Step 2 Locate And Install Sensor(S); Location Considerations - YSI MultiDO 5400 User Manual

Step 2 Locate and Install Sensor(s)

Throughout the manual, the term "probe" refers to the end of the cable where the
sensor is located and the term "sensor" refers to the sensing portion of the cable/
probe assembly.
DO Sensors
5X00 instruments can be configured with 1, 2, 3, or 4 dissolved oxygen (DO) sensors
depending on the model. (models 5400 and 5500D-04 can be configured with up to
4 DO probes; model 5500D-02 can be configured with up to 2 DO probes; model
5500D-01 can be configugured with 1 DO probe.) Auxiliary (aux) inputs 3, 4, 5 and/
or 6 can be configured as temperature inputs. YSI 5400 instruments use a YSI 5421-X
DO (galvanic)/temperature, and/or a YSI 5420-X DO (galvanic) sensor assembly.
YSI 5500 instruments use YSI 626250 ODO (Optical Dissolved Oxygen) sensors.
DO sensors for 5400 instruments require a properly installed membrane. The 5420
and 5421 galvanic sensors use a
struments require a sensing cap. 5500 instrument sensor caps are factory calibrated
with sensor cap coefficients. It is important to retain sensor cap coefficients (provided
by YSI) for the life of the sensor.
Temperature Sensors
Temperature sensor(s) must use a 10K thermistor (at 25˚C). See Appendix 6 Alpha
A Curve - page 256.
Aux temperature sensors can be configured as the temperature source for DO sys-
5400
tems on YSI 5400 instruments. Aux temperature sensor(s) cannot be configured as
DO temperature sources on YSI 5500 instruments. YSI 5500 DO systems always
use the temperature from the YSI ODO probe. For accurate DO measurements,
ensure that the temperature reading for each DO channel is representative of the
temperature at that DO sensor's location. This is important when using the same
temperature input source for multiple DO sensors. Example - if the temperature
source for DO1 and DO2 is the temperature sensor connected to Aux 3 at the DO1
sensor location, it is important that the temperature at the DO2 sensor location is
the same as at DO1 sensor location.
See Chapter 4 Sensor Setup - page 150, for information on configuring 5X00 sen-
sor systems. User defined DO system configuration items include:
- Display format (i.e. units of measure. For example, mg/L or % saturation,
°C or °F);
- Temperature source (5400 only);
Installation and Wiring
2 mil Teflon membrane. ODO sensors for 5500 in-
YSI 5X00
34
- Salinity input value (user entered salinity value of the water being monitored);
- Elevation;
- Setpoint, control, and alarm values and ranges;
- Control and alarm relay assignments;

Location Considerations

Readings gathered at the sensor location(s) are data logged and processed by the
5X00 instrument. Output control and alarm devices are configured to respond to
sensor values. Therefore, it is essential to have accurate readings at the sensor loca-
tion. Locate sensors according to the below specifications.
Locate sensor end of probe assembly:
5400
•
in a location that represents the entire system
•
where the water flow is at least 6 inches per second (15.24 cm/sec) for 2.0
mil Teflon membrane
•
in a location that is free from debris (e.g. algae); ideally at a 45˚ angle from
vertical position and directed with the flow - figure 3.10
Figure 3.10
•
in a well mixed, free-flowing area; midstream and mid-depth typically gives
representative readings; the probe assembly and cable are fully submersible
up to the cable connector
•
submersed at all times so liquid level fluctuations do not expose the sensors
to the atmosphere
•
so the sensor/probe cabling is not routed near rotating machinery and/or
equipment involving electrical switching or regulation
•
so that the sensor assembly and cabling are located away from sources of
electrical interference such as UV sterilizers, florescent lighting, ballasts,
pumps, any high voltage peripheral devices, etc.
Installation and Wiring
YSI 5X00
35