When a material or object holds a net electrical charge, either positive or negative, it is said to have a static charge. Charges will slowly decrease over a period of time. The length of time that this takes is dependent on the resistance of the material. For practical purposes the two extremes can be taken as plastics, which will hold a charge for a long period of time and metal, which will hold a charge for a relatively short period of time.
There are many factors that affect static charge, these include:
- Humidity – Generally speaking, the dryer the environment, the higher level of static charge.
- Type of Material – some materials are more readily charged than others, please refer to the triboelectric series to see which materials are readily charged.
- Repetition – repeated actions such as friction or separation will increase the level of charge found on a material.
- Change in Temperature – higher temperatures reduce static charge because heat increases molecular movement, which makes it harder for static electricity to build up. Cooler temperatures, however, help static charges accumulate and stay on materials.
There are three main causes of static electricity: friction, separation and induction:
Friction – Two materials are rubbed together.
Separation – Two materials are pulled apart.
Induction – When a material is in the presence of a strong electric field.
Static electricity can cause many problems for all production and manufacturing processes such as:
Contamination – static charges can attract dust and contaminants from machine frames floor and environment.
Static discharges – Electrostatic shock to operators, electronics and fire prevention.
Material misbehaviour – Static charges will make products and materials misbehave causing machine downtime.
Material damage – damage to coatings or surfaces from sparks.
The range of Meech measuring equipment has been specifically designed to provide accurate readings of electrical charges, the performance (both AC and DC) and the surface resistivity. These handheld devices are easy to use and vitally important to diagnosing static electricity issues. Please refer to the Measuring Equipment product page for more details.
AC ionisers are short range FIXED output systems. Their design allows for no adjustment, producing more negative than positive ions. As the bar becomes dirtier the off-set voltage gets larger, resulting in a greater risk of damage to voltage sensitive products/materials.
For applications where static must be controlled effectively with no risk of damage the new line of DC Hyperion products would be favourable.
All active ionisers must be maintained. The regularity of a maintenance schedule will depend on the working environment. Every Meech ioniser has been designed to minimise the time required for maintenance. However, the cleaner the bar the better the performance and product life span. We would recommend you visually inspect your static control equipment daily and clean accordingly.
However, the Meech Hyperion range of ionising bars remains unique, having Ion Current Monitoring built into the whole range. Continuous monitoring of the ionising bar’s performance allows the customer to be alerted when a bar needs cleaning.
Firstly, the bar should be disconnected from any power source. The emitter pins and top surface of the ionising bar can be cleaned with a regular toothbrush. Depending on the amount of contamination, a toothbrush may be sufficient. If the contamination is hard to remove, the use of IPA (Isopropyl Alcohol) will give very effective cleaning.
The body of the bar should also be wiped with a soft cloth, using IPA if necessary.
Yes, we offer both AC and DC static control equipment certified for use in ATEX zones. Please refer to the relevant Baseefa certificates to diagnose which zone the equipment is approved for use in.
For full information on our EX ionising range.