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Variable Area Flow Meters

Variable Area Flow Meters

Blue-White® Variable Area Flow Meters

Variable Area Flow Meters (Rotameters) are a cost-effective solution for applications involving the measurement of industrial process water. Blue-White® offers direct-reading variable area flow meters to provide an accurate, safe, and economical method of measuring flow.

Variable Area Flow Meters

Explore Variable Area Flow Meters (Acrylic)

F-300 Variable Area Flow Meter

F-300
Pitot Tube Acrylic Flow Meter

GPM LPM
2 - 1900 8 - 7200
PSI Bar
75 5.2
Pipe Sizes
1”, 1¼”, 1½”, 2”, 2½”, 3”, 4”, 6”, 8”

F-400 Acrylic Flow Meter

F-400
Acrylic Flow Meter

GPM LPM
.025 - 5 .1 - 20
PSI Bar
150 10.3
Pipe Sizes
¼”, ⅜” , ½” F/NPT

F-410 Acrylic Flow Meter

F-410
Acrylic Flow Meter

GPM LPM
1 - 20 4 - 80
PSI Bar
150 10.3
Pipe Sizes
¾”, 1” F/NPT

F-420 Acrylic Flow Meter

F-420
Acrylic Flow Meter

GPM LPM
5 - 50 20 - 200
PSI Bar
130 8.9
Pipe Sizes
1” F/NPT, 1½” M/NPT

F-430 Acrylic Flow Meter

F-430
Acrylic Flow Meter

GPM LPM
4 - 100 15 - 375
PSI Bar
130 8.9
Pipe Sizes
1½”, 2” F/NPT

F-550 Acrylic Flow Meter

F-550
Acrylic Flow Meter

GPM LPM
.025 - 20 .1 - 75
PSI Bar
250 17.2
Pipe Sizes
1/4”, 3/8”, 3/4” and 1” male NPT

Explore Variable Area Flow Meters (Polysulfone)

F-440 Polysulfone Flow Meter

F-440
Polysulfone Flow Meter

GPM LPM
.025 - 10 .1 - 37.5
PSI Bar
175 12
Pipe Sizes
⅜”, ½”, ¾” M/NPT

F-450 Polysulfone Flow Meter

F-450
Polysulfone Flow Meter

GPM LPM
.1 - 10 .4 - 40
PSI Bar
175 12
Pipe Sizes
⅜”, ½”, ¾” F/NPT

F-451 Polysulfone Flow Meter

F-451
Polysulfone Flow Meter

GPM LPM
.5 - 40 2 - 155
PSI Bar
150 10.3
Pipe Sizes
1” F/NPT (Polysulfone), 1½” F/NPT (PVC)

F-452 Polysulfone Flow Meter

F-452
Polysulfone Flow Meter

GPM LPM
2 - 175 8 - 675
PSI Bar
150 10.3
Pipe Sizes
2” F/NPT

F-460 Polysulfone Flow Meter

F-460
Polysulfone Flow Meter

GPM LPM
.1 - 5 .4 - 20
PSI Bar
150 10.3
Pipe Sizes
1/2″ and 3/4″ female NPT fittings

F-461 Polysulfone Flow Meter

F-461
Polysulfone Flow Meter

GPM LPM
1 - 35 4 - 130
PSI Bar
150 10.3
Pipe Sizes
1″ female NPT fittings

F-462 Polysulfone Flow Meter

F-462
Polysulfone Flow Meter

GPM LPM
2 - 80 8 - 300
PSI Bar
150 10.3
Pipe Sizes
2″ female NPT fittings

How do Variable Area Flow Meters Work?

Blue-White® Variable Area Flow Meters (rotameters) measure the volumetric flow of liquids. They have an orifice and a float that can move vertically inside a tube with an increasing diameter from bottom to top. As the fluid flows through the tube, it forces the float upward. The clearance space (annular area between the float and the tube wall) between the float and the tube increases as the float moves toward the top of the meter. The larger clearance area towards the top requires more fluid to force the float higher. The greater the flow, the higher the float is raised.

tapered tube illustration

Advantages of a Variable Area Flow Meter

  • Cost effective

    Low cost compared to other flow measurement devices

  • Reliable

    Trouble-free operation ensures years of accurate flow measurement and repeatability

  • Simple

    Very easy to install and maintain

  • Flexible

    No power required, which means they can be used virtually anywhere

Applications

Explore Articles

Variable Area Flow Meter FAQ

A variable area flow meter is a type of differential pressure flow meter. Variable area flow meters are simple and versatile devices that operate at a relatively constant pressure drop and measure liquids, gases, and steam flow.

One of the earliest and most well-known flow measurement principles is the variable area flow measurement approach. As a result, of all the flow-measuring technologies now on the market, variable area flowmeters (commonly referred to as rotameters) have one of the largest installed bases. This technology has several benefits, including dependability, accuracy, simplicity of installation, and readability. Also, these meters are frequently used because the measurement method is mechanical in nature and can be used in instances without power.

The following are the three main types of variable area flow meters:

Glass Tube Variable Flow Meters​

The glass tube indicating type is the most common variable area flow meter form. The float is machined from metal, glass, or plastic, while the tube is made from borosilicate glass. The meter’s scale can be calibrated to read air or water directly, or it may have a scale that reads a percentage of range or an arbitrary scale that can be used with conversion equations or charts.

Metal Tube Flow Meters

When strong working pressure, a wide temperature range, water hammering, or other pressures would break glass metering tubes, stainless steel, metal tube flow meters are utilized. The majority of fluids, including corrosive liquids and gasses, can be used with metal tube flow meters.

Plastic Tube Variable Flow Meters

Several versions of variable area flow meters use plastic tubes because of their inexpensive cost and great impact strength. Usually made of polycarbonate, they have either metal or plastic end fittings. While installing plastic end fittings, care must be taken to prevent thread distortion. For applications where metal wetted parts cannot be tolerated, for as with deionized water or corrosives, meters with an all-plastic structure are available.

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