From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of the causes and composition of sludge build-up in car radiators, with a proposed preventative heat treatment.
| Identifier | ExFiles\Box 27a\3\ Scan074 | |
| Date | 26th October 1929 | |
| x4516. H11/EJW. 26.10.29. Laboratory. RE. BLOCKING OF CAR RADIATORS. The sludge that accumulates between the radiator tubes has the approximate composition :- Hydrated oxide of iron ................. 78 % Aluminium hydroxide .................... 8 % (when using 8% copper aluminium head) Calcium and magnesium carbonates ..... 7 % Copper and zinc oxides ................ 2 % Balance .............................. Traces of chlorine, siliceous matter, oil, and fluff. The scum on the tubes themselves is generally much higher in calcium carbonate, chlorine, and zinc. The most important factors governing the amount of sludge produced are :- (1) The resistance of the cast iron surface to corrosion. (2) The nature of the water or solution circulating. (3) The potential due to the presence of the aluminium alloy cylinder head. (4) The progressive roughening of the radiator tubes by corrosive action and deposit. (This tending to collect suspended particles and hinder the water flow.) From laboratory tests which are still in progress it appears that the best simple procedure for the protection of the cast iron is the heating of the cylinder block for two or three hours at a temperature of 500°C. to 600°C. This treatment tends to supplement and re-inforce the more or less damaged internal skin of the water jacket, and results in a coherent scale which stands up to prolonged boiling and cooling under similar conditions to those existing in service. This protective treatment should in itself reduce the amount of sludge to a fraction of that normally produced. | ||