45
Sensor Installation
•
Reference Port
—This port provides a reference to atmosphere. The flow meter
measures level by comparing the back pressure against the bubble in the bubbler line
with ambient air pressure. As the water level increases, the back pressure pushing
against the bubble increases.
The transducer first reads the pressure in the bubbler line, then, at regular intervals,
switches to the reference port to compare it to the atmospheric pressure. This
pressure difference is converted to a number which represents the liquid level. At a
regular interval, both the bubbler port and the reference port are switched to open air
together and electronically zeroed to eliminate any drift due to changing barometric
pressure.
If the flow meter is to be located where there is
any
threat of temporary submersion
you should attach a length of ¼-in. ID tubing to both the reference port and the intake
port barbed fittings. Route the ends of this tubing to a safe area that is free from the
possibility of submersion. Reattach both desiccant cartridges to the tubing, with the
cartridge openings facing downward to ensure that moisture, condensation, and/or
precipitation does not accumulate in the vent openings of the cartridge. This
precaution will protect the air pump and internal plumbing systems from water
damage.
Do not leave the desiccant cartridges with the vent openings facing up!
•
Bubbler Line Port
—The bubbler line connects from this port to the measurement
point in the primary device. Push the
1
/
8
” (3.17 mm) ID vinyl bubbler tubing over the
brass barbed fitting. No clamps are required.
6.6.1.1 Meter-End Cable Terminations
Bubbler Area/Velocity sensors are terminated with a velocity connector and bubbler tube
or with bare leads and the bubbler tube. Use the bubbler with bare leads at sites where
the sensor cable is routed through a conduit.
1.
At the meter end of the conduit, connect the cable to the meter with a junction box
(
2.
Connect the bubbler tube to the brass tubing coupler in the junction box.
3.
Connect another section of tubing from the brass coupler to the top connector on the
Intake Port Dryer Canister.
4.
Connect the velocity leads to the junction box terminals as indicated on the junction
box.
6.6.1.2 Routing the Bubbler Line
There are several important things to consider when routing the bubbler line.
•
Route the tubing so that it slopes downward from the flow meter or sensor cable to the
flow stream whenever possible. This assures that any condensation that forms in the
tubing will drain out of the tube. If moisture collects in a low spot in the tubing it could
restrict the flow of air and cause erroneous readings.
•
Don't use more bubbler line than you need. Remove excess coils of tubing to
decrease the likelihood of moisture problems, cuts, or kinks.
•
Use a single continuous length with no spliced connections to eliminate the possibility
of air leaks.
•
Use care not to cut or kink the tubing during installation.
Содержание Sigma 950
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Страница 20: ...18 Introduction...
Страница 34: ...32 Basic Programming Setup...
Страница 50: ...48 Sensor Installation...
Страница 82: ...80 Maintenance...
Страница 83: ...81 Appendix A Program Flow Charts Figure 22 Overview of Basic Program Menus...
Страница 84: ...82 Program Flow Charts Figure 23 Setup Flow Chart...
Страница 85: ...83 Program Flow Charts Figure 24 Options Flow Chart...
Страница 86: ...84 Program Flow Charts Figure 25 Alarms Menus Flow Chart...
Страница 87: ...85 Program Flow Charts Figure 26 Calibration Menus Flow Chart Page 1...
Страница 88: ...86 Program Flow Charts...
Страница 102: ...100 Programming Features...
Страница 106: ...104 Primary Devices Head Measurement Locations...
Страница 126: ...124 SCADA Modbus System Guidelines...