Sondes
Section
2
YSI Incorporated
Drinking Water Monitoring Systems Operations Manual
2-38
For the
Unattended sample
mode, the free chlorine sensor should be calibrated AFTER a logging study
has been underway for 2-3 hours to assure the stabilization of the free chlorine sensor in the flowing tap
water. The setup of the logging study (or Unattended Sampling) is described in detail in
Section 2.7
UNATTENDED SAMPLING
and
2.9.1 Run UNATTENDED SAMPLING
. To view the logged data
to assure stability prior to calibration, see
Section 2.9.3 File
.
To calibrate the free chlorine sensor, carry out the following steps:
•
Make certain that the flow of water through the flow cell is 500-1000 mL per minute (minimum
500 mL/min) and that the flow is set to the rate at which you will carry out your monitoring study.
•
Interface to the sonde using a 650 display/logger, a PC running EcoWatch for Windows, or a 6500
Process Monitor. If you are using a PC or the 650 Display/Logger, select
8-Advanced
and then
2-Setup
and make certain that
Autosleep RS232
is active as shown in the box below.
•
Set up your Unattended Sampling study as described above and allow readings to be logged to
internal memory for 2-3 hours. Using the
File|View
command as described in Section 2.9.3,
inspect the free chlorine readings and after they are stable proceed with the calibration as
described below. If you are using a 6500 Process Monitor, observe the real-time readings on the
display for 2-3 hours and make certain they are stable before proceeding with the calibration.
•
Collect a sample of water from the outlet hose of the flow cell and immediately analyze it for free
chlorine using an independent method, e.g., the DPD method with a YSI 9100 Photometer.
•
If using a PC or 650 Display/Logger for sonde interface, return to the Main menu using the
Esc
key and select
2-Calibrate
and then
4-Free Cl2
.
•
NOTE: If using a 6500 Process Monitor for the sonde interface, perform the calibration according
to the instructions in Section 4 of the 6500 manual.
•
At the prompt, input the independently determined free chlorine value and press
Enter
. A
display similar to that shown below will appear on either the computer monitor or the 650 display.
The calibration will occur automatically after the countdown on the screen reaches zero.
-------------Advanced setup-----------
1-(*)VT100 emulation
2-( )Power up to Menu
3-( )Power up to Run
4-( )Comma radix
5-(*)Auto sleep RS232
6-(*)Auto sleep SDI12
7-( )Multi SDI12
8-( )Full SDI12
Select option (0 for previous menu): 0
