Honeywell STG78S Pressure Transmitter

Honeywell STG78S Pressure Transmitter: Complete Technical Datasheet for SmartLine STG700 Series

Product Overview

The Honeywell STG78S Pressure Transmitter is a high-performance gauge pressure measurement instrument from the industry-leading SmartLine STG700 family. Engineered to withstand the most demanding industrial environments, the Honeywell STG78S delivers exceptional measurement accuracy and long-term stability through advanced piezoresistive sensor technology integrated with on-chip temperature compensation capabilities. Honeywell STG78S pressure transmitters are designed for monitoring, control, and data acquisition applications requiring reliable performance across a wide range of process pressures and temperatures.

The Honeywell STG78S belongs to the SmartLine® family of products, which have been fully tested and are compliant with Experion® PKS, providing the highest level of compatibility assurance and seamless integration capabilities for modern process automation systems-12. As a gauge in-line transmitter, the STG78S is screwed directly onto a 1/2″ male NPT nipple and can be installed in hazardous environments for accurate, repeatable pressure measurement-1. Dual head gauge pressure configurations of the Honeywell STG78S are also available for applications involving reaction vessels in the chemical industry and level applications with process temperatures up to 257°F/125°C-1.

Core Sensor Technology

The Honeywell STG78S utilizes a state-of-the-art piezoresistive sensing platform that integrates multiple sensing elements within a single chip. This advanced sensor architecture combines process pressure measurement with on-board static pressure and temperature sensing, enabling comprehensive temperature compensation that delivers superior overall performance across the full application range-13. The STG78S incorporates a “three-in-one” piezoresistive sensor that integrates differential pressure sensing, temperature sensing, and static pressure measurement capabilities, producing a fully compensated output signal that maintains exceptional accuracy across varying operating conditions-6.

The Honeywell STG78S sensor features ion-implanted silicon technology that automatically corrects errors caused by process temperature variations and static pressure changes, resulting in industry-leading measurement precision. This advanced compensation ensures that STG78S transmitters deliver consistent, reliable measurements regardless of fluctuating environmental conditions.

Technical Specifications

Performance Characteristics

The Honeywell STG78S delivers exceptional accuracy of ±0.065% of calibrated span, with optional enhanced accuracy of ±0.04% available for applications requiring even tighter measurement tolerances-12. Long-term stability is rated at ±0.02% of URL per year for up to 10 years, ensuring consistent performance over extended operational periods. The STG78S offers a turndown ratio of 100:1, providing exceptional application flexibility and reducing the need to stock transmitters with multiple ranges or electronic modules-6.

Electrical Specifications

Honeywell STG78S transmitters support bidirectional communication and configuration between operator and transmitter via HART protocol, enabling remote monitoring, diagnostics, and parameter adjustments without interrupting process operations-6. The STG78S can replace virtually any 4–20 mA transmitter currently on the market, offering seamless retrofitting capabilities.

Environmental and Mechanical Specifications

The Honeywell STG78S is designed to withstand harsh industrial environments, with IP66/IP67 enclosure ratings ensuring reliable operation in dust-laden and wet conditions. Its modular construction allows for field replacement of components without requiring complete transmitter replacement.

Pressure Connection and Wetted Materials

Honeywell STG78S configurations offer multiple material options for process compatibility:

Standard head material: 316 Stainless Steel with 316L SS diaphragm

Optional materials: Hastelloy C-276 for corrosive process media

O-ring gasket: PTFE (Teflon) standard; Viton optional

Bolts/Nuts: Carbon steel (galvanized) or 316 SS per NACE requirements

Fill fluid options: Silicone Oil 200 or Fluorinated Oil CTFE for oxygen service

Display and User Interface

The Honeywell STG78S features a modular alphanumeric LCD display with the following capabilities:

Display size: 2 lines, alphanumeric

Position adjustments: 0°, 90°, 180°, 270° rotatable

Configurable screens: Four programmable display screens

Measurement units: Pa, kPa, MPa, kg/cm², torr, atm, inH₂O, mH₂O, bar, mbar, inHg, ftH₂O, mmH₂O, mmHg, psi

Square root output indication: Calculated flow (square root) value display

Languages: English, Russian

The display module can be added or removed in the field and includes internal configuration buttons for basic device setup including range/engineering unit selection, loop test, loop calibration, and zero/span setting-6. For models with the LCD display configured, three magnetic buttons enable full operational configuration of all transmitter parameters without removing the housing cover.

