How to choose a magnetic gear pump for resins and adhesives

Resins, adhesives, and other viscous compounds are used in the production of electronics, composite materials, coatings, packaging, and industrial equipment. Their delivery requires a stable flow rate, but the properties of such liquids can vary significantly depending on their composition and temperature.

Magnetic gear pumps can be used for pumping resins and adhesive compounds with moderate viscosity. However, as viscosity increases, it is necessary to reduce the pump speed and additionally check the required torque, differential pressure, and motor power.

For very high-viscosity media, a magnetic gear pump may not be suitable. Therefore, before selecting equipment, it is necessary to evaluate the actual operating parameters of the fluid.

Why Viscosity is Crucial

Viscosity indicates the fluid's resistance to flow. The higher it is, the more force the pump requires to move the medium through the pipeline.

An increase in viscosity can lead to the following consequences:

• increased torque;
• increased motor load;
• worsened suction conditions;
• increased pressure losses in the pipeline;
• reduced permissible speed;
• difficult startup after a long shutdown.

Therefore, a pump cannot be selected based solely on the required flow rate. It is necessary to know the fluid's viscosity specifically at the actual operating temperature.

How Temperature Changes Fluid Properties

Temperature and viscosity are closely related. As temperature decreases, many resins and adhesives become more viscous, and as temperature increases, they become more fluid.

If only the viscosity value at room temperature is used for calculation, the actual pump load may differ significantly from the expected.

For example, after equipment shutdown and fluid cooling, the startup viscosity can be significantly higher than the operating viscosity. In this case, the pump and motor will require a greater starting torque.

When selecting, it is recommended to specify:

• startup viscosity;
• viscosity at normal operating temperature;
• minimum and maximum process temperature;
• changes in media properties during operation.

When the MG Series Can Be Considered

Macxi MG series magnetic gear pumps can be considered for pumping resins and adhesive compounds with moderate viscosity, provided chemical compatibility of materials and compliance with other operating parameters.

The gear mechanism is suitable for creating a stable flow, and the magnetic drive transmits rotation without a traditional dynamic shaft seal. This helps reduce the risk of fluid leakage through the pump's drive section.

Depending on the task, the MG series can be used in systems for:

• single-component resin supply;
• adhesive compound dosing;
• coating application;
• mixing liquid components;
• supplying materials to process equipment;
• laboratory and pilot plants;
• automated production lines.

However, the final applicability is determined not by the fluid's name, but by its actual characteristics and operating conditions.

Why Lower Speed is Required for More Viscous Fluid

For a fluid with elevated viscosity, an excessively high rotational speed can impair the filling of the pump's working chambers and increase the load on the drive.

Typically, as viscosity increases, the pump's operating speed must be reduced. At the same time, a pump head with a different displacement may be required to maintain the desired flow rate.

Therefore, configuration selection includes not only choosing the pump head but also determining:

• pump displacement;
• permissible rotational speed;
• required torque;
• power and type of motor;
• speed control method;
• permissible differential pressure.

For the MG series, the motor is recommended to be selected according to specific operating conditions.

Limitations for Very High Viscosity Media

A magnetic gear pump is not suitable for every viscous fluid. If the viscosity is too high, problems may arise with fluid delivery to the inlet, equipment startup, and transmission of the necessary torque.

Additional attention is required for media that:

• have very high viscosity;
• harden quickly after shutdown;
• crystallize when temperature decreases;
• polymerize inside the pump head;
• contain large or solid particles;
• require significant pressure for movement through the pipeline.

Under such conditions, the applicability of a magnetic gear pump must be pre-confirmed by technical specialists. Sometimes, a different pump type or a change in the technological system's design may be required.

High Viscosity Does Not Mean MGR is Necessary

The MGR series should not be chosen simply because the fluid has elevated viscosity.

The need for a wear-resistant series is primarily determined by the abrasive properties of the medium, the presence of particles, fillers, and other conditions capable of causing wear to internal components.

For a clean resin or adhesive with moderate viscosity, the MG series is usually considered first. If the fluid contains solid inclusions or abrasive components, information about their composition, size, and concentration must be provided separately.

After analyzing this data, Macxi specialists can determine whether a wear-resistant design is required and whether a magnetic gear pump is suitable.

What Data is Required for Selection

For preliminary technical analysis, it is recommended to provide the following information.

1. Fluid Name and Composition

Specify the type of resin, adhesive, or other material, as well as the solvents, hardeners, and additives used. If available, it is desirable to provide a technical passport or SDS.

2. Viscosity at Operating Temperature

Specify the viscosity value and the temperature at which it was measured. If the viscosity changes significantly during startup and operation, both values must be provided.

3. Required Flow Rate

The minimum, nominal, and maximum flow rates should be specified. For dosing processes, permissible deviation and repeatability requirements are also important.

4. Inlet and Outlet Pressure

For calculation, inlet pressure, outlet pressure, and actual system differential pressure are required.

5. Operating Temperature

Specify the normal, minimum, and maximum fluid temperatures, as well as the need for preheating or temperature maintenance.

6. Presence of Particles or Fillers

If the medium contains particles, their material, maximum size, concentration, and abrasiveness must be specified.

7. Operating Mode

It is important to communicate:

• continuous or intermittent operation;
• duration of a single operating cycle;
• number of starts and stops;
• need for flow rate control;
• proposed flushing method;
• startup conditions after a long shutdown.

8. Motor and Control Requirements

Specify the power supply voltage, required speed control method, installation conditions, and requirements for continuous operation.

How to Reduce the Risk of Operational Problems

For stable system operation, it is recommended to:

• avoid dry running, if not permitted for the selected configuration;
• ensure sufficient fluid supply to the pump inlet;
• account for pressure losses in the pipeline;
• do not exceed the recommended rotational speed;
• do not start the pump with hardened fluid;
• provide for flushing after process shutdown;
• monitor temperature and viscosity changes;
• install motor overload protection.

The startup, shutdown, and cleaning procedure must be developed considering the properties of the specific material.

Macxi Pump Head and Motor Selection

For resins and adhesive compounds with moderate viscosity, Macxi specialists can consider the MG series magnetic gear pump head and select a suitable motor.

As viscosity increases, it usually requires a reduction in rotational speed and an additional check of the pump head's displacement, torque, differential pressure, and motor power.

If the medium has very high viscosity, contains particles, or hardens quickly, the applicability of a magnetic gear pump must be confirmed separately.

Send us the fluid parameters and operating conditions. Our specialists will conduct a preliminary analysis and suggest a suitable configuration or inform you about application limitations.