Extech Instruments RH520B User manual

USER MANUAL
Paperless Humidity/Temperature Chart Recorder
Model RH520B
Additional User Manual Translations available at www.extech.com

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Introduction
Congratulations on your purchase of the Extech RH520B Temperature + Humidity Chart
Recorder. The RH520B measures and displays Temperature, Humidity, and Dew Point.
The remote (detachable) probe senses the ambient conditions while the LCD display graphs and
provides numerical representation of the readings. Programmable audio-visual alarms alert the
user when ambient conditions reach alarm presets. The optional alarm module permits
automatic relay switching when alarm presets are reached.
The RH520B Internal Memory can store up to 49,152 measurements for later transfer to a PC.
Careful use of this instrument will provide years of reliable service.
CAUTIONS
This device is not a toy, it contains hazardous objects as well as small parts that children can
swallow. Contact a physician immediately if an object is swallowed.
Do not leave batteries or packing material unattended; they can be dangerous to children.
If the device is to be unused for an extended period, remove the batteries to prevent them
from draining.
Expired or damaged batteries can cause cauterization on contact with the skin. Use
protective gloves when necessary.
Do not short-circuit batteries or discard them in a fire.
FCC Compliance
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to
part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful
interference in a residential installation. This equipment generates, uses, and can radiate radio frequency
energy and, if not installed and used in accordance with the instructions, may cause harmful interference to
radio communications. However, there is no guarantee that interference will not occur in a particular
installation. If this equipment does cause harmful interference to radio or television reception, which can be
determined by turning the equipment off and on, the user is encouraged to try to correct the interference by
one or more of the following measures:
1. Reorient or relocate the receiving antenna.
2. Increase the separation between the equipment and receiver.
3. Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
4. Consult the dealer or an experienced radio/TV technician for help.
WARNING
Changes or modifications not expressly approved by the party responsible for compliance could void the
user's authority to operate the equipment.

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RH520B Description
1. Remote sensor
2. Sensor cable
3. LCD Display
4. Swivel keypad / table-top
stand
5. PC interface jack
6. Universal alarm module jack
7. AC adaptor jack
8. DATA RESET button (clears recorded measurement data and alarm history)
9. Temperature units select switch (C or F)
10. PROGRAMMING RESET button (clears programming changes but retains measurement
data and alarm history)
11. Display CONTRAST adjust
12. Sensor cable storage area
13. ‘AA’ 1.5V batteries
14. Sensor cable run
15. Wall mount holes
1
2
3 4
5
6
7

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DISPLAY DESCRIPTION
1. Temperature measurement graph
2. Internal memory usage meter
3. Vertical axis scale limits
4. Cursor / Alarm indicators
5. Push-button lock-out status indicator
6. Time display
7. Relative Humidity (RH) measurement graph
8. Date display
9. Function indicators
10. Numerical temperature reading display
11. Numerical RH reading display
12. Battery status indicator
2
3
4
3
5
6 7 8
9
9
10
11
9
12
MAX
MIN
ALARM
MAX
MIN
SET
DEW POINT

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PUSH-BUTTON DESCRIPTION
VIEW Return the LCD to the Standard View
Escape from any setting function without storing value changes
Scrolls highest and lowest (MAX/MIN) readings when in Standard View
ALARM Display or Set alarm values
TIME Display a reading stored at specific Time and Date
Set and Display the recording Sampling Rate
Set the Time and Date
SET Used in combination with other buttons to set new parameter values
Stores new parameter values and returns to the Standard View
TEMP Used in combination with other buttons to set the vertical graph range
Used in combination with other buttons to set temperature alarm values
Used in combination with the RH button to display Dew Point
RH Used in combination with other buttons to set the vertical graph range
Used in combination with other buttons to set RH alarm values
Used in combination with the TEMP button to display Dew Point
Right, left, down, and up arrow buttons for scrolling data and navigating the
display

