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A. W. Lake

Flow meters for Liquid Applications.

  • Positive Displacement Flow Meters
  • Gear Flow Meters
  • Turbine Flow Meters
  • Variable Area Flow Meters

Positive Displacement (PD) Flow Meters:

Volumetric flow measurement instruments ideal for low flow rates, highly viscous fluids, and measurement of flows involving starts and stops or pulsing. Positive displacement flow meters are similar in design to the gear pump.  The principle of operation is reversed however; instead of the gears driving the fluid, the fluid drives the gears.  A non-intrusive hall-effect sensor detects the movement of the gear and as each gear tooth passes the sensor, a square wave pulse is produced and a discrete volume of liquid is measured. The resulting pulse train is proportional to the actual flow rate and provides a highly accurate representation of the fluid flow.

Spur Gear Flow Meter:

In Spur gear positive displacement flow meters, fluid travels around two round gears and is pushed through the meter’s internal chamber from inlet to outlet. The discrete volume of liquid trapped between each gear tooth is measured, as opposed to the Oval gear meter where a much larger volume between gears is swept through the chamber.    

Helical Gear Flow Meter:

Possibly the most accurate PD meter in which two intersecting cylindrical bores are fitted with two interlocking helical screw-shaped gears. Because gear orientation is inline with flow, as the fluid passes through, the gears rotate with very little pressure drop. These flow meters are highly accurate over wide flow ranges and are compatible with very high viscosity fluids.

Rotary Piston Flow Meter:

In this design a rotary piston oscillates in the circular internal chamber displacing a fixed amount of fluid with each rotation. This style accommodates ultra low flows and high flows, as well as high pressures.

Turbine Flow Meters:

Axial turbine flow meters are designed with wear resistant internal components to provide trouble-free operation and a long service life. Fluid entering the flow meter is first conditioned by the inlet flow straightener which reduces turbulence in the fluid.  The moving fluid causes the rotor to spin at a speed that is proportional to its flow rate.  As the turbine blades on the rotor pass through the magnetic field of the pickup, an electronic pulse is generated.  This pulse train signal can then be used to monitor the fluid’s actual flow rate or the total amount of fluid that has passed through the flow meter.  The number of electronic pulses generated by the meter, per unit volume, is known as its K-Factor.  Each flow meter is calibrated to find its unique K-Factor, which is supplied with the flow meter when purchased.

Variable Area Flow Meters:

Variable flow meters, often referred to as “rotameters,” measure flow rate of a liquid or gas by relating linear displacement of an internal “float” or sharp-edged orifice plate to a corresponding flow rate. As flow rate increases, the orifice area that the flow moves through also increases – thus, the term “Variable Area.” Variable Area meters either allow flow through a peripheral orifice formed between a tapered wall and a float as in the traditional rotameter, or an annular orifice and an internal tapered metering pin in the Lake Monitor. The attributes of the Lake Variable Area flow meter are a linear relationship between flow rate, pressure differential and piston displacement. Flow rate is read on Variable Area meters by aligning the position of the piston/float to an adjacent calibrated scale.

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