The Dwyer Visi-Float series VFB flowmeter is a 4" scale air flow meter with 1/8" female NPT inlet and outlet connections for inline monitoring and measuring of air flow with an accuracy of + or – 3% of full scale, and is precision machined from solid acrylic plastic to resist breakage and provide a clear view of the scale. Black scale graduations are hot-stamped into the plastic for distinct readings. This lightweight flowmeter has a metal mounting insert for panel mounting and can also be supported directly by system piping. Models are available for measuring air flow in scfh, scfm, lpm, or cc/min. Some models come with a brass or stainless steel metering valve for precise adjustment of air flow, or with a pointer flag for clear-cut readings. Inlet and outlet connections are brass except for models with stainless steel wetted parts and the connections are on the back of the flowmeter except for models that have end connections. This flowmeter is commonly used for measuring air flow in medical equipment, air samplers, gas analyzers, pollution monitors, chemical injectors, and cabinet purging equipment, among other devices.
||4" (on average)
||+ or – 3% of full scale
||1/8" female NPT inlet and outlet
|Pressure and temperature rating
||Without valve: 100 psig/6.9 bar @ 65 degrees C/150 degrees F; with valve: 100 psig/6.9 bar @ 48 degrees C/120 degrees F
||Body: acrylic plastic; O-ring: Buna-N; metal parts: brass (standard) or stainless steel (applicable models); float (varies by range): black glass, nickel/copper alloy, stainless steel, or aluminum
|Dimensions (H x W x D)
||169.9 x 34.93 x 31.75 mm/6-11/16 x 1-3/8 x 1-1/4 inches
||0.20 to 0.25 kg/7.2 to 8.8 oz.
*Note: H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back.
Anemometers, also called wind meters, measure air velocity and are most commonly used for weather monitoring to determine wind speed and for HVAC applications to determine air flow within ducts. In addition to air velocity, anemometers may measure wind direction, air pressure, air flow volume, air temperature, humidity, light, and other properties. The most common types of anemometer are cup, vane, hot-wire, and Pitot tube. Cup and vane anemometers calculate air velocity based on the number of rotations of the cups or vane. Hot-wire anemometers calculate air velocity by measuring the change in electrical resistance as air flow cools a heated wire. Pitot tube anemometers measure air pressure within a tube and calculate air velocity based on the difference in pressure between the air inside and outside of the tube. Many anemometers have digital readouts and can display air velocity readings in different units of measure, such as meters per second (m/s), feet per minute (ft./min. or fpm), knots, miles per hour (mph), and kilometers per hour (km/h).
Dwyer Instruments manufactures measurement and control instruments, including pressure gauges, flow meters, level instrumentation, temperature instrumentation, and air quality monitors. The company, founded in 1931, is headquartered in Michigan City, IN.