Omega Products PX751CA-1 User Manual

SMART PRESSURE TRANSMITTER

HIGH STABILITY, LOW DRIFT

PX751 Series

25 inH2O to 6000 psi

Starts at

$

1875

PX751, $1875,
shown smaller
than actual size.

2-Way Communications,

⻬

Remote
Reranging,
Access to Difficult-to-Reach
or Hazardous Areas

⻬ Improved Performance,

Increased Accuracy,
Greater Stability and
Noise Resistance

⻬ Diagnostic Capabilities,

Continuous On-Line
Self-Check, Selectable
Failure Alarm, Loop Test

⻬ Transmitter Data Base

Includes Configuration,
Calibration, and Materials

⻬ Greater Performance,

Wider Rangeability (100:1),
Transmitter Security,
Selectable Linear/Square
Root Output, Multi-Drop

⻬ High Stability and Low

Drift Ensure Accurate
Measurements for Years

⻬ Fast, Dynamic Response
⻬ Tighter Control

and Reduced
Maintenance Costs

⻬ Pressure and

Temperature Output

Troubleshooting,

Reconfiguring,

Coplanar Design—

Differential, Gage, or

Absolute Pressure!

PX751C coplanar transmitter,
$1875, with flange, $150, shown
smaller than actual size.

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PX751C SMART TRANSMITTER

LCD Meter Options

The LCD meter can be digitally
customized by the user to meet
process needs. The meter can be
configured to display engineering
units, percent of range, or custom
user scale, or to alternate between
any 2 of these.

Power Supply

The DC power supply should
provide power with less than 2%
ripple. The transmitter requires a
minimum of 250 Ω of loop resistance
to communicate with a HartTMbased
communicator. With 250 Ω drop, the
transmitter will require a minimum of
16 Vdc to output 20 mA.

Diagnostics and Service

The diagnostic and service functions
listed here are primarily for use after
the transmitter is installed in the field.

The Transmitter Test feature helps
verify that the transmitter is
operating properly, and can be
performed either on the bench or in
the field. The transmitter test
command initiates an extensive
diagnostics routine that can quickly
identify potential electronics
problems. If the transmitter detects
a problem, messages to indicate the
source of the problem are displayed
on the communicator screen.

The Loop Test feature is designed
to verify proper loop wiring and
transmitter output, and should only
be performed after the user installs
the transmitter. This function tests
the output of the transmitter, the
integrity of the loop, and the
operations of any recorders or
similar devices installed in the loop.

Calibration

Calibrating a smart transmitter is
different from calibrating an analog
transmitter. The smart transmitter
requires 3 steps:
⻬ Rerange—sets the 4 and 20 mA
points to the desired pressures.
⻬ Sensor Trim—adjusts the
position of the factory
characterization curve to optimize
the transmitter performance over a
specified pressure range or to
adjust for mounting effects.

PX751C

(Shown Installed with 3-Valve Manifold)

⻬ Analog Output Trim—adjusts the
analog output to match the plant
standard or the control loop.

Advanced Functions

Cloning: Quickly copies the same

configuration to multiple units. The
cloning process involves configuring
a transmitter, saving the configuration
data, then sending a copy of the
data to a separate transmitter.
Multidrop: Communication
between the host and the
transmitter takes place digitally with
the analog output of the transmitter
deactivated. With HartTMsmart
protocol, up to 15 units can be
connected on a single pair of twisted
wires or over leased phone lines.

B

Burst Mode: Provides faster digital
communications to control system
by eliminating the time required
for the control system to request
data from the transmitter. Burst
mode applies only to the
transmission of dynamic data
(pressure and temperature).

Low-Power Option

User-selectable
3-wire 1 to 5 Vdc or 0.8 to 3.2 Vdc
outputs are available with the
low-power option. The digital signal
is superimposed on the voltage
signal, available to any host
conforming to HartTMprotocol.
Low-power units operate on
6 to 12 Vdc with no load.

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PX751C SMART TRANSMITTER

SPECIFICATIONS AND REFERENCE DATA

Specifications

Service:

Liquid, gas and vapor applications

Zero and Span Adjustment:

Zero and span values can be set anywhere
within the range limits stated in tables.
Span values must be greater than or
equal to the minimum span stated in the
range limits tables.

4 to 20 mA Models

Output:

2-wire 4 to 20 mA output, user selectable
for linear or square root; digital process
variable superimposed on 4 to 20 mA
signal, available to any host that conforms
to the HartTMprotocol

Power Supply:

External power supply required. Standard
transmitter operates on 10.5 to 55 Vdc
with no load. A minimum of 250 Ω of loop
resistance is required to communicate
with a Hart

TM

based communicator. With
250 Ω drop, the transmitter will require a
minimum of 16 Vdc to output 20 mA.

Load Limitations:

)

Load (Ω

1935

1500

1000

500

0

10.5 20 30 40 55

Communications require a minimum loop
resistance of 250 Ω.

1

For CSA approval, power supply must not

exceed 42.2 V.

Operating Region

Voltage (Vdc)

42.4

1

Low Power Models

Output: 3-wire 1 to 5 Vdc or 0.8 to 3.2 Vdc

user selectable. Also user selectable for
linear or square root output configuration.
Digital process variable superimposed on
4 to 20 mA signal, available to any host
that conforms to the HartTMprotocol.

