Page 4 of Bearing Units Plastic Housing Series by NTN Corporation Japan

dimensions for dust cover unit mm inch cover number rm-204 rm-205 rm-206 rm-207 rm-208 36 41 50 60 68 l d1 1 32 1 8 1 32 2 8 2 16 dimensions d2 50 55 64 74 84 1 32 2 32 2 32 2 16 3 16 29.5 31.0 35.0 38.0 40.0 l 1 32 1 32 1 8 1 2 1 16 1.2 0.05 inches d2 d1 cover w ater and chemical resistance of housing valox 420 ® among engineering plastics valox has better water absorption characteristics 0.06 at 23 over 24 hours and better dimensional stability valox is made of crystallized polymer and while not affected by organic solvents is affected by alkaline making it important to consider the operating environment the table demonstrates valox s chemical resistance when soaked in solvent at 30 or 90 days 1 1 chemicals hydrochloric acid 10 acid sulfuric acid 36 deterioration ratio temperature number of days soaked 30 days 23 23 60 23 23 23 23 23 23 23 60 96 100 100 100 93 87 100 100 100 90 89 97 84 88 88 chemicals ethyl alcohol methyl alcohol isopropyl alcohol acetone methyl ethyl keton ethyl acetate methylene chloride ethylene grycole zinc chrolide 10 calcium chrolide 10 sodium chrolide 5 temperature deterioration ratio number of days soaked 30 days 90 days 96 82 100 74 80 86 54 100 94 98 97 99 91 100 86 90 96 54 100 97 98 97 90 days 85 97 60 88 10 23 23 23 23 23 23 23 23 23 23 23 acetic acid 10 potassium hydroacid 5 alkaline sodium hydroacid 10 ammonia hydroacid 10 motor oil brake oil oil gasoline regular organic solven sodium remarks 1 deterioration is the strength after test divided by the strength before test the ·¦ symbol indicates that results could not be measured as the test piece dissolved remarks 2 the values listed in the table are not guaranteed as they are the result of soaking without operating stresses on the sample because this strength data is general it does not apply under all operating conditions actual housing strength will vary depending on the type and concentration of liquid temperature load etc remarks 3 technical data provided by general electric company anti-corrosion capability ntn recommends ratings of to for optimum corrosion resistance excellent poor condition materials martensite stainless steel austenite stainless steel polyester plastics sus440c sus410 sus304 scs13 valox 420 atmosphere dry wet water acid hydrochloric acid natural water sodium water nitric acid sulfuric acid polypropylene polyethylene high carbon steel carbon steel cast iron remarks this data is obtained by observation of the surface conditions of materials note that these anti-corrosion capabilities are altered by anti-corrosion surface treatment not recommended for use in liquid suj2 3

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