Honeywell STF735 Flange Mounted Transmitter

Honeywell STF735 Flange Mounted Transmitter

Product Overview

The Honeywell STF735 Flange Mounted Transmitter is a high-performance member of the SmartLine® ST700 family, engineered around advanced piezoresistive sensor technology for flange mount pressure and liquid level measurement in demanding process environments. The Honeywell STF735 Flange Mounted Transmitter integrates differential pressure sensing with on-chip static pressure and temperature compensation, delivering exceptional measurement accuracy and long-term stability across a wide range of process conditions.

The SmartLine family has been fully tested and complies with Experion® PKS standards, ensuring the highest level of compatibility assurance and seamless integration capabilities. The Honeywell STF735 Flange Mounted Transmitter may be installed directly onto a tank flange and is offered with a variety of tank connections including flush and extended diaphragm configurations. As a mid-to-high range flange mount transmitter within the ST700 series, the STF735 fills the gap between the STF725 (400 inH₂O URL) and the STF73F (700 KPa URL) variants.

Performance Specifications

Pressure Ranges and Limits

The Honeywell STF735 Flange Mounted Transmitter features a pressure range of -700 to 700 inH₂O (-1743 to 1743 mbar). The upper range limit (URL) for the Honeywell STF735 Flange Mounted Transmitter is 700 inH₂O (1743 mbar), with a lower range limit (LRL) of -700 inH₂O (-1743 mbar). The minimum span for the Honeywell STF735 Flange Mounted Transmitter is 7 inH₂O (17.4 mbar), making it suitable for applications requiring fine pressure resolution in taller tanks and higher liquid level measurements.

The Honeywell STF735 Flange Mounted Transmitter offers a turndown ratio of up to 100:1, providing exceptional rangeability that reduces inventory requirements and allows a single device to cover multiple measurement scenarios. The static pressure capability for the Honeywell STF735 Flange Mounted Transmitter is rated up to 4500 psig (310 bar), ensuring reliable operation under high static line pressures.

Accuracy and Long-Term Stability

The Honeywell STF735 Flange Mounted Transmitter delivers reference accuracy of up to 0.05% of calibrated span as standard, with an optional 0.04% accuracy available for critical custody transfer and high-value applications.

Long-term stability for the Honeywell STF735 Flange Mounted Transmitter is rated at 0.02% of URL per year, sustained over a period of 10 years of continuous operation. This exceptional stability reduces calibration frequency and lowers total ownership costs across the lifecycle of the Honeywell STF735 Flange Mounted Transmitter.

Dynamic Response

The Honeywell STF735 Flange Mounted Transmitter achieves a dynamic response time as fast as 100 milliseconds, enabling rapid detection of process changes and real-time control loop performance.

Automatic Compensation

Automatic static pressure and temperature compensation is embedded directly into the sensor chip architecture, ensuring that the Honeywell STF735 Flange Mounted Transmitter maintains accuracy even under fluctuating process and environmental conditions. The piezoresistive sensor technology integrated into the Honeywell STF735 Flange Mounted Transmitter combines pressure sensing with on-chip temperature compensation, providing complete and fully compensated output signals across a wide range of application pressures and temperatures.

Electrical Specifications and Communication

Output and Communication Protocols

The Honeywell STF735 Flange Mounted Transmitter supports multiple communication protocols to accommodate various control system architectures:

4-20 mA dc with HART® (Version 7.0) – 10.8 to 42.4 VDC supply voltage

Honeywell Digitally Enhanced (DE) Protocol – 15 to 49.3 VDC supply voltage

FOUNDATION™ Fieldbus Protocol – 9 to 32 VDC supply voltage

All variants of the Honeywell STF735 Flange Mounted Transmitter support the above communication protocols, and the transmitter includes polarity-insensitive electrical connections that simplify installation and reduce the risk of wiring errors.

Materials of Construction

Wetted Materials

The Honeywell STF735 Flange Mounted Transmitter offers a comprehensive selection of wetted materials to accommodate a wide variety of process media and corrosive environments:

316L Stainless Steel – Standard option for general industrial applications

Hastelloy® C-276 – For highly corrosive and acidic media

Monel 400 – Suitable for seawater and reducing acid environments

Tantalum – For extreme corrosion resistance in aggressive chemical service

Enclosure and Housing

The Honeywell STF735 Flange Mounted Transmitter is housed in a low-copper (<0.4%) aluminum alloy enclosure with pure polyester powder coating, providing excellent corrosion resistance in industrial environments. A stainless steel housing option is available for applications requiring enhanced durability and marine-grade protection.

