Bronkhorst LIQUI-FLOW L30 - Manual (Page 7)

BRONKHORST HIGH-TECH B.V.
9.17.044 page 7
1.1.3 Valves
LIQUI-FLOW L30 controllers are fitted with a modular valve. The valve is attached by means of a port
connector.
Valves for liquids
C2I valve
Direct operating valve
for liquids (“open”
sleeve) metal sealed
with purge connector.
C2 valve = normally
closed
C5I valve
Direct operating
valve for liquids
(“open” sleeve) metal
sealed.
C5 valve = normally
closed
1.2 Sensor principles
1.2.1 LIQUI-FLOW L30 sensor
Measuring Principle
The LIQUI-FLOW model for flowrates up to about 20kg/h is basically a straight pipe. On this pipe a
configuration of sensors and heaters is placed. The heater temperature is maintained at a certain level
above the incoming liquid temperature.
The power needed to maintain this temperature while the fluid is flowing is measured.
Furthermore the output temperature downstream, at a certain distance from the heater is measured,
resulting in the delta-T signal (T
out
-T
in
).
By combining the two signals, the transfer function of the instrument can e descried according to the
following equation:
m p signal
c K
T
Power
V   


V
signal
= output signal
c
p
= specific heat

m
= mass flow