Application: Differential Measurement - Traveling Screen
Problem: Facilities such as power plants and waste treatment plants bring in large volumes of
water through channels, either for use or treatment. Large bars or screens, called traveling
screens, are placed in the channels to collect debris from the water. This prevents
the debris from being drawn into the process where it could damage pumps and other
equipment. Eventually, however, the screen becomes clogged and reduces flow.
Solution:
AMETEK model 575F Intrinsically Safe Submersible Pressure Transmitter with
LevelMate III
The LevelMate III Level System or a customer-supplied controller can be used to activate
alarms or automatic cleaning equipment when the screen becomes clogged.
Two Model 575/675 Submersible
Transmitters (4-wire millivolt only)
are connected to a meter/controller
to provide differential measurement.
One transmitter is placed upstream of the screen and one downstream–each transmitter the same distance from the floor
of the channel. The meter/controller is programmed to see and display only the difference between the two transmitters. As the
screen becomes clogged, the water level downstream of the screen becomes lower, resulting in a lower pressure measurement
signal from the downstream transmitter. When the difference between the two transmitters reaches the programmed set points,
the meter relays activate an alarm or an automatic cleaning system to remove the debris and restore flow.
This method can be used for other differential pressure measurement applications within certain accuracy limits. For
turbulent applications, the
Model 675 Level Transmitter will stay in place due to the heavy base of the Shark Cage,
weighing over seven pounds.
Click here for the full application note.