Process Connections and Flange Options

The Honeywell STF735 Flange Mounted Transmitter supports a variety of tank connection options. The flange variant for the Honeywell STF735 Flange Mounted Transmitter is available in ANSI Class 150 with MAWP up to 285 psi (19.6 bar), ANSI Class 300 with MAWP up to 740 psi (51 bar), or DN PN40 with MAWP up to 580 psi (40 bar), varying by material and temperature. Flush diaphragm and extended diaphragm versions are available for viscous or solids-laden media.

Environmental Specifications

The Honeywell STF735 Flange Mounted Transmitter is designed for reliable operation in harsh industrial environments across the following parameters:

Ambient Operating Temperature: -40°C to +85°C

Storage Temperature: -55°C to +120°C

Ingress Protection: NEMA 4X, IP66/IP67 ratings

Relative Humidity: 0 to 100% RH

These environmental specifications ensure that the Honeywell STF735 Flange Mounted Transmitter maintains performance integrity in outdoor installations, washdown areas, extreme climate conditions, and hazardous area classifications.

Display and Configuration

The Honeywell STF735 Flange Mounted Transmitter features a modular LCD display that can be added or removed in the field without affecting performance or certification status. The display supports 0°, 90°, 180°, and 270° position adjustments for optimal viewing in any mounting orientation. The alphanumeric LCD display supports a comprehensive range of measurement units including Pa, kPa, MPa, kg/cm², torr, atm, inH₂O, mH₂O, bar, mbar, inHg, ftH₂O, mmH₂O, mmHg, and psi.

External zero, span, and configuration capability for the Honeywell STF735 Flange Mounted Transmitter is provided via three externally accessible buttons, enabling field adjustments without opening the enclosure. The modular design characteristics of the Honeywell STF735 Flange Mounted Transmitter allow meter bodies, electronic modules, and display indicators to be replaced or added in the field without affecting overall performance or approval body certifications.

Diagnostics and Safety Features

On-Board Diagnostics

The Honeywell STF735 Flange Mounted Transmitter incorporates comprehensive on-board diagnostic capabilities that provide advanced warning of potential failure events, minimizing unplanned shutdowns and reducing overall operational costs. Diagnostic features include critical and non-critical monitoring with NAMUR NE-43 compliance.

Safety Design and Certifications

The Honeywell STF735 Flange Mounted Transmitter features an integral dual seal design conforming to ANSI/NFPA 70-202 and ANSI/ISA 12.27.0 standards, providing the highest level of safety for applications where primary pressure containment failure could lead to hazardous conditions.

The Honeywell STF735 Flange Mounted Transmitter offers world-class overpressure protection and is certified for use in safety instrumented systems with full compliance to SIL 2/3 requirements, meeting IEC 61508 standards.

Agency Approvals

The Honeywell STF735 Flange Mounted Transmitter carries multiple international certifications for hazardous area installations, including FM, CSA, ATEX, IECEx, NEPSI, KOSHA, EAC, CCoE, UATR, SAEx, INMETRO, and marine certifications from ABS, BV, DNV, KR, and LR.

Physical Specifications

Weight: Approximately 3.8 kg (8.4 lbs) with aluminum housing

Conduit acceptance: Accommodates up to 16 AWG (1.5 mm diameter) wire

Static pressure limit: 4500 psig (310 bar)

Maximum allowable working pressure: Up to 4500 psig (310 bar) depending on flange rating

Application Suitability

The Honeywell STF735 Flange Mounted Transmitter is ideally suited for a wide spectrum of liquid level and low-to-medium pressure measurement applications requiring high accuracy and reliability. The -700 to 700 inH₂O pressure range with 7 inH₂O minimum span makes the Honeywell STF735 Flange Mounted Transmitter particularly well-suited for:

Tank level measurement in storage and process vessels up to 50 feet of liquid head

Natural gas custody transfer applications

Energy and material balance calculations

Boiler drum level monitoring and control

Chemical and petrochemical process vessels

Filter monitoring and differential pressure across filtration systems

Hydrostatic tank gauging in closed vessels

Liquid level measurement in refineries, chemical plants, and water treatment facilities

The Honeywell STF735 Flange Mounted Transmitter is part of the comprehensive SmartLine ST700 family, which includes absolute pressure transmitters (STA700), gauge pressure transmitters (STG700), differential pressure transmitters (STD700), and remote diaphragm seal transmitters (STR700), providing a complete pressure measurement solution for any process application.