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The Making of a Market Leader – The Magnehelic® Differential Pressure Gage

The name of the Magnehelic® Differential Pressure Gage was derived from the terms Magnet and the Helix. The Magnehelic® Gage is a simple yet elegant solution, which solved a problem faced by customers who wanted to measure low differential pressure. Historically the industry measured differential
Molded Plastic Manometers Series Mark II

pressure with a liquid filled manometer. The manometer worked on the principle that the difference in air pressure is measured as a function of gravity and liquid density. The challenge, however, was that the liquid in the manometer evaporates over time. This means that individuals would need to regularly add more liquid and re-calibrate the device. Continue reading “The Making of a Market Leader – The Magnehelic® Differential Pressure Gage”

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Balancing a HVAC System with Multiple Diffuser Types

The Problem

  • Standard air flow hoods do not correct for diffuser type when balancing a system.
  • Proportional balancing is extremely difficult when a mixture of diffusers are present, due to the inaccuracy of standard hoods on slot diffusers.
  • Below is a sample of diffusers tested on Dwyer’s Precision Air Calibration Station (Figure A) with a standard air flow hood followed by the Dwyer SMART Air Hood™ Balancing Instrument (Series SAH).

Figure A: Precision Air Hood Calibration Station
 Continue reading “Balancing a HVAC System with Multiple Diffuser Types”

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Air Velocity and Flow Measurement with Pitot Tubes

Dwyer Instruments offers many styles of Pitot tubes, which are a commonly used sensor  for monitoring air velocity and flow rate in heating, ventilation, and air conditioning.

Pitot tubes are based on Bernoulli’s equation, which states an increase in the speed of a fluid occurs simultaneously with an increase in dynamic pressure and a decrease in static pressure.  Pitot Tubes sense the dynamic pressure of the fluid flow at a particular point and were invented by French Engineer Henri Pitot in the early 18th century.

Continue reading “Air Velocity and Flow Measurement with Pitot Tubes”