Characteristics of Limitations - Inlet Pulse in Hose Pump

The characteristics of hose pumps were discussed earlier, specifically the issue of pulses at the discharge end. Pulses in the discharged liquid are easily visible and noticeable, but those at the inlet end are less obvious.

The pulses at the discharge end are caused by the sudden recoil of the hose when the pump tube roller leaves. So, how are the pulses at the inlet end generated and manifested?

In a peristaltic pump, suction of liquid occurs as the roller moves forward, causing the hose to recoil and create negative pressure. Due to the strong recoil force of the hose in this hose pump, negative pressure can reach up to 95% vacuum.

Pulse generation at the inlet: As the roller of the hose pump rotates, it contacts and flattens the pump tube, causing the liquid to move forward with the previous roller. However, during the period when this roller has not completely flattened the inlet end of the pump tube, the volume of the inlet end decreases, resulting in a reduction in flow rate into the pump. Once this roller flattens and continues moving forward, the flow rate will increase again.

Consequences of inlet pulses: In addition to causing wear on the pump tube, inlet pulses in hose pumps also consume a portion of system pressure. However, since the fluid at the inlet is flowing towards the outlet, the overall pressure loss is much smaller compared to that at the outlet. This is because the reverse flow is offset by the intake flow. Generally, in system design, we do not consider inlet pulse issues.

Having discussed the inlet pulses and outlet pulses of hose pumps, where should we pay special attention to pulses and use pulse dampeners to reduce them?

1. Pipelines that cannot be subjected to pulse impact
2. Processes that cannot tolerate pulses
3. Systems that explicitly prohibit pulsations