Test Checks Burst Point and Freeze Protection

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Burst Point and Freeze Protection

We tested each product for glycol content using a refractometer and either the ethylene glycol or propylene glycol scale, as appropriate. In the case of Camcos Arctic Ban and Sudburys Winter Stor, some portion of the freeze protection is provided by ethanol, and such mixtures cannot be easily evaluated by any field method (test tape, gravity, refractometer) unless the exact proportion is known, which we find troublesome.

Unfortunately, there is no ASTM or generally agreed upon standard test for burst point; we used the same test as many manufacturers using 50-milliliter vials.

To test corrosion protection, we immersed bundles of metal coupons (copper, aluminum, and brass, galvanically coupled) in the antifreeze products, tap water (control), and vodka for two months.

To test chemical compatibility, we reviewed past tests involving toilet joker valves and water system components, and dug into our leftover parts bin for some new tests with ethanol. We examined the parts for cracking and stiffening. None were horrible, but the result will vary according to concentration, temperature, polymer formulation, and winterizing agent formulation.

To test freezing and burst point, the vials were placed in a glycol bath in a freezer set to 0 degrees. At 20 degrees, the vial containing seawater cracked; by 10 degrees, several of the samples began to freeze; and by 0 degrees, all samples had gelled completely, except for Star brite -50, which gelled at -5 degrees. By -10 degrees, all of the samples were solid.

After repeated freeze/thaw cycling at 0 degrees, we pulled a small sample from the top of the duplicate samples and tested freeze point by refractometer. During partial freeze, ice floats, separating the water from the glycol, so the material at the top had lost as much as 7 percent of its glycol content, reducing protection-another reason not to rely too heavily on theoretical burst-point temperatures for determining the right concentration.

We also monitored evaporation at 70 degrees and relative humidity at 65 percent. Only the ethanol-based products were noticeably affected: as a result of evaporation, their freeze point was raised by 2 degrees.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.

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