When pumping high-viscosity media, how should the speed of a screw pump be adjusted to ensure proper operation?

2026-01-10 10:35:29

When pumping high-viscosity media, adjusting the speed of a screw pump is a critical step to ensure proper operation and minimize wear. Here are some suggestions:

Pre-startup Preparation:

Before starting the screw pump, determine the direction of rotation to ensure the pump does not rotate in the reverse direction.

Never run the screw pump dry without media to avoid damaging the stator.

If the pump is newly installed or has been idle for several days, it is recommended to first inject a sufficient amount of oil into the pump body and use a hose clamp to rotate it several times before starting it.

Speed Adjustment Principles:

When pumping high-viscosity media, a lower speed should be selected. This is because high speeds increase frictional power, which increases pump wear.

The specific speed range is determined based on the pump specifications and the viscosity of the media. Generally speaking, for large pumps (with a main rod outer diameter of 60mm or more), when the media viscosity is high (such as greater than 20°E or 150cm/s), a speed of 970 rpm or 720 rpm is appropriate. If the viscosity is higher (e.g., greater than 80°E or 600 cst), it is recommended to further reduce the speed, preferably within the range of 200-500 rpm. For smaller pumps, the speed can be slightly higher, but the principle of low viscosity for high speed and high viscosity for low speed should still apply.

Operational Precautions:

During screw pump operation, regularly add lubricant to the bearing housing to maintain proper lubrication.

If leakage is detected at the shaft end, promptly address or replace the oil seal to prevent leakage.

If any abnormalities are detected during operation, such as increased noise or vibration, stop the pump immediately, investigate the cause, and troubleshoot.

Regular Maintenance:

Perform regular maintenance on screw pumps, including checking coaxiality, tightening bolts, and cleaning the pump body.

Select appropriate replacement parts, such as rubber sleeves, based on the characteristics of the medium and pump usage.