MRC 8758 User manual

OPERATION MANUAL
HEAT INDEX WBGT METER
Model:
8758
8778
8758 8778

INTRODUCTION
WBGT(wet-bulb globe temperature) was
developed as a monitoring basis at US
military training camps and became
widespread for the use in workplaces
and sports situations. It is suggested in
an international standard ISO 7243 and
many governments such as OSHA (US
Occupational Safety & Health Adminis-
tration), SMA(Sports Medicine Australia),
and Japan Society for Occupational
Health in establishing the permissible
heat exposure limits in occupational
health, sports or other physical activities.
The applications of the heat index can be
in construction, iron and steel foundries,
bricks-firing plants, glass facilities, boiler
rooms, mining sites, army training,
marathon, beach activities and so on.
Features:
Direct measurement of the radiation
effect with a brass black ball.
Adjustable WBGT alarm threshold
Audible beeper for heat stress
monitoring
Sensor protecting mechanism
Easy self calibration for humidity
PC connect for data analysis
1
Thank you for purchasing the Heat Index
WBGT meter. The handy meter measures
air temperature, globe temperature, and
humidity to give heat stress index for
using in control of physical activity in hot
environment to limit the danger of heat-
related injuries
(See appendix)

2
CONTROLS AND INDICATORS
LCD display
Function Keys
Turn on and off the meter
Enter alarm setting mode
Select digit in setting mode
Exit from setting mode
Select display mode
Shift IN/OUT mode
Increase value in setting
+ Set as non-sleep
o
+ Select C or F
+ + Enter RH calibration
o
Symbol indication
WBGT Wet Bulb Globe Temperature
TG Black Globe Temperature
TA Air Temperature
% Relative Humidity
C/F Celsius/Fahrenheit
IN Indoor (no sun)
OUT Outdoor (full sun)
Low battery indicator
DP/REC Vain icons in these
models.
NEXTNEXT
MODEMODE
MODEMODE
MODEMODE
NEXTNEXT
NEXTNEXT
MODEMODE

IN/OUT switch
To measure WBGT without or with
direct sun exposure under IN/OUT
modes, hold down for more
than 1 second to switch.
Select Unit
Press and simultaneously in
o
measuring mode to select C or
oF.
3
OPERATING INSTRUCTIONS
MODEMODE
MODEMODE
NEXTNEXT
MODEMODE
1. POWER ON/OFF
Press to turn on and turn off the
meter. All indicators are shown on
the LCD when power on, and then
enter measuring mode.
2. MEASUREMENT
Slide down the protecting sheath
of sensor before measurements.
Pull up to
protect sensor
Design patent
pending
Select display mode
The meter measures TA(Air Temp),
TG (Globe Temp.), RH (Relative
Humidity), and calculates WBGT.
Press to select modes. An icon
shows on the top to indicate the
current operation mode. (Fig. A)
Fig. A

3. ALARM SETTING
The meter features audible alarm
to give warning for possible heat
stress in the environment. When
WBGT value reaches the alarm
threshold, the value starts to blink
with continuous beep(about 70 dB).
The alarm stops when measured
value falls below the threshold or
the meter is turned off.
The alarm threshold is adjustable
for different applications. Hold
down for 2 seconds to turn on
the meter and enter alarm setting.
The current setting displays with a
blinking digit. Press to increment
the value and to select digit.
After new alarm threshold is set,
press for 2 seconds to return to
measuring mode.
The setting range is 20.0~37.2 C
(68.0~99.0 F). "OUT" will show if
setting is out of range. (Fig. B)
o
o
MODEMODE
NEXTNEXT
NEXTNEXT
Fig. B
4
4. BATTERY REPLACEMENT
appears on the LCD when battery
voltage gets low. To replace battery
by opening the compartment on the
rear of the meter.

5
Unscrew the black
globe with sensor
sheath (see pic. A)
before calibration.
Follow the illustration
on page 7 to recap
sensor sheath after
completing calibration.
Pic. A
The meter can be calibrated on the
humidity by end users with 33% and
75% salt solution. The ambient
condition is recommended to be at
o
23+/-2 C and stable humidity. Users
can terminate the calibration anytime
by turning off the meter.
RH CALIBRATION
6. TRIPOD MOUNTING
The meter can fit on a tripod for long
time monitoring. A built-in thread is
on the rear side of the meter.
5. AUTO POWER OFF
The meter turns off automatically
after 20 minutes non-operation.
To override the function, hold down
and for 2 seconds to turn on
the meter. The LCD will display “n”
and then enter measuring mode.
(Fig. C)
MODEMODE
Fig. C
Sensor
probe
Sensor
connector
Black globe
with sensor
sheath

Note:
The RH value difference between the
meter display and calibration standard
should be within +/-0.3%, otherwise
it is a failed calibration.
The blinking “7X.X%” shows on the
screen and meter is now calibrating.
Wait about 60 mins.until blinking stops
,it means the calibration is completed
and meter returns to measuring mode.
6
75% calibration
After 33% calibration, plug the sensor
probe into 75% salt bottle, then press
for 2 seconds to start.
MODEMODE
33% calibration
Plug the sensor probe into 33% salt
bottle(Pic A1),hold down , ,and
buttons for 2 seconds to power on the
meter until blinking “3X.X%” appears.
Meter is now calibrating, and will finish
in about 60 mins. when the value stops
blinking.
Note:
Strongly recommend to use one hand to
press one button, and use two fingers
of the other hand to press two buttons
simultaneously . This is easier for you
to operate 3 keys.
MODEMODE
NEXTNEXT
Pic.A1
Salt solution

