Yokogawa digitalYEWFLO (DY) - Manual (Page 15)

<3. INSTALLATION>
3-5
IM 01F06A00-01EN
• Piping for Avoiding Bubbles
Flows containing both gas and liquid cause
problems. Avoid gas bubbles in a liquid fl ow.
Piping should be carried out to avoid bubble
generation.
Install the valve on the downstream side of the
fl owmeter because pressure drop across the
control valve may cause gas to come out of the
solution.
F0304.ai
Flow
Flow
Flow
(Good)
(Good)
(No Good)
Control
Value
(No Good)
(3) Multi-Phase Flow
digitalYEWFLO can measure gas, liquid
and steam when there is no change in state.
However, accurate measurement of mixed
fl ows (e.g. gas and liquid) is not possible.
F0305.ai
(No Good)
(No Good)
Mist flow
(No Good)
Stratified flow
Bubble flow
Liquid
Flow
Gas Flow
(4) Pipeline Diameter and digitalYEWFLO
The process pipeline inner diameter should be
slightly larger than the vortex fl owmeter inner
diameter, schedule 40 or lower pipe should be
used for 1/2 to 2 inch fl owmeters and schedule
80 or lower pipes for 3 to 16 inch fl owmeters.
F0306.ai
(No Good) (Good)
D
1
D
1
< D
2
D
1 • D
2
D
2
D
1
D
2
(5) Waterproof Construction
The vortex fl owmeter is of IP67, Type 4X, JIS C
0920 watertight protection. However, it cannot
be used under water.
3.3 Maintenance of Piping
(1) Pipe cleaning
• Flushing of pipe line (Cleaning)
Flush and clean scale, incrustation and sludge
on the inside of pipe wall for newly installed pipe
line and repaired pipe line before the operation.
• Fluid Carrying Solids
Do not measure fl uids that carry solids
(e.g. sand and pebbles). Make sure users
periodically remove solids adhering to the
vortex shedder.
• Obstruction of fl ow fl uids may cause to make
a chemical reaction and the fl uid will be
crystallized and hardened, and be deposited on
the pipe wall and shedder bar.
In those cases, clean shedder bar.
(2) Bypass piping
Bypass piping is convenient for the
maintenance of digitalYEWFLO (vortex
shedder cleaning, etc.).
F0307.ai
Flow
Bypass shut-off valve
Upstream shut-off valve Downstream shut-off valve
digitalYEWFLO