DIGITAL
PSYCHROMETER
USER’S MANUAL
SAM990DW
Please read this manual
carefully and thoroughly
before using this product.
GENERAL TOOLS
& INSTRUMENTS
80 White Street
New York, NY 10013-3567
PHONE (212) 431-6100
FAX (212) 431-6499
TOLL FREE (800) 697-8665
e-mail:
sales@generaltools.com
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
GeneralToolsNYC
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.
S
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.
DISPLAYING MINIMUM AND MAXIMUM READINGS
The SAM990DW automatically tracks the maximum and
minimum (highest and lowest) RH values and
temperatures (ambient, Dew Point and Wet Bulb) sensed
over a measurement “session”—the time during which
you make measurements at multiple locations and/or
under different conditions. Each session begins when you
power on the unit; it typically ends 20 minutes later with
the activation of the APO function.
The value of being able to quickly determine the hottest or
coolest, or wettest or driest area of several possibilities
should be obvious.
To display the minimum RH level and temperature sensed
during a measurement session, press and hold the
MN/MX
once. Doing so will cause both readings to appear
on the LCD, with the term
MIN
at the right of the RH%.
To switch to the maximum RH level and temperature
detected over the same period, press and hold the
MN/MX
button again. This will change
MIN
to
MAX
.
To resume displaying real-time readings, press and hold
the
MN/MX
button again.
To clear the Min and Max session values from memory,
press and hold the
RST
button until the LCD briefly shows
all possible display indications, and then returns to
showing real-time, Min or Max readings.
SPECIFICATIONS
Temperature Measurement Range:
-4° to 122°F (-20° to 50°C)
Temperature Measurement Accuracy: ±1.8°F (±1°C)
Temperature Measurement Resolution: 0.1°
RH Measurement Range: 0 to 100%
R
RH Measurement Accuracy: ±3% at 77°F (25°C)
from 10 to 90% RH; ±4% elsewhere
RH Measurement Resolution: 0.1%
Dew Point Measurement Accuracy: ±1.2°F (±0.6°C)
Auto Power Off Trigger: 20 minutes of front-panel inactivity
Dimensions: 6.7 x 1.85 x 0.5 in. (170 x 22 x 13mm)
Weight: 4 oz. (113g)
Power Source: 2 “AAA” batteries (included)
OPERATING & MAINTENANCE TIPS
When the entire displays flashes, the batteries’ voltage
has fallen below the threshold needed to assure accurate
measurements. Replace weak or dead batteries
immediately.
Never immerse the temperature-humidity sensor at the
top of the SAM990DW in liquid. Doing so will permanently
damage the sensor and void the instrument’s limited
warranty.
A small amount of condensation visible on the LCD will not
affect the unit’s accuracy.
WARRANTY INFORMATION
In the U.S, General warrants its instruments and
accessories against defects in material or workmanship
for one year from the date of purchase. General will
replace or repair the defective unit, at its option, subject to
verification of the defect.
This warranty does not apply to defects resulting from
abuse, neglect, accident, unauthorized repair, alteration, or
unreasonable use of the product.
Any implied warranties arising from the sale of a General
product, including but not limited to implied warranties of
m
merchantability and fitness for a particular purpose, are
limited to the above. General shall not be liable for loss of
use of the product or other incidental or consequential
damages, expenses, or economic loss, or for any claim of
such damage, expenses, or economic loss.
State laws vary. The above limitations or exclusions may
not apply to you.
We encourage you to register your product online. General
will extend your warranty an additional 60 days if you
register at www.generaltools.com/ProductRegistry.
RETURN FOR REPAIR POLICY
Every effort has been made to provide you with a reliable
product of superior quality. However, in the event your
instrument requires repair, please contact our Customer
Service to obtain an RGA (Return Goods Authorization)
number before forwarding the unit via prepaid freight to
the attention of our Service Center at this address:
General Tools & Instruments
80 White Street
New York, NY 10013
212-431-6100
Remember to include a copy of your proof of purchase,
your return address, and your phone number and/or e-mail
address.
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