TDI ESD Chairs Resistance to Groundable Point Test Positions

ESD SPECIFICATIONS:

Surface Resistivity

  • Fabric:  Grade III ESD Fabric – 4.5×106 Average (BS6524: 1984)
  • Vinyl: Grade III ESD Vinyl – 108 Ohms/Sq or lower (ASTM D-257)

Rate of Decay – 5000 Volts down to 500 Volts 

  • Fabric: Grade III ESD Fabric – .20 Seconds (apex.)
  • Vinyl: Grade III ESD Vinyl – .35 Seconds (apex.)

chair test procedure fig 1

Figure 1 – Setup for 1 Wheel Measurement; Other 4 Wheels on Insulative Support Surface

RH: 24.4%
Temp: 23.8C

Vinyl Chair Test Results

 1 Wheel  A  B  C  D  E
 Seat  2.6E7  2.9E7  3.2E7 3.4E7  3.5E7  (ohms)
 Foot Rest  4.7E2  8.5E3  5.0E2  3.9E3  3.8E3
Back  9.8E7  1.1E8  8.1E7  6.6E7  7.5E7
 2 Wheels  E-A  A-B  B-C  C-D  D-E
 Seat  3.5E7  3.5E7  3.6E7  3.7E7  3.6E7  (ohms)

chair testing procedure fig 2

Figure 2 – Identifying the Wheels (A-E)

 

ESD Chair Features:

  • CASTERS Standard:  Conductive Die Cast Steel Dual Wheel Caster with Brake
    Optional:  Conductive Die Cast Steel Dual Wheel Caster without Brake
  • Spring loaded clip in back upright makes connection between back and control.
  • Footring – Metal to metal cylinder contact.
  • Testing – All chairs are tested for continuous path to ground from seat and back before shipment.