CAUTION:
Reassemble the globe with caution by
fitting the pin (Pic. B) into the connector
(Pic.C). It helps to position by targeting
the screw holes on the sheath and the
meter. Incorrect installation may
damage the sensor.
Sensor
pin
Sensor
connector
Pic.B
Pic.C
Important:
Screw holes
for targeting
to assemble
the globe.
Pic. D
? Error message on the display
E2: The value is under range. Improper
sensor installation.
E3: The value is over range.
E4: The value is in error because of
the original data. Improper sensor
installation.
E11: RH calibration error. Do the
calibration again.
E32/E33: Circuit error. Return to the
vendor for repair or replacement.
? Power on but no display
Check whether the batteries are in
good contact and correct polarity, or
take out the batteries for one minute
and reinstall and retry.
? Calibration failure
a.Check the battery voltage or replace
with new batteries.
b.Check whether the sensor is well
plugged into the salt bottle and no air
comes in. Check ambient condition.
TROUBLESHOOTING
7

8
RS232 INTERFACE
The meter can do PC link for
data analysis
on-line
logging and via RS232
interface and software.
The protocol is as follows.
B.Format
(Transmitting ASCII code by every
second while meter is on.)
Wxxx.xC(F):Txxx.xC(F):Txxx.xC(F)
:Hxx.x%LRCCRLF
Note: The 1st value is WBGT, the 2nd is
TA, the 3rd is TG, and the 4th is RH.
A.9600 bps, 8 data bits, no parity.
SPECIFICATION
8758 8778
Black ball size 40(D)x35(H)mm 75(D)x75(H)mm
Air Temp. range 0~50℃ (32~122℉)
Air Temp. accuracy ±0.6℃
Globe Temp. range 0~80℃ (32~176℉)
Indoor ±2℃ (15~40℃)
±2.5℃ (Others)
±1℃ (15~40℃)
±1.5℃ (Others)
Globe
Temp.
accuracy Outdoor ±3℃ (15~40℃)
±3.5℃ (Others)
±1.5℃ (15~40℃)
±2℃ (Others)
WBGT Temp. range 0~50℃ (32~122℉)
WBGT Formula
Indoor/Outdoor and no sun:
WBGT=0.7WB + 0.3TG
Outdoor and full sun:
WBGT=0.7WB + 0.2TG + 0.1TA
RH range 0~100%
RH accuracy ±3% (10~90%RH)
±5% (other range)
Resolution 0.1℃/℉, 0.1%RH
Response time 15 seconds typical
Operating condition 0~50℃, 0~95% RH
Storage condition -20~65℃, 0~95% RH
Meter size 40(H)x48.7(W)x254(L)mm – 8758
75(H)x75(W)x278.2(L)mm – 8778
Battery life
(without beep)
1000 hours (Alkaline)
250 hours (General purpose)

MATERIALS SUPPLIED
Meter
2pcs AAA batteries
Operation manual
Plain box packaging
This package contains:
Optional accessory:
33% calibration salt (VZHR33AZ)
75% calibration salt (VZHR75AZ)
RS232 cable and software
9
WARRANTY
The meter is warranted to be free from
defects in material and workmanship
for a period of one year from the date
of purchase. This warranty covers normal
operation and does not cover misuse,
abuse, alteration, neglect, improper
maintenance, or damage resulting from
leaking batteries. Proof of purchase is
required for warranty repairs. Warranty is
void if the meter has been opened.
RETURN AUTHORIZATION
Authorization must be obtained from the
supplier before returning items for any
reason. When requiring a RA (Return
Authorization), please include data
regarding the defective reason, the meters
are to be returned along with good packing
to prevent any damage in delivery and
insured against possible damage or loss.

APPENDIX
PERMISSIB LE HEAT EXPOSURE THRESHOLD LIM IT
Source: ACGIH 1992(The American Conference
of Governmental Industrial Hygienists)
WBGT INDEX AND PHYSICAL EXERCISE
Value:WBGT
Recommendations to heat exposure level
for working and physical activity!
WBGT Flag Activity Intensity
< 80 F White Normal activity. Caution
< 26.7 C should be taken.
80-84.9 F Green Discretion is required
26.7-29.4 C in planning intense
physical activity.
ctivity for new
29.4-31 C and unacclimatized
persons should be
curtailed.
88-89.9 F Red Intense exercise must
31-32.2 C be curtailed for those
with less than 12 weeks
training in hot weather.
Be on high alert
> 90 F Black Cancel all outdoor
> 32.2 C exercise.
o
o
o
o
o
85-87.9 F Yellow Intense a
o
o
o
o
o
Source: Manual of Naval Preventive Medicine
(NAVMED P-5010)
Work/rest regimen Light Moderate Heavy
(Each hour)
o o o
Continuous work 30 C 26.7 C 25 C
o o o
/86 F /80 F /77 F
o o o
75% work, 25% rest 30.6 C 28 C 25.9 C
o o o
/87 F /82 F /78 F
o o o
50% work, 50% rest 31.4 C 29.4 C 27.9 C
o o o
/89 F /85 F /82 F
o o o
25% work, 75% rest 32.2 C 31.1 C 30 C
o o o
/90 F /88 F /86 F
10

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