Document 1QvEbYGwGz6qgmVydqv9mGrv5

CC: S. W. Ellis S. H. Markette R. W. Forloines TO: FROM: .0 N. DANIELSON C. M. BECK August 27, 1982 ROLLAWAY PORTABLE DUST COLLECTOR The intake air velocity of the Tepco Model 21 Rollaway dust collector in Central Shops was checked on 7/28/82 and found to be inadequate. The hose arm was replaced and the collector was again monitored using the Alnor Type 8500 Thermo-anemometer. Ten measurements were taken at the face of the cone on 8/26/82. The table below compares the BEFORE and AFTER measurements with manufacturer specifications: Measured Spec BEFORE . AFTER Ai r Volume Area of Cone 686 cfm - 220.2 cfm .687 sq. ft. 669.8 cfm - Area of Duct Duct Velocity - 3500 fpm .196 sq. ft. 1123.4 fpm - 3417.3 fpm Cone Face Velocity (998.5 fpm*) 320.5 fpm 975 fpm Ca pt ure Velocity (at 1') 2000 fpm ** ^Calculated from specs. **Unable to measure due to extraneous wind currents ** The air volume and dust velocity measurements are very close to the specifications now. The ACGIH recommended duct design velocity for grinding ventilation is 3500 fpm. The manufacturer's specification for capture velocity is impossible to attain at their own air volume and duct velocity specs. Calculated from these, however, the cone face velocity (spec) is 998.5 fpm, which is very close to the measured 975 fpm. Annual velocity checks will ensure that the collector maintains adequate performance. DUP 0814680 CMB:sgd "SAFETY IS MY RESPONSIBILITY" DU 009962