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KEYPAD QUICK REFERENCE (ALSO SHOWN ON REAR OF THE RH520B HOUSING)
Key-press
Function
Second / Alternate Keystrokes
VIEW
Selects view mode
VIEW modes: Normal, TEMPmax,
RHmax, TEMPmin, RHmin
SET
Saves new settings
VIEW to cancel, exit mode
ARROW KEYS
Scroll through selections
Movers cursor through stored
points
TIME
View reading at specific
time/date
Arrow keys to select, VIEW to
exit
TEMP + RH
View Dew Point temp.
VIEW to exit
ALARM
Step back through ALARM
points
ALARM selects next Alarm, VIEW
to exit
SET + TEMP +
ALARM
Enters Set TEMP Alarm mode
ALARM selects HIGH/LOW, SET to
save
SET + RH + ALARM
Enters Set RH Alarm mode
ALARM selects HIGH/LOW, SET to
save
TIME + VIEW
View Sample Rate
VIEW to exit
SET + TIME + VIEW
Enter Set Sample Rate mode
SET to save, VIEW to exit
SET + TIME
Enter Set Time/Date mode
SET to save, VIEW to exit
SET + TEMP + UP
Enter Set TEMP Vertical Scale
mode
TEMP selects upper/lower, SET to
save
SET + RH + UP
Enter Set RH Vertical Scale
mode
RH selects upper/lower, SET to
save

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Getting Started
POWER
1. The RH520B runs on battery power or AC adaptor (5VDC 1A). Battery power consists of three
(3) ‘AA’batteries. See the Battery Replacement section of this manual when
changing/installing the batteries. Note: Batteries and adaptor are supplied.
2. Plug the AC adaptor in the AC adaptor jack shown in the Description section. The batteries
will act as battery back-up in the event of an AC power failure.
3. Once the batteries are installed or the adaptor properly connected, the RH520B will begin
displaying.
4. In the unlikely event that the AC power AND the battery back-up fails, the RH520B will
require a “Programming Reset” to reset the display. Press the RESET button located inside
the battery compartment. “Reset” clears all settings. Time, Date and the logging interval
need to be entered. The measurement data and alarm history, however, will still be retained
in the non-volatile memory.
5. The 5-segment battery life indicator allows the user to track the status of the battery. When
all 5-segments are dark, the battery is fully charged. Segments switch off as the battery ages.
When the battery indicator has only one segment left the batteries must be replaced
immediately.
NOTE: Always set the Date, Time, and Sample rate immediately after batteries have been
installed or after the RESET button in the battery compartment has been pressed.
Then press the Data Reset button on the rear face of the meter for >4 seconds to
clear any recorded data.
MOUNTING THE RH520B
The RH520B can be used in the following ways:
1. Placed on a table top where the swivel keypad is employed as the table stand
2. Wall mounted using the rear mounting holes
MEASUREMENT PROBE
The probe is attached to the meter with a 1-meter cable and can be used stored in the RH520B
probe cradle or remotely. The probe cable length can be easily extended with an RJ45 cable and
a gender changer.
PUSH-BUTTON LOCK-OUT SECURITY FEATURE
The RH520B can be secured from tampering by having its push-buttons locked.
1. Press for approx. 1 second and release the UP, DOWN, LEFT, and SET arrow buttons
simultaneously to lock-out the push-buttons.
Note: The security lock-out can only be performed from the main view screen. If a scroll key
or the time button was pressed prior to setting up the lock-out, the user must scroll back to
the main screen.
2. Press for approx. 1 second and release the UP, DOWN, LEFT, and SET arrow buttons
simultaneously to restore the operation of the push-buttons

