YOKOGAWA TB820D, User Manual, Page: 25 / 87

<2. INSTALLATION, PIPING, AND WIRING>
2-14
IM 12B01B30-02EN 2nd Edition : June 09 , 2021-00
2.2.3 System Using a Pressurized Head Tank (/D1)
In a system using an open head tank, air bubbles may form from air dissolved in a sample under
the reduced pressure in piping and enter into the detector, resulting in an incorrect measurement.
For low turbid waters where the effect of air bubbles is a concern, install a pressurized head
tank to prevent pressure changes in the piping from the head tank to the detector outlet and thus
prevent air bubbles from occurring in the pipe.
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.
An optional pressurized head tank for low turbidity measurement (option code “/D1”), shown in
Figure 2.24, is available from Yokogawa.
15
140
110
50
15
145 35
Drain
ø8/ø6 PE tube coupling
Drain plug
Sample water outlet (to detector)
ø8/ø6 PE tube coupling
Needle valve
(Material: SUS316)
Pressure gauge
(Range: 0 to 500 kPa)
Sample water inlet
ø8/ø6 PE tube coupling
Approx.
332
Approx.
127
4-ø6.2 holes
Unit: mm
Figure 2.24 Pressurized Head Tank for Low Turbidity