Power Consumption:

3 mA, 18 to 36 mW

Minimum Load Impedance:

100 kΩ (V

Indication:

Optional 2-line, 5-digit LCD meter
Overpressure Limits: Transmitters

withstand the following limits without
damage:

Gage/Differential Models (CA/CD):

Range 1:

0 to 2000 psig (0 to 13.8 MPa)

Ranges 2 to 5:

0 to 3626 psig (0 to 25 MPa)

OUT

+ wiring)

Absolute Models (CA):

Range 0: 0 to 60 psia (0 to 413.7 kPa)
Range 1: 0 to 120 psia (0 to 827.4 kPa)
Range 2: 0 to 300 psia (0 to 2070 kPa)
Range 3: 0 to 1600 psia (0 to 11030 kPa)
Range 4: 0 to 6000 psia (0 to 41370 kPa)

High-Process Temperature
Models (HP/HG)

All Ranges, 0 to 3626 psig
(0 to 25 MPa) “T” Style Gage and
Absolute Models (TA/TG):

Range 1: 0 to 750 psia (0 to 5.2 MPa)
Range 2: 0 to 1500 psia (0 to 10.3 MPa)
Range 3: 0 to 1600 psia (0 to 11.0 MPa)
Range 4: 0 to 6000 psia (0 to 41.4 MPa)
Range 5: 0 to 15000 psia (0 to 103.4 MPa)

Static Pressure Limits

Differential Pressure Models Only:

Operates within specification between
static line pressure of 0.5 psia and
3626 psig; 2000 psig for range 1 (ranges
2 and 3 for high-accuracy models)

Burst Pressure Limits:

All Except Type T:

10,000 psig (69 MPa)

Type T:

Ranges 1 to 4: 11,000 psi (75.8 MPa)
Range 5: 26,000 psig (179 MPa)

Failure Mode Alarm: User selectable to

drive output either high or low when gross
transmitter failure is detected

Temperature Limits

Ambient: -40 to 85°C (-40 to 185°F);

with integral meter, -20 to 80°C (-4 to 175°F)

Storage: -46 to 110°C (-50 to 230°F);

with integral meter, -40 to 85°C (-40 to 185°F)

Process Temperature Limits

Differential, Gage and Absolute:

Silicone Fill Sensor1with
Coplanar Flange -40 to 250°F
Side Flange -40 to 300°F
Level Flange

Horizontal Mount -40 to 250°F
Vertical Mount -40 to 300°F

Inert Fill Sensor Option10 to 185°F

High-Temperature Models:

Fill Material Temperature Range

D.C. Silicone 200
Inert -50 to 350°F
Neobee M-20

Type “T” Gage and Absolute:

Silicone Fill Sensor
Inert Fill Sensor

1

1

1

1

-40 to 375°F

0 to 375°F

-40 to 250°F

-22 to 250°F

Humidity: 0 to 100% RH
Turn-On Time: Performance within

specifications less than 2.0 seconds after
power is applied

Volume Displacement:

<0.08 cm

3

(0.005 in3)

Damping: User selectable from
0 to 36 seconds for one time constant.
This software damping is in addition to
sensor module response time.

3, 4

2

2

2

2

2

2

PX751H high-process temperature
traditional flange differential and
pressure gage, $2860, shown
smaller than actual size.

All Models

Response Time:

Dead Time (Td): 45 ms nominal
Time Constant (Tc): 55 ms
Update Rate: 20 times/s minimum

Vibration Effect: < ±0.1% of URL per

gram when tested from 15 to 2000 Hz
in any axis relative to pipe-mounted
process connection

Power Supply Effect:

<0.005% of calibrated span per volt
RFI Effects: ±0.1% of span from 20 to

1000 MHz, and field strength up to 30 V/m

Transient Protection (Optional):

Meets IEEE standard 587, Category B
meets IEEE standard 473,
surge withstand capability 2.5 kV crest,
1 MHz waveform

Process Connections (All Except
Level, High-Pressure Gage and
Absolute Models):

1

⁄4-18 NPT on 21⁄8" centers;

1

⁄2-14 NPT on 2, 21⁄8, or 21⁄4" centers

Level Models:

High-Pressure Side: 2, 3 or 4",

Class 150, 300 or 600 flange

50, 80 or 100 mm: PN40 or

High Gage or Absolute Pressure:

1

⁄4-18, 1⁄2-14 female, G1⁄2 A DIN 16288
male (available in stainless steel for
ranges 1 to 4) or autoclave type F-250-C
(pressure relieved

1

⁄4 OD high pressure tube 60° cone;

9

⁄16-18 gland thread;

available in stainless steel for range 5 only)

Wetted Parts:

Flanges: Plated carbon steel standard;

stainless steel, Hastelloy C or Monel
optional (available on PX751C only)

Wetted O-Rings: Glass-filled TFE

Housing: Low-copper aluminum with

polyurethane paint

Cover O-Rings: Buna-N
Note: Calibrations at 20°C (68°F) per

ANSI Z210.1

1

Process temperatures above 185°F (85°C)
require derating the ambient limits by a 1.5:1
ratio (0.06:1 ratio for Type H).

2

104°C ( 220°F) limit in vacuum service;

71°C (130°F) for pressures below 0.5 psia.

3

71°C (160°F) limit in vacuum service.

4

Not available on model PX751CA.

10

⁄16 flange

B-237