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Programming the RH520B
SETTING THE TIME AND DATE
1. From the Standard View, press the SET and TIME buttons simultaneously
2. The SET indicator will appear
3. Use the UP and DOWN arrow buttons to set the time
4. Use the LEFT and RIGHT arrow buttons to step through the minutes, hours, AM/PM/24-
Hour, day, month, and year parameters
If AM or PM is selected, the date format will be MONTH-DAY-YEAR
If 24-hour is selected, the date format will be DAY-MONTH-YEAR
5. Press SET at any time to store the new value and revert to the Standard View
6. Press VIEW at any time to return to the Standard View without storing any changes
CLEARING THE INTERNAL MEMORY
Press the RESET button (located inside the battery compartment) to clear the display and
measurement parameters (sample rate, vertical resolution), and to reset the display.
Press the DATA RESET button (located on the back of the unit) to clear all the stored readings,
the MAX/MIN values, and the Alarm history.
SELECTING THE UNIT OF MEASURE FOR TEMPERATURE (oC/oF)
The oC/oFswitch, located inside the battery compartment, is used to select the unit of measure
for temperature displays
SETTING THE VERTICAL RESOLUTION FOR THE TEMPERATURE GRAPHIC DISPLAY
1. Press the SET, TEMP, and UP arrow buttons simultaneously
2. The upper temperature range indicator will flash, and the SET icon will appear
3. Use the UP-DOWN buttons to change the upper temperature value (5° increments).
4. Press the TEMP button and the lower temperature range indicator will flash
5. Use the UP-DOWN buttons to change the lower temperature value (5° increments) Note that
the upper and lower temperature values cannot overlap, and the upper value cannot be less
than zero
6. Press the TEMP button to toggle upper and lower range values
7. Press the SET button at any time to store a value and return the instrument to the Standard
View
8. Press VIEW at any time to return to the Standard View
Important: After powering on the unit and setting the Date, Time, or Sample Rate you
MUST clear the internal data memory. If you do not clear the internal data memory
you will not get the correct Time and Date stamps (2004) with your recorded data.
Press the Data Reset button on the rear face of the meter for >4 seconds.

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SETTING THE VERTICAL RESOLUTION FOR THE RH GRAPHIC DISPLAY
1. Press the SET, RH, and UP arrow buttons simultaneously
2. The upper RH range indicator will flash, and the SET icon will appear
3. Use the UP-DOWN buttons to change the upper RH value in 10% increments
4. Press the RH button and the lower RH range indicator will flash
5. Use the UP-DOWN buttons to change the lower RH value in 10% increments
6. Note that the upper and lower RH values cannot overlap
7. Press the RH button to toggle upper and lower range values
8. Press the SET button at any time to store a value and return the instrument to the Standard
View
9. Press VIEW at any time to return to the Standard View
SETTING THE RECORDING SAMPLE RATE
The Sampling Rate is the rate at which the RH520B automatically records measurements
1. Press the SET, VIEW, and TIME arrow buttons simultaneously from the Standard View
2. The current Sample Rate (in minutes) will appear in the numerical temperature display area
3. The whole minutes area of the numeric display will flash
4. The MIN and the SET icons will switch on. All other TEMP and RH indicators and numeric
displays will switch off
5. The projected TIME and DAYS representing the moment the internal memory will be full
(based on the sample rate) is displayed in the TIME and DATE display areas.
6. Use the UP-DOWN arrow buttons to increment/decrement the rate. Use the LEFT-RIGHT
arrow buttons to step through the units of time
7. Sample rates can be set from 0.1 minutes (6 seconds) up to 199.9 minutes
8. Press the SET button at any time to save changes and return to the Standard View
9. Press VIEW at any time to return to the Standard View without saving the changes
SETTING THE TEMPERATURE ALARM LIMITS
1. Press the SET, TEMP, and ALARM buttons simultaneously from the Standard View
2. The ALARM, SET, and MAX indicators will switch on. All of the RH indicators will switch off
3. Use the UP-DOWN arrow buttons to increment/decrement the HIGH temperature alarm
limit. Use the LEFT-RIGHT arrow buttons to step through the decades
4. Press the ALARM button. The MIN (low alarm) indicator will switch on
5. Use the UP-DOWN arrow buttons to increment/decrement the LOW temperature alarm
limit. Use the LEFT-RIGHT arrow buttons to step through the decades
6. The HIGH and LOW alarm limits cannot overlap
7. Use the ALARM button to toggle between the HIGH and the LOW alarm limits
8. Press the SET button at any time to save changes and return to the Standard View

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9. Press VIEW at any time to return to the Standard View without saving the changes
SETTING THE RH ALARM LIMITS
1. Press the SET, RH, and ALARM buttons simultaneously from the Standard View
2. The ALARM, SET, and MAX indicators will switch on. All of the TEMP indicators will switch off
3. Use the UP-DOWN arrow buttons to increment/decrement the HIGH RH alarm limit. Use the
LEFT-RIGHT arrow buttons to step through the decades
4. Press the ALARM button. The MIN (low alarm) indicator will switch on
5. Use the UP-DOWN arrow buttons to increment/decrement the LOW RH alarm limit. Use the
LEFT-RIGHT arrow buttons to step through the decades
6. The HIGH and LOW alarm limits cannot overlap
7. Use the ALARM button to toggle between the HIGH and the LOW alarm limits
8. Press the SET button at any time to save changes and return to the Standard View
9. Press VIEW at any time to return to the Standard View without saving the changes

