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
C2 valve
Direct operating valve for liquids
(“open” sleeve) metal sealed with
purge connector.
C2 valve = normally closed
C4 valve
Direct operating valve for gases and
liquids. (bellow)
C4 valve = Normally closed.
C5 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
Φ
⋅
⋅
∆
=
V
signal
= output signal
c
p
= specific heat
Φ
m
= mass flow
