YOKOGAWA TB820D, User Manual, Page: 28 / 87

<2. INSTALLATION, PIPING, AND WIRING>
2-17
IM 12B01B30-02EN 2nd Edition : June 09 , 2021-00
2.2.4 System without a Head Tank
This is a simple system where a sample is taken from the process and directly introduced into the
detector. This system configuration can be used when a sample contains a negligible amount of
air bubbles or when the turbidity of a sample is high and the effect of air bubbles is nonsignificant.
By installing a throttle at the detector outlet side, it is possible to prevent pressure change and
thus air bubbles from occurring in the piping from a sampling point to the detector outlet.
CAUTION
Sample conditions and ambient temperature must meet the specifications: maximum pressure:
500 kPa; sample temperature: 0 to 50°C; ambient temperature: -5 to 55°C. Any failure to meet
the specifications may damage the detector or other instruments.
When the sample pressure is reduced by using a pressure regulator or by other means, air
bubbles may form in the piping. In that case, consider the use of an open head tank.
The piping diagram of a system without a head tank is shown in Figure 2.25.
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F3-34E.ai
Sample Water
Inlet
Drain Port
Sample
Outlet
TB
820D
Detector
Drain Valve
Sample
Tap Water
Sample
Valve
Zero Turbidity
Filter
Sample
Supply Valve
Zero Water Supply Valve
Tap Water
Valve
Drain
Drain
Sample
Zero Water
Flow Control Valve
Sample
Effluent
Zero Water
Drain Valve
Other Turbidity Detectors
Process Piping
Figure 2.25 Piping Diagram
(1) Piping of the Sample Line to the Detector
This piping is for introducing a sample into the measurement cell of the detector. Install valves
and pipes by referring to the diagram in Figure 2.25.
1. For the piping from a sampling point to the sample valve in the sample line to the detector,
use a hose/tube with sufficient diameter that provides adequate flow of sample to prevent
clogging. The hose/tube also should withstand the sample pressure. One example is a rigid
PVC tube with nominal size of 16 (22 mm OD).
2. To the sample inlet of the detector, connect a 3-way (tee) or appropriate fitting
corresponding to the inlet’s connection size (Rc1/2 or 1/2 NPT). This allows switching of the
sample flow and the zero water flow.
3. For the piping between the sample and the detector, connect a supply valve to one end of
the 3-way tee fitting and connect a hose/tube that can withstand the flow and the pressure
of a sample between two valves using fittings corresponding to the connection sizes of each
valve.