Wahl Heat Spy DHS40 Series User manual

DHS40 SERIES
HIGH PERFORMANCE HAND HELD
INFRARED THERMOMETER
USER MANUAL
MODELS
DHS401M
DHS40MT
DHS40P3
DHS40LT
DHS402M
DHS40F4
DHS40P7
DHS403M
DHS40G5
DHS40G7
WD1119 Rev A
06/12/23
Palmer Wahl Instruments, Inc.
234 Old Weaverville Road
Asheville, NC 28804
Toll Free: 800-421-2853
Phone: [phone]
Fax: [phone]
www.palmerwahl.com

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Contents
Heat Spy Warranty ..................................................................................................................................................... 4
Safety Instructions.................................................................................................................................................. 4
Acceptable Operation ........................................................................................................................................ 4
Unacceptable Operation .................................................................................................................................... 4
Instrument Disposal ........................................................................................................................................... 4
Laser Warning..................................................................................................................................................... 4
Includes .............................................................................................................................................................. 5
DHS40 Specifications.............................................................................................................................................. 5
DHS40 Product Line................................................................................................................................................ 6
Principle of Operation ................................................................................................................................................ 8
Basics of Infrared Thermometry ............................................................................................................................ 8
Target Ratio............................................................................................................................................................ 9
DHS40 Optics Diagrams........................................................................................................................................ 10
DHS40 Features.................................................................................................................................................... 10
Trigger .............................................................................................................................................................. 10
LCD Display ICONS............................................................................................................................................ 11
Control Panel.................................................................................................................................................... 13
°F / °C Switch .................................................................................................................................................... 14
Laser Switch...................................................................................................................................................... 14
Laser ................................................................................................................................................................. 15
Laser Specifications .......................................................................................................................................... 15
Caution .................................................................................................................................................. 15
Optical Sight ..................................................................................................................................................... 15
Telescopic Sight................................................................................................................................................ 16
Tri-Pod Connection........................................................................................................................................... 16
Trigger Lock ...................................................................................................................................................... 16
Power Source ................................................................................................................................................... 17
Emissivity.............................................................................................................................................................. 17
Typical Emissivity Values.................................................................................................................................. 18
Maintenance and Troubleshooting...................................................................................................................... 19
Return for Calibration Service.............................................................................................................................. 19
Appendix I: Emissivity of Common Materials .......................................................................................................... 20

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Hints for Choosing and Using ........................................................................................................................... 20
How it works......................................................................................................................................................... 20
When to use ......................................................................................................................................................... 20
Temperature at a distance............................................................................................................................... 20
Temperature of Moving Material .................................................................................................................... 20
Temperature of Small, Low Mass Material ...................................................................................................... 21
Temperature of Areas too Hot for Personnel .................................................................................................. 21
Temperature of Rough Surfaces ...................................................................................................................... 21
Temperature Requiring Quick Measurement.................................................................................................. 21
Emissivity Table .................................................................................................................................................... 22
Metals............................................................................................................................................................... 22
Non-Metals....................................................................................................................................................... 23
Thank you for purchasing a Wahl High Performance Hand-Held Infrared Thermometer.
We appreciate your business.

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Heat Spy Warranty
Manufacturer warrants all Wahl Heat Spy Fixed Infrareds manufactured by us to be free from defects in material
or workmanship under normal use and service. The Manufacturer agrees to repair or replace any product listed
above which upon examination is revealed to have been defective due to faulty workmanship or material if
returned to our factory, transportation charges prepaid, within the product specific warranty period of two (2)
years from date of purchase. This warranty is in lieu of all other warranties, expressed or implied and of all
obligations or liabilities on its part for damages including but not limited to normal wear and tear or consequential
damages following the use or misuse of this or any instrument sold by the Manufacturer. In addition, if the product
is tampered with in any way or calibrated in any way other than by the instructions supplied by Palmer Wahl, it
will immediately void the warranty. No agent is authorized to assume, for the manufacturer, any liability except
as set forth above. Freight cost to return item(s) for evaluation, duties and other fees are not covered by the
manufacturer.
Product is automatically registered for warranty by serial number at time of purchase. Serial number must
remain attached to product upon return.
Safety Instructions
This document contains important information and should be kept with the instrument at all times during its
operational life. Other users of this instrument should be given these instructions with the instrument. Future
updates to this information can be found at www.wahlheatspy.com and must be added to the original
document. The instrument can only be operated by trained personnel in accordance with these instructions and
local safety regulations.
Acceptable Operation
This instrument is intended only for the measurement of temperature. The instrument is appropriate for
continuous use and operates reliably in demanding conditions, such as in high environmental temperatures, as
long as the documented technical specifications for all instrument components are adhered to. Compliance with
the operating instructions is necessary to ensure the expected results.
Unacceptable Operation
This instrument should not be used for medical diagnosis.
Replacement Parts and Accessories: Use only original parts and accessories approved by the manufacturer. The
use of other products can compromise the operation, safety, and functionality of the instrument.
Instrument Disposal
Disposal of old instruments should be handled according to professional and environmental regulations of your
area for electronic waste.
Laser Warning
The instrument could be equipped with a Class 2 laser. Class 2 lasers shine only within
a visible area at an intensity of 1 mW. The laser functions only to locate and mark
surface measurement targets. Do not aim the laser at people or animals.
DO NOT AIM THE LASER AT THE EYE AS EYE DAMAGE WILL RESULT.

