Choosing a Pump for Honey Transfer: Flow Rate Comes First

When pumping honey and other high-viscosity media, engineers often try to use one pump model for multiple duties. But flow rate, not viscosity, is often

 the deciding factor. A recent honey project shows why.

The Application

ParameterDuty 1Duty 2

MediumHoneyHoney

Flow rate500 L/H0.3–0.6 m³/h

Viscosity3000 cP1000–1800 cP

MotorStandardStandard

For Duty 1, a CYB1.6-2y rotary lobe pump was selected: 25 mm ports, 304 SS wetted parts, 1.1 kW VFD motor, 140 rpm.

For Duty 2, the better choice is a small-flow magnetic drive pump, size 12.0 — not the CYB1.6-2y.

Why Duty 2 Needs a Small-Flow Pump

Duty 2 looks easier because the viscosity is lower. But its flow range, 0.3–0.6 m³/h, is far below the 1.6 m³/h maximum of the CYB1.6-2y.

Flow mismatch: A rotary lobe pump is positive displacement, so flow drops linearly with speed. Running 0.3 m³/h on a 1.6 m³/h pump means dropping below

 roughly 30 rpm — too slow for stable, low-pulsation output.

Internal slip: Large rotor clearances are sized for high displacement. At low speed and small flow, internal recirculation takes a bigger share of output, reducing

 actual delivered flow.

Better fit: A magnetic drive pump size 12.0 is built for small-flow, medium-viscosity duties. It handles 1000–5000 cP well and meters 0.3–0.6 m³/h more accurately

 than a large lobe pump throttled down.

The Takeaway

Duty 2's challenge is flow rate, not viscosity. Since the CYB1.6-2y already covers Duty 1, there is no reason to force Duty 2 onto the same platform. Choose a 

small-displacement magnetic drive pump with VFD or servo control instead.

Match the pump's displacement to the required flow first, then confirm viscosity and materials. An oversized pump costs you in stability, accuracy, and reliable

 output.

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