Question 1

How do I select the right BLDC motor size for my pump?

Accepted Answer

Start with the required flow rate and head pressure. Multiply flow (m³/h) by head (m) and divide by 367 to get the hydraulic power in kW, then divide by pump efficiency (typically 0.5-0.7) to find motor shaft power. Add a 15-20% safety margin. For most small to mid-size water and circulation pumps, this puts you in the 50W-800W range that Shenghe covers with standard BLDC platforms.

Question 2

Can a BLDC motor control pump flow rate without a valve?

Accepted Answer

Yes. BLDC motors paired with a compatible controller allow stepless speed adjustment via PWM or analog signal. Reducing motor speed directly reduces pump impeller speed and therefore flow rate, following the affinity laws. This eliminates throttling valves, cuts energy waste by up to 50% compared to fixed-speed operation, and reduces water hammer in piping systems.

Question 3

What shaft sealing is needed when a BLDC motor drives a pump?

Accepted Answer

For wet-end pumps with a mechanical seal between pump and motor, an IP54-rated motor is usually sufficient since the motor itself stays dry. For submersible or close-coupled designs where moisture may reach the motor housing, IP65 or higher is recommended. Shenghe offers stainless steel shafts and double-lip oil seals as standard on pump-duty motors. For chemical or corrosive fluids, we also supply ceramic shaft sleeves on request.

Question 4

How much more efficient is a BLDC pump motor compared to a brushed DC motor?

Accepted Answer

Brushless DC motors typically achieve 85-92% electrical-to-mechanical efficiency versus 70-80% for brushed motors of the same size. In pump duty, where the motor runs continuously for hours, this 10-15 percentage point gap translates to significant energy savings and lower heat generation. Less heat means longer bearing and seal life, which is critical in pump applications where downtime for seal replacement is costly.

Parameter	Range
Voltage	DC 24V / 48V
Rated power	50 W — 800 W
Motor speed	1500 — 4000 RPM
Gear ratio	3:1 — 100:1 (planetary)
Output torque	0.5 Nm — 80 Nm
Protection	IP54 / IP65
Shaft	Stainless steel standard on pump models
Feedback	Hall sensor + optional encoder

BLDC Motor For Pump And Fluid Handling Systems.

Replacing Brushed And AC Induction Motors In Pump Systems

Typical Pump Motor Spec Range

Pump Application Use Cases

Technical Details For Pump Duty

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