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CALIBRATION: Two-point, temperature-corrected buffer
calibration is standard. To reduce errors caused by
impatient operators, the Model 3081 pH/ORP transmitter
does not accept calibration data until programmed stabil-
ity limits have been met. If data are not acceptable, the
transmitter displays an error message and does not
update the calibration. The transmitter recognizes every
buffer scale in common use in the world. Manual two-
point and one-point calibration are also available.
AUTOMATIC TEMPERATURE COMPENSATION:
Temperature compensation is completely automatic. The
Model 3081 pH/ORP transmitter is compatible with two,
three, and four wire Pt 100, Pt 1000, and 3K Balco
RTDs.
SOLUTION TEMPERATURE COMPENSATION: The
Model 3081 pH transmitter features solution temperature
compensation. The transmitter calculates and displays
the pH at 25°C from the pH measured at any tempera-
ture. The temperature coefficient of the liquid being
measured must be known.
SENSOR DIAGNOSTICS: Continuous diagnostics alert
the user to impending or existing sensor failure.
Diagnostic messages in plain language aid in trou-
bleshooting. The manual contains a thorough, step-by-
step troubleshooting guide.
HOUSING: The Model 3081 pH/ORP transmitter hous-
ing meets NEMA 4X standards. The transmitter tolerates
outdoor and harsh plant environments. The housing also
meets NEMA 7B explosion-proof standards.
HAZARDOUS AREA INSTALLATION: Circuits in the
Model 3081 pH/ORP transmitter are designed and built
to be intrinsically safe when used with the appropriate
safety barrier.
OUTPUT: The 4 to 20 mA output signal is fully
adjustable between 0 and 14 pH and between -1400
and 1400 mV. During hold and fault conditions the out-
put can be programmed to remain at the last value or go
to any value between 3.8 and 22 mA.
1.2 ACCESSORIES
1.2.1 Power Supply. Use the Model 515 Power Supply
to provide the dc loop power required by the Model 3081
pH/ORP transmitter. The Model 515 provides either a
single source of power at 48 Vdc and 200 mA or two iso-
lated sources at 24 Vdc and 200 mA each. A junction
box (PN 2002188) allows as many as nine 3081
pH/ORP transmitters to be powered from each output.
For more information refer to product data sheet 71-515.
1.2.2 Alarm Module. The Model 230A Alarm Module
receives the 4-20 mA signal from the Model 3081
pH/ORP transmitter and activates two alarm relays.
Specify alarm configuration at the time of ordering.
High/high, low/low, and high/low are available. Dead
band is adjustable as high as 15% of full scale. For more
information, refer to product data sheet 71-230A.
1.2.3 Model 275 HART® COMMUNICATOR. The Model
3081 pH/ORP transmitter is compatible with the Model
275 HART communicator. The HART Communicator
allows the user to view pH or ORP, temperature, and
current output. The user can also program and configure
the transmitter and can download data for transfer to
another transmitter or computer. The Model 275 commu-
nicator attaches to any wiring terminal across the output
loop. A 250 ohm load must be between the power supply
and the transmitter. Order the Model 275 communicator
from Rosemount Measurement. Call (800) 999-9307.
Year 2000 Compliance: Millennium Status
Rosemount Analytical , Uniloc Division, certifies that all
instruments designed and manufactured by the Uniloc
Division, do not have calendars. No instruments manu-
factured by Uniloc Division keep track of days, months,
or years. This has been validated by reviewing all test
and calibration procedures. In calibrating and setting up
instruments for shipping, there is no step in any proce-
dure to enter a date.
MODEL 3081 pH/ORP SECTION 1.0
DESCRIPTION AND SPECIFICATIONS