DIGITAL
PSYCHROMETER
USER’S MANUAL
SAM990DW
Please read this manual
carefully and thoroughly
before using this product.
INTRODUCTION
Thank you for purchasing General Tools & Instruments’
(General’s) SAM990DW Digital Psychrometer.
The SAM990DW is a psychrometer because it can
measure relative humidity (RH) as well as ambient, Dew
Point and Wet Bulb temperatures.
The Dew Point (DP) temperature 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.
The Wet Bulb (WB) temperature is the temperature that a
volume of air would have if it were cooled to saturation
(100% RH) by the evaporation of water into it, with the
latent heat coming from the volume of air. The WB
temperature is the temperature you feel when your skin is
wet and exposed to moving air as opposed to the actual
air temperature—the dry bulb temperature.
KEY FEATURES
• Measures and displays RH as a percentage + ambient,
DP and WB temperatures in °C or °F on a dual-readout
LCD
• Min/Max memory + data hold
• 20-minute Auto Power Off (APO)
• 1-year limited warranty
WHAT’S IN THE PACKAGE
The SAM990DW comes in a blister pack with two “AAA”
batteries. A hard copy of this user’s manual is inside the
fold-over blister card.
SETUP INSTRUCTIONS
INSTALL BATTERIES
To open the battery compartment, turn the SAM990DW
over, place your thumb on the area of the battery
compartment cover marked
OPEN
, and slide the cover
down and away.
Install the two included “AAA” batteries in series in the
compartment. To do so, slide each battery into its half of
the compartment cathode (- side) first, so the cathode
contacts the coiled spring. If the batteries have been
installed correctly, when side by side they should face in
opposite directions.
OPERATING INSTRUCTIONS
To begin, grasp the sides of the sensor protection cap at
the top of the unit and pull the cap until it releases.
To power on the unit
, press the
ON/OFF
button. After a
few seconds, the LCD will begin showing real-time RH
readings on the top line and real-time ambient
temperature readings on the bottom line.
The SAM990DW’s default temperature unit is degrees
Fahrenheit. To switch to degrees Celsius, press and hold
the
C/F
button until the lower readout changes.
To display the real-time Dew Point temperature
on
the lower readout, press and hold the
td/WBT
button until
td
appears at the lower left of the LCD.
To display the real-time Wet Bulb temperature on the lower
readout, press and hold the
td/WBT
button a second time,
until
WB
appears at the lower left of the LCD.
To return to showing ambient temperature on the lower
readout, press and hold the
td/WBT
button a third time,
until
WB
disappears.
GENERAL TOOLS
& INSTRUMENTS
80 White Street
New York,NY10013
-
3567
PHONE (212) 431
-
6100
FAX (212) 431
-
6499
TOLL FREE (800) 697-8665
e-mail:
www.generaltools.com
SAM990DW User’s Manual
Specifications subject to change
without notice
NOTICE - NOT RESPONSIBLE FOR
TYPOGRAPHICAL ERRORS.
©2014
GENERAL TOOLS & INSTRUMENTS
MAN# SAM990DW
7/11/14
General Tools & Instruments
(8 pages)
(1 pages)
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