Toxicological information on propylene glycol. Compiled on the Hazardous Substance Data
Bank (HSDB). National Library of Medicine. Bethesda, Md. toxnet.nlm.nih.gov/cgibin/sis/htmlgen?HSDB
ATSDR: - retrieved 3 Sept 2015, original source: www.atsdr.cdc.gov/phs/phs.asp?id=1120&tid=240
Heating boiler antifreeze, usually a non-toxic polypropylene glycol anti-freeze and water mixture is installed in hot water heating boilers and plumbing systems to reduce the risk of expensive freeze damage to the heating system piping and of course to avoid costly water or even mold contamination that occurs when an unattended building suffers burst heating piping and leaks.
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 "Antifreeze & Heat Transfer Fluid", Noble Company, PO BOx 350, Grand Haven MI 49417-0350, Tel: 80-878-5788, Email: email@example.com, Web page: http://www.noblecompany.com/, NOBURST product series product literature, retrieved 10/8/2012, original source: http://www.noblecompany.com/Portals/0/PRODUCT%20INFO/ Product%20Guides/Noburst%20PIG%200811%20lr.pdf [Copy on file as Noburst_Product_Lit_PIG_0811_lr.pdf]
 Rhomar RhoGard™ Antifreeze, Rhomar Water Management, Inc., Propylene glycol antifreeze and heat transfer fluid, Rhomar Website: http://www.rhomarwater.com. This product is rated safe for aluminum and other metals such as cast iron, copper, and steel, and includes corrosion protection.
 Utility Chemicals No-Freez (non-toxic antifreeze, perhaps a good idea if the heating system includes a tankless coil). This product uses propylene glycol as its active ingredient. Utility Manufacturing Co., Inc., 700 Main St., Westbury NY 11590, Tel: 516-997-6300.
 E-Z Red S102 or EZRSP102 Antifreeze Hydrometer (less than $10. U.S.), available at Amazon and from E-Z Red Company, E-Z Red Company
8 Leonard Way PO Box 80 Deposit, NY 13754, Tel: 1.800.522.7947, E-mail: firstname.lastname@example.org, Website: www.ezred.com
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