Honeywell STG745 Pressure Transmitter

Honeywell STG745 Pressure Transmitter

Honeywell STG745 Pressure Transmitter: Full Technical Specifications & Datasheet

The Honeywell STG745 Pressure Transmitter stands as a benchmark for high-performance gauge pressure measurement across demanding industrial environments. As a core member of the SmartLine® ST700 series, the Honeywell STG745 Pressure Transmitter integrates advanced piezoresistive sensor technology with on-chip static pressure and temperature compensation, delivering exceptional accuracy and long-term stability over a wide range of operating conditions-2-3. Engineered for rigorous applications including boiler high-pressure monitoring, fuel feed control, and chemical reactor pressure management, the Honeywell STG745 Pressure Transmitter offers a robust solution for both in-line and dual-head mounting configurations-.

Key Performance Specifications of the Honeywell STG745 Pressure Transmitter

The Honeywell STG745 Pressure Transmitter delivers industry-leading measurement precision. The STG745 achieves reference accuracy up to 0.065% of calibrated span, ensuring reliable data acquisition for critical process control loops-2. Long-term stability is rated at 0.02% of Upper Range Limit (URL) per year for up to five years, minimizing calibration frequency and reducing total cost of ownership-2. Some product variants of the STG745 extend this stability to 0.020% of URL per year for up to ten years, further enhancing reliability in continuous operation-3.

Span, Range Limits, and Turndown Capability

The Honeywell STG745 Pressure Transmitter is specified with a maximum span of 500 psi (35 bar) and a lower range limit (LRL) of -14.7 psi (-1.0 bar)-2. The minimum span is 5 psi (0.35 bar), supporting a turndown ratio of up to 100:1-2. This exceptional rangeability allows a single STG745 to cover multiple measurement points, reducing inventory requirements and simplifying maintenance logistics.

Environmental and Safety Compliance of the STG745

The Honeywell STG745 Pressure Transmitter features an integral dual seal design complying with ANSI/NFPA 70-202 and ANSI/ISA 12.27.0, ensuring safe operation even in the event of a primary seal failure-2. The STG745 is fully compliant with SIL 2/3 requirements as a standard feature, meeting IEC 61508 safety integrity level standards for use in safety instrumented systems (SIS)-2. Hazardous area approvals for the STG745 include FM, CSA, ATEX, IECEx, NEPSI, and KOSHA, enabling deployment in explosive atmospheres worldwide-. Ingress protection ratings for the STG745 housing range from IP65 to IP68, providing robust resistance to dust and water ingress in harsh field environments–.

Response Time, Diagnostics, and User Interface of the STG745

Response time for the Honeywell STG745 Pressure Transmitter is as fast as 100 milliseconds, supporting real-time control applications-2. The STG745 is equipped with comprehensive on-board diagnostic capabilities that continuously monitor sensor health, electronics integrity, and communication status-2. The alphanumeric display of the STG745 provides intuitive readout of process variables, while external zero, span, and configuration capability allows field adjustments without removing the housing covers-2. Polarity-insensitive electrical connections on the STG745 simplify wiring and reduce installation errors-2.

Communications and Output Protocols for the STG745

The Honeywell STG745 Pressure Transmitter offers multiple communication options to integrate with existing control systems. The STG745 supports Honeywell Digitally Enhanced (DE) protocol, HART® version 7.0, and FOUNDATION™ Fieldbus-2-3. For legacy systems, the STG745 also provides standard 4-20 mA analog output-. This flexibility ensures the STG745 can be deployed in both new installations and retrofit projects without requiring significant control system modifications.

Construction and Process Connections of the STG745

The Honeywell STG745 Pressure Transmitter features a modular design, allowing field replacement of electronic modules without recalibrating the sensor-2. Wetted materials for the STG745 are available in 316L stainless steel or Hastelloy-C276, providing corrosion resistance for aggressive process media-. The process connection of the STG745 is 1/2″ NPT female or male, with optional G 1/2 connection, and also supports IEC 61518 oval flange configuration-. In-line configuration of the STG745 is designed to screw directly onto a 1/2″ male NPT nipple, enabling straightforward installation in existing piping systems-.

Model Configuration and Ordering Information for the Honeywell STG745

The Honeywell STG745 Pressure Transmitter is available through a comprehensive model code system. A typical ordering code for the STG745 is STG745-E1AC4A-1-A-AHS-11C-B-50A0, where each alphanumeric segment specifies wetted materials, process connection type, output protocol, housing options, and approval ratings-3. Another available configuration of the STG745 is STG745-F1GC4A-1-A-AHS-11S-A-60A0,01, offering alternative material and connection selections for specific application requirements-13. When ordering the STG745, users should specify the required pressure range, output signal, hazardous area classification, and process connection type.

