Honeywell STR745G Remote Diaphragm Seal Transmitter

Honeywell STR745G Remote Diaphragm Seal Transmitter

Product Overview

Honeywell STR745G Remote Diaphragm Seal Transmitter is a high-performance member of the SmartLine® ST700 family, engineered specifically for applications demanding extended pressure range capability with remote diaphragm seal isolation. The STR745G combines Honeywell‘s advanced piezoresistive sensor technology with on-chip static pressure and temperature compensation, significantly reducing the thermal effects that commonly challenge remote seal measurements. This design delivers exceptional accuracy, long-term stability, and reliable operation across a broad spectrum of process pressures and temperatures.

The STR745G SmartLine Pressure Transmitter transmits process pressure through fill fluid within remote flanges and capillaries, isolating the electronics from corrosive, viscous, crystallizing, or high-temperature process fluids while maintaining measurement integrity. Honeywell offers the STR745G with a comprehensive range of seal configurations including flush flange seals, flange seals with extended diaphragm, pancake seals, sanitary seals, chemical tee Taylor wedge, saddle seals, threaded process connection seals, calibration rings, stainless steel armored capillaries, PVC-coated stainless steel armored capillaries, 2-inch stainless steel nipples, and welded meter bodies.

Application Note: STR745G Remote Diaphragm Seal Transmitter is the preferred choice when standard pressure ranges are insufficient, as it handles up to ±500 psig of gauge pressure—making it ideal for medium-to-high pressure processes involving corrosive or high-temperature media.

Key Features of Honeywell STR745G SmartLine® Pressure Transmitter

The STR745G SmartLine Pressure Transmitter with Remote Diaphragm Seals delivers a comprehensive suite of performance-enhancing features:

The STR745G‘s 100:1 turndown ratio allows a single transmitter to cover multiple pressure ranges, reducing inventory requirements and simplifying engineering specifications. STR745G achieves its performance through a single piezoresistive sensor integrating pressure measurement, static pressure sensing, and temperature compensation—all on one chip. The comprehensive on-board diagnostics help maintain high uptime, meet regulatory requirements, and achieve stringent quality standards.

Performance Insight: STR745G Remote Diaphragm Seal Transmitter’s 0.065% accuracy combined with 0.02% per year stability ensures reliable measurement across five-year calibration cycles, significantly reducing maintenance frequency and operational costs.

Detailed Technical Specifications

The following technical parameters define the performance envelope of Honeywell STR745G Remote Diaphragm Seal Transmitter:

Pressure Ranges and Span Limits

Accuracy and Performance

STR745G‘s accuracy specification applies across the full turndown range, meaning STR745G calibrated at 500 psig and turned down to measure 5 psig maintains the same 0.065% accuracy—critical for applications requiring wide rangeability with remote diaphragm seals.

Electrical and Communication Specifications

Integration Note: STR745G Remote Diaphragm Seal Transmitter with HART v7.0 protocol is fully backward compatible with HART v5.x and v6.x host systems. It is also fully compatible with Honeywell Experion PKS for the highest level of integration assurance.

Physical Specifications and Materials of Construction

The STR745G SmartLine Pressure Transmitter’s modular design allows field replacement of electronic modules, display units, and terminal blocks without de-pressurizing the process—significantly reducing maintenance downtime and lowering operational costs. Modular design also reduces inventory needs, as fewer spare components cover multiple configurations.

Environmental and Safety Certifications

Remote Seal Configurations

STR745G Remote Diaphragm Seal Transmitter supports an extensive range of remote seal types to match virtually any process connection requirement:

Each seal configuration includes a specific ordering code. For example, STR745G-11A01B0-AFAAE21DS-A-EHS-11S-A-11A0 designates a single remote seal (high side) with 316 SS bonnet bolts, Silicone Oil 200 fill fluid, 10 ft (3.0m) stainless steel armored capillary, flush flanged seal with 3.5-inch diaphragm and 3-inch ANSI 150 flange rating, Monel 400® diaphragm, 316L SS non-wetted materials, FM approvals, 316 SS housing, 4-20mA HART output, standard display, and angle mounting bracket. STR745G-11A01B0-AFCAE21DS-A-BHS-11C-B-11A0-F1,F5 represents another configuration variant with different approvals and options. The ordering code follows Honeywell’s modular selection guide, enabling precise specification of fill fluids, wetted materials, capillary lengths, and seal dimensions.

