MS-121-DWYR

Overview

The Dwyer Instruments MS-121-DWYR is a micro differential pressure transmitter from the MS series, designed for measuring low differential pressures and air velocity. It features a 4-20 mA two-wire output and supports multiple measurement ranges including 0.1, 0.25, and 0.5 inches of water column (w.c.), as well as corresponding metric values of 25, 50, and 100 Pascals (Pa). The device offers high accuracy, with specifications of ±1% for larger ranges and ±2% for the 0.1" w.c. range. It operates on a 10-35 VDC power supply and includes a field-adjustable LCD display option.

Feature Summary

• Provides linear differential pressure or square-rooted air velocity output
• Features a rotatable LCD display for clear reading in various orientations
• Supports field-adjustable zero and span calibration via digital buttons
• Constructed with UL94 V-0 rated flame-retardant housing for safety

Applications

• Filter status monitoring in air handling units
• Indoor pressure monitoring in pharmaceutical and semiconductor cleanrooms
• Duct static pressure measurement in commercial buildings
• Air velocity and volume measurement in variable air volume systems

Procurement Notes

Verify the specific suffix code to confirm the exact measurement range and enclosure type required for your installation. Ensure the power supply voltage matches the 10-35 VDC specification for the two-wire configuration. Confirm whether the optional LCD display is included in the ordered part number, as it is not standard for all base configurations.

Selection Notes

Select this model when precise measurement of very low differential pressures is required in HVAC or industrial environments. The MS-121 is suitable for applications where a 4-20 mA signal is needed for integration with PLCs or DCS systems. Consider the MS-321 variant if a 0-10 V output is preferred instead of current loop signaling.

Part Context

This component belongs to the Dwyer MS series of MagnaSense® differential pressure transmitters. The series is known for stability and versatility in building automation control systems. The MS-121 specifically denotes the 4-20 mA output version with wall or panel mount capability, distinguishing it from pipe-mount or voltage-output variants within the same family.

FAQ

What is the maximum response time for the MS-121?

The response time is adjustable between 0.5 and 15 seconds, allowing users to configure the 95% response time based on application needs.

Can the MS-121 measure both positive and negative differential pressure?

Yes, the sensor can be configured for unidirectional or positive/negative combined ranges depending on the specific factory configuration selected.