Fieldpiece ARH4 User Manual

AUTO OFF

ARH4

RELATIVE
HUMIDITY HEAD
Model ARH4

OPERATOR’S MANUAL

Introduction

The Fieldpiece model ARH4 measures both
relative humidity and ambient air temperature.
The ARH4 also calculates dew point and wet bulb
temperatures.

The head converts RH%, ambient temperature,
dew point temperature, and wet bulb temperature
to a voltage at a rate of 1 RH% or degree to
1mVDC. Set the meter to mVDC to display RH% or
temperature directly.

The ARH4 snaps directly onto the Fieldpiece
HS series DMM. For other meters, use Fieldpiece
ADLS2 test leads or AHDL1 handle adapter.

To get an accurate reading, allow enough time
for the sensors to come to equilibrium. The bigger
the change, the longer the time the ARH4 may need
to calibrate to ambient conditions. Usually not more
than a couple minutes for even large changes.

Auto off

The accessory head turns off automatically after
approximately 10 minutes to lengthen battery life. To
disable "Auto off" function, remove rubber cover on
front and slide switch to right.

Features:

1. Measures Temp and RH%

2. Calculates wet bulb and dew point
temperatures

Dew point and wet bulb

The "dew point" is the temperature at which water

vapor condenses forming fog or dew. Wet bulb is the
temperature measured after cooling by evaporation
of water. If you know temperature and relative
humidity, dew point and wet bulb temperatures can
be calculated.

The ARH4 measures relative humidity and

ambient temperature. The ARH4 calculates wet bulb
and dew point temperatures. The chart on the back
of the accessory head can be used to estimate wet
bulb temperature if you know RH% and ambient
temperature (dry bulb).

Operating instructions

1. Remove cap covering sensor at the top.

2. Connect to COM and Volts jacks. To use with
any Fieldpiece “stick” meter, slide the head
over the meter. For most other meters, use the
Fieldpiece ADLS2 test leads or AHDL1 adapter
handle.

3. Select parameter on accessory head.

4. Select mVDC range on meter and read param­eter directly on meter.

Specications:

Low battery indication: Red LED is lit when the

voltage drops below the operating level.
Output impedance: 500Ω approx
Operating environment: 32OF to 120OF (0 OC to 50

O

C) at <95%RH

Storage temperature: -4OF to 140OF (-20OC to

60OC) <80%RH with battery removed
Accuracy: Stated accuracy at 73OF±10OF

(23O±5OC), <95%RH
Battery: 9V
Dimensions: 146mm(H) x 67mm(W) x 32mm(D)
Weight: approx. 180g including battery

Temperature

Sensor: thermister temperature sensor
Range: -4°F to 140°F (-20°C to 60°C)
Resolution: 0.1°C / 0.1°F
Accuracy:
±1°F 32°F to 113°F
±2°F -4°F to 32°F,
113°F to 140°F

±0.5°C 0°C to 45°C
±1°C -20°C to 0°C,
45°C to 60°C
Output: 1mV/°C,1mv/°F

Relative Humidity

Sensor: Capacitive humidity sensor
Range: 0% to 100%RH
Accuracy:
±2.5%@77°F(25°C), 10% to 90% RH
±5%@77°F(25°C), <10%RH, >90%RH
Output: 1mV/%RH
Sensor response time: 60 seconds typical for 90%

of total range

Sensor hysteresis (excursion of 10% to 90% to 10%

RH): ±1%RH typical

Warranty

The ARH4 is warranted to the original purchaser
against defects in material or workmanship for a
period of one (1) year from the date of purchase.
During the warranty period, Fieldpiece Instruments
will, at its option, replace or repair the defective unit.

This warranty does not apply to defects resulting
from abuse, neglect, accident, unauthorized repair,
alteration, or unreasonable use of the instrument.
Any implied warranty arising out of the sale of
Fieldpiece's products including but not limited to

implied warranties of merchantability, and tness

for purpose, are limited to the above. Fieldpiece
shall not be liable for incidental or consequential
damages.

State laws vary, so the above limitations or
exclusions may not apply to you. This warranty gives

you specic legal rights, and you may also have

other rights which vary from state to state.

Service

Call Fieldpiece Instruments for one-price-

x-all warranty service pricing. Send check or

money order for the amount quoted. Send the
meter freight prepaid to Fieldpiece Instruments.
Send proof of date and location of purchase for
in-warranty service. The meter will be repaired or
replaced, at the option of Fieldpiece, and returned
via least cost transportation.

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