2.  When a variable area flow meter is combined
with a differential pressure regulator, it
becomes a self combined flow controller.
 They are low flow rate of either gas or liquid
 Usually serve to protect pressure taps from
contacting hot or corrosive fluid.
 It become a self contained flow controller .

4.  The main components of the illustrated purge
flow regulator are a glass tube rota meter, an
inlet needle valve, and a differential pressure
regulator.
 The purge flow is fixed by adjusting springs
#1and #2 for a particular pressure difference,
usually in the range of about 60–80 in. (150–200
cm) of water
 This constant pressure drop (P2– Po) is then
maintained across the flow control valve (V)

5.  The configuration in Figure maintains the
outlet pressure (Po) constant by compensating
any variation in the inlet pressure Pi by
changing the regulator valve opening.

6.  Controls the flow rate to instrument line to prevent
obstructions or to keep corrosive media away from
delicate instrument.
 Some viscous fluid will coagulate and clog
instrument lines when not in motion. It is very
difficult to clean these line and even more difficult
to service process instruments when this occurs.
By keeping a steady purge flow of an inert gas or
liquid, you can prevent this from happening .

7.  if your process is corrosive and can damage
your instruments over prolonged contact. You
can purge these system with a steady flow and
avoid the cost of specialty materials or custom
made products

8. Flow switches are used to
determine if the flow rate are
above or below a certain
point. This value can be
fixed or adjustable

9.  1) Folding paddle switch
 2) Thermal flow switch
 3) By pass flow switch
 4) Capacitor type flow switch

10. It is least expensive type flow
switches
At no flow the paddle hang loosely
in a pipe in which it is installed.
As flow is initiated, the paddle begins to swing
upward in the direction of the flow stream , this
direction of the paddle is translated in to mechanical
motion by on of several technique, including a pivoting
cam, a flexure type or a hallows assembly

11. On of the most popular
solid state design is the
thermal flow switch .
All heat actuated flow
switches senses the
movement or stoppage of
the process steam by
detecting the cooling effect (the temperature change )
on one or more probes.

12.  Thermal flow switches consists of one heater
probe and two sensor probe connected to
wheat stone bridge.
 When the flow stop . Imbalance occurs in the
bridge .

13. They have an externally
adjustable vane that create
a differential pressure in
the flow stream .
This differential pressure
forces a proportional flow
through the tubing that
bypass the vane .

14.  A piston retained by a spring in this bypass
tubing and will move laterally, this piston’s
movement actuates a switch .

15.  Can be use for fairly low flow rate
 Their ability to be externally adjusted is very
desirable feature.

16. Capacitance type flow switch
can detect the absence or
presence of liquids or
slurries , which usually relate
to flow/ no flow condition.
This can prevent pumps from running dry.
The capacitor type flow switch is a capacitance switch tha
fit between two flat faced flange in standard pipe sizes
between 2 to 8 inches.

17.  When the ring sensor contain air, it detect a
dielectric constant of 1 .
 When the flow start, it detect the dielectric
constant of the flowing fluid, which is greater
then 1, which corresponding increase in radio
frequency current flow and operate the switch
accordingly .

18. THANKS