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).
Letter from a supplier detailing the properties of molded insulation products, Pyroplax and Thermoplax.
| Identifier | ExFiles\Box 24\2\ Scan135 | |
| Date | 20th April 1921 | |
| COPY. THE CUTLER-HAMMER MFG. CO. Electric Controlling Devices, Boston, Mass. April 20, 1921. Rolls-Royce of America, Inc. Springfield, Massachusetts. Attention. - Mr.A.C.Ross. Assn't.to Pur.Agt. Gentlemen, SUBJECT - SAMPLES OF MOLDED PRODUCTS. We are forwarding to you today, under separate cover, samples of molded products as you requested. The grey material shown under the trade name of pyroplax is a cold molded fire resisting insulation with capacity of with-standing temperatures ranging from 1100 to 1400 degrees Fahrenheit, and at any temperature below these it will not expand, contract, loose its shape or deteriorate with age. This material has an average dielectric strength of 60 volts per mill and across breaking strength of approximately 1400 lbs. per square inch under standard tests. We can furnish pyroplax in either a grey, the same as the sampl, or a brown finish; the grey being used where high heat is encountered while the brown works very well where it is exposed to weather conditions as it is impregnated to make it weather resisting. The impregnating process gives the brown pyroplax a smoother surface than the white and it will take a slight polish. This material can be molded within commercial limits of 5/1000 to 10/1000, however, the more generous the limit allowed the lower the cost of production. Thermoplax, the brown and black materials of which we are sending samples, is used in practically 80% of our molding. This material is also cold molded under high pressure, and can be furnished in either black or brown finish and will take an extremely high polish in either color. Thermoplax is heat resisting up to approximately 800°F.{Mr Friese} It will not warp, shrink, expand, or soften when subjected to temperatures ranging from this maximum down to 300F. below 0. It is water-proof and highly resistant to atmospheric agents. Thermoplax has a dielectric strength of 70 to 110 volts per mill and a cross breaking strength of 1100 to 2700 lbs. per square inch under standard tests. Inserts can be molded in either thermoplax or pyroplax when they are supported substantially and in direct line of pressure. The curing of this material causes the piece to shrink slightly | ||