Series-MARK-II-MPAVM

Supported Applications

The Dwyer Series Mark II Molded Plastic Air Velocity Meters are inclined-vertical manometers designed for portable or stationary uses to measure air velocity and differential pressure. These instruments provide direct reading capabilities specifically intended for applications such as air filter gages, duct measurements, and general airflow monitoring in HVAC systems.

Models configured with the "-AV" suffix (e.g., Mark II 27, Mark II 40-1-AV) are designated as Air Velocity Meters. The series is designed for use with Dwyer Series 160 Pitot tubes to measure air velocity in ducts; however, pitot tubes are not included and must be purchased separately.

Operating Conditions & Performance

The series delivers a measurement accuracy of ±3% FS (Full Scale) or 3% Accuracy across its various ranges. The instruments accommodate moderate overpressures via overflow tanks on Model 25 configurations or float-operated overflow traps on Model 40 variants.

• Measurement Ranges: Available in air velocity scales of 0 to 7,000 FPM (Mark II 27), 0 to 10,500 FPM (Mark II 28), and 0 to 21 MPS (Mark II 40-250 Pa-AV). Differential pressure ranges include .10–0–1.00" w.c., .20–0–2.400" w.c., 10–250 Pa, 20–0–600 Pa, and metric water column options.
• Fluid Requirements: Models utilize specific indicating fluids based on the range: Red gage fluid (specific gravity .826) for lower ranges such as Mark II 27, MM-80, M-700Pa, and Model 40 variants; Blue oil/gage fluid (specific gravity 1.9 or 1.910) for higher pressure models like Mark II 26, 28, MM-180, and Model 41 variants.
• Pressure Limits: Do not exceed internal pressures of 15 psi (100 kPa). Specific model warnings note a limit of 10 PSI or 0.703 bar for certain configurations.
• Ambient Temperature: Operating limits are documented up to 140°F (60°C) and 150°F (65°C), depending on the specific model variant.

Configuration Options

The Series Mark II offers a configurable envelope of ranges, fluids, and mounting options to suit different installation needs. The housing is constructed from thick white styrene-acrylonitrile or molded plastic, providing durability for field use.

• Mounting & Housing: Units can be mounted on any vertical surface using included mounting screws. An optional A-612 Portable Stand is available specifically for Models 27 and 28 to facilitate portable testing.
• Process Connections: The series supports connections via barbed tubing adapters, 1/8" NPT fittings, or direct attachment to sheet metal ducts. Accessories typically include two tubing connectors (for 1/8" pipe), washers, nuts, and lengths of vinyl tubing.
• NIST Calibration: Specific variants are available with "-NIST" suffixes (e.g., MARK II 27-NIST, MKII 40-250PA-AV-NIST) indicating NIST-traceable calibration options.
• OEM Options: All models can be supplied with custom logos or special scales in OEM quantities upon consultation with the factory.

Key Product Differences

The series distinguishes between standard differential pressure manometers and dedicated air velocity meters based on scale calibration. Models ending in "-AV" feature dual-scale calibrations that display both static/differential pressure (in inches w.c., mm w.c., or Pa) and direct air velocity readings.

• Model 27 vs. Model 28: Mark II 27 covers the range of 0 to 7,000 FPM using red fluid (.826 s.g.), while Mark II 28 extends to 0 to 10,500 FPM and utilizes blue oil (1.9 s.g.).
• Model 40 vs. Model 41: The Model 40 family uses red fluid (.826 sp. gr.) for ranges such as .10–0–1.00" w.c. and 10–250 Pa. The Model 41 family utilizes blue fluid (1.910 sp. gr.) for higher pressure ranges like .20–0–2.400" w.c. and 20–0–600 Pa.
• Dimensional Differences: Physical dimensions vary by model; for example, Mark II 27 measures approximately 1-1/4" wide x 5-29/32" high, while the Model 40 series (e.g., 40-250 Pa-AV) is significantly longer at 10-5/8" to accommodate its inclined scale.