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Variable Area Flowmeters

Variable Area Flowmeters

Variable Area Flowmeters

Swagelok® variable area flowmeters measure the flow rate of liquids and gases by means of a tapered tube and float. The float is pushed up by increasing fluid flow and pulled down by gravity as fluid flow decreases. Simple installation; easy to read. No wearing parts

  • Limit switches available
  • 10-to-1 turndown ratio (the lowest measurement is one tenth of the full-scale reading); measurement ranges are available in U.S. customary and metric scales
  • Meters are marked with the fluid media and unit of measure for which they are calibrated
  • Meters can be factory calibrated to customer process specifications

Every Swagelok variable area flowmeter is factory calibrated to the selected media, flow range, and accuracy class using clean, dry air for air flow range models and water for water range models. Meters can be calibrated to user-specific applications.

M Series Variable Area Flowmeters (M1, M2, M4, and M4H Models)

Swagelok M series models feature metal measuring tubes for applications in which temperature or pressures contribute to difficult operating conditions. Because direct readings are not possible with metal tubes, these flowmeters are equipped with mechanical or electronic displays.


Measured Flow Ranges
Air 0.18 to 1.8 through 670 to 6,700 std ft³/h; 5.0 to 50 through 18,000 to 180,000 std L/h
Water 0.08 to 0.8 through 270 to 2,700 U.S. gal/h; 0.3 to 3.0 through 10,00 to 10,000 L/h
Temperature Ranges
Process M1, M2: –40 to 302°F (–40 to 150°C)
M4, M4H: –40 to 572°F (–40 to 300°C)
Ambient M1, M2: –4 to 158°F (–20 to 70°C)
M4, M4H: –40 to 248°F (–40 to 120°C)
Maximum Inlet Pressure Up to 2888 psig (199 bar)
Process Connections 1/4 to 1 1/4 in. NPT;
1/2 to 1 in. ASME flange
Accuracy Class 1.6, 2.5, 4.0

G Series Variable Area Flowmeters (G1, G2, G3, G4, GM, and GP Models)

Swagelok G series models use glass measuring tubes for visibility of the process fluid and direct flow reading.


Measured Flow Ranges
Air 0.018 to 0.18 through 18 to 180 std ft³/h; 0.5 to 5.0 through 500 to 5,000 std L/h
Water 0.065 to 0.65 through 4.2 to 42 U.S. gal/h; 0.04 to 0.4 through 16 to 160 L/h
Temperature Ranges
Process 23 to 212°F (–5 to 100°C)
Ambient –4 to 212°F (–20 to 100°C)
Maximum Inlet Pressure Up to 145 psig (10 bar)
Process Connections 1/4 in. NPT; G 1/8 (ISO 228); G 1/4 (ISO 228)
Accuracy Class 1.0, 2.5, 4.0

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Safe Product Selection: The complete catalog contents must be reviewed to ensure that the system designer and user make a safe product selection. When selecting products, the total system design must be considered to ensure safe, trouble-free performance. Function, material compatibility, adequate ratings, proper installation, operation, and maintenance are the responsibilities of the system designer and user.

⚠ Warning: Do not mix/interchange Swagelok products or components not governed by industrial design standards, including Swagelok tube fitting end connections, with those of other manufacturers.