EMISSION CONTROL SYSTEMS — Dash Pot (DP) System EC-9 INSPECTION OF VTV 1. CHECK AND CLEAN FILTER ON VTV (a) Check the filter for contamination or damage. (b) Using compressed air, clean the filter. 2. CHECK VTV BY BLOWING AIR INTO EACH SIDE (a) Check that air flows without resistance from B to A. (b) Check that air flows with difficulty from A to B.