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Display Modes
STANDARD VIEW
The Standard View is the display state of the RH520B when it is turned on. Refer to the diagram
in the display description section of this manual for a representation of the Standard View. To
reach the Standard View at any time, press the VIEW button. Note that the display automatically
reverts to the Standard View five (5) minutes after the last button press.
CURSOR
The CURSOR location is indicated by a small diamond located between the two graphs. See
diagram. There is one diamond for each horizontal pixel in the graph (64 positions). The date,
time, and measurements for the data point selected by the cursor are shown in the Time/Date
and numerical measurement display fields.
Each press of the RIGHT ARROW button will move the cursor to the right. When the cursor
reaches the right-side limit, the graph will move to the left. Holding the button down will
speed the scrolling rate. When the cursor reaches the oldest (last) reading, it will stop.
Each press of the LEFT ARROW button will move the cursor to the left. When the cursor
reaches the left side limit, the graph will move to the right. Holding the button down will
speed the scrolling rate. When the cursor reaches the newest (latest) reading, it will stop.
Each press of the UP ARROW button will shift the graph to the next set of 64 values; to the
left of the ones currently displayed (the cursor will not move).
Each press of the DOWN ARROW button will shift the graph to the next set of 64 values; to
the right of the one displayed (the cursor will not move).

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MAX-MIN DISPLAYS
1. Press the VIEW button in the Standard View to display the highest (MAX) and lowest (MIN)
temperature and RH readings from all the stored measurement records.
2. When viewing the
highest readings, the
MAX indicator will switch
on. When viewing the
lowest readings, the MIN
icon will switch on.
3. The cursor will move to
the location of the MIN
or MAX reading within
the graph. If not within
the graph currently displayed, the cursor will move to the right-most position and the graph
will shift accordingly so that the relevant data point can be viewed.
4. Use the VIEW button to step through the highest and lowest temperature readings and then
the highest and lowest RH readings. When the MAX or MIN indicator is ON under the
temperature reading digits, the display is showing the MAX or MIN temperature. When the
MAX or MIN indicator is ON under the RH reading digits, the display is showing the MAX or
MIN relative humidity.
ALARM DISPLAYS
1. Press the ALARM button from the Standard View to analyze the most recent alarm activity
(temperature or humidity), if any. The ALARM display icon and the relevant upper
(temperature) or lower (RH) graph pixel will flash.
2. The cursor will move to the location within the graph. If not within the graph currently
displayed, the cursor will move to the right-most position and the graph will shift accordingly
so that the relevant data point can be viewed.
3. Press the ALARM button again to view the second most recent set of Alarms (if no alarms,
the Standard View will appear)
4. Press the ALARM button again to view the third most recent set of Alarms (if no alarms, the
Standard View will appear)
5. This procedure can
continue until no
further alarms exist
and pressing the
ALARM button will
only bring up the
Standard View
6. In the example
diagram, the RH520B
is showing a high
temperature alarm (MAX and ALARM indicators on).

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USING THE CLOCK TO SORT THROUGH STORED READINGS
1. Press the TIME button in the Standard View mode
2. Use the ARROW buttons to select the time of day.
3. The temperature and humidity readings for the selected Time will display.
4. Press VIEW to return to the Standard View.
DEW POINT DISPLAY
Press the TEMP and the RH buttons simultaneously to view the Dew Point reading. The DEW
POINT display icon will switch on above the temperature. See the diagram below. Press VIEW to
return to the standard view mode.

