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).
The physical properties, construction, and leakage tests of Sinterkorund sparking plugs.
| Identifier | ExFiles\Box 58\2\ Scan074 | |
| Date | 3rd May 1934 guessed | |
| 2. E&I.827. The plug body is of steel and the "Sinterkor-und" insulator with central electrode rests on a copper washer which beds upon a shoulder in the plug body as shown. A second copper washer beds on the shoulder of the insulator and the plug centre is secured in position by the top edge of the plug body being spun over a brass sleeve which presses on the second copper washer. The gas tightness of the plug is dependent upon the soundness of the joint made by the above copper washers and upon the homogeneity of the cemented joint between the central electrode and the "Sinterkorund" insulator. Table 1 below gives the gas space volume and weight of each of the three types of Siemens plugs and of a standard aero sparking plug. Table 1. | Type of Plug. | Weight. | Gas space volume. | |-------------------|----------------|-------------------| | Siemens A.G.10 | 3 oz. 3 drams. | 2.0 cu.cm. | | " A.G.20 | 3 oz. 3 drams. | 1.7 cu.cm. | | " A.G.30 | 3 oz. 3 drams. | 1.3 cu.cm. | | Standard plug. | 3 oz. 1 dram. | 1.1 cu.cm. | 3. Physical properties of "Sinterkorund". Details of the physical properties of "Sinterkorund" have been published in the German technical press and a resume of the results is given in Leaflet No.6249 published by the Research and Standardisation Committee of the Institution of Automobile Engineers (See Appendix to this Report). The results show that "Sinterkorund" is superior to mica, porcelain, steatite and sillimanite in respect of heat conductivity and electrical resistivity. It is also less affected by high temperatures and has a considerably higher melting point. Qualitative experiments were made at R.A.E. to determine the resistance of the material to injury by handling. It was found that "Sinterkorund" successfully resisted attempts to fracture by dropping from a height of 10 to 12 feet on to a concrete floor and by repeated impact. 4. Gas leakage tests. Each of the plugs was tested for gas leakage at 100 lb. per sq.inch air pressure atmospheric temperature. The results are given in table 2 below. | ||