Emerson Rosemount 148 temperature transmitter

Emerson Rosemount 148 temperature transmitter

Product Overview

The Rosemount 148 Temperature Transmitter is a DIN B style head mount device that converts low-level sensor signals into a standard 4–20 mA DC signal relatively insensitive to lead length and electrical noise-. This transmitter is designed for single point temperature measurement applications across industrial process environments, offering a cost-effective alternative to wiring sensors directly while delivering superior measurement accuracy and reliability.

As a fundamental temperature measurement solution within the Rosemount portfolio, the 148 transmitter accepts universal sensor inputs and provides reliable performance where basic temperature monitoring is required. For applications demanding higher precision or advanced diagnostics, the Rosemount 248 and 3144P models offer additional capabilities, while the 148 remains a practical choice for straightforward temperature measurement points-.

The 148 transmitter is a key component of Emerson’s Complete Point Solution (CPS) program, which allows the device to be factory-assembled with a sensor, thermowell, and connection head as a ready-to-install assembly-54. This approach simplifies procurement, reduces field wiring work, and ensures component compatibility. When ordered with the XA option code, the transmitter can be assembled to any compatible sensor, thermowell, and extension accessory from Emerson-.

Key Technical Specifications

Input and Sensor Compatibility

The Rosemount 148 accepts a wide range of sensor inputs, providing flexibility across different measurement needs:

The transmitter’s universal input capability means a single model number can be configured for different sensor types, reducing inventory requirements. The device supports 2-wire, 3-wire, and 4-wire RTD configurations. For 3-wire RTD installations, lead wire resistance errors are minimized through the transmitter’s design-37. When using 2-wire RTD connections, lead lengths should be kept short (under three feet of 20 AWG wire) to avoid significant error; longer runs require third or fourth leads-37.

Output and Power

Environmental and Operating Limits

Performance Accuracy

The Rosemount 148 delivers reliable measurement accuracy across various sensor inputs:

Failure Mode Configuration

The transmitter can be configured for standard or NAMUR-compliant failure mode operation:

Microprocessor failures will always drive the output above 23 mA-5.

EMC and Environmental Compliance

Hazardous Area Certifications

The Rosemount 148 is available with multiple hazardous location approvals for global installation flexibility:

Temperature code T5: ambient –50 to 75°C; T6: ambient –50 to 40°C (FM I5). For CSA K6 certification, ambient limit is –50 to 85°C-43.

Model Number Breakdown: 148HNNANOQ4XA

The complete model number for a Rosemount 148 transmitter follows a structured code that defines all configuration options. Understanding this code is essential for proper specification and ordering. Here is the breakdown for model 148HNNANOQ4XA:

Alternative configurations commonly found in the field include:

148HAHANOQ4XA – Universal head, NEMA 4X, factory default configuration, 4–20 mA HART output, hazardous location certified

148HDPANOQ4XA – Different housing configuration with standard approval package

Configuration Options Explained

Housing Code (position 4) : The “H” indicates a universal stainless steel housing suitable for demanding environments. The “U” option provides a universal head with similar ratings-40.

Enclosure Type (position 5) : “N” designates a universal head with NEMA 4X rating. This provides protection against corrosion, windblown dust and rain, splashing water, and hose-directed water.

Sensor Input (positions 6–7) : “NA” specifies that the transmitter is ordered as a stand-alone unit without a pre-mounted sensor. When the XA option code is added (as seen at the end of the model string), the transmitter can be assembled to any sensor, thermowell, and extension accessory-.

Configuration (positions 8–9) : “NO” indicates factory default configuration settings. The transmitter can be custom-configured at the factory for specific sensor types, measurement ranges, and damping values upon request.

Output Signal (position 10) : “Q” specifies the 4–20 mA output with HART protocol, allowing digital communication with configuration tools.

Certifications (positions 11–12) : “4X” represents a hazardous location certification package, typically CSA (Canadian Standards Association) approval for use in classified areas.

Product Assembly (position 13) : “A” denotes standard assembly configuration.

