Extech Instruments HT30 User manual

User's Manual
Heat Stress WBGT Meter
Model HT30
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Introduction
Congratulations on your purchase of Heat Stress WBGT (Wet Bulb Globe Temperature) Meter. This
meter measures and displays Heat Stress Index (WBGT), which is how hot it feels when humidity is
combined with temperature, air movement, and direct or radiant sunlight. Black Globe Temperature
(TG) monitors the effects of direct solar radiation on an exposed surface. It also measures air
temperature (TA) and Relative Humidity (RH). Additional features include: selectable units of °F/°C,
Auto power off with override, and a built-in RS-232 interface with optional 407752 Windows®
software. This meter is shipped fully tested and calibrated and, with proper use, will provide years of
reliable service.
Meter Description
1. Black Globe temperature sensor
2. RH and Temperature sensors with protective cover
3. LCD display
4. /SET
5. NEXT
6. MODE/
7. RS-232 interface
8. Battery compartment (on rear)
DISPLAY
Symbol Function
WBGT Wet Bulb Globe Temperature
TG Black Globe Temperature
TA Air Temperature
RH% Relative Humidity
OUT Indoor (no sun)
IN Outdoor (in full sun)
C/F Celsius/Fahrenheit
Low Battery indicator
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Meter Operation
1. Press the /SET button to power the instrument on/off.
2. Slide down the protective sensor cover before taking measurements.
3. Press the MODE/button to select the desired display mode: Wet Bulb Globe Temperature
Index (WBGT), Air Temperature (TA), Black Globe Temperature (TG), or Relative Humidity
(RH). An icon will appear in the display indicating the current selection.
4. To select the preferred temperature unit (°F or °C), simultaneously press and release the
MODE/and NEXT buttons. The F or C icon will appear in the display.
5. The meter measures WBGT index with (IN) or without (OUT) direct sun exposure. Hold down
the MODE/ for more than 1 second to alternate between settings. The IN or OUT icon will
appear in the display.
Alarm Setting
The HT30 has a user settable heat stress alarm. The HT30 will emit an audible beep when the heat
stress WBGT reaches the level previously set by the user. The alarm will continue beep until the
measured WBGT temperature falls below the alarm level set by the user, or the meter is turned off.
The setting range is from 68.0 to 99.0°F (20.0 to 37.2°C).
1. To enter the alarm setup mode, hold down the /SET button for more than 2 seconds when
turning the meter on.
2. The current alarm setting will be displayed with the most significant digit blinking.
3. Use the MODE/button to increment the digit.
4. To set the next digit, momentarily press the NEXT button.
5. After all of the digits are set, press and hold the NEXT button for 2 seconds to return to the
measuring mode.
NOTE: The OUT icon will appear in the display If the new setting is out of the setting range of the
alarm.
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Auto Power Off
The Auto Power Off feature automatically turns the meter off after approximately 20 minutes. To
disable this feature, hold down the /SET and MODE/for 2 seconds when powering on the
meter. The meter will momentarily display an “n” and enter measuring mode. The meter will reset to
auto power off mode when it is powered off.
Battery Replacement
When it is time to replace the batteries, the low battery indicator appears in the bottom left-hand
corner of the LCD display. To replace the battery:
1. Open the battery compartment on the back of the meter.
2. Replace the two AAA batteries and close the compartment.
You, as the end user, are legally bound (Battery ordinance) to return all used batteries and
accumulators; disposal in the household garbage is prohibited!
You can hand over your used batteries / accumulators at collection points in your community
or wherever batteries / accumulators are sold!
Disposal: Follow the valid legal stipulations in respect of the disposal of the device at the
end of its lifecycle
RS-232 PC Interface
The RS-232 serial data port (3.5mm phono jack) is located on the right side of the meter. The PC
interface hardware is intended for use with the Extech software package, Part Number 407752
which includes Windows® compatible software and PC interface cable. This software will allow you
to Stream data from the meter to the PC software (Data Acquisition).
For more information, contact Extech or refer to the 407752 User's Manual.
Error Messages
An error message will appear on the display if the meter fails an internal diagnostic test.
1. E2: The value is under range.
2. E3: The value is over range.
3. E4: The value is in error.
4. E11: RH Calibration error.
5. E33: Circuit error. Repair/replacement necessary.
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Specifications
Wet Bulb Globe Temperature (WBGT) 0°C to 50°C (32°F to 122°F)
WBGT Accuracy Calculated from measured parameters
TG Black Globe Temperature range 0 to 80°C (32°F to 176°F)
TG Accuracy Indoor ±2°C (4°F)
Outdoor ±3°C (5.5°F)
TA Air Temperature range 0°C to 50°C (32°F to 122°F)
TA Accuracy ±1°C (1.8°F)
Relative Humidity (RH) 0 to 100%RH
RH Accuracy ±3% (at 25°C, 10 to 95%RH)
Resolution 0.1°F/°C; 0.1%RH
Operating Temperature 0°C to 50°C (32°F to 122°F)
Operating Humidity Max. 80% RH
Power Supply Two AAA batteries
Battery Life Approx 1000 hours
Dimensions Meter: 254 x 48.7 x 29.4mm (10x1.9x1.1")
Black Ball: 40mm, 35mm (1.57 Dia., 1.37H)
Weight 136g (4.8oz)
Optional Accessories PC software and cable (407752)
HT30 WBGT calculations:
WBGT = Wet bulb Globe temperature
WB = Wet bulb temperature (Calculated from temperature and Humidity)
TG = Globe temperature
TA = Air temperature
OUT of the Sun (Indoors)
WBGT = 0.7xWB + 0.3xTG
IN full Sun (Outdoors)
WBGT = 0.7xWB + 0.2xTG + 0.1xTA
Sensor - Wet bulb calculator (sea level pressure)
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
Know These Heat Disorder Symptoms
Heat
Disorder Symptoms First Aid
Sunburn Redness and pain. In severe cases,
swelling of skin, blisters, fever,
headaches.
Ointment for mild cases if blisters appear. If breaking occurs,
apply dry sterile dressing. Serious, extensive cases should be
seen by a physician.
Heat
Cramps
Painful spasms usually in muscles of
legs and abdomen possible. Heavy
sweating.
Firm pressure on cramping muscles, or gentle massage to
relieve spasm. Give sips of water. If nausea occurs,
discontinue use.
Heat
Exhaustion
Heavy sweating, weakness, skin cold,
pale and clammy. Pulse thready.
Normal temperature possible. Fainting
and vomiting.
Get victim out of sun. Lay down and loosen clothing. Apply
cool wet cloths. Fan or move victim to air conditioned room.
Sips of water. If nausea occurs, discontinue use. If vomiting
continues, seek immediate medical attention.
Heat
Stroke
(or
sunstroke)
High body temperature (106°F, or
higher). Hot dry skin. Rapid and
strong pulse. Possible
unconsciousness.
Heat stroke is a severe medical emergency. Summon
medical assistance or get the victim to a hospital
immediately. Delay can be fatal.
Move the victim to a cooler environment. Reduce body
temperature with cold bath or sponging. Use extreme caution.
Remove clothing, use fans and air conditioners. If temperature
rises again, repeat process. Do not give fluids.
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