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Control Valve Trim Styles and Flow Characteristics

Hi-Flow™ Valve Cutaway

Hi-Flow™ Control Valves vary the flow in a system by throttling the valve plug in and out of the valve seat. The corresponding flow rate through the valve is based on the valve plug and seat type, which is part of the valve trim. Dwyer Instruments, Inc. offers several flow characteristics, needle plugs, and restricted trim options for the Hi-Flow™ Control Valve series.

There are two types of inherent flow characteristic trim styles available in the Hi-Flow™ product line: Linear and Equal percentage. Continue reading “Control Valve Trim Styles and Flow Characteristics”

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What are Thermo-Anemometers or Hot Wire Air Velocity Sensors?

Thermo-Anemometers

Dwyer Instruments, Inc. offers many air velocity measuring products that use thermal or hot-wire sensors as the sensing element. There are fixed duct mount styles for continuous monitoring, such as the Air Velocity Transmitters, Series 641, and portable insertion styles for testing, such as the Thermo-Anemometer Test Instrument, Model 471B and the Thermo-Anemometer Probe, Series AP2.

Continue reading “What are Thermo-Anemometers or Hot Wire Air Velocity Sensors?”

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Flow Measurement with Orifice Plates

Dwyer Instruments, Inc. offers many types of flow measuring products including orifice plates, which are used as a flow sensing element with a differential pressure monitor.

Orifice Plates

Orifice plates are a primary flow element, detecting the flow of a fluid passing through the plate by sensing the pressure drop across the plate. When a fluid flows through a restriction in a pipe, it creates a pressure difference between upstream and downstream of the restriction. This pressure difference is proportional to flow rate according to Bernoulli’s principal, similar to a Pitot tube.  Orifice plates are commonly used as they are simple to use, low cost, work with gases or liquids, and require low maintenance.  Adversely, they do have large pressure losses with about 50% of the pressure drop not recoverable.  Continue reading “Flow Measurement with Orifice Plates”

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Submersible Level Transmitters

Submersible Level Transmitters

The Mercoid® Division of Dwyer Instruments, Inc. offers four series of submersible level transmitters with different features suitable for different applications: the FBLT, PBLT, MBLT, and SBLT.

Submersible Level Transmitters are pressure transmitters manufactured to read hydro-static pressure from inside the fluid. These transmitters are submersed into the fluid that they are measuring and will give an output proportional of the fluid level above the sensor location. Continue reading “Submersible Level Transmitters”

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Bimetal Thermometers

Dwyer Instruments, Inc. offers many temperature measuring products that use bimetal sensors as the sensing element.

Bimetal Thermometers measure temperature based on the differences in thermal expansion properties of metals. Pieces of metals with different thermal expansion coefficients are attached to each other in an assembly.

As the temperature applied to the metal sensor assembly increases, the metal strip with the larger temperature coefficient of expansion expands more.  Continue reading “Bimetal Thermometers”