Machinery Lubrication magazine published by Noria Corporation
Issue link: http://www.e-digitaleditions.com/i/1250226
www . machinerylubrication.com | May - June 2020 | 23 depending on the system pressure. e higher schedule pipe has thicker walls to contain the force of the higher pressure, thus the higher schedule pipe has a smaller inside diameter. Although the pipe may look the same on the outside, the fluid velocity will be higher through a greater schedule pipe. For most systems, turbulence can be kept to an acceptable level using the following guidelines: Pump Suction Lines Most hydraulic pumps have a suction line that is larger than the pressure line. is is because the inlet velocity must be very low to allow fluid to freely flow into the pump. Any ML This thermal image shows a hot spot in the bend of a pipe. Pipe Size (Inches) SCHEDULE 40 PIPE GPM@ 2 ft./sec. GPM@ 5 ft./sec. GPM@ 10 ft./sec. GPM@ 15 ft./sec. GPM@ 20 ft./sec. GPM@ 25 ft./sec. 1/8 .35 .89 1.8 2.7 3.5 4.4 1/4 .65 1.6 3.2 4.9 6.5 8.1 3/8 1.2 3 6 9 12 15 1/2 1.9 4.8 9.5 12 19 23.8 3/4 3.3 8.4 16.7 25.1 33.4 41.8 1 5.4 13.5 27 40.6 54.1 67.7 1 - 1/4 9.4 23.4 46.8 70.3 93.7 117 1 - 1/2 12.7 31.9 63.7 95.6 127 159 2 21 52.5 105 157 210 263 2 - 1/2 30 75 150 225 300 375 3 46.3 116 232 347 463 579 Pipe Size (Inches) SCHEDULE 40 PIPE GPM@ 2 ft./sec. GPM@ 5 ft./sec. GPM@ 10 ft./sec. GPM@ 15 ft./sec. GPM@ 20 ft./sec. GPM@ 25 ft./sec. 1/8 .35 .89 1.8 2.7 3.5 4.4 1/4 .65 1.6 3.2 4.9 6.5 8.1 3/8 1.2 3 6 9 12 15 1/2 1.9 4.8 9.5 12 19 23.8 3/4 3.3 8.4 16.7 25.1 33.4 41.8 1 5.4 13.5 27 40.6 54.1 67.7 1 - 1/4 9.4 23.4 46.8 70.3 93.7 117 1 - 1/2 12.7 31.9 63.7 95.6 127 159 2 21 52.5 105 157 210 263 2 - 1/2 30 75 150 225 300 375 3 46.3 116 232 347 463 579 restriction of inlet flow will cause the pump to cavitate and ultimately destroy itself. A pipe, tubing or hose chart can be used to determine the proper diameter pipe. ese charts should be available from the manufacturer. Since a schedule 40 pipe would be required for a suction line, use the sample schedule 40 pipe chart in Table 1 to size the line. In this example, let's assume the system pump has been upgraded to one that delivers 30 gallons per minute (GPM). Since you do not want to exceed 5 feet per second, look down the 5 feet per second column to find the flow rate. Notice that a 1¼-inch pipe can handle up to 23.4 GPM without exceeding a fluid velocity of 5 feet per second, while a 1½-inch pipe can Table 1. A sample schedule 40 pipe chart. Table 2. Another example of a schedule 40 pipe chart.