Dwyer Series 475 & 477-AV Handheld Digital Manometer & Air Velocity Kits
Posted on: 29/07/2026
Featuring multi-unit digital LCD displays, FM/UL intrinsically safe approval, stainless steel Pitot tubes, and complete accessory field kits in hard cases. The ultimate solution for HVAC engineers in air balancing, AHU filter testing, and system commissioning.
1. When to Choose a Handheld Manometer Over Fixed Pressure Gauges?
While fixed differential pressure gauges (such as Magnehelic gauges or pressure transmitters) provide continuous monitoring at single stationary locations, field engineers and HVAC technicians require handheld digital manometers for flexible, multi-point field operations:
• Commissioning & System Acceptance: Measuring across multiple ductwork locations to prepare official validation reports.
• AHU & Ductwork Air Balancing: Measuring static pressure, velocity pressure, and volumetric flow across air distribution networks.
• Periodic Maintenance & Troubleshooting: Detecting clogged filters, duct leakages, or unexpected pressure drops instantly.
• Fixed Gauge Calibration Cross-Checking: Serving as a portable reference standard to verify the accuracy of installed line gauges.
2. Key Advantages & Technical Highlights of Series 475 / 477-AV
The Dwyer 475 & 477-AV series stand out with superior engineering features:
• Multi-Unit Digital Display: Large LCD screens (1/2" or 0.4" back-lit) display real-time pressure in selectable English or Metric engineering units, eliminating manual conversion errors.
• Intrinsically Safe Certification: Series 475-FM models carry FM/UL Intrinsically Safe ratings for hazardous, explosive environments.
• 2-in-1 Differential Pressure & Air Velocity: When combined with stainless steel Pitot tubes, -AV models seamlessly measure both air velocity and static pressure. Series 477-AV automatically calculates air velocity and volumetric flow without manual math.
• Field-Ready & Portable: Powered by standard 9V batteries, enclosed in durable housings, and supplied in protective polyethylene carrying cases with fitted foam inserts.
• Assembled in the USA: Manufactured to strict quality standards, ensuring long-term field reliability.
3. Detailed Product Kit Configurations & Specifications
Dwyer offers comprehensive field kits tailored for HVAC testing and industrial balancing:
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Kit Model Series
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Available Ranges
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Kit Components Included
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Series 475-XX-FM-AV
(Fixed 6" Pitot Tube)
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• 475-00-FM-AV: 0–4.000 in w.c.
• 475-0-FM-AV: 0–10.00 in w.c.
• 475-1-FM-AV: 0–20.00 in w.c.
• 475-2-FM-AV: 0–40.00 in w.c.
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• Series 475 Digital Manometer (±0.5% FS accuracy, 0.01 resolution, 1/2" LCD, low battery indicator).
• Stainless steel Pitot tube Model 166-6-CF 6" with integral compression fitting.
• Two A-303 static pressure tips with magnetic mounts.
• Two 4-1/2' rubber tubing sections (3/16" ID).
• A-397 step drill bit (3/16"–1/2").
• AV-A-532 air velocity slide rule, 9V battery, Polyethylene hard case.
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Series 475-XXT-FM-AV
(Telescopic 36" Pitot Tube)
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• 475-00T-FM-AV: 0–4.000 in w.c.
• 475-0T-FM-AV: 0–10.00 in w.c.
• 475-1T-FM-AV: 0–20.00 in w.c.
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• Series 475 Digital Manometer (±0.5% FS accuracy, FM/UL Intrinsically Safe).
• Stainless steel Telescopic Pitot Tube Model 166T 36" (adjustable 11.5" to 36" / 29.2–91.4 cm).
• Two A-303 magnetic static pressure tips.
• Two 4-1/2' rubber tubing sections, A-397 step drill bit, AV-A-532 slide rule, 9V battery, Polyethylene case.
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Series 477AV-XXXT-AV
(Auto Air Velocity & Volumetric Flow)
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• 477-000T-AV: 0–1.000 in w.c.
• 477-00T-AV: 0–4.000 in w.c.
• 477-0T-AV: 0–10.00 in w.c.
• 477-1T-AV: 0–20.00 in w.c.
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• Series 477AV Digital Manometer (±0.5% FS accuracy, automatic air velocity & volumetric flow calculations, 40-reading memory, 0.4" back-lit LCD, audible/visual over-pressure alarm).
• Model 166T 36" Telescopic Pitot Tube.
• Two A-303 static pressure tips, two rubber tubes, A-397 step drill, AV-A-532 slide rule, 9V battery & Polyethylene case.
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4. Recommended Field Tool Combination for HVAC Engineers
To build an all-around field testing kit, DLK recommends pairing air and hydronic instruments:
1. Air System Balancing: Dwyer Series 475 or 477-AV Portable Air Velocity Kit (with Pitot Tube).
2. Hydronic System Balancing: Dwyer Series 490A Hydronic Differential Pressure Meter. For chilled water systems, the Series 490A measures pressure differentials across pumps, control valves, and heat exchangers (chillers/condensers).
Combining Series 475/477-AV and Series 490A provides complete air and water diagnostic capability for field engineers.
Contact DLK for Consultation & Quotation
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24/7 Hotline: 0937972339
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Sales Department: 0783683479
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Email: info@dlk.com.vn
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Address: 111/7, Vuon Lai Street, Phu Tho Hoa Ward, Tan Phu District, Ho Chi Minh City