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Holdstock Standard Test Method No. 001

TRIBOELECTRIC CHARGING BEHAVIOUR

INTRODUCTION

Tribocharging, or triboelectric charging, is one of the most common ways in which materials and objects acquire electrostatic charge. Tribocharging occurs whenever surfaces contact, rub together and separate. There are numerous factors that determine how much charge is generated by tribocharging, including the chemical nature of materials and surfaces, physical form, electrical properties, contact pressure, rubbing geometry, speed of rubbing and separation, environmental conditions (temperature, humidity), etc. Although measurement of electrical properties, e.g. resistance, charge decay time, is relatively uncomplicated, such measurement only addresses some of the relevant determining factors and so can only be used as guide to triboelectric charging behaviour.

The test method described in this standard is used for measuring the quantity of charge generated on materials by tribocharging. The method was originally developed for testing textile materials, but it can easily be adapted to testing other materials.

The test method described in this standard is nominally equivalent to that described in Shirley Method 18: 2000.

 

1     Scope

 

This standard specifies a test method for measuring the quantity of charge generated and retained on a test material after tribocharging by rubbing with reference materials.

The method is suitable for testing textile materials and other materials that can easily be cut to size.

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Holdstock Standard Test Method No. 002

ELECTROSTATIC DISCHARGING BEHAVIOUR

INTRODUCTION

Electrostatically charged materials can cause electrostatic discharges when approached by earthed conductors, or by isolated conductors of sufficient size. Electrostatic discharges have the potential to damage or disrupt electronic devices and systems. In explosive atmospheres and in areas where explosive or pyrotechnic substances are handled, electrostatic discharges can cause ignition if sufficient energy is released. Discharge energy cannot be measured directly. However, the presence or absence of electrostatic discharges is relatively easy to determine, and the quantity of charge transferred in an electrostatic discharge can be measured.

The test method described in this standard is used for measuring of the quantity of charge transferred in electrostatic discharges from materials after tribocharging, according to HSTM-001. The method was originally developed for testing textile materials, but it can easily be adapted to testing other materials.

The test method described in this standard is nominally equivalent to that described in Shirley Method 15: 2000.

 

1     Scope

 

This standard specifies a test method for measuring the quantity of charge transferred from a test material via an electrostatic discharge to an electrode of defined geometry.

 

The method is suitable for testing textile materials and other materials that can easily be cut to size.

 

A relationship between charge transferred in an electrostatic discharge and the probability of the discharge causing ignition of an explosive atmosphere can be established within certain boundaries relating to the test method and the nature of materials under test (Gibson & Lloyd, 1965). The relationship is valid provided the spatial and temporal characteristics of discharges do not vary significantly. In reality, these parameters are likely to vary with variations in materials. Therefore, although charge transfer can be a useful parameter to measure as part of a comprehensive evaluation of materials, the use of charge transfer as a single determinant for evaluating the incendiary propensity of materials is not recommended.

 

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Holdstock Standard Test Method No. 003

ELECTROSTATIC IGNITION TESTING

INTRODUCTION

Electrostatically charged materials can cause electrostatic discharges when approached by earthed conductors, or by isolated conductors of sufficient size. In explosive atmospheres and in areas where explosive or pyrotechnic substances are handled, electrostatic discharges can cause ignition if sufficient energy is released. Discharge energy cannot be measured directly, and indirect methods for evaluating ignition propensity are not without limitation (see HSTM-002).

The test methods described in this standard are used for determining the propensity for materials to ignite explosive atmospheres after electrostatic charging. The method was originally developed for testing textile materials, but it can easily be adapted to testing other materials.

The test methods described in this standard are nominally equivalent to those described in Shirley Method 138: 2000.

CAUTION: The test methods specified in this standard involve the use of high voltage power supplies and flammable gases that may present hazards if handled incorrectly, particularly by unqualified or inexperienced personnel. Users of this standard are encouraged to carry out proper risk assessments and pay due regard to local regulations before undertaking any of the test procedures.

 

1     Scope

This standard specifies test methods for determining the propensity for materials to ignite defined explosive atmospheres after electrostatic charging under laboratory conditions that simulate end use applications.


A method is described that is suitable for testing textile materials and other materials that can easily be cut to size. Other methods are described that are suitable for testing garments.


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Holdstock Standard Test Method No. 004

BODY VOLTAGE CHAIR TEST

INTRODUCTION

Electrostatically charged apparel can induce significant electrical potential, or body voltage, on the wearer if the resistance between the wearer and earth is greater than about 108 Ω. Electrostatic discharges from the human body can occur when a person touches earthed conductors, or isolated conductors of sufficient size. Electrostatic discharges have the potential to cause shocks to people and damage or disrupt electronic devices and systems. In explosive atmospheres and in areas where explosive or pyrotechnic substances are handled, electrostatic discharges can cause ignition if sufficient energy is released.


The risk of shock, damage to electronics or ignition by a discharge from the human body is related directly to the body voltage as summarised in Table 1.


Table 1. Sensitivity to electrostatic discharges from the human body

 

Hazard

Body voltage above which hazard may occur

Damage to magneto-resistive drive heads (hard disk drives)

~ 10 V

Damage to integrated circuits

~ 1000 V

Damage to resistors

~ 5000 V

Ignition of hydrogen

~ 1500 V

Ignition of typical hydrocarbon fuel

~ 5000 V

Shock

~ 2000 V

 

The test methods described in this standard can be used to evaluate the propensity of garments and full garment assemblies to acquire charge when contacting and rubbing against other materials. By using standard garments, the charging propensity of materials that may contact garments, e.g. upholstery materials, can also be evaluated.


The test methods described in this standard are nominally equivalent to those described in Shirley Method 16: 2001 and Shirley Method 17: 2001.

1     Scope

This standard specifies test methods for determining the propensity for materials to acquire and retain electrostatic charge. Charge generated is quantified by measuring the electrical potential induced on the body of a person, i.e. body voltage.

The test methods can be used to evaluate any garment or garment assembly that can be worn over parts of the body that are in contact with a seat when sitting. Alternatively, the test methods can be used to evaluate seats and seat materials, or flexible materials that can be fitted over a seat.


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