Methods for Flow Rate Adjustment of Melt Metering Pumps Specifically for Meltblown Machines

Here are the main methods for adjusting the flow rate of melt metering pumps specifically for meltblown machines:

I. Stroke Adjustment Method

Principle: The flow rate is adjusted by changing the stroke length of the plunger or diaphragm. A longer stroke means more melt is delivered each time, resulting in a higher flow rate; conversely, a shorter stroke results in a lower flow rate.

Classification:

Manual Adjustment: The stroke length of the plunger or diaphragm is directly adjusted via a knob or handle when the pump is stopped or running. This method is simple and easy to implement but has relatively low accuracy and cannot achieve automatic control, making it suitable for situations where frequent flow rate adjustments are not required.

Automatic Adjustment: The stroke is automatically adjusted through driving adjustment mechanisms such as electric actuators, stepper motors, and pneumatic systems. Automatic adjustment offers advantages such as high accuracy, fast response, and programmability, making it suitable for situations requiring automated control. For example, pneumatic control adjusts the stroke by changing the air pressure signal, while electric control achieves this by changing the electrical signal.

II. Frequency Adjustment Method

Principle: The flow rate is adjusted by changing the driving frequency of the metering pump, which alters the reciprocating frequency of the plunger or diaphragm. A higher frequency means more reciprocations and a higher flow rate; conversely, a lower frequency results in a lower flow rate.

Implementation: For electrically driven metering pumps, frequency adjustment is typically achieved through frequency converters or Programmable Logic Controllers (PLCs).

III. Pressure Adjustment Method

Principle: The flow rate is indirectly controlled by changing the outlet pressure of the metering pump. For some metering pumps operating under high pressure, the flow rate is closely related to the outlet pressure.

Implementation:

Pressure Relief Valve Adjustment: By installing a pressure relief valve, the outlet pressure of the metering pump is reduced, thereby decreasing the flow rate. This method is suitable for flow rate adjustment under low pressure conditions but has lower accuracy and is susceptible to pipeline resistance.

Pressure Relief Valve Regulation: When the outlet pressure exceeds the set value, the pressure relief valve automatically opens to release excess pressure, thereby reducing the flow rate. This method is suitable for flow rate adjustment under high pressure conditions and offers safety and reliability but has a slower response speed.

Proportional Control Valve: By installing a proportional control valve, precise control of the outlet pressure is achieved, ensuring stable flow rates. This method is suitable for situations requiring high flow rate accuracy.

IV. Parallel Connection of Multiple Pumps Adjustment Method

Principle: Flow rates are added or shared by connecting multiple metering pumps in parallel.

Applications:

Flow Rate Addition: When the flow rate of a single metering pump is insufficient to meet process requirements, the total flow rate can be increased by connecting multiple metering pumps in parallel. This method is suitable for flow rate adjustment under high flow conditions.

Flow Rate Sharing: When the flow rate of a single metering pump is too high, multiple metering pumps can be connected in parallel to share the flow rate, improving flow stability and accuracy. This method is suitable for situations requiring precise flow rate control.

V. Precautions

When adjusting melt metering pumps, be careful not to over-adjust to avoid affecting the quality of meltblown products. Consider the influence of the viscosity and temperature of meltblown materials on the operation of the metering pump. Regularly clean the gears or plungers inside the metering pump to prevent material accumulation from affecting its operation.

In summary, there are various methods for adjusting the flow rate of melt metering pumps specifically for meltblown machines. The appropriate adjustment method should be selected based on actual needs. During the adjustment process, attention should be paid to operational norms and safety to ensure the stable operation of the metering pump and the quality of meltblown products.

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