Antifreeze solutions

TABLE 5.13 Compositions of Aqueous Antifreeze Solutions Continued)... 

PETROLEUM-NOTffiNCLATURE IN TTiE PETROLEUM INDUSTRY] (Voll8) -of antifreeze solutions [ANTIFREEZES AND DEICING FLUIDES] (Vol 3)... 

Corrosion Inhibition. Another important property of antifreeze solutions is the corrosion protection they provide. Most cooling systems contain varied materials of constmction including multiple metals, elastomeric materials, and rigid polymeric materials. The antifreeze chosen must contain corrosion inhibitors that are compatible with all the materials in a system. Additionally, the fluid and its corrosion inhibitor package must be suitable for the operating temperatures and conditions of the system. 

Fluid Specifications. The performance characteristics of all antifreeze solutions are governed by fluid specifications, that have been developed over the years by industry standards committees, such as the American Society for Testing and Materials (ASTM) and the Society of Automotive Engineers (SAE). Additionally, most engine and/or cooling system manufacturers have thek own compositional specifications to which the fluids must conform. 

Soldered brass seldom gives trouble. In radiators, antifreeze solutions have been alleged to cause corrosion, possibly because materials such as ethylene glycol sometimes detach protective deposits. Sodium nitrite, valuable as a corrosion inhibitor for other metals in a radiator, tends to attack solders, but sodium benzoate is safe and, in addition, protects the soldered joint against the action of nitrites. In an investigation of other inhibitors in ethylene glycol solutions, 1% borax, either alone or in combination with 0-1% mercaptobenzothiazole, appeared to be satisfactory. 

In all circumstances it is important to ensure that the inhibitor is chemically compatible with the liquid to which it is added. Chromates, for example, cannot be used in glycol antifreeze solutions since oxidation of glycol by chromate will reduce this to the trivalent state which has no inhibitive properties. 

Alkali-metal phosphates have been incorporated in antifreeze solutions but there are indications of unfavourable behaviour with aluminium alloys... 

Locomotive diesels As larger volumes of coolant are required in railway locomotives than in road vehicles, the cost of inhibition is proportionally greater. An additional factor is the possibility of cavitation attack of cylinder liners. These considerations place a restriction on the choice of inhibitors. In the past, chromates have been used at concentrations of up to 0-4%, but their use presents handling and disposal problems. Chromates cannot be used with ethanediol antifreeze solutions. A IS I borate-metasilicate at a concentration of 1 % has been used in the UK. Nitrate is added to this to improve inhibition of aluminium alloy corrosion. Tannins and soluble oils are also used, but probably to a lesser extent than in the past. The benzoate-nitrite formulation (formerly BS 3151) is effective and has been used by continental railways . ... 

An antifreeze solution is prepared containing 50.0 cm3 of ethylene glycol, C2H602 (d = 1.12 g/cm3), in 50.0 g of water. Calculate the freezing point of this 50-50 mixture. 

Anode Electrode at which oxidation occurs and toward which anions move, 481-485,496 Antifreeze solution, 270 Antimony, 63... 

Antifreeze sprinkler system a wet pipe system that contains an antifreeze solution and that is connected to a water supply. 

Small wet pipe systems can be protected by an antifreeze solution. The extent of the system should be limited to 20 sprinkler heads or less. For systems over 20 sprinkler heads, a dry pipe system should be used. 

The salt is a buffering agent in antifreeze solutions. Other apphcations are in fertihzers nondairy creams and culturing of antibiotics. 

Glycerol is used (l) in the manufacture of high explosives, e.g,. glyceryl trinitrate ( nitroglycerin ), which is the main component of dynamite. (2) in antifreeze solutions, especially for automobile radiators. (3) to maintain a moisi condition in fruits and tobacco, (4) in cosmetics and skin preparations, and (5) to prepare glycerol phosphoric acid, used in medicine, and "boroglyceride" used as, a preservative. See Table l... 

Glycol is used (l) in antifreeze solutions, especially for automobile radiators (2) in the preparation of ethers and esters, especially nitrate for explosive (3) as a solvent substitute for glycerol. 

Y" l Sarah F. McDuffie and Cather-MJI ine E. Matthews, "Antifreeze Solutions The Colligative Properties of Antifreeze," The Science Teacher, Vol. 63,1996,41-43. 

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