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Vacuum Pipe Pressure Loss Data

Fluids Systems Design and Engineering

Pressure Loss Data for Sizing Vacuum Pipe, Low Pressure Vacuum System

Allowable Piping Pressure Loss This is calculated using the allowable pressure loss for the system divided by the equivalent run of pipe in hundreds of feet. For example, if the measured run is 300 feet and the vacuum system has a large percentage of fittings and valves versus long straight runs of pipe, add 50 percent of the total run for fittings (150 feet), which equals 450 feet of equivalent run. The allowable system pressure loss is calculated at 5 inches of mercury, so divide the allowable system pressure loss by the equivalent run times 100 to obtain the number in 100 feet of pipe. The result is a piping pressure loss of 1.1 inches of mercury per 100 feet. However, this calculation must be made in terms compatible with the chart or table for flow rate and pressure loss per length of pipe that you have selected for sizing.

Standard Air Flow, cfm (L/min)	Pressure Drop per 100 ft (30 m) of Pipe, in. Hg (kPa)
	Nominal Pipe Size, in. (DN)
	¾ (20)	1 (25)	1¼ (32)	1½ (40)	2 (50)	2½ (65)	3 (80)	4 (100)
1 (28.3)	0.15 (0.5)	-	-	-	-	-	-	-
2 (56.6)	0.39 (1.3)	0.10 (0.3)	-	-	-	-	-	-
3 (85.0)	0.77 (2.6)	0.19 (0.6)	-	-	-	-	-	-
4 (113.3)	1.24 (4.2)	0.31 (1.1)	0.10 (0.3)	-	-	-	-	-
5 (141.6)	1.78 (6.0)	0.44 (1.5)	0.14 (0.5)	-	-	-	-	-
6 (169.9)	2.40 (8.1)	0.60 (2.0)	0.19 (0.6)	-	-	-	-	-
7 (198.2)	-	0.77 (2.6)	0.24 (0.8)	0.12 (0.4)	-	-	-	-
8 (226.6)	-	0.95 (3.2)	0.31 (1.1)	0.15 (0.5)	-	-	-	-
9 (254.9)	-	1.17 (4.0)	0.38 (1.3)	0.18 (0.6)	-	-	-	-
10 (283.2)	-	1.38 (4.7)	0.45 (1.5)	0.22 (0.7)	-	-	-	-
15 (424.8)	-	2.80 (9.5)	0.88 (3.0)	0.44 (1.5)	0.12 (0.4)	-	-	-
20 (566.4)	-	-	1.46 (4.9)	0.72 (2.4)	0.19 (0.6)	-	-	-
25 (708.0)	-	-	2.20 (7.4)	1.09 (3.7)	0.29 (1.0)	-	-	-
30 (849.6)	-	-	-	1.52 (5.1)	0.41 (1.4)	0.14 (0.5)	-	-
35 (991.2)	-	-	-	2.00 (6.8)	0.54 (1.8)	0.18 (0.6)	-	-
40 (1132.8)	-	-	-	2.50 (8.4)	0.67 (2.3)	0.22 (0.7)	0.10 (0.3)	-
45 (1274.4)	-	-	-	-	0.81 (2.7)	0.27 (0.9)	0.12 (0.4)	-
50 (1416.0)	-	-	-	-	0.99 (3.3)	0.33 (1.1)	0.14 (0.5)	-
60 (1699.2)	-	-	-	-	1.34 (4.5)	0.45 (1.5)	0.19 (0.6)	-
70 (1982.4)	-	-	-	-	1.79 (6.1)	0.60 (2.0)	0.26 (0.9)	0.07 (0.2)
80 (2265.6)	-	-	-	-	2.30 (7.8)	0.77 (2.6)	0.32 (1.1)	0.09 (0.3)
90 (2548.8)	-	-	-	-	-	0.96 (3.2)	0.41 (1.4)	0.11 (0.4)
100 (2832.0)	-	-	-	-	-	1.17 (4.0)	0.50 (1.7)	0.14 (0.5)
125 (3540.0)	-	-	-	-	-	1.71 (5.8)	0.74 (2.5)	0.20 (0.7)
150 (4248.0)	-	-	-	-	-	2.30 (7.8)	0.99 (3.3)	0.27 (0.9)
175 (4956.0)	-	-	-	-	-	-	1.28 (4.3)	0.35 (1.2)
200 (5664.0)	-	-	-	-	-	-	1.61 (5.4)	0.44 (1.5)

Source: Courtesy of Ohmed.
Note: Based on copper pipe type L, ASTM B88.