A flow meter comprises an inflow chamber having a first fluid inlet,
an outflow chamber housed in the inflow chamber and having a second
fluid inlet, which is in fluid communication with the inflow chamber,
and a fluid outlet by which fluid can drain from the outflow chamber,
and a sensing device having a elongate sensor which is positioned
at, or adjacent to and downstream of, the second fluid inlet. The
second fluid inlet is of limited dimensions so that, in use, a head
of fluid is formed in the inflow chamber and the flow rate of the
fluid passing through the second fluid inlet is monitored based
on the extent of the elongate sensor which is covered by the fluid.
This invention comprises the use of a variable orifice valve as
a flow controller and flow meter. Pressure measurements are taken
upstream and downstream of the variable orifice valve by way of
a differential pressure measurement mechanism. The differential
pressure measurement mechanism may comprise two separate absolute
pressure measurement devices or a single differential pressure measurement
device. Flow rate through the valve is determined from the pressure
drop across the valve. In wellbores having multiple zones, a variable
orifice valve together with a differential pressure measurement
mechanism may be deployed for each zone. The flow rate through each
of the zones and at the surface can then be monitored and controlled.
A lower cost turbine flow meter comprised of an inner housing constructed
out of a high permeable material surrounded by an outer housing
constructed out of a lower cost, lower permeable material. A port
is placed in the outer housing that runs down to the surface of
the inner housing to detect the rotation of turbine rotors that
rotate inside the meter as fluid or gas flows through the meter.
A pickoff coil is placed in the port to generate a magnetic signal
to penetrate through the inner housing wherein the turbine rotor
vanes superimpose a pulse signal on the magnetic signal. The lower
cost turbine flow meter can be used for any application for measuring
fluid or gas, and may be used in a service station environment for
measuring fuel or vapor in vapor recovery applications.
A mass flow meter employs discrete chip-type temperature sensors
to sense a fluid flow rate. The sensor can be a semiconductor chip
such as SiC or silicon, or thin film tungsten on an AlN substrate.
The sensors can be distributed symmetrically with respect to the
conduit through which the fluid flows, and can be connected in a
four-sensor bridge circuit for accurate flow rate monitoring. An
output from the mass flow meter can be used to control the fluid