Functional Specifications - Emerson Rosemount5081 Instruction Manual

Certification conditions
Non incendive certification
Certification conditions
Certification standards
2.4

Functional specifications

The tables below display the specifications for measuring different substances with the
5081.
Table 2-4: pH/ORP
pH range
ORP range
Calibration/standardization
Preamplifier location
Automatic temperature compen-
sation
Accuracy
Repeatability
Stability
Instruction Manual
0 to 14
-1400 to +1400 mV
The automatic buffer recognition uses stored buffer values and their temperature
curves for the most common buffer standards available worldwide. The transmit-
ter also performs a stabilization check on the sensor in each buffer. A manual two-
point calibration is made by immersing the sensor in two different buffer solutions
and entering the pH values. The microprocessor automatically calculates the slope
which is used for self-diagnostics. An error message is displayed if the pH sensor is
faulty. This slope can be read on the display and/or manually adjusted if desired.
An on-line, one-point process standardization is accomplished by entering the pH
or ORP value of a grab sample as measured by a lab reference.
A preamplifier must be used to convert the high impedance pH electrode signal to
a low impedance signal for transmitter use. The integral preamplifer of the 5081
may be used when the sensor to transmitter distance is less than 15 ft. (4.5 m). A
sensor with a built-in preamplifier or a junction box can be used if distance is lon-
ger than 15 ft. (4.5 m).
External 3 or 4 wire Pt 100 RTD or Pt 1000 RTD, located in the sensor, compen-
sates the pH reading for temperature fluctuations. Compensation covers the
range 5 to 270 °F (-15 to 130 °C). Manual temperature compensation is also select-
able.
±01 mv at 25 °C (77 °F) ± 0.01 pH
±01 mv at 25 °C (77 °F) ±0.01 pH
0.25% / year at 25 °C (77 °F)
Description and specifications
Connect per control drawings 1400676 or
1400677 for Intrinsically Safe Installations.
Class I, Division 2, Groups A, B, C, D
T4 T max. 70 °C
amb
4X enclosure type
For non-incendive field wiring, see installation
drawings 1400676 or 1400677.
Certified to FM Approvals standards: 3600:2011,
3610:2015, 3611:2016, 3615:2006, 3810:2005,
and ANSI/NEMA 250:1991
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