General Tools General Tools SAM990DW Manual

GENERAL TOOLS

General Tools & Instruments

GeneralToolsNYC

& INSTRUMENTS

99 Washington Street
Melrose, MA 02176

Phone [phone]
Toll Free 1-800-517-8431

Visit us at www.TestEquipmentDepot.com

SAM990DW User’s Manual

Specifications subject to change

without notice

NOTICE - NOT RESPONSIBLE FOR

TYPOGRAPHICAL ERRORS.

DIGITAL

PSYCHROMETER

USER’S MANUAL

GENERAL TOOLS & INSTRUMENTS

©2014

MAN# SAM990DW

7/11/14

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.

INSTRUCTIONS

SETUP

INSTALL BATTERIES

To open the bat ter y co mpart ment, tu rn the SAM99 0DW
over, place your thumb on the area of the battery

OPEN

compartment cover marked

, 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 begi n, gr asp the si des o f the senso r pro tectio n ca p a t
the top of the unit and pull the cap until it releases.

To powe r on t he un it

, 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

C/F

button until the lower readout changes.

the

To disp lay t he re al-tim e Dew Po in t tempe rature

the lower readout, press and hold the

td

appears at the lower left of the LCD.

td/WBT

on

button until

To dis play the real -tim e W et Bulb tem pera tu re o n the lo wer

td/WBT

readout, press and hold the

WB

until

appears at the lower left of the LCD.

button a second time,

To retu rn to sho wing ambien t tem pera ture on t he lo wer
readout, press and hold the

WB

until

disappears.

td/WBT

button a third time,

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 disp lay th e min imum R H lev el an d temp era ture sensed
during a measurement session, press and hold the

MN/MX

on the LCD, with the term

once. Doing so will cause both readings to appear

MIN

at the right of the RH%.
To sw itch t o the maxi mum R H leve l and temp era ture
detected over the same period, press and hold the

MN/MX

button again. This will change

MIN

to

MAX

.
To resu me di splayi ng rea l-tim e rea dings, pr es s an d hold
the

MN/MX

button again.

To cl ea r the Min a nd Ma x sess ion v alues from memor y,

RST

press and hold the

button until the LCD briefly shows
all possible display indications, and then returns to
showing real-time, Min or Max readings.

SPECIFICATIONS

Tempera tur e Mea sureme nt Ra nge:

-4° to 122°F (-20° to 50°C)
Tempera tur e Mea sureme nt A cc ura cy: ±1. 8°F (± 1°C)
Tempera tur e Mea sureme nt Re soluti on: 0. 1°
RH Measurement Range: 0 to 100%

Measurement Accuracy: ±3% at 77°F (25°C)

RH

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

antability and fitness for a particular purpose, are

merch
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:

Remember to include a copy of your proof of purchase,
your return address, and your phone number and/or e-mail
address.

99 Washington Street
Melrose, MA 02176

Phone [phone]
Toll Free 1-800-517-8431

Visit us at www.TestEquipmentDepot.com