Honeywell STT85A temperature transmitter

Honeywell STT85A temperature transmitter

Product Overview

The Honeywell STT85A is a fully integrated temperature probe assembly that combines the high-performance SmartLine STT850 transmitter with precision temperature sensing elements in a single, installation-ready package. Engineered for demanding process automation environments, the STT85A delivers accurate, reliable temperature measurement while significantly reducing engineering, ordering, installation, and commissioning time.-3

The STT85A belongs to Honeywell’s SmartLine family of temperature probe assemblies—a comprehensive lineup that also includes the STT820 rigid probe assembly, STT830 thermowell assembly, and STT840 flanged thermowell assembly.-1As an integrated solution based on the STT850 transmitter, the STT85A caters to tough industrial applications and includes a variety of temperature elements, thermowells, and extension types to meet diverse measurement requirements.-9

Key Technical Specifications

Sensor Compatibility:

RTD Types: Platinum (Pt100), Copper, Nickel, Nickel/Iron

Thermocouple Types: E, J, K, N, T

Temperature Ranges:

RTD: -58 to +932°F

Thermocouple: Up to +2300°F

Communication Protocols: Analog, DE, HART, Fieldbus Foundation (FF)-1-10

Performance Characteristics

Accuracy & Stability

The STT85A’s integrated STT850 transmitter delivers digital accuracy up to 0.1°C for RTD inputs, with long-term stability of 0.01% of URL per year sustained for ten years.-10This performance level allows the STT85A to replace virtually any existing temperature transmitter in the field.-10

Response Time

With a 130 ms update time, the STT85A provides near real-time temperature data to control systems, supporting rapid process adjustments and minimizing lag in critical applications.-10

Sensor Matching

The STT85A includes sensor matching capability for higher accuracy. By calibrating the transmitter to the specific characteristics of the installed RTD or thermocouple, the STT85A compensates for individual sensor variations and achieves measurement precision beyond standard tolerance levels.-10

Environmental & Durability Specifications

Protection Ratings

The STT85A is available with IP66, IP68, NEMA 4, and NEMA 4X protection grades, ensuring reliable operation in harsh industrial environments exposed to moisture, dust, and corrosive agents.-1

Hazardous Area Certifications

Explosion-proof: Class 1 Div 1 (Groups B, C, D) for flammable gas/vapor atmospheres; Class 2 Div 1 (Groups E, F, G) for combustible dust environments-19

ATEX and IECEx certified for international hazardous location compliance-1

Material Options

Housing material options include aluminum for general-purpose applications and 316 stainless steel for corrosive or high-humidity environments, along with cast iron and polypropylene for specialized installations.-1

Applications & Industries

The STT85A is ideally suited for process manufacturers, Original Equipment Manufacturers (OEMs), and Engineering Procurement Construction (EPC) contractors requiring installation-ready temperature measurement solutions.-1

Typical Applications:

Oil & Gas: Process temperature monitoring in refineries and pipelines

Chemical Processing: Reactor temperature control and exothermic reaction management

Power Generation: Boiler feedwater, steam temperature, and turbine inlet monitoring

Pharmaceuticals: Sterilization validation and bioreactor temperature control

Food & Beverage: Pasteurization, cooking, and cold storage temperature monitoring

Pulp & Paper: Digester and drying cylinder temperature measurement

Compatible Systems: Honeywell Experion PKS, Distributed Control Systems (DCS), Programmable Logic Controllers (PLC), and any 4-20 mA loop-powered input card

Ordering Information