Endress+Hauser promag 31, Руководство по эксплуатации

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1. System Description
1.1 Fields of application
The measuring system Promag 31 possesses the PTB licence for the transport of cold
water (waste water) and at an attractive price offers accurate magnetic-inductive flow
measurement of fresh water with a minimum conductivity of 5
µ
S/cm. The measuring
system operates within a temperature range of 0 to 30 degrees celsius and can be
deployed for the following uses in the supply of drinking water:
Local water network Internal monitoring of delivery pipe network
Junctions Calculation of the bill from the main supply pipe
Tank inlet points
(incl. pump stations) Monitoring of the water source. For example, the
amount of ground water.
Tank outlet points Certification for the amount supplied to the
delivery network
Overland supply pipe of a water
network Monitoring of the withdrawal and supply of
different water works in a supply pipe
1.2 Principle of measurement
In accordance with Faraday’s law of induction, a voltage is induced in a conductor
that is moved through a magnetic field. In the magneto-inductive principle of
measurement the flowing medium represents the moving conductor. The induced
voltage is proportional to the flow velocity and is fed to the measuring amplifier by a
pair of electrodes. Across the cross-section of the pipe the flow volume is calculated.
The DC magnetic field is generated by a switched direct current of alternating
polarity. Together with the patented “Integrated Autozero Circuit” this assures a stable
zero point and makes the measurement independent of the medium and insensitive to
entrained solid particles. In our works every unit is calibrated on modern calibrating fa-
cilities, referable to international standards. There is no need for it to be adapted to
suit changing media.
b
a
0
28y
01
U
e
= B
⋅
L
⋅
v
Q = v
⋅
A
U
e
= induced voltage
B = magnetic induction
L = distance between electrodes
v = flow velocity
Q = volume flow
A = pipe cross-section
Fig. 1
Promag 31 1. System Description
Hauser 5