Desco 19240 Operation, Installation And Calibration Instructions

Wrist Strap Tester - Operation, Installation
and Calibration Instructions
Pass Range 800K Ohms to 10 Megohms, 9 Volt Battery Operation
Figure 1. Model 19240 Wrist Strap Tester
Description
Per ANSI/ESD S20.20, test equipment is required to
enact the Compliance Verification Plan Requirement. Test
equipment shall be selected to make measurements of
appropriate properties of the technical requirements that are
incorporated into the ESD program plan. The Touch Tester
can be used to fulfil ESD-S1.1, "The wrist strap system
should be tested daily to ensure proper electrical value"
(paragraph 6.1.3). Being a portable battery powered tool,
it is perfect for small labs or for a supervisor to spotcheck
workers and/or ensure compliance.
Figure 2. Testing a wrist strap
DESCO EAST - One Colgate Way, Canton, MA 02021-1407 • (781) 821-8370 • Fax (781) 575-0172 • Web Site:
TB-3017 December 2009 Page 1 of 2
TECHNICAL BULLETIN TB-3017
DESCO WEST - 3651 Walnut Avenue, Chino, CA 91710 • (909) 627-8178 • Fax (909) 627-7449
The Wrist Strap Tester
is a battery operated
"on demand" wrist strap
tester. When the wearer
of a wrist strap plugs
in their coil cord and
touches the metallic
surface of the Wrist
Strap Tester, a path for
current flow is completed
from the wearer's skin,
through the wrist strap.
This action will cause the
green "test good" LED
to light as long as the
resistance of the circuit
path is between 800k
ohms and 10 megohms.

Installation

The Wrist Strap Tester
is battery powered.
When received, open the
battery compartment and
install the battery, and
you will be ready to test
your wriststraps.
Figure 3. Recording results.
Note: the low battery
indicator flashes every
time the unit is used. When battery fail indicator is constant,
check voltage of battery and/or replace it.

Operation

A wrist strap cord is plugged into the banana jack. When
the wearer of a wrist strap touches the metallic test button,
the green "test good" LED will light if the operator-to-ground
resistance is between 800k ohms and 10 megohms.
If the operator-to-ground resistance is below 800K, the
red "LOW" LED will light and the alarm will sound. If the
operator-to-ground resistance is above 10M, the red "HIGH"
LED will light and the alarm will sound. Per ESD Handbook
TR20.20 paragraph 5.3.2.4.3 Test Procedure, "If the [wrist
strap test] resistance is still too high, dry skin might be the
problem. Dry skin conditions can be resolved by applying
moisturizing lotion on the wrist and repeating the resistance
test again. The moisturizing lotion should be one that is
compatible with process requirements." If after application
of ESD lotion such as Reztore™ ESD Hand Lotion, the
resulting test is still fail "HIGH" or fail "LOW", the operator
should notify their supervisor to have the wrist strap and cord
checked.
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