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SAMPLE RATE DISPLAY
1. Press the VIEW and the TIME buttons simultaneously from the Standard View mode
2. Both numerical displays will switch off so that the LCD can show only the sample rate in
minutes (the MIN display icon will switch on)
3. The projected TIME-DAYS that the internal memory will be full (based on the current sample
rate) is displayed in the TIME and DATE display areas
4. To change the sample rate, refer to the programming section of this manual.
5. Press the VIEW button to return to the Standard View
Factory Default Settings
Default LCD mode: Standard View
Temperature Graph Vertical Resolution: -20 to 40oC
RH Graph Vertical Resolution: 0 to 100%
TEMP and RH Alarm Limits: 0 (low) and 100 (high)
Sample Rate: One (1) reading stored per minute

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Alarm Conditions and the Alarm History
When in Standard View mode:
If the ALARM display icon is flashing –an Alarm condition currently exists.
If the ALARM display icon is ON steady –there are past Alarms to view in the Alarm history.
Use the ALARM button to view the Alarm history as described elsewhere in this manual.
If an Alarm is tripped, press the ALARM button to silence it.
Press and hold the SET button for 2 seconds to clear an alarm through the external relay
module.
When in Alarm View or Time View mode:
If the ALARM display icon is flashing –the cursor is currently on an Alarm condition.
If the ALARM display icon is ON steady –there are past Alarms to view in the Alarm history.
Use the cursors or the ALARM button to view the Alarm history as described elsewhere in this
manual.
Note that the Alarm display icon and the external alarm relay module can be controlled
separately as indicated in the statements above.
Battery Replacement
The 5-segment battery life indicator allows the user to track the status of the battery. When all
5-segments are dark, the battery is fully charged. Segments switch off as the battery ages. When
the battery indicator has only one segment left the batteries must be replaced immediately.
1. Open the battery compartment on the rear of the instrument
2. Remove the old batteries and replace with three (3) heavy duty alkaline ‘AA’ batteries
observing polarity
3. Replace the battery compartment cover securely
4. The RH520B will require a “Programming Reset” to reset the display. Press the RESET
button located inside the battery compartment. “Reset” clears all settings. Time, Date
and the logging interval need to be entered. The measurement data and alarm history,
however, will still be retained in the non-volatile memory.
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, gratuitously, at the collection
points in our branches 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

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Specifications
Display Graphical LCD
Temperature Range/Accuracy -17 to 50oC (0.0 to 120.0oF) / ±1.0oC (1.8oF)
-30 to -17oC (-22.0 to 0oF) / 3oC (±5.4oF)
50 to 60oC (120.0 to 140oF) / 3oC (±5.4oF)
Humidity Range/Accuracy 1 to 99% / ±3.0% RH
Dew point temperature -28 to 60oC (-20.0 to 140.0oF)
Internal memory storage 49,152 complete reading sets
Sampling interval Selectable recording rate: 0.1(6 seconds) to 199.9 minutes
Graph scaling User selectable in 5oC/F in 10% increments
Low battery indication 5-segment battery indicator
Alarm output 3.5mm Mono Phone Plug,
Maximum: 3.4mA @ 5 VDC,
Minimum Output Voltage: 2.5 VDC
Power supply Three (3) ‘AA’ batteries and AC adaptor (included)
DC 5V 1A, 3.5mm x 1.35 mm plug
Battery life 4 weeks typical, using alkaline batteries
Operating Temperature CONTROL MODULE and DISPLAY: 0 to 50oC (32 to 120oF)
SENSOR: -30 to 60oC (-22 to 140oF)
Operating Humidity CONTROL MODULE and DISPLAY: 90% RH max.
SENSOR: 99% RH max.
Dimensions 127 x 196 x 23mm (5.0 x 7.7 x 0.9")
Weight 357g (12.6oz)
Transfer logged data using the PC Interface
Software installation procedure and operational instructions are located in the RH520B software
available on the www.Extech.com/Software web page.

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Two-year Warranty
FLIR Systems, Inc. warrants this Extech brand instrument to be free of defects in parts and workmanship for
two years from date of shipment (a six-month limited warranty applies to sensors and cables). To view the full
warranty text please visit: http://www.extech.com/support/warranties.
Calibration and Repair Services
FLIR Systems, Inc. offers calibration and repair services for the Extech brand products we sell. We
offer NIST traceable calibration for most of our products. Contact us for information on calibration
and repair availability, refer to the contact information below. Annual calibrations should be
performed to verify meter performance and accuracy. Product specifications are subject to change
without notice. Please visit our website for the most up-to-date product information:
www.extech.com.
Contact Customer Support
Customer Support Telephone List: https://support.flir.com/contact
Calibration, Repair, and Returns: [email protected]
Technical Support: https://support.flir.com
Copyright ©2013-2020 FLIR Systems, Inc.
All rights reserved including the right of reproduction in whole or in part in any form
www.extech.com