Peristaltic hose pumps are known for their reliability in tough applications — from slurry to chemicals to shear-sensitive fluids. But if your system is showing signs of pulsation, surging, or even foaming, it might be time to look closer at the setup.
Key Takeaways
- Peristaltic pumps create fluid in pulses, which can lead to issues like pulsation, surging, and foaming.
- Common causes of flow problems include system inertia, backpressure issues, and the nature of the fluid being pumped.
- To reduce pulsation, consider using a dampener, increasing hose diameter, and adding backpressure.
- It’s important to check suction conditions to prevent foaming, especially with low-viscosity liquids.
- Pulsation isn’t always detrimental, but it can be problematic in precision applications such as dosing or when using sensitive filters.
Let’s break down what’s really going on, and what you can do to smooth things out.
1. Understanding the Nature of Peristaltic Flow
Unlike centrifugal or diaphragm pumps, a peristaltic pump delivers fluid in pulses. As the rotating shoe or roller compresses the hose, it displaces a fixed volume of liquid — creating a repeating pressure wave. This is what gives peristaltic pumps their self-priming and dry-run capabilities, but it also introduces a rhythmic, intermittent flow.
That’s not a flaw — it’s part of the design.
But in some systems, those pulses create problems like:
- Vibrations in downstream piping
- Flow surges into tanks or filters
- Foaming or air entrainment in sensitive fluids
- Inconsistent dosing accuracy
2. Common Flow Problems (and What Causes Them)
Pulsation
Every rotation creates a pulse. At low speeds, it’s usually manageable. But at higher RPM or with longer hoses, the effect amplifies.
Surging
This is often a result of system inertia or lack of backpressure — the fluid accelerates and decelerates, especially with compressible fluids or long discharge runs.
Foaming
Foaming is often seen when pumping low-viscosity or protein-rich liquids. The repeated squeezing action introduces air, especially if the suction line isn’t fully primed or if there’s cavitation.
3. How to Reduce Pulsation and Stabilise Flow
Use a Pulsation Dampener
A properly sized dampener on the discharge line can absorb shock waves and smooth out flow. It acts like a hydraulic buffer, especially valuable when feeding instruments, filters, or dosing points.
Increase Hose Diameter and Slow the Speed
Larger hoses move more volume per rotation. By increasing hose size and slowing RPM, you reduce the frequency of pulses while maintaining flow rate. This is especially effective in dosing or transfer applications.
Add Backpressure
Some systems benefit from a small backpressure valve to keep the hose fully expanded between compressions. This reduces recoil effects and improves metering accuracy.
Check Suction Conditions
Foaming often starts at the suction side. Ensure the hose is fully primed, the suction line is short and flooded if possible, and no air is entering around fittings.
Consider a Multi-Roller Design
Some peristaltic pumps offer multi-roller configurations (common in tube-style lab pumps). More rollers = more pulses per rotation = smoother flow.
4. When Is Pulsation Actually a Problem?
Pulsation isn’t always bad. For heavy slurries, it can help keep solids in suspension. For tough chemical transfer, it often has no impact.
But if your application involves:
- Inline instrumentation (flowmeters, pressure sensors)
- Downstream filters or membranes
- Precision dosing or filling
- Foaming-sensitive liquids (e.g. proteins, cosmetics, syrups)
… then it’s worth addressing.
5. Final Thoughts
Peristaltic pumps are built tough — but like any piece of equipment, their performance can be optimised. If you’re dealing with inconsistent flow, foam, or vibration, it doesn’t mean the pump is wrong. It just means the setup could use a tweak.
A dampener, a different hose size, or even adjusting RPM might be all it takes.
Need help diagnosing your system? Our team has experience across food and beverage, mining, water treatment, and chemical industries. We’ll help you keep things flowing — without the foam and fuss.
