4210 Flow Meter
Section 2 Programming
2-15
The HYSTERESIS menu lets you set the range over which the
level (or other condition) can vary before the flow meter responds
to the change.
In the PROGRAM section of the software there are several steps
that require a change in a condition to make the flow meter carry
out certain actions. For example, step 6 programs the flow meter
to enable (activate) a sampler. In that step, you select a condition
(or set of conditions) that must occur before the sampler is
enabled. You enter a value (level is an example) that must be met
before the enabling occurs.
But what if this value is met and then falls away? It is possible
for a condition to vary rapidly over a narrow range. Without hys-
teresis, the flow meter will turn the sampler off and on
repeatedly, causing a condition known as chattering, that would
result in very erratic operation of the sampler.
With hysteresis, you can enter a value that will keep the flow
meter from responding to insignificant changes in the enabling
condition. You should select a value for hysteresis that is narrow
enough to allow the flow meter to respond to any serious change,
but broad enough to ignore minor changes that could cause chat-
tering. Press Enter and the following will appear:
The next several menus may or may not appear, depending on
selections you make in PROGRAM. They concern alarm/enable
hysteresis set points for parameter sensing—temperature, pH,
and D.O.
If you want to set hysteresis for any of these items, you should
enable them when you work through the program section, then
re-enter the SETUP section (Hysteresis) and they will appear.
Note that you can have temperature alone, or temperature with
either pH or D. O. You must have temperature with either pH or
D. O.
Note
The 4210 cannot measure pH and D.O. at the same time
unless you use the YSI sonde. Selection of one will prevent the
other from appearing on the menus later.
The following will appear if you are measuring temperature:
The following will appear if you are measuring pH:
The following will appear if you are measuring D. O:
(or mg/l depending on units selected in PROGRAM.)
FLOW RATE ENABLE/ALARM
HYSTERESIS X.XXX CFS (or other units of measure)
TEMPERATURE ENABLE/ALARM
HYSTERESIS XX.XXX DEG F (or C)
pH ENABLE/ALARM
HYSTERESIS X.XXX pH
DO ENABLE/ALARM
HYSTERESIS X.XXX PPM
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