Capacity problems, cavitation and increased energy consumption in pumps are often the result of conditions on the suction side of pumps.
In general – as a general rule – keep the suction fluid flow velocity in boiling liquids below the following values:
| tube hole | Maximum speed of boiling liquid | ||
|---|---|---|---|
| inches | mm | m/s | pes/s |
| 1 | 25 | 0,3 | 1 |
| 2 | 50 | 0,3 | 1 |
| 3 | 75 | 0,3 | 1 |
| 4 | 100 | 0,3 | 1 |
| 6 | 150 | 0,35 | 1.1 |
| 8 | 200 | 0,38 | 1.2 |
| 10 | 250 | 0,45 | 1,5 |
| 12 | 300 | 0,45 | 1,5 |
Boiling liquids – due to cavitation – can be extremely difficult to pump. If the pressure at any point within a pump drops below the vapor pressure of the liquid being pumped, vaporization or cavitation will occur. For example, the water 100 O F (38 O C) boils or vaporizes if exposed to a vacuum of 28 in Hg . The problem with cavitation increases with higher temperatures.
Source: https://www.engineeringtoolbox.com/pump-suction-flow-velocity-boiling-fluid-d_230.html
