General EP8703 User manual

CALIBRATABLE
3-FUNCTION
THERMO-
HYGROMETER
USER’S MANUAL
EP8703
Please read this manual carefully and
thoroughly before using this product.

TABLE OF CONTENTS
Introduct on . . . . . . . . . . . . . . . . . 2 – 3
Key Features . . . . . . . . . . . . . . . . . . . . 4
What’s n the Box . . . . . . . . . . . . . . . . 4
Product Overv ew . . . . . . . . . . . . . 4 –6
Setup Instruct ons . . . . . . . . . . . . 6 –7
Install Battery . . . . . . . . . . . . . . 6 –7
Operat ng Instruct ons . . . . . . . . . 7 –8
Mak ng Bas c Measurements . . 7 –8
Cal brat ng the Meter . . . . . . . . . 8 – 10
Spec f cat ons . . . . . . . . . . . . . . . . . . 11
Operat ng & Ma ntenance T ps . . . . . 12
Warranty Informat on . . . . . . . . . . . . 13
Return for Repa r Pol cy . . . . . . . . . . 14
INTRODUCTION
Thank you for purchasing General Tools
& Instruments’ EP8703 Calibratable
3-Function Thermo-Hygrometer. Please
read this user’s manual carefully and
thoroughly before using the instrument.
The EP8703 can measure any
environment’s ambient temperature,
relative humidity (RH) and dew point. These
measurements are typically made by three
groups of users:
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• Water damage restoration contractors
• HVAC/R system installers and technicians
• Professionals charged with monitoring
and maintaining the environment of
facilities such as office buildings,
greenhouses, food and equipment storage
facilities, wineries, freezers, shipping
containers, computer rooms, labs,
libraries, museums and saunas.
The dew point is the temperature below
which the water vapor in a volume of air at
a given constant barometric pressure will
condense into liquid water at the same rate
at which it evaporates. Condensed water is
called dew when it forms on a solid surface.
Another way to think of the dew point is as
an air saturation temperature associated
with relative humidity (RH). A high RH value
indicates that the dew point is close to the
current ambient air temperature. At 100%
RH, the dew point temperature is equal to
the ambient temperature because the air is
completely saturated with water.
The EP8703 is powered by one “9V” battery
(included).
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KEY FEATURES
• umbo backlit display with 2-line readout
• Field calibratable using optional 33% and
75% salts
• °F/°C switch
• 20-minute Auto Power Off function
• Low battery indicator
WHAT’S IN THE BOX
The EP8703 comes fully assembled in a box
along with a sensor protection cap, a “9V”
battery and this user’s manual.
PRODUCT OVERVIEW
Figure 1 shows all of the controls, indicators
and physical structures on the front, top and
bottom of the EP8703. Figure 2 shows all
text and icons that could appear on the
unit’s LCD. Familiarize yourself with the
positions and functions of all buttons,
structures and icons before moving on to
the Setup Instructions and Operating
Instructions.
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Fig. 1. The EP8703’s controls, indicators
and physical structures
A. Humidity and temperature sensors
B. LCD
C. (Power on/off) button
D.
F/C button
E. Battery compartment
F.
DEW button
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A
B
C
D
F
E

Fig. 2. All possible display indications and
their eanings
A. Low battery icon
B. °C indicator
C. °F indicator
D. Temperature readout
E. Dew point temperature indicator
F. Relative humidity (RH) readout
SETUP INSTRUCTIONS
INSTALL BATTERY
1. The meter’s battery compartment (Fig. 1,
Callout E) is accessible from the bottom
of the unit. Use a Phillips-head
screwdriver to loosen the single screw in
the back of the unit that holds the yellow
battery compartment cover in place. Set
the cover and screw aside.
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A
F
E
D
B
C

2. Plug the included “9V” battery into the
wired socket inside the compartment.
The terminals of the battery and the
socket mate in only one way, with the
smaller male terminal plugging into the
larger female terminal.
3. Replace the battery compartment cover
and tighten the screw to secure it to the
housing.
OPERATING
INSTRUCTIONS
MAKING BASIC
MEASUREMENTS
Before making any measurements, rotate
the sensor protection cap with your thumb
and index finger so the three vents are open
to the ambient environment from both the
front and back. Press the button to
power on the meter. The dual displays will
immediately begin reading out humidity and
ambient temperature measurements made
by the sensors at the top of the unit.
To display the dew point te perature
(instead of ambient temperature) on the
lower readout, press the
DEW button. The
reading will be accompanied by the symbol
DEW at its left. To return to displaying
ambient temperature, press the
DEW button
again.
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By default, the EP8703 displays ambient
and dew point temperatures in °F.
To
switch to °C
, press the F/C button.
Pressing any button turns on the green
backlight for 10 seconds.
To extend the life of the “9V” battery
powering the EP8703, the unit’s Auto Power
Off (APO) function will automatically shut
down the instrument if no front-panel
buttons are pressed within any 20-minute
period.
To disable the APO function , power
on the unit in a special way by pressing and
holding the
DEW button while pressing the
button. The LCD will confirm that you
are disabling the APO function by displaying
its complete set of icons until you release
the
DEW button. The APO function will be
enabled the next time you power on the unit
in the normal way.
To power off the EP8703 , press and hold
the button for at least 3 seconds.
CALIBRATING THE METER
Your EP8703 was calibrated at the factory,
so its measurements should remain within
their specified tolerance for several years.
However, you can re-calibrate the unit
yourself to reassure yourself of the
accuracy of readings, especially after the
instrument has been operated for many
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hours in a dusty environment.
To calibrate the EP8703, you must use two
jars of standard calibration salt: one
containing a 33% solution of MgCl and the
other a 75% solution of NaCl. Both are
available for purchase from General as part
numbers HR33 and HR75.
Before beginning the calibration
procedure—which is a turnkey process but
takes at least 80 minutes to complete—you
must disable the APO function so the
instrument can remain on for more than
20 minutes.
To disable the APO function ,
power on the unit in a special way by
pressing and holding the
DEW button while
pressing the button.
Following is the calibration procedure:
1. With the unit powered on and the APO
function disabled, rotate the sensor
protection cap to open its three vents and
expose the humidity sensor to the
environment.
2. Press and hold the
DEW and F/C buttons
at the same time, and then release them.
This will cause
_ _ . 1 to appear on the
lower readout.
3. Turn the unit upside-down and insert the
sensor structure in the opening of the
33% salt bottle after removing the bottle’s
cap. The fit should be tight, with no air
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leaking into the bottle.
4. Leave the unit upside-down in the 33%
salt bottle for at least 40 minutes. The
calibration to 33% is fully automatic and
requires no interaction or checking by
you.
5. Remove the meter from the 33% salt
bottle and again press, hold and release
the
DEW and F/C buttons at the same
time. Doing so this time will cause
_ _ .2
to appear on the lower readout.
6. Turn the unit upside-down and insert the
sensor structure in the opening of the
75% salt bottle after removing the
bottle’s cap. The fit should be tight, with
no air leaking into the bottle.
7. Leave the meter upside-down in the
75% salt bottle for at least 40 minutes.
The calibration to 75% is fully automatic
and requires no interaction or checking
by you.
8. The unit is calibrated when two cycles—
one at 33% and the other at 75%—have
been completed. It is important that the
33% calibration precede the 75%
calibration. Reversing the order, or
performing either calibration twice, will
produce an error message when the unit
is restarted.
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