Static eliminators used to remedy common static problems

Pneumatics & Hydraulics

July 2006 Pneumatics & Hydraulics

Static electricity causes problems when the temperature and humidity drops. The types of problems that can be expected in production facilities are:

* Materials tearing, jamming or curling.

* Webs and films clinging to themselves.

* Electronic sensors failing, thereby causing false readings.

* Dust attraction ruining surface finishes.

* Product clinging to itself, rollers and machine beds.

* Hazardous sparks or shocks.

Charged conductors, for example metals, discharge completely when grounded while insulators like plastic, do not conduct static electricity. The use of carbon brushes or grounded tinsel to ground machinery has little effect on these surfaces.

EXAIR manufactures a complete range of static eliminators to remedy common static problems. The Super Ion Air Knife, with its curtain of laminar airflow, is recommended for applications involving high speeds, large surfaces or complex geometries. It is effective up to 6 m. The manufacturer avers that it provides the best performance of all ionisers. Other static eliminators include the Air Cannon, the Ion Air Gun and the Ion Air Jet. The entire range use the manufacturer's engineered airflow products to minimise air use and noise while effectively eliminating static by moving more ions to the product surface.

In applications where airflow will possibly disturb the product, the manufacturer's Ionising Bars and Ionising Point can neutralise the charge when mounted within a couple of centimetres of the surface and do not require airflow.

It is often difficult to isolate the source of the static but EXAIR's handheld, digital Static Meter can be used to locate its source and severity. The meter indicates the surface voltage and polarity up to 20 kV measured at a distance of 25 mm. Features include a pushbutton 'hold' for readings and automatic 'power off'. It is supplied with a hard shell case and calibration certificate traceable to NIST (National Institute of Standards and Technology).

The Static Meter can also be used to demonstrate that an ioniser is functioning by first measuring the charge on the product surface with the meter, then exposing the product to the ionised airflow and finally measuring the charge on the product surface again. The ioniser is functioning properly if the charge reads 0 volts.

If the charge remains on the product surface, it should be verified that the ioniser is connected properly to a grounded power supply. It is also possible that the ioniser has become dirty, in which case, cleaning by scrubbing any dust and contaminants with a small brush is required. Cleaning with chemical is not recommended as some chemicals are conductive and create a conductive path from the emitter to the grounded surface. Flammability of certain solvents is also an issue.

For more information contact Rodney or Alan, ETEST, 031 702 8302, [email protected], www.etest.co.za

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Pneumatics & Hydraulics

Static eliminators used to remedy common static problems

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