Series-476A

Supported Applications

The Dwyer Series 476A Single Pressure Digital Manometer and the related Series 478A Differential Pressure Digital Manometer are portable instruments designed for measuring low pressures in air and compatible gases. Documented applications include verifying field instrumentation performance and adjusting fuel mixtures on combustion systems.

Operating Conditions & Performance

The series features a rugged extruded aluminum housing with an accuracy of ±1.5% full-scale at 72°F (22.2°C), which includes linearity and repeatability, and hysteresis of ±0.1% FS. The maximum pressure rating is 5 psig (0.34 bar) per the manual or 5 psig (0.74 bar) as noted in the data sheet table; both sources cite a limit near this value.

Operating ambient temperature ranges from 32 to 104°F (0 to 40°C), while process temperatures are rated for 0 to 140°F (-17.8 to 60°C). The units utilize a 9 V alkaline battery, installed non-functional and user replaceable, with an automatic shut-off after 20 minutes of inactivity.

Resolution varies by model range: the Series 476A-0 offers 0.02 in w.c., while Series 478A models provide resolutions of 0.01 in w.c. or 0.1 in w.c. depending on the selected pressure span.

Measurement Ranges and Units

• Series 476A-0: -20.0 to 20.0 in w.c., with selectable units including bar, psi, in Hg, kPa, mm Hg, mbar, and mm w.c.
• Series 478A-0: -4.00 to 4.00 in w.c., offering resolution of 0.01 in w.c.
• Series 478A-1: -60.0 to 60.0 in w.c., offering resolution of 0.1 in w.c.

Note: When subjected to electromagnetic interference at 837 MHz (10 V/m), accuracy is reduced to 5.0% full scale.

Configuration Options

The series supports configurable pressure ranges and measurement types, including single pressure for the Series 476A and differential pressure for the Series 478A. Process connections are designed for use with 3/16" or 1/4" ID tubing; specific wetted materials require consultation with the factory.

Key features include electronic zeroing, one-button auto-zero, instant unit selection across up to nine English and metric units, and a 4-digit LCD display. The instruments are made in the U.S.A. and carry CE certification.

Available Options and Accessories

• -NIST Suffix: Adds a NIST traceable calibration certificate to any model (e.g., 478A-1-NIST).
• A-402A Carrying Case: A tough gray nylon pouch with double zippers and a belt loop, measuring 7-1/2"H x 3"W x 2-1/4"D (191 x 76 x 57 mm).
• A-47X-BOOT: A protective magnetic rubber boot.

Key Product Differences

The primary distinction between the two series is the measurement type: Series 476A measures single pressure, while Series 478A measures differential pressure. Within the Series 478A family, model numbers differentiate by range and resolution:

• Model 478A-0 covers a -4.00 to 4.00 in w.c. span with finer resolution.
• Model 478A-1 covers a wider -60.0 to 60.0 in w.c. span with coarser resolution.

All models share the same physical dimensions of approximately 2-13/16" x 6-17/32" x 5-57/64" and a weight of 10.8 oz (306 g).