Installation and Configuration

STR745G SmartLine Pressure Transmitter simplifies field installation and commissioning through several user-centric design features:

External Zero, Span, and Configuration: Three externally accessible buttons allow field adjustment of zero, span, and basic configuration parameters without removing the housing cover—no special tools or handheld communicator required for routine adjustments.

Polarity Insensitive Wiring: Electrical connections tolerate reversed polarity, preventing wiring errors from damaging STR745G and reducing commissioning time.

Modular Display: The alphanumeric LCD display module can be added or removed in the field and rotated in 90° increments to accommodate any mounting orientation. Advanced graphics LCD options include bar graphs, trend graphs, and multi-language support.

Flexible Configuration Methods: STR745G Remote Diaphragm Seal Transmitter can be configured via integral buttons, a handheld device such as the Honeywell Versatilis Configurator, or PC software including Honeywell Field Device Manager—even without a display module installed.

Multi-Unit Display: STR745G supports display in engineering units including psi, bar, mbar, Pa, kPa, MPa, kg/cm², Torr, atm, inH₂O, mH₂O, inHg, ftH₂O, mmH₂O, and mmHg.

Installation best practices for STR745G SmartLine Pressure Transmitter include mounting the transmitter at or below the lower process connection for liquid applications, ensuring vertical capillary runs are properly supported to prevent sagging, maintaining minimum bend radius of 6 inches (152 mm) on armored capillaries, verifying fill fluid compatibility with process temperature extremes, and performing zero trim after installation with equalized pressure across both seals.

Industry Applications

STR745G Remote Diaphragm Seal Transmitter excels in demanding process environments where extended pressure range capability combined with remote seal isolation is required. Primary application areas include:

Oil and Gas / Hydrocarbon Processing — Refinery column level measurement, pipeline differential pressure monitoring, separator and treater level control, crude oil tank level with interface detection, and high-pressure hydrocarbon processing.

Chemical Processing — Flow measurement of slurries and high-viscosity process fluids, corrosive chemical storage tank level, reactor pressure and level monitoring, crystallizer and evaporator pressure control, acid and caustic service with corrosion-resistant wetted materials.

Power Generation — Boiler drum level measurement, condenser level monitoring, feedwater heater level control, steam pressure measurement with remote seals for high-temperature isolation.

Pulp and Paper — Digester pressure and level, black liquor tank measurement, paper machine stock approach systems, chemical recovery boiler monitoring.

Pharmaceutical and Biotechnology — Sanitary tank level measurement (3A compliant configurations), fermenter and bioreactor pressure monitoring, purified water and WFI storage tank level.

Food and Beverage — Sanitary process vessels, cooking and mixing tanks, storage silo level, CIP/SIP system pressure monitoring.

Water and Wastewater Treatment — Sludge level measurement, chemical storage tank level, pump suction pressure monitoring.

Application Example: STR745G-11A01B0-AFAAE21DS-A-EHS-11S-A-11A0 with Monel 400® wetted diaphragm and high-temperature fill fluid handles corrosive process media at up to 500 psig while delivering ±0.065% gauge pressure measurement accuracy.

STR745G is also well-suited for high-temperature process fluids (up to 338°C / 640°F depending on seal and fill fluid selection), high-pressure distillation column level measurement, viscous and crystallizing liquids, sanitary applications requiring 3A compliance, and tank applications requiring density or interface measurement.

Why Choose Honeywell STR745G Over Competitors?

STR745G SmartLine Pressure Transmitter with Remote Diaphragm Seals offers distinct advantages compared to alternative remote seal transmitters:

STR745G‘s combination of 100:1 turndown, 0.065% accuracy, 500 psig maximum range, and comprehensive onboard diagnostics delivers exceptional value for applications requiring remote diaphragm seals at medium-to-high pressure ratings. The integral dual seal design provides ANSI/ISA 12.27.0 certification as standard, and full compliance to SIL 2/3 requirements comes standard—not as an add-on option. STR745G is also available with a 15-year warranty, further demonstrating Honeywell‘s confidence in long-term reliability.