Complete Model Number Configuration Examples

The Honeywell STG78S part number follows a comprehensive selection code structure. The following are actual complete part numbers for reference:

STG78S-E1G000-1-0-GHS-12C-A-00-A6-F1-TP-0000 – 0–42 MPa range, 316 SS/316L SS wetted materials, silicone oil fill fluid, 1/2″ NPT connection, NEPSI explosion-proof and intrinsically safe approvals, standard accuracy, 4–20 mA with HART output-2

STG78S-F1H000-1-C-BHB-11C-B-00A0-TP-FX-FG-F1 – 316 SS wetted materials, CTFE fill fluid, M20 electrical connection, HART protocol with custom application software, standard accuracy and calibration-26

STG78S-E1G000-1-A-AHS-11C-A-00A0-00-0000 – 0–6,000 psi range, 316 SS wetted materials, standard accuracy, HART protocol, polyester powder-coated aluminum housing, standard display with internal buttons

STG78S-E2G000-1-A-AHS-11 – 0–6,000 psi range, CTFE fill fluid, explosion-proof approval, 4–20 mA with HART output

Model Number Code Breakdown

Advanced Features

Diagnostic Capabilities

Honeywell STG78S transmitters offer comprehensive on-board diagnostic capabilities that provide digital access to device health monitoring-6. These diagnostics deliver advanced warning of possible failure events, minimizing unplanned shutdowns and reducing overall operational costs. The self-diagnostic function continuously monitors sensor integrity, electronics performance, and communication status, helping maintain high uptime and meet regulatory requirements.

Safety and Compliance

The Honeywell STG78S incorporates an integral dual seal design based on ANSI/NFPA 70-202 and ANSI/ISA 12.27.0 standards, ensuring maximum safety in process applications-26. Key certifications include:

SIL 2/3 compliance – full compliance as standard configuration

ATEX explosion-proof and intrinsically safe (optional)

IECEx certification

CSA certification

CE marking

NEPSI certification for Chinese hazardous area requirements

NACE MR0175/MR0103 compliance for H₂S service (optional)

Modular Design

Honeywell STG78S pressure transmitters feature a fully modular construction that enables easy field maintenance and configuration-6. Key modular components include:

Replaceable sensor module – removable without de-pressurizing the process

Replaceable electronics module – field-swappable without recalibration

Optional display module – add or remove in the field

Interchangeable housing options – explosion-proof and weatherproof variants

This modular design eliminates the need to stock transmitters with multiple ranges or electronic modules, allowing users to redefine range or replace electronics without purchasing additional transmitters-6.

Overpressure Protection

The Honeywell STG78S provides robust overpressure protection with static pressure limits capable of withstanding overpressure events without damage to the sensing element. Optional over-pressure leak test certificates (1.5X MAWP) are available for critical applications.

Applications

The Honeywell STG78S is ideal for a broad range of industrial pressure measurement applications where high-pressure capability up to 6,000 psi is required:

Oil & Gas Industry

High-pressure measurement in boilers and fuel feeds

Hydrocarbon recovery processes

Pipeline pressure monitoring

Wellhead pressure measurement

Fracking pressure monitoring

Chemical & Petrochemical Facilities

High-pressure reaction vessel monitoring (up to 6,000 psi/420 bar)

Process control in distillation columns

Reactor pressure measurement

Chemical feed systems

Catalyst regeneration pressure monitoring

Power Generation

Boiler pressure monitoring

Steam system pressure measurement

Turbine inlet pressure control

Fuel gas pressure regulation

Coal gasification processes

Water & Wastewater Treatment

Pump discharge pressure monitoring

Filter differential pressure measurement

Distribution system pressure control

Tank Level Measurement

High-temperature tank level applications (up to 126°C)

Storage vessel hydrostatic level measurement

Process vessel level control

High-Pressure Industrial Processes

Hydraulic system pressure monitoring

High-pressure injection systems

Industrial compressor monitoring

Installation Considerations

The Honeywell STG78S in-line design enables direct mounting onto a 1/2″ male NPT nipple, facilitating simple and secure installation-1. For optimal performance:

Mount the transmitter in a location with minimal vibration

Ensure ambient temperature remains within specified limits

Use appropriate conduit seals for hazardous area installations

Allow sufficient access for external zero/span adjustment buttons

Consider heat tracing or insulation for process temperatures exceeding ambient limits

For liquid applications, mount transmitters below the tap to allow gas buildup to dissipate

Use at least two screws for wall mounting and maximum diameter U-bolts for pipe mounting

Configuration Tools

Honeywell STG78S transmitters can be configured using multiple methods:

Integrated three-button configuration module – usable in all electrical and environmental conditions, enabling configuration of all transmitter parameters when the LCD display is fitted

MCT202 Multi-Protocol Communicator – field configurable for DE and HART transmitters, usable in intrinsically safe environments

SCT3000 Configuration Toolkit – provides a simple method for configuring DE protocol transmitters using a PC as the configuration HMI

Field Device Manager (FDM) – manages HART and Fieldbus device configurations

HART DTM – available for ST 800, ST 700, SMV800, and other Honeywell devices, organizing configuration parameters under Configuration, Monitoring, Diagnostics, and Maintenance for an optimized user experience