What Is Static Electricity and how it is cerated?

What Is Static Electricity and how it is cerated?.

Common Electrostatic Problems

Common Electrostatic Problems.

Common Electrostatic Problems

Identification of the problem

There are four main troublesome difficulties arising in industry, deriving from electrostatic charges, with a fifth affecting only the electronics industry but with very serious and costly consequences.

 

Electrostatic attraction (ESA)

Airborne particles are attracted to charged surfaces or indeed charged airborne particles are attracted to a surface, which could be totally free of any charge. This problem effects most plastic based industries in one form or another, spoiling finishes of painted products and causing rejects in quality in the food, pharmaceutical and medical industries.

In the printing industry dust attraction damages print finishes or indeed printing plates.  The film industry also suffers with low quality prints and poor resolution projections in the cinemas.

The microscopic nature of semiconductor manufacture can be affected by this problem.

 

Material Misbehavior 

This is another form of ESA. However, instead of the contamination of products, the problem manifests itself in the form of the product itself, usually webs, fibres or sheets, sticking to themselves or equipment, misrouting or repelling.

Automated processes are particularly prone to this problem.

 

Operator/Personnel Shocks

This is becoming increasingly significant as companies look to improved safety standards. Whilst shocks can be painful the effects are usually quite safe and short lived. However, in extreme cases, the debilitating effects can cause personnel collision or entrapment with associated machinery or can even initiate a fire or an explosion in hazardous areas.

Electrostatic Discharge (ESD)

This problem is associated to electronics assembly, installation and field service and also electronic component manufacture.

Voltages as low as 5 volts, which have no real meaning in other industries, can cause catastrophic failure of electronic components or much worse, latent damage which results in field failure, by far the most costly in terms of repair and manufacturers’ reputation.

 

Shavo Technologies manufacture and supply a wide range of electrostatic products and anti static equipments that provide ESD protection and measurement, static generation, electrostatic control and elimination.

What Is Static Electricity?

When a material or object holds a net electrical charge, either positive or negative, it is said to have a static charge. The term static is a relative one as in many cases static 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 and metal. Plastics generally have very high resistivities. This allows them to maintain static charges for long periods of time; on the other hand metals have very low resistances and an earthed metal object will hold its charge for an imperceptibly small period of time.

Static electricity is usually measured in volts. Whilst mains voltages of 220 volts AC are considered dangerous, levels of static electricity of 100 kV are common.

The voltage present on a material is dependent on two factors; the amount of charge on the material and the capacitance of the material. The simple relationship is Q=CV where Q is the charge, V the voltage and C the capacitance of the material. It can be seen that for a given charge on a material, the lower the capacitance the higher the voltage and vice versa.

Plastics generally have very low capacitive values and hence a small charge can produce very high voltages. Conversely metals tend to have high capacitive values and therefore a relatively high charge will produce low voltages. This is why, in practice, problems with static electricity are most noticeable when working with plastic, as it is the voltage level which causes the attraction of dust, operator shock and misbehavior of materials.

There are two main types of static electricity, volumetric and surface. Volumetric static charges are charge imbalances within the body of a material whereas surface static electricity is only present on the very outer surface of a material.  In practice nearly all the static electricity problems found in industry relate to surface charges.

Whilst there is no way of neutralising volumetric static charges they rarely cause a problem and their effects are normally minimal when compared to surface static charges.

How Is Static Created?

There are three main causes of static electricity; friction, separation and induction.

Friction

As two materials are rubbed together the electrons associated with the surface atoms on each material come into very close proximity with each other. These surface electrons can be moved from one material to another. The direction in which the electrons travel either from Material A to Material B or vice versa depends on the Triboelectric Series

Materials on the positive side of the Triboelectric Series will tend to give up their surface electrons and become positively charged whilst conversely materials on the negative side of the series tend to gain electrons and hence a negative charge.

The harder the two materials are pressed together the greater the exchange of electrons and hence a higher charge is generated. A practical example is if a piece of polythene is rubbed on a nylon carpet with gentle force a moderate negative charge will be generated on the polythene, whereas if the force is increased a larger negative charge will be achieved.

The speed of the rubbing action also has that effect on the level of charge, the faster the rubbing the higher the level of charge. This is due to the surface electrons gaining heat energy generated by the friction. This extra energy allows them to break their atomic bonds and transfer to other atoms.

Separation

 The method of charging by separation is similar to that of friction. When two materials are in contact the surface electrons are in close proximity to each other and upon separation have a tendency to adhere to one material or the other dependent upon their relative positions on the Triboelectric Series.

The faster the separation of the materials, the higher charge generated and conversely, the slower the separation the lower the charge. A common example is of a PVC web moving over a Teflon coated roller, as the materials separate the electrons will tend to adhere to the Teflon, generating a net negative charge on the Teflon and a net positive charge on the PVC.

Induction

Whilst of interest technically, induction does not play a significant role in our field. Static charges can be generated when materials are in the presence of a strong electric field.

