Kamstrup MULTICAL 21 User Manual

TECHNICAL DESCRIPTION MULTICAL® 21 & flowIQ® 2101 /..02 /..03
56 Kamstrup A/S •Technical Description • 5512-897_J1_GB • 06.2016
In principle, flow is determined by measuring the flow velocity and multiplying it by the area of the
measuring pipe:
AFQ 
where:
Q
is the flow
F
is the flow velocity
A
is the area of the measuring pipe
The area and the length which the signal travels in the sensor are well-known factors. The length which the
signal travels can be expressed by
VTL 
, which can also be written as:
V
L
T 
where:
L
is the measuring distance
V
is the sound propagation velocity
T
is the time









21
11
VV
LT
In connection with ultrasonic flow sensors the velocities
1
V
and
2
V
can be stated as:
FCV 
1
and
FCV 
2
respectively
where:
C
is velocity of sound in water.
Using the above formula you get:
FCFC
LT




11
which can also be written as:
22
2
)()(
)()(
FC
F
LT
FCFC
FCFC
LT






As
FC
,
2
F
can be omitted and the formula reduced as follows:
2
2



L
CT
F
To minimize the influence from variations of the velocity of sound in water, the latter is measured via
absolute time measurements between the two transducers. These measurements are subsequently in the

Kamstrup MULTICAL 21 Specifications

General

Brand	Kamstrup
Model	MULTICAL 21
Category	Measuring Instruments
Language	English