The ins and outs of pumps: mechanical seal vs sealless magnetic drive pumps

Distributor of Techniflo magnetic drive pumps in Australia and New Zealand, Global Pumps discusses the difference and value of sealless magnetic drive pumps vs mechanical seal pumps.

There two broad categories of pumps used in the industries: the pumps with mechanical seals and sealless magnetic drive pumps.

Mostly the mechanical seal pumps are used and selected because of a lack of knowledge regarding mag drive pumps.

Some of the important points of comparison are:

1) Sealing of the fluid being pumped:

In the mechanical sealed pumps there is a mechanical seal that prevents the leakage of the fluid being pumped. However, some amount of fluid always keeps on leaking through the mechanical seal for its lubrication and cooling. Some of the mechanical seals can be cooled by the external fluids. In the magnetic drive pumps no mechanical seal is required. There is shell or containment part of the pump that forms a complete and sealed enclosure through which the fluid being pumped cannot leak. Thus the magnetic drive pumps are sealless zero leakage pumps.

2) Wearing of the seal and maintenance:

The mechanical seal comprises of the moving and the stationary parts and they are in contact with each other. The faces and elastomers of the mechanical seal start wearing after certain period of time and the amount of fluid leaking through it goes on increasing and they have to be replaced from time-to-time. Since the magnetic drive pumps contain no seals there is no wearing of its parts, so no replacements are required and therefore requires less maintenance.

3) Mode of driving or pump design:

In the traditional pumps with mechanical seal there is coupling between the driving motor and driven pump shafts for the transfer of power to the impeller. This arrangement makes it necessary to have the mechanical seal to prevent the leakage of the fluid. In the magnetic drive pumps the drive shaft is surrounded by a set of magnets. When this shaft rotates it transfers is magnetic field to the impeller shaft through the shell through which the fluid passes. Thus there are no opening involved in the magnetic drive pumps and a completely sealed enclosure is formed for the fluid.

4) Type of fluids being pumped or application:

Though pumps with mechanical seals can be used for pumping hazardous fluids some leakage of fluid may always be involved. By the inherent design the magnetic drive pumps offer zero leakage of pump being fluid so they are highly reliable for pumping hazardous corrosive fluids, aggressive fluids, difficult to seal fluids, expensive fluids, pure fluid and slurries. Magnetic drive pumps are made up of non-metallic components that offer outstanding corrosion resistance.

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