Adjusting the pump flow rate by adjusting the valve is one of the most commonly used flow control methods. The principle is to adjust the outlet valve opening to change the pipeline characteristic curve, thereby adjusting the pump operating point to achieve flow control.
Specific operation method:
• Install a regulating valve on the pump outlet pipe.
• Gradually reduce the valve opening to increase pipe resistance.
• This causes the pump's operating point to shift to the left along the performance curve, reducing flow.
Advantages and disadvantages of valve adjustment
ADVANTAGES:
• Easy to operate: Simply adjust the valve opening, no complex equipment required.
• Quick response: Flow rate can be continuously adjusted, and adjustments are immediate.
• Low cost: Compared to other control methods, valve system investment is minimal.
DISADVANTAGES:
• Increased energy consumption: When the valve is closed for a short time, flow resistance increases, consuming additional energy.
• Reduced efficiency: The pump may operate outside of its optimal efficiency point.
• Potential risks: Extremely low flow rates may cause cavitation, vibration, and increased temperature.
Comparison of other flow regulation methods
Adjustment Method | Principle | Applicability | Advantage | Disadvantage |
| Valve adjustment | Changing pipeline resistance | Centrifugal pumps | Simple operation and low cost | High energy consumption and low efficiency |
| Variable frequency speed regulation | Changing pump speed | Various pumps | Energy-saving, high efficiency and precise control | High equipment costs |
| Bypass regulation | Partial liquid reflux | Reciprocating pump | Solve the problem of continuous operation with small flow | High energy consumption and low efficiency |
| Cutting impeller | Changing the impeller size | Long-term fixed adjustment | No additional energy loss | Irreversible regulation |
Recommendations and precautions
• Short-term adjustment: If you only need to temporarily reduce the flow rate, valve adjustment is the easiest way.
• Long-term adjustment: If frequent adjustment is required or energy saving is required, it is recommended to consider variable frequency speed regulation.
Safe Operation:
• Avoid excessively small valve openings (recommended: no less than 30%) to prevent cavitation and vibration.
• Monitor pump outlet pressure and temperature changes.
• Regularly check valve sealing performance.
Economic considerations: Although valve adjustment has low initial cost, it consumes high energy in the long term, so comprehensive evaluation is required.
Conclusion:
Simply adjusting a pump's flow rate through valve adjustment is a viable and commonly used method.
However, it can be energy-intensive and potentially risky.
For long-term or frequent flow control needs, more efficient methods such as variable frequency drive (VFD) are recommended.
