Mag Drive Pump Operation and Troubleshooting

From steel processing plants to chemical manufacturing, a mag drive pump is the go-to solution for myriad applications. Across multiple industries, facility engineering, operations and technicians turn to a mag drive pump for safe, reliable fluid transfer.

For successful operation in any application, best practices are key. Whether the pump is used for wastewater processing, electroplating and anodizing, or chemical manufacturing and distribution, proper start-up and maintenance remain crucial. For optimal results in any mag drive pump application, use the following best practices and troubleshooting tips.

Best Practices for Mag Drive Pump Operation

Note that best practices for start-up and ongoing operation of a mag drive pump may vary based on the specifications of each model. Following are the fundamental procedures for initial start-up and operation of a non-self-priming mag drive pump. Follow these seven steps for successful pump operation.

1. Pre-check

Before starting the pump, ensure the motor fan can rotate freely. To check this, insert a screwdriver through the fan cover to rotate the fan manually. Additionally, verify that all flange and hold-down bolts are tightened before start-up.

2. Prime

Fill the pump from a flooded suction tank (gravity) or liquid from an outside source. Ensure the pump is filled with liquid and the inlet (suction) valve is open.

3. Discharge valve prep

Open the discharge valve completely and then close it so that there is no trapped air in the suction and discharge line.

4. Rotation check

Once the pump is full of fluid, verify that the rotation of the motor/pump is the correct direction. To perform this check, jog the motor for approximately half a second, observing the rotation from the fan end. Refer to the rotation arrow on the housing or in the product manual.

Note: If the rotation is reversed, this will cause a significant reduction in flow and pressure.

5. Start-up

Once the above pre-start checks are complete, ensure the pump is full of liquid and the inlet (suction valve) is fully open. Turn on the pump and slowly open the discharge valve. Verify that the pump has proper flow and pressure and is running without excessive noise or vibration.

6. Suction valve operation

Keep the suction valve in the fully open position. Never use this valve to regulate the flow rate. Use the discharge valve instead.

Note: It is not necessary to jog the motor or adjust the valves on subsequent pump starts provided that the pump and piping remain full of fluid.

7. Power monitor

For pumps with ceramic, PTFE, or silicon carbide bushings, use of a power monitor is strongly recommended. This will stop the pump and help prevent damage if the pump runs dry.

Adherence to these procedures will reduce operational problems with a mag drive pump. However, if issues arise, use the following troubleshooting tips to evaluate and resolve the situation.

5 Troubleshooting Tips for Mag Drive Pump Operations

1. Insufficient pressure

If a mag drive pump is experiencing insufficient pressure, this is typically caused by one of four issues.

  • Check for air or gas in the fluid being pumped.
  • Confirm that the impeller diameter is not too small.
  • Verify that the system head is not lower than anticipated.
  • Check to see if the motor speed is insufficient or if the motor rotation is incorrect.

2. Insufficient discharge

If there is no discharge or insufficient discharge, this can be caused by one of several common problems with a mag drive pump. Check each of these variables and make necessary corrections to restore sufficient discharge.

  • There may be air leaks in the suction piping.
  • The pump might not be primed.
  • The system head may be higher than anticipated.
  • The valve may be closed.
  • The viscosity or specific gravity may be too high.
  • The suction lift might also be too high.
  • The suction line or impeller vanes may be clogged.
  • The motor rotation may be incorrect.

3. Loss of prime

Potential causes include a leaking suction line, air or gas in the fluid, a leaking foot valve, foreign matter in the impeller, or a leaking valve. Additionally, the foot valve or suction opening may not be sufficiently submerged, or the suction lift may be too high or insufficient NPSHa (net positive suction head available).

4. Excessive power consumption

When a mag drive pump is consuming excessive power, this is usually caused by one of several issues. Check for excessive flow, verify that the head is not lower than the rating, and confirm that the specific gravity and viscosity are not too high.

5. Vibration/noise

While some noise is expected from mag drive pump operation, excessive noise is a potential red flag that something may not operating correctly. Check for foreign objects in the impeller. Ensure the motor and piping are properly secured. Look for drive magnet rubbing. Lastly, check for improper suction or feed, which can cause pump cavitation.

Bonus tips

Maintenance is key to optimal mag drive pump operation. Follow a regular maintenance schedule for each mag drive pump. The recommended schedule depends on the nature of the fluid being pumped and the specific application. Use the following guidelines for typical recommendations.

  • Initial maintenance – Remove and examine the mag drive pump after an initial 6 months or 2,000 hours of operation (sooner for pumps that transfer fluids with solids, at high temperatures, or other conditions that could cause accelerated wear).
  • Ongoing maintenance – Remove from service annually for examination.

We're Here to Help

For additional assistance regarding product operation or repair, contact the Finish Thompson mag drive pump experts via our toll-free Technical Service Hot Line, 1-800-888-3743.

If you need spare parts, these can be ordered from your local Finish Thompson distributor. Refer to the pump model number for ordering. See our full product selection for reference at and learn more about our premier mag drive pump series below.

Meet Our Mag Drive Pump Series

DB Series – Flooded Suction Design Mag Drive Pump Series

  • High efficiency
  • No seals, so there are no leaks
  • Hours of run-dry capability
  • Strongest neodymium magnets
  • Rugged construction

Finish Thompson DB Series Mag Drive Pump

SP Series – Self Priming Mag Drive Pump Series

  • Run-dry capability
  • Lightning-fast priming
  • No seals, so there are no leaks
  • Powerful deep vacuum, capable of lifting fluid from as deep as 25 ft. (7.6 meters)
  • Corrosion-resistant materials handle the most difficult applications

Finish Thompson SP Series Mag Drive Pump

MSDB Series – Multi-stage Design Mag Drive Pump Series

  • Much higher heads at lower flows
  • Heads up to 300 feet (91.5 meters)
  • 2 and 3-impeller models
  • 5 year warranty

Finish Thompson MSDB Series Mag Drive Pump

UltraChem® Series – ANSI Dimensional Mag Drive Pump Series

  • ETFE lhousing lining and internal components for superior corrosion resistance
  • Tough ductile iron construction
  • Sealless design for leak-free performance
  • ANSI dimensional for easy installation
  • Large assortment of sizes

Finish Thompson UC Series Mag Drive Pump

About Finish Thompson

Finish Thompson Inc. designs and manufactures pumps for the safe transfer of a wide variety of corrosive liquids. Products include sealless mag-drive centrifugal pumps with run-dry capability, mechanically sealed pumps, drum and barrel pumps, vertical mag-drive pumps, multi-stage pumps and FTI Air line of air operated double diaphragm (AODD) pumps. For durable solutions for your applications, contact Finish Thompson Inc.

Technician maintaining a Finish Thompson mag drive pump