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Includes
The DHS40 comes included with 9V Alkaline Battery (PN:12232), Trigger Lock (PN:9852), Carrying Case (PN:
12423-04), Certificate of Conformance (on packing slip), and user manual (available for download).
DHS40 Specifications
DHS40 Specifications
High Performance Hand-Held Infrared
MEASURING
SPECIFICATIONS
Model Numbers
1M / 2M / 3M
MT / F4 / G5 / G7 / P7 / LT
P3
Optical
100:1
30:1
30:1
Accuracy 1
± 0.25% of reading
or ± 1°C
± 0.6% of reading or ± 1°C
± 0.6% of reading
or ± 1°C
Repeatability 2
± 0.10% of reading
± 0.30% of reading
± 0.30% of reading
LCD Resolution
1°F / 1°C
1°F / 1°C
1°F / 1°C
Response Time 3
5 mS
150 mS
750 mS
Emissivity
0.10 to 1.00
0.10 to 1.00
0.10 to 1.00
ELECTRONIC
SPECIFICATIONS
Display
LCD with Back Light, 128 x 64 DOT
Keyboard
4 - Key - MENU, UP, DOWN, ENTER
Alarm
High or Low
Signal Processing
MAX / MIN / AVG / Delta T / Temperature
SENSOR
SPECIFICATIONS
Ambient Temperature
0° to 50°C (32° to 122°F)
Storage Temperature
-20° to 70°C (-4° to 158°F)
Relative Humidity
10% to 95% non-condensing
POWER
Power Supply
9 V DC Battery
Battery Life
30 hours, approximately
ENCLOSURE
Housing Material
Aluminum
EMI Interference
Designed for Maximum EMI and RFI Protection
Housing Dimensions /
Weight
13 x 6 x 15.5 in (330.2 x 152.4 x 393.7mm) / 2.2 lbs. (0.99 kg)
1at ambient temperature 23°C, ε =1.0, NIST transfer standard.
2at ambient temperature 23°C.
390% of value.
The Wahl DHS40 conforms to RoHS requirements
according to EU Directive (EU) 2015/863- amending
Annex II to Directive 2011/65/EU for restriction of
Hazardous substances.

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DHS40 Product Line

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Principle of Operation
DHS40 Series Hand-held-IR sensors use a modular structure and component interchangeability to ensure an
instrument is ideally suited for each particular application. It also simplifies field troubleshooting, repair and
calibration.
Basics of Infrared Thermometry
Every object emits some amount of infrared radiation. As the object temperature increases, the intensity of the
radiated energy increases. This emitted energy is related to a term called emissivity which is a number between
0 and 1 which is the object emitted energy in relation to a black body perfect radiator. A perfect radiator has an
emissivity of 1 meaning that all the energy being emitted belongs to it whereas the measured target of interest
may have part of its emitted energy being reflected from something else. We want to factor out the reflected
energy by selecting a correct emissivity setting. The emissivity of most common materials is known, either
exactly or closely as some objects will vary due to age and cleanliness. See more information about emissivity
and a table of values for common materials in Appendix I.
Detector
Thermopile
A thermopile is a tight cluster of a large number of tiny specialized thermocouples. They are connected together
to form a single measuring point and the output is the difference between the ambient temperature the head
electronics are in (the cold junction) and the target temperature collected and determined by the optical system
wavelength filter and the thermopile (hot junction).
The waveband is determined by an additional optical filter chosen by the manufacturer for the specific
application. This is to reduce or eliminate emitted wavelengths, which might belong to the target or might be
unwanted reflections that are of no interest for the measurement application.
Wahl provides six (6) different spectrums in our thermopile versions. They are 3.43 micron, 3.9 micron, 4.11 to
4.72 micron, 5.0 micron, 7.9 micron and 8 to 14 micron.
Photodiode
Both Silicon and InGaAs photodiode principles are completely different from thermopile: the collected energy is
transformed into electron flow. The result is a current proportional with the incident energy.
This transformation is very fast, taking only a few µS. The response time of the measuring system is limited by
the electronics; high resolution and low energy consumption makes it a little bit slower. The waveband is
determined by the physical characteristic of the sensor.
Wahl provides three (3) different spectrums in our photodiode versions, 1.0 micron, 1.6 micron and 2.4 micron.
Lens and Filter
The specifications of the lens decisively determine the optical path of the infrared thermometer, characterized
by the ratio Distance to Spot size. The spectral filter selects the wavelength range, which is relevant for the

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temperature measurement. The detector and the processing electronics transform the emitted infrared
radiation into electrical signals.
Target Ratio
The actual area being measured is determined by the distance-to-spot ratio of the model you are using; this
varies from model to model. As the distance from the object being measured increases, the spot size of the area
being measured also increases.
Wahl provides two (2) optics options for the DHS40 model, one (1) for both the photodiode and one (1) for the
thermopile versions.
Maximum Distance and Spot Size
Use the size of the object being measured, together with the optical resolution of the infrared thermometer to
determine the maximum distance between the two. The object being measured should completely fill the field
of view of the optics to prevent any potential errors.
Proper Placement of Sensor:
To achieve the best results, the spot size of the infrared thermometer should be smaller than the object being
measured.
Before using, review the target to ratio tables on the following pages for the appropriate Optics image for your
model to determine the correct distance and visual field.
Target greater than spot size
Target equal to spot size
Target smaller than spot size

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DHS40 Optics Diagrams
DHS40 Features
Trigger
The trigger is contoured to fit the index finger. This is a single position trigger, which turns the instrument on
when pulled. The display will show blank for a fraction of a second before the first reading appears to allow the
microprocessor to complete its initial calculation cycles.