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3700 Portable Samplers
Section 3 Programming Guidelines
3-4
You can combine the types of sample pacing and sample distri-
bution. Thus, you can take time- or flow-paced sequential
samples and time- or flow-paced composite samples. Each combi-
nation of pacing is noted below.
Time-Paced Sequential – In a time-paced sequential sample,
samples are collected at equal increments of time. Each bottle
receives one sample.
Flow-Paced Sequential – In a flow-paced sequential sample,
samples are collected at equal volumes of flow, as measured by
an associated flow meter. Each bottle receives one sample.
Time-Paced Composite – In a composite time sample, the indi-
vidual samples are combined into a single container. Samples are
collected at equal increments of time.
Flow-Paced Composite – In a composite flow sample, the indi-
vidual samples are combined into a single container. Samples are
collected at equal increments of flow volume, as measured by an
associated flow meter.
Multiplexing – Yo u c a n m u l t i p l e x b o t h t i m e - p a c e d a n d
flow-paced sequential samples. Multiplexing places more than
one sample in a bottle at different sample events or places a
sample in several bottles at the same sample event. There are
t w o t y p e s o f m u l t i p l e x i n g : s a m p l e s - p e r- b o t t l e a n d
bottles-per-sample.
Samples-per-Bottle Multiplexing – I n s a m p l e s - p e r- b o t t l e
multiplexing, the 3700 deposits a number of individual samples
in the same bottle. Samples-per-bottle multiplexing is useful
when you need to collect a series of small composite samples. In
samples-per-bottle multiplexing, users can modify the normal
sampling cycle (relocate distributor, pre-sample purge, sample
delivery, post-sample purge) by altering the number of times the
distributor is relocated.
Because a bottle will receive more than one sample from more
than one sample event, the distributor does not relocate to a new
bottle at each sample event. At the first sample event, the dis-
tributor relocates, if necessary, to the appropriate bottle. The
normal sampling cycle is completed. At the next sample event,
the distributor does not relocate, and a second sample is
deposited into the same bottle.
Compositing multiple samples continues up to the programmed
number of samples. After the last sample is deposited in the
bottle, the sampler pauses until another sample event occurs, the
distributor then rotates to the new bottle position, and multiple
samples are deposited into the new bottle. Figure 3-2 illustrates
samples-per-bottle multiplexing.
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