The use of filter pumps in galvanic technology has increased sharply over the years. In the past, a filter pump in a galvanic workshop was used exclusively for periodic filtering. They had only one filter pump at their disposal, which was to serve the entire workshop.

In particular, the emergence of glossy nickel baths, which are sensitive to floating impurities, has strongly stimulated the use of filter pumps. These filters are also vital for the technical applications of galvanic technology.

More and more filter pumps are being used on baths for which people previously thought this was not necessary, such as sensory and cadmium baths, tin baths and also on chrome baths.

Usually these filter pumps are now used for bath filtration, whereby other advantages are also obtained, such as bath movement and optionally through the combination with a heat exchanger for keeping the bath fluid at the right temperature.

A filter pump is made up of three parts, which are assembled on one frame into one whole:

• A pump
• An electric motor to drive the pump
• A filter

Sometimes people encounter difficulties, for example due to the special nature of the liquids that has to be filtered. These liquids are often aggressive and they are sensitive to contaminants, which may possibly be caused by the materials of the filter pump.

The seal of the pumps can be damaged by crystallized bath salts in the filter mechanism during standstill and cooling (especially nickel baths are notorious for this).

However, these difficulties can be considered as resolved. Most filter pumps are self-priming and can automatically receive a final rinse with clean water after switching off.

The most important part of the filter pump is the filter element. There are a several types of this:

• Filter discs
• Filter cartridges
• Filter paper
• Filter bag
• Absorption fiber

The filter discs have the advantage that a large filter surface is accommodated in a small space. For this, filters papers are used that may consist of two layers (coarse thick paper with thin fine paper on top) and the so-called precoat filters, made of cloth, synthetic fabric or metal mesh, which are used for the commissioning of the filter pump with the aid of suitable filter pulp (filter aid), must be covered. Carbonated filter paper exists for continuous cleaning of the bath liquid.

Besides that, filter cartridges are also pre-coat filters. They have the great advantage that by reversing the flow direction, the filter cake with the contaminants is detached from the cartridge and can be easily removed by washing away.

This article of the importance of filter pumps in electroplating technology has been compiled and developed by the Dutch ION. The complete article about galvanizing can be found here.