INVESTIGATION OF THE WEAR RESISTANCE OF POLYMER-GRAPHITE MATERIALS (AS APPLIED TO FACE PACKINGS),

An experimental device was used to determine the wear resistance of a polymer-graphite pair of face packing rings for pumps handling HC1 and Hsub 2 SO 4. It consisted of a small pressure vessel containing HC1 and 3 atm of pressure over which was mounted a vertically rotating shaft around which was mounted a vertically rotating shaft around which the packing rings had been placed. The hard plastic ring was made of KF-10 molded plastic containing polytetrafluorethylene, ground quartz and organosilicon resin. The graphite ring was fashioned from E-grade antifriction material and all other parts of the device which came into contact with the acid were made of phenolformaldehyde impregnated graphite. Tests were conducted after a preliminary run-ib of 4-6 hr to permit the packing to wear sufficiently to provide a good seal. By this time the coefficient of friction and leakage of acid around the shaft had been reduced to acceptable minimums. It was found that after prolonged standing overnight the friction coefficient had increased, suggesting that there was a lack of lubricant acid in the friction joint. A check of the friction surfaces revealed that the plastic ring was covered with a thin graphite film that was difficult to scrape off, but which was easily removed with alcohol. Author