Honeywell STD725 Differential Pressure Transmitter

Technical Specifications & Model Code Breakdown

The Honeywell STD725 Differential Pressure Transmitter stands as a premier solution in the SmartLine STD700 series, engineered for high-precision differential pressure measurement across critical industrial processes. Designed for liquid, gas, and steam applications—including flow metering, level monitoring, and filter condition tracking—the STD725 integrates advanced piezoresistive sensor technology with on-board static pressure and temperature compensation, delivering unrivaled performance in harsh operating environments. This technical guide explores core specifications, design advantages, and comprehensive model code interpretation for key variants like STD725-E1AC4AS-1-0-AHS-11S-A-00A0-00-0000, equipping engineers and procurement specialists with data-driven insights for optimal process integration.

Core Technical Specifications

The STD725 Differential Pressure Transmitter sets industry benchmarks for accuracy and stability, with technical parameters tailored for high-demand applications:

Measurement Range: Upper Range Limit (URL) of 100 kPa (400 in H2O), Lower Range Limit (LRL) of -100 kPa (-400 in H2O), with a minimum span of 1 kPa

Accuracy: ±0.065% of calibrated span (optional ±0.04% high-accuracy mode), ensuring precision for custody transfer and critical control loops

Turndown Ratio: Industry-leading 100:1, enabling wide-range measurement without compromising accuracy

Stability: 0.02% URL per year (5-year stability of 0.015% URL available), minimizing calibration and maintenance needs

Static Pressure Rating: Standard 31.5 MPa (4567 psi) static pressure tolerance, suitable for high-pressure process lines

Response Time: 100 ms, supporting real-time process monitoring and control

Operating Temperature: -40°C to +85°C (-40°F to +185°F) ambient; -40°C to +110°C (-40°F to +230°F) process temperature

Output & Communication: 4-20 mA analog with HART 7.0 protocol (default), plus FOUNDATION Fieldbus and Honeywell DE options

Wetted Materials: 316L stainless steel (standard), with Hastelloy C-276, Monel, and Tantalum available for corrosive media

Enclosure & Protection: Low-copper aluminum with polyester powder coating (or 316 stainless steel), IP66/IP67 ingress protection, and dual seal design meeting ANSI/NFPA 70-202 and ANSI/ISA 12.27.0 standards

Power Supply: 10.8–42.4 VDC (24 VDC nominal), two-wire loop-powered design

Model Code Interpretation: STD725-E1AC4AS-1-0-AHS-11S-A-00A0-00-0000

Honeywell’s modular coding system encodes full configuration details for the STD725, with breakdown for the flagship STD725-E1AC4AS-1-0-AHS-11S-A-00A0-00-0000 and related variants:

STD725: Base model—SmartLine differential pressure transmitter, 100 kPa URL capability

E: Wetted materials—316L stainless steel (process diaphragm/body)

1: Process connection—1/2” NPT female thread

A: Output signal—4-20 mA with HART 7.0 communication

C: Enclosure material—polyester-coated aluminum

4: Electrical connection—dual 1/2” NPT ports

A: Local display—alphanumeric LCD for on-site configuration

S: Approvals—general industrial, non-incendive for Class I, Division 2 hazardous areas

1: Static pressure rating—31.5 MPa standard

0: Special features—no remote seals or capillary extensions

AHS: Mounting & safety—standard inline, external zero/span adjustment, SIL 2 compliant

11S: Diagnostics—full self-diagnostics, surge/lightning protection, reverse polarity protection

A: Power—24 DC loop power

00A0: Calibration—factory-calibrated 0–100 kPa, no custom range

00: Accessories—no mounting brackets or valve manifolds

0000: Reservedcodes—no additional specifications

Additional high-config variants include STD725-E1HC4AS-1-0-AHS-11C-B-11A0-FX,F1,TP-0000 (Hastelloy C wetted materials, ATEX/IECEx approvals) and STD725-E1AS4AS-1-A-AHS-11S-A-21A0-F1 (stainless steel enclosure, extended temperature range), demonstrating the series’ customization flexibility.

Design Advantages & Industrial Applications

The Honeywell STD725 Differential Pressure Transmitter excels in oil and gas refining, chemical processing, power generation, and water treatment. Models like STD725-E1AC4AS-1-G-CHS-11S-A-00A0-0000 (flange process connection, corrosive service) and STD725-E1HS1AS-1-C-BHS-11C-B-00A0-F1 (high-static-pressure service) deliver consistent performance in extreme conditions. Its fully welded sensor module prevents media ingress, while modular electronics simplify field maintenance. Advanced diagnostics enable predictive maintenance, reducing unplanned downtime.