ESD STM3.1-2000IONIZATION

THE ESD ASSOCIATION

May14, 2003

ESD STM3.1-2000

• Presented by: Gary Seale - V.P. Membership - Texas ESD Association

• Regional Manager - Simco Ionization

• Scope, Purpose, & Application

• Definitions

• Safety

• Specific Requirements

ESD STM3.1-2000CONTENTS

• Room Ionization

• Laminar Flow Ionization

• Worksurface Ionization

• Compressed Gas Ionizers-Guns/Nozzles

• Test Equipment

• Annex A

ESD STM3.1-2000

• Scope - Standard establishes measurement techniques, to determine ion balance and charge neutralization

• Purpose - Standard provides test methods & procedures for evaluating air ionization equipment & systems

• Application - Provide performance data, qualify equipment for use

ESD STM3.1-2000

• Definitions

• Air conductivity - Ability of air to conduct current under influence of an electric field.

• Air Ions - Clusters of 10 molecules bound by polarization forces to a singly charged oxygen or nitrogen molecule.

• Charge decay - Decrease/neutralization of net electrostatic charge

ESD STM3.1-2000

• Charge plate monitor - Instrument used to measure decay times

• Compressed gas ionizers - Ionizer tools used to neutralize charges and remove particles with high pressure gas

• Corona - Production of positive & negative ions by a very localized high electric field

ESD STM3.1-2000

• Discharge Time: Time necessary for a voltage to decay from an initial value to some arbitrarily chosen value. (typically 10% of beginning value)

• Emitter - A conducting sharp object, needle or wire, which will cause a corona discharge when kept at high potential

ESD STM3.1-2000

• Neutralize - Canceling the effect of a field from a given charge, by conducting the field to ground, or introducing an equal opposite charge.

• Offset voltage - Observed voltage on a charge plate that has been placed in an ionized environment.

ESD STM3.1-2000

• SAFETY REQUIREMENTS

• Electrical - Peak current limited for installation (emitter tips)

• Ozone - Generation not to exceed limit defined by OSHA 1910

• Radioactive - License from N.R.C.

• Mfg. to meet all requirements of Title 10, Part 20, Code of Federal Regulations

ESD STM3.1-2000

• Installation - Conform to any applicable electrical, mechanical, and safety codes.

• Noise exposure, PSI used, relief design

• Discharge test time - Plate charged to initial voltage and discharged to 10% of that value. Time required for both polarities monitored and recorded.

ESD STM3.1-2000

• Offset voltage test - Ground plate to “zero” Monitor plate in ionized environment for deviation from zero.

• Locations - See Table 1

• Same conditions for all tests, no equipment adjustments.

• Peak offset voltage - DC ionizers measured for peak voltages and reported.

ESD STM3.1-2000• Table 1- Test Setups and Test Locations

• Equipment Figure References Number of Test Locations Offset Voltage/Time Interval CPM Initial Voltage

• Room Ionization

• Grids, AC 3 2 1-5 Min. 1000

• Bars, Pulsed & DC 3 2 1-5 Min. 1000• Single polarity emitter 4 3 1-5 Min. 1000

• Dual DC line 5 3 1-5 Min. 1000

• Pulsed DC emitter 6 2 1-5 Min. 1000

• Laminar Flow Hood• Vertical 7 & 8 7 1-5 Min. 1000

• Horizontal 9 & 10 5 1-5 Min. 1000

• Worksurface Ionization• Bench Top 11 12 1-5 Min. 1000

• Overhead 12 & 13 12 1-5 Min. 1000

• Compressed Gas Ionization

• Guns and Nozzles 14 1 10 sec. - 1 Min. 1000

ESD STM3.1-2000

• Room Ionization

• Testing - Monitor clear 5’ horizontal area, System on for 30 minutes previously.

• Test person grounded - 5 feet outside area

• Discharge time for 1000 to 100 volts - both polarities

ESD STM3.1-2000

• Laminar air flow velocity recorded

• Measurements taken 5’ under emitters & recorded

• Discharge and offset voltage

• (1 min. test criteria) taken and recorded

ESD STM3.1-2000

• Example: Room Ionization Emitters

ESD STM3.1-2000

• LAMINAR FLOW HOOD IONIZATION

• Test area unobstructed, surface area dissipative and properly grounded

• Test person grounded

• Discharge time from 1000 to 100 volts measured for both polarities, + Offset V.

• Air flow recorded - test positions as per specification - See slide 17

ESD STM3.1-2000

ESD STM3.1-2000

• Discharge time measured & recorded, offset voltage measured (1 minute min.) & recorded

• Example: Laminar flow bar

ESD STM3.1-2000

• WORKSURFACE IONIZATION

• Test in unobstructed area, surface static dissipative and properly grounded

• Test person grounded, discharge for both polarities, 1000- 100 volts measured

• Measure w/heater on & off, w/filters, at min & max airflow, air velocity measured and reported

ESD STM3.1-2000

ESD STM3.1-2000

• S3.1 Test Criteria

ESD STM3.1-2000

• Benchtop test results

ESD STM3.1-2000

• Example: Benchtop product

ESD STM3.1-2000

• Overhead Test Criteria

ESD STM3.1-2000

• Overhead test - Side view

ESD STM3.1-2000

• Discharge time and offset voltage (1 min.) should be measured at each test location

• Example - Overhead Ionizer

ESD STM3.1-2000

• COMPRESSED GAS IONIZERS - GUNS AND NOZZLES

• Test w/out obstructions to airflow, test personnel grounded, surface dissipative and grounded

• Discharge 1000 to 100 volts, both polarities.

• 30 psi input pressure, 6’ from charge plate

ESD STM3.1-2000

• Discharge time and offset voltage measured and reported as per drawing #14.

ESD STM3.1-2000

• Example - Compressed air ionizing gun

ESD STM3.1-2000

• TEST EQUIPMENT - Charge Plate

• 6” x 6” conductive plate -minimum/maximum capacitance limits

• Construction criteria - no more than 10% discharge of plate voltage in 5 minutes

ESD STM3.1-2000

• ANNEX A

• Air ions - Definition - Natural ions discussion - Radiation and corona induced ionization

• Mobility and ion current - Formula review, ion movement, current density

• Neutralization current - Neutralization current proportional to charge & opposite conductivity of the air

ESD STM3.1-2000

• Neutralization rate - Charges decay relative to the conductivity of the air.

• Ion depletion - Charged fields may partially deplete the air of ions. Which may slow discharge rates. Air velocity significantly reduces this effect

• Charge Plate definition/capabilities

ESD STM3.1-2000

• Offset voltage definition/acquisition of.

• Importance of ionization equipment maintenance - cleaning, emitter replacement, nuclear replacement, insure full volume of air flows