The surface of a material in close proximity to a high positive voltage will tend to become positively charged. The method of charging is caused by ionisation of the air between the surface of the material and the voltage source which carries surface electrons away from the material to the source, (ionisation is explained in methods of elimination).

An example of induction is operators working near charged materials. The operator will himself become charged and on touching an earthed object will discharge to it, giving the operator an electric shock – often mistaken for a shock from the mains supply.

Shavo Technologies manufacture and supply a wide range of electrostatic products and anti static equipment that provide ESD protection and measurement, static generation, electrostatic control and elimination.

GAST Air Motors from Shavo Group

Known industry wide for their rugged construction and reliability, Gast Air Motors and air powered Gear motors are available in lubricated models.

Lubricated Air Motors come in seven basic models up to 9.5 HP (7.1 kW); motor speeds are variable from 300 to 10,000 RPM.  Non-lubricated versions, which require absolutely no lubrication, come in three basic models ranging from .18 to .82 HP (0.13 to 0.61 kW) and with motor speeds up to 4,000 RPM.  Choose from hub, foot, face, NEMA C-flange, or Metric D Series interface mountings and clockwise, counter-clockwise, or reversible rotations; four and eight vane models are also available.

Air powered Gear motors are available in right-angle and in-line models offering a maximum torque range of 73 to 5,200 lb. in. (8 to 587 Nm) and gear ratios from 10:1 to 60:1 single reduction gear reducers.  A full line of recommended accessories is also available.

Features:

  • Variable Speed
  • Non – Electrical Sparking
  • Cool Running
  • Compact and Portable
  • Operate in All Positions
  • Mounting Flexibility
  • Will not burn out

 

Typical Applications:

  • Mixing Equipment
  • Conveyor Drivers
  • Pump Drives
  • Food Packaging
  • Pharmaceutical Packaging

Since 1921, Gast Manufacturing, Inc. has embraced its position as a leader in the design and manufacture of air-moving products, as well as quality air motors, vacuum generators, compressors, and vacuum pumps.

Shavo Technologies Pvt. Ltd.  is a leading Air Motor Supplier and are sole Indian Business Associates of GAST Manufacturing Inc. USA

TESCOM Vaporizing Regulator from Shavo Technologies

VAPORIZING Regulator

TESCOM™ 44-5800 Series offers superior heat transfer technology. With a high tolerance to voltage spikes and high ambient temperatures, this regulator is designed for worldwide applications. Ideal for use in liquid petroleum analyzer, petrochemcial / refinery analyzers and sampling systems.

— For worldwide use: Designed for 90-125 VAC / 190-230 VAC, 50/60 Hz

— 4-20 mA analog output for remote temperature monitoring and data acquisition

— Optional LCD temperature display

— Optional heating capacity up to 400 watts for faster response to flow variations

— Optional panel mounting

— Advanced heat transfer technology

— Single turn heater temperature control dial

— CSA, ATEX, and IECEX Certification to T4 Rating

— NACE MR0175 / ISO 15156

The design has been optimised to reduce the effects of contamination and to allow easy maintenance.

TESCOM designs and manufactures a wide range of standard and custom engineered pressure control solutions for a diverse world market. From components like pressure regulators and valves, to pressure systems and assemblies, TESCOM provides expert application and customer support for simple industrial applications to high tech complex projects.

Shavo Group of Companies in association with TESCOM manufactures high- Pressure regulators upto 20,000 psig. Tescom products are designed to work with all types of fluids, both corrosive and non-corrosive. Quality is designed and built into every Tescom product. Regulators are inspected and tested at every stage. Tescom manufactures over 70 standard models of high-pressure regulators to meet almost any requirement.

New Static Generator from Meech Demonstrates Greater Versatility

Meech International announces the launch of the Model 992v3 Static Generator. This new product further advances Meech’s position as a leader in static control solutions. The new 30kV Model 992v3 can be operated in either Constant Voltage or Constant Current Mode to generate a controlled level of static charge that will create a temporary bond between materials, one of which must be insulative.

The addition of Constant Current Mode allows the performance of the Model 992v3 to be optimised for a variety of applications and a diverse range of materials. The result is maximum pinning effect without the risk of overload.

Meech has specialized in providing industrial electrostatic solutions for over 40 years. Meech products are currently in a wide range of industries ranging from packaging to contact lens manufacture. Meech’s extensive product range is supported by an excellent client-service infrastructure with sales advisors in the U S and Europe, and distributors throughout the world. Meech was the first specialist manufacturer of static elimination worldwide to be approved as an ISO 9002 registered Company.

Shavo Technologies Pvt. Ltd. represents some of the choicest engineering manufacturers in the world and is sole Indian Business Associate of Meech Eliminators Limited. Meech manufacture and supply a wide range of anti-static equipment and variety of electroststic products that provide ESD protection and measurement, static generation, electrostatic control and elimination.

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