FIGURE 6-2. Fan Meter
2.2 Fan Meter. Fan meters consist of a housing with a multiblade rotor
mounted on a spindle at right angles to the direction of flow (Figure 6-2).
Flow enters the meter case, strikes the rotor tangentially, causing rotation.
The speed of rotation is determined by the velocity of the liquid and the
configuration of the chamber and rotor. Single jet type q eters are the
simplest example. In the single jet meter, fluid enters the meter through a
single tangential inlet. A single outlet port is located diametrically
opposite the inlet. The multijet type meter has the same general features as
the single jet meter. Liquid enters the working chamber of the multijet meter
through a number of tangential inlets around the circumference and leaves
through another set of orifices placed at a higher level in the chamber.
2.3 Pressure Losses. Pressure losses in turbine and fan meters are
substantially less than orifice plate meters. Expected pressure loss is in
the range of 0.4 to 0.8 psi.
3. TURBINE METER. The turbine meter is used more often than the fan meter.
The rotor is helical and is mounted on a shaft parallel to the flow
direction. Turbine flowmeter rotors are supported by ball bearings or ball
sleeve bearings. Bearings are exposed to the process as long as the flowmeter
is in the process pipeline. Bearing life depends on several factors. One
factor is the floweter duty cycle, the actual operation expressed as a
percentage of total time. Bearing life also is related to corrosion
qualities and cleanliness of the process stream have a positive effect on