Hach SIGMA 900, Руководство пользователя

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Flow Proportional Operation
8837prg.fm
Section 5
5.14.5 Timed Bottle—Pre-Advanced Mode
When using the timed bottle mode explained above, there may come a case
where the bottle fills up before the desired time for the bottle is complete.
Normally, if this occurs and a new sample is requested, the sample is missed
because the bottle is full and it is not time to move to the next bottle. Pre-
Advance mode enables the sampler to automatically advance to the next
bottle before the preset bottle time is complete and then does not advance to
the next bottle once the initial bottle time has expired. See the example below:
• A user defines 1 bottle of four bottles per 60 minutes using the timed
bottle choice.
• The user starts the program at noon. Bottle one begins to fill but the flow
during the period causes the bottle to fill completely by 12:35.
• A new sample is requested at 12:40 due to the flow demand. With pre-
advance mode enabled, the sampler automatically moves the arm to
bottle number 2 and begins to fill that bottle even though the 60 minutes is
not up yet.
• At 1:00, the sampler was supposed to advance from bottle one to bottle
number 2 but it is already on bottle two because of the above listed
events. Instead, it remains on bottle 2 until 2:00 at which time it will
advance to bottle 3 unless a “pre-advance” condition occurs between that
time.
5.15 Flow Proportional Operation
5.15.1 How to Calculate Pulses/Counts
5.15.1.1 Flow Proportional Sampling Intervals—Using External Pulses
The sampler is equipped to receive either a momentary dry contact closure or
a +5 to +12 V dc pulse from a flow meter, where each pulse represents a
known flow increment.
For example, if the flow meter is set to send a flow pulse for every 1000
gallons of measured flow and the sampler can count 1 to 9999 flow pulses
between sample intervals, the sampler can be programmed to receive 10
pulses between samples to take one sample for every 10,000 gallons of liquid
flow.
To determine the number of flow pulses between sample intervals, determine
the total number of samples (represented by
n in the following examples) to
be collected, and the period of time over which they are to be collected. Also
know the total flow,
Q , during the sampling program. The following two-step
method should be useful for determining the value for
INTV = _ _ _ _ CNTS
during setup.
1. Determine f , where f represents the flow increment between samples and
n represents the total number of samples to be collected.
f
Q
n
---- =