Teledyne 4250 Installation And Operation Manual page 79

For any of these conditions, you can set the point at which change
in the selected condition causes the flow meter to send a flow
pulse to the sampler. The following menu will appear:
(Selected CONDITION)
• GREATER THAN • • LESS THAN • • RATE OF CHANGE •
If you select GREATER THAN, the flow meter will ask you to
enter a maximum value for the selected condition, which if
exceeded, will trigger the flow pulse.
If you select LESS THAN, the flow meter will ask you to enter a
minimum value for the selected condition. If the condition falls
below that value later, the flow meter will send a flow pulse to
the sampler.
If you select RATE OF CHANGE, the flow meter will ask for two
values: one for the condition, and the other for the time interval
over which the change occurs.
After you have determined what condition will signal the
sampler and under what circumstances, the following menu will
appear:
SELECT OPERATOR
• DONE • • OR • • AND •
SELECT OPERATOR allows you to trigger the sampler from a
single condition or from two conditions. Suppose you wanted to
trigger the sampler from only one condition and that condition
was LEVEL. You would select level as the condition, and then
identify what change in LEVEL would be the trigger. Then you
would select DONE for the SELECT OPERATOR step. Selection
of DONE will advance the flow meter to the next program step.
However, suppose you wanted to select two conditions, either of
which would trigger the sampler. In such a case you would select
OR for the SELECT OPERATOR step. The menu will return to
the one listing the conditions. This will let you define the second
condition. Now the flow meter will trigger the sampler when
either condition changes.
Finally, suppose you had a situation where you wanted changes
in two conditions to occur before you signalled the sampler. In
that case you would select AND for the SELECT OPERATOR
step. Then you would define the second condition. Now the flow
meter will signal the sampler only after both conditions have
changed.
The next screen on the flow meter (after you have established the
conditions for sampler pacing) will request the following.
(Entering 0 sends no pulses.)
CONDITION TRUE PACING INTERVAL
PACE EVERY X MINUTES
This option allows you to send flow pulses periodically to the
sampler during the time the conditions you established for
sampler pacing are being met.
4250 Flow Meter
Section 2 Programming
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