YOKOGAWA TB820D, User Manual, Page: 32 / 87

<3. PREPARATION for OPERATION>
3-3
IM 12E01B30-02EN 2nd Edition : June 09 , 2021-00
3.7 Supplying a Sample and Adjusting the Flow
Rate
Supply a sample to the detector and adjust its flow rate.
System Using an Open Head Tank (Option code /D3) (See Piping Diagram in Figure 2.20)
(1) Open the sample valve to supply a sample to the head tank.
(2) Completely open the sample supply valve to allow the sample to flow into the detector.
(3) Check that the sample is drained from the detector drain. Then, close the drain valve.
(4) Adjust the opening of the valve at the sample out of the detector so that the sample
overflows and is surely drained from the head tank.
(5) Measure the drainage volume at the sample outlet of the detector using a beaker or relevant
measure. The rate of flow to the detector must be in the range of 1 to 10 L/min.
System Using a Simple Head Tank (Option code /D2) (See Piping Diagram in Figure 2.22)
(1) With the outlet valve after the detector open completely, open the valve at the inlet of the
simple head tank gradually and completely.
(2) By gradually closing the valve at the sample out of the detector, adjust the flow rate so the
sample is thoroughly drained from the drain of the simple head tank.
(3) Close the sample supply valve while checking the turbidity reading until the influence of air
bubbles disappears. Check that the sample is overflowing from the drain of the simple head
tank.
System Using a Pressurized Head Tank (Option code /D1) (See Piping Diagram in Figure 2.24)
(1) Completely open the bypass valve at the top of the head tank, the sample supply valve, and
the needle valve at the sample outlet of the detector.
(2) Open the sample valve to supply a sample to the head tank.
(3) Gradually close the bypass valve at the top of the head tank until the rate of flow from the
sample outlet of the detector is in the range of 0.05 to 10 L/min. The rate of drainage from
the bypass valve should be secured to the extent that air bubbles are removed.
(4) Pressure changes in the line between the sampling point and the detector outlet should be
controlled to prevent air bubbles from occurring. For this, gradually close the valve at the
sample outlet of the detector until the pressure gauge at the tops of the pressurized head
tank approximates the pressure of the sample and until the rate of flow from the sample
outlet of the detector is in the range of 0.05 to 10 L/min. Check the pressure gauge at the top
of the pressurized head tank. The gauge must read under 500 kPa.
System without a Head Tank (See Flow Diagram in Figure 2.25)
(1) With the valve at the sample outlet of the detector opened completely, open the sample
valve (immediately after the sampling point) in the sample line.
(2) Open the sample supply valve to supply a sample to the detector.
(3) Adjust the opening of the valve at the sample out of the detector until the rate of flow from
the sample outlet of the detector is in the range of 0.05 to 20 L/min.
(4) Pressure changes in the line between the sampling point and the detector outlet should be
controlled to prevent air bubbles from occurring. For this, gradually close the valve at the
sample outlet of the detector until the rate of flow from the sample outlet of the detector is
in the range of 0.05 to 20 L/min. Before taking this procedure, make sure that the sample
pressure of the process is under 500 kPa.