MS-321

Overview

The Dwyer Instruments MS-321 is a micro differential pressure transmitter designed for measuring low-pressure differentials and air velocity. It features a 0-10 V analog output signal and supports mounting on walls or panels. The device accommodates small measurement ranges of 0.1, 0.25, and 0.5 inches water column (equivalent to 25, 50, and 100 Pa). It operates on a three-wire power supply configuration requiring either 17-36 VDC or isolated 21.6-33 VAC. The unit provides high accuracy with specifications of ±1% for the 0.5" w.c. and 100 Pa ranges, and ±2% for the 0.1" w.c. and 25 Pa ranges under standard conditions.

Feature Summary

• Provides a linear 0-10 V analog output signal proportional to the measured differential pressure.
• Supports field-adjustable calibration using digital keys for zero and span adjustments.
• Features an optional four-digit LCD display for local monitoring of process variables.
• Constructed with a NEMA 4X (IP66) rated enclosure suitable for harsh industrial environments.

Applications

• Monitoring filter clogging in HVAC systems
• Measuring airflow velocity in ductwork
• Monitoring cleanroom pressure differentials
• Tracking fan performance status

Procurement Notes

Verify the specific pressure range required, as the MS-321 is available in 0.1, 0.25, and 0.5 inch w.c. variants. Confirm the need for the optional LCD display, as it may affect the part number suffix. Ensure the installation environment meets the operating temperature limits of 0 to 150°F. Check that the control system input impedance is compatible with the minimum load requirement for the 0-10 V output signal.

Selection Notes

Select the MS-321 when a voltage output is preferred over current signals for short-distance transmission. This model is specifically designated for wall or panel mounting configurations. Compare against the MS-121 series if a 4-20 mA loop-powered output is required instead. Consider the MS-322 variant only if pipe mounting is necessary for the application geometry.

Part Context

The MS-321 belongs to the Dwyer MS Series of micro differential pressure transmitters. This family includes models with both 4-20 mA and 0-10 V outputs, catering to various industrial instrumentation needs. The series is engineered for low-pressure applications involving air and non-combustible compatible gases, offering stability and precision for environmental monitoring tasks.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Verify compatibility with existing wiring and control interfaces before considering alternative manufacturers.