Yokogawa DM8C/VD6 Liquid Density Analyzer - Manual (Page 36)

< 3. INSTALLATION, PIPING AND WIRING >
3-10
IM 12T03A01-02E
3.3 Piping
The vibration type density meter requires the following piping;
(1) Sample liquid conduit
(2) Air piping for maintenance
(3) Steam piping
(4) Piping for air purge
Sample liquid conduit is a pipe to conduct measuring liquid to the density detector. Air piping for
maintenance is to obtain air to blow away liquid from the vibrator at maintenance (vibrator cleaning,
calibration with standard solution). Steam piping which is installed according to requirement is to
obtain a steam to heat the sample liquid conduit. Air purge piping is necessary when the converter is
installed in dusty environment.
The sample liquid conduit referred here indicates pipes between the main process pipe and the
sampling equipment. For piping within the sampling equipment, refer to Section 3.1.2.
3.3.1 Sample Liquid Conduit
This piping conducts the measuring liquid to the sampling unit. The main process pipe should have
two sampling taps (sample inlet and sample return) as shown in Figure 3.14. The sample conduit
from the sample inlet is connected to ‘SAMPLE IN’ of the sampling unit and the other conduit from the
sample return to ‘SAMPLE OUT’ of the sampling unit.
The piping procedure is as follows:
(1) Select the tap locations for the sample inlet and the sample return to make the pressure
difference between them become at least 0.1 MPa.
(2) The pipe length between the sample inlet and the SAMPLE IN should not exceed 10 m. Use
stainless steel pipe of nominal diameter 15 mm or Sch 40 to 80.
(3) Install stop valves and drain valves near the sampling unit.
Sampling unit
for vibration type density meter
Drain valve Drain valve
Sample conduits
(10 m max.)
Main process pipe line
Tap valve Stop valve
P in (Pressure at inlet)
2 MPa > P
in
•3
out
+ 0.1 MPa)
P
out
(Pressure at outlet)
Figure 3.14 Sample Liquid Conduits
(4) Avoid sharp bending of the pipe to prevent accumulation of sludge.