tailieunhanh - flame safeguard control phần 9

Một cánh buồm nhỏ bằng kim loại, gắn trên một pivOI, 9Klends inlolhe dòng không khí. Cơ khí liên kết truyền mol ion cánh buồm để chuyển đổi một. Chuyển đổi hoặc phá vỡ khi luồng không khí Bảng VI bao gồm chuyển đổi hành động, vận tốc không khí điều hành, chỉ đạo, kích thước cánh buồm và malerial, | FIG. 8-PRESSURE DROP vs. CAPACITY FOR A TYPICAL BUTTERFLY VALVE. MAXIMUM OPENING ANGLES SHOWN ARE USEO as trial settings when adjusting VALVES FOR HIGH FIRE. sure regulator outlet pressure by in. wc to allow tor the additional pressure drop across the 2 inch SSOVs. This requires estimating a new pressure drop tor the pressure regulator. SSOVs and Firing Rafe Control plus repeating the sizing procedure. SIZING CHART FOR FIRING RATE CONTROL VALVE Butterfly Valves are often used for Firing Rate Control Valves. Since a Butterfly Valve does not provide tight closure a safety shutoff control valve SSOV must be used upstream. In addition to the butterfly control valve size we need to know the maximum opening angle in degrees used as a trial setting when adjusting a Butterfly Valve to high fire. In our example the estimated pressure drop across the firing rate control is inches wc with a capacity of 10 500 cfh at standard conditions. a. If ssov estimated and actual pressure drop are the same. Mark the intersection of the estimated Butterfly Valve pressure drop and capacity X on Fig. 8. Use the valve size and opening angle indicated by the nearest slanted line below X. In this case applying the estimated pressure drop results In a 2 inch valve with a maximum opening angle of 4 5 degrees. b. If ssov actual pressure drop is less than the Add the pressure drop difference inch wc to the pressure drop available lor the Butterfly Valve. in. wc Mark the intersection ot 7 3 in. wc and the capacity Use the valve size and opening angle indicated by the nearest slanted line below In this case we have a 2 inch valve with a 40 degree opening. 294 .Staing. An dAppitoatkari -ri. Of Large Gasyaf eiiH V5055 VALVE SIZING NOMOGRAPH PRE jUAE OAO0 Ml 15 HH M2 140 000 - V5O55 VALVE SIZING CHART SMCrFIC GRAVITY correction r I - 500 7 Ỉ0P HP OUTLET PRESSURE 4PỈI Gauge E n 7 20 7 15 1 10 REOUIAEO information Type of Gm -__ _ ọ ci Fie G