Installation and Mounting

Physical Installation Procedure

The Rosemount 148 transmitter mounts directly into a connection head. The standard installation sequence involves the following steps-:

Attach the thermowell to the pipe or process container wall

Assemble the transmitter to the sensor by pushing the transmitter mounting screws through the sensor mounting plate

Wire the sensor to the transmitter according to the appropriate wiring diagram (see sensor connection tables)

Insert the transmitter-sensor assembly into the connection head

Mount the assembled unit into the thermowell

Thread the connection head cover into place

For DIN rail mounting applications, special mounting hardware is available to mount the head mount transmitter to a DIN rail-1.

Sensor Wiring Guidelines

The transmitter accepts multiple RTD and thermocouple configurations. Wiring connections must follow the terminal assignments:

When mounting the transmitter remotely from a 3-wire or 4-wire RTD, the device will operate within specifications for lead wire resistances up to 60 ohms per lead, which is equivalent to approximately 6,000 feet of 20 AWG wire-37.

Connection Head Temperature Considerations

The transmitter specification limit is 85°C ambient temperature inside the connection head. When measuring high-temperature processes, extension length between the thermowell and the connection head must be considered to keep the transmitter within its operating limits. A reference table in the manual provides extension length requirements for various combinations of ambient temperature and process temperature-1.

Configuration and Commissioning

Factory Configuration

The Rosemount 148 must be configured for certain basic variables to operate. In many cases, all these variables are pre-configured at the factory when ordered with specific requirements-. Standard factory configuration includes default settings for sensor type (user-selectable), measurement range, damping value (5 seconds default), and failure mode behavior.

PC-Based Configuration Interface

The Rosemount 148 PC Programmer is available as a configuration tool consisting of a programmer, cables, and software-54. The PC-based HART configuration interface delivers the necessary tools for transmitter configuration, including sensor type selection, range setting, sensor error correction, and various other options-23. The software enables reading information such as address, status, serial number, type, and setup, as well as changing detector configuration-.

Configurable Parameters

Key parameters that can be configured include:

Sensor type (RTD type and alpha value, thermocouple type, mV, or ohms)

Lower and upper range limits

Damping value (0 to 32 seconds, 5 seconds default)

Output failure mode (high, low, or NAMUR-compliant)

Tag identification (32 characters with HART 7 protocol support)

Sensor error correction (offset adjustment)

Compatibility and System Integration

Compatible Sensors and Accessories

The Rosemount 148 is compatible with a comprehensive range of Emerson temperature sensors and accessories. For pipe clamp installations, the Rosemount 0085 Pipe Clamp Temperature Sensor covers a temperature range of –328 to 572°F (–200 to 300°C) and can be direct-mounted to the transmitter-. For RTD applications, the Rosemount 214C RTD Temperature Sensor provides reliable performance, with maximum ice point resistance drift of 0.05°C after 150 hours of 1g vibration testing from 20 to 500 Hz-.

When ordered as a complete point solution, the transmitter can be factory-assembled with any compatible sensor, thermowell, and extension accessory from Emerson-. This approach ensures proper mechanical fit and reduces field installation time.

System Architecture

The transmitter’s 4–20 mA output with HART protocol integrates seamlessly with:

Distributed Control Systems (DCS)

Programmable Logic Controllers (PLC)

Asset Management Software (AMS)

HART communicators (475 Field Communicator)

PC-based configuration systems

The signal loop may be grounded at any single point or left ungrounded, providing installation flexibility-37.

Maintenance and Support

Stability and Calibration Interval

The Rosemount 148 maintains a stability specification of ±0.15% of reading or 0.15°C for twelve months, allowing extended calibration intervals and reduced maintenance costs-5. This stability performance is consistent across both RTD and thermocouple inputs.

Warranty Coverage

The Rosemount 148 is available with limited warranty options of 12 months, 18 months, 3 years, or 5 years-58. Extended warranty coverage provides additional assurance for critical temperature monitoring points.

Documentation Reference

Key documentation for the Rosemount 148 includes:

Product Data Sheet: Document number 00813-0100-4148-1

Reference Manual: Document number 00809-0100-4148-1

Quick Start Guide for basic installation

Installation drawings for hazardous location installations

Factory Calibration and Surge Protection

For applications requiring additional protection, the optional Rosemount 470 Transient Protector prevents damage from transients induced by lightning, welding, heavy electrical equipment, or switch gears-5.