YOKOGAWA AXG1A Installation Manual page 11

(3) Required Lengths of Straight Runs
Based on JIS B 7554 "Electromagnetic Flowmeters" and
our piping condition test data, we recommend the piping
conditions as shown in the following figures. This is not
always enough when the piping line incorporates multiple
conditions at the same time.
Gate valve
Reducer
fully open
pipe
2D
5D or more or more 0 is allowable. 0 is allowable. 10D or more 2D or more
90-degree bend
Tee
5D or more 0 is allowable. 5D or more
Figure 3.1.1 Required Lengths of Straight Runs
*1: Do not install anything in the vicinity that may interfere
with the magnetic field, induced signal voltages, or flow
velocity distributions of the flowmeter.
*2: A straight run may not be required on the downstream
side of the flowmeter. However, if a downstream valve
or other fitting causes irregularity or deviation in flows,
provide a straight run of 2D to 3D on the downstream side.
*3: The valves shall be mounted on the downstream side so
that deviated flows do not occur in the sensor and to avoid
startup from an empty condition.
*4: In case the piping conditions are compounded, install
on the straight pipe section where the upstream part is
sufficiently rectified.
(4) Maintaining Stable Fluid Conductivity
IMPORTANT
Do not install the flowmeter where fluid conductivity
tends to become uneven. If chemicals are fed near
the upstream side of a magnetic flowmeter, they may
affect the flow rate's indications. To avoid this situation,
it is recommended that the chemical feed ports be
located on the downstream side of the flowmeter. If
it is unavoidable that chemicals must be fed on the
upstream side, provide a sufficient length of straight
run (approximately 50D or more) to ensure the proper
mixture of fluids.
(Correct)
(Incorrect)
Downstream side
Upstream side
Figure 3.1.2 Chemical Injection
D: Sensor Size
Expander
pipe
Various valves
2D
0 is allowable. 10D or more or more
F0301.ai
F0302.ai
<3. Installation>
(5) Precautions for Use of Liquid Sealing
Compounds
IMPORTANT
Care must be taken in using liquid sealing compounds
on the piping, as it may have a negative influence on
the flow indications by flowing out and covering the
surfaces of an electrode or grounding ring. In particular,
care must be taken if a liquid sealing compound is used
in the case of vertical piping.
(6) Service Area
Select locations where there is adequate space to service
installing, wiring, overhauling, etc.
(7) Bypass Line
It is recommended to install a bypass line to facilitate
maintenance and zero adjustment.
Bypass valve
Block
valve
Figure 3.1.3 Bypass Line
(8) Supporting the Flowmeter
CAUTION
Do not secure the flowmeter separately to prevent the
vibrations, shocks, and expansion and contraction forces
of the piping from affecting it. Fix the pipes first, then
support the flowmeter with the pipes.
10
Block valve
F0303.ai
IM 01E24A01-01EN