Industry Applications of the STG745

The Honeywell STG745 Pressure Transmitter is optimized for applications requiring high accuracy under varying static pressure and temperature conditions-2. Typical installations for the STG745 include hydrocarbon recovery processes, petrochemical refining units, steam boiler systems, and pressure monitoring for chemical reactors-. The dual-head configuration of the STG745 is specifically suited for tank level measurement where process temperatures reach up to 257°F (125°C)-. In-line versions of the STG745 provide reliable pressure measurement for fuel feed lines and high-pressure reaction vessels-.

Why Choose the STG745 for Your Pressure Measurement Needs

The Honeywell STG745 Pressure Transmitter combines advanced sensor technology with practical field engineering features that reduce installation time and maintenance costs. The automatic temperature compensation built into the STG745 ensures measurement accuracy remains stable across ambient and process temperature fluctuations-2. The modular design of the STG745 allows users to replace the electronic module or redefine measurement range without purchasing a new transmitter-15. For plants seeking to standardize on a single gauge pressure transmitter across multiple pressure ranges, the 100:1 turndown of the STG745 provides the necessary flexibility to cover diverse measurement points with one model family.

Compatibility and Integration of the STG745

The Honeywell STG745 Pressure Transmitter is fully tested and compliant with Experion® Process Knowledge System (PKS), providing the highest level of compatibility assurance and integration capabilities for Honeywell distributed control systems-3. The STG745 can replace any existing 4-20 mA transmitter currently on the market, making it an ideal choice for control system upgrades or plant expansions-15. For digital plant environments, the HART 7.0 and Foundation Fieldbus options of the STG745 enable access to additional diagnostic data and multivariable information beyond the primary pressure reading.

Calibration and Maintenance of the STG745

Routine calibration of the Honeywell STG745 Pressure Transmitter is simplified by external zero and span adjustment capability, allowing field technicians to trim the device without opening the electronics housing-2. The long-term stability specification of the STG745 means annual calibration is sufficient for most applications, though users in SIL-rated loops should follow the validation schedule defined by their safety plan. The modular construction of the STG745 ensures that if an electronic failure occurs, the module can be replaced in the field and the device can return to service without a full recalibration procedure-15.

Technical Summary for the Honeywell STG745 Pressure Transmitter

Model: STG745 (SmartLine® ST700 Series Gauge Pressure Transmitter)

Measurement Type: Gauge pressure (dual-head and in-line configurations)

URL/Max Span: 500 psi (35 bar)-2

LRL: -14.7 psi (-1.0 bar)-2

Minimum Span: 5 psi (0.35 bar)-2

Turndown Ratio: Up to 100:1-2

Reference Accuracy: Up to 0.065% of calibrated span-2

Stability: 0.02% of URL per year for five years (extended options available)-2

Response Time: As fast as 100 ms-2

Output Protocols: 4-20 mA, HART® v7.0, DE, FOUNDATION™ Fieldbus-2

Safety Certifications: SIL 2/3 compliant, integral dual seal per ANSI/NFPA 70-202 and ANSI/ISA 12.27.0-2

Hazardous Area Approvals: FM, CSA, ATEX, IECEx, NEPSI, KOSHA-

Ingress Protection: IP65 to IP68-

Process Connection: 1/2″ NPT (M/F), G 1/2, IEC 61518 oval flange-

Wetted Materials: 316L SS or Hastelloy-C276-

Enclosure Material: Aluminum-

Power Supply: 24 VDC typical-

Display: Alphanumeric with external configuration capability-2

Diagnostics: On-board with continuous health monitoring-2

Compliance: NAMUR NE-43, Experion® PKS tested-3

For engineers and procurement professionals seeking a gauge pressure transmitter that combines field-proven reliability with advanced digital capabilities, the Honeywell STG745 Pressure Transmitter delivers the performance required for critical process applications. Contact your local Honeywell representative or authorized distributor for detailed pricing, availability, and application engineering support for the STG745.

Frequently Asked Questions about the Honeywell STG745 Pressure Transmitter

Q: What is the difference between STG745 and STG740?
A: Both models share the same pressure range of 0-500 psi (0-35 bar)-2. The STG745 typically includes additional configuration options and approvals, while the STG740 represents the base configuration. Consult the Honeywell model code guide for specific differences.

Q: Can the STG745 be used for level measurement?
A: Yes, the dual-head configuration of the STG745 is suitable for tank level applications with process temperatures up to 257°F (125°C)-.

Q: Does the STG745 require a separate power supply?
A: The STG745 operates on standard 24 VDC loop power, drawing its operating power from the 4-20 mA current loop-.

Q: What is the warranty period for the STG745?
A: The Honeywell STG745 Pressure Transmitter typically comes with a 12-month factory warranty, with extended warranty options available-3.

Q: Is the STG745 compatible with Foundation Fieldbus H1 networks?
A: Yes, the STG745 can be ordered with FOUNDATION™ Fieldbus output protocol for integration into FF H1 segments-2.