Series VXZ Flow-rate Characteristics Note) Use this graph as a guide. In the case of obtaining an accurate flow rate, refer to pages 31 through to 35. How to read the graph The pressure differential for a o10 orifice to supply a flow of 25 L/min (VXZ23 A, port size 3/8) will be ΔP . 0.05 MPa. The optimum size for a pressure differential of ΔP . 0.4 MPa and a flow of 50 L/min will be the VXZ23 A (o10 orifice, port size 1/4). For Air For Water (P1 + 1.033) = (1 to 1.89)(P2 + 1.033) Upstream pressure of valve P1 1.0 MPa Sonic Critical pressure Downstream pressure of valve (P2) [MPa] 1.0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 VXZ2 Port size 1/4 VXZ2 Port size 3/8 VXZ2 VXZ2 VXZ2 3A3A4B5C6D 0.9 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 1,000 2,000 3,000 1,000 2,000 3,000 4,000 2,000 4,000 6,000 8,000 10,000 5,000 10,000 15,000 20,000 5,000 10,000 15,000 20,000 Flow rate Q [L/min] o10 o10 o15 o20 o25 (P1 + 1.033) . 1.89 (P2 + 1.033) Flow rate Q [L/min] Pressure differential ΔP (P1 . P2) [MPa] 500 400 300 200 100 50 40 30 25 20 10 0.01 0.02 0.03 0.04 0.05 0.1 0.2 0.3 0.4 0.5 VXZ2 o25 Cv = 12 6 D VXZ2 o20 Cv = 9.2 5 C VXZ2 o15 Cv = 5.3 4 B 3 A 3 A How to read the graph The sonic range pressure to generate a flow of 6,000 L/min (ANR) is P1 . 0.47 MPa for a o15 orifice (VXZ24 B) and P1 . 0.23 MPa for a o20 orifice (VXZ25 C). The optimum size for an upstream pressure P1 = 0.45 MPa and a flow of 6,000 L/min will be the VXZ24 B (o15 orifice, port size 1/2). Subsonic VXZ2 Port size 3/8 o10 Cv = 2.4 VXZ2 Port size 1/4 o10 Cv = 1.9 36