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Sample Sequencer
General Description
General Description
The SENTRY Sample Sequencer is a microprocessor-based instrument capable of electronically
switching up to eight sample streams or sensors one at a time to one analyzer and of providing
signals to recorders, alarms and computers. A manifolded Sentry sampling valve specially designed
to obtain optimum representative samples is available for sample stream switching with the Sample
Sequencer. The Sample Sequencer reduces the number of required analyzers while maintaining
equivalent data accuracy. Reliable sample analysis comparison is obtained by using a Sample
Sequencer with one dedicated analyzer. In addition, significant operation cost savings are obtained
by not having to install, maintain and service multiple analyzers.
The Sample Sequencer is capable of operating in the cycle mode for continuous-type analyzers or in
the batch mode for batch-type analyzers. In addition, the Sequencer is capable of measuring the
analyzer analog output signal and converting the analog signal to digital data to be sent out via the
Sequencer's RS-485 serial data communication port. Using the RS-485 capability, one can connect a
PC via twisted pair cable to one or more sequencers for remote monitoring, control and data
acquisition.
Plug-in output boards are supplied to switch the analyzer analog signal to different recorder points or
to provide contact closure channel number indication for recorders. The boards also provide eight
independent commutated alarm contacts for low/high analog alarm and analyzer system alarm
indication. Optional boards are available to provide 0-1 VDC channel number indication for recorders
or to track and hold independently isolated analog signals.
Figures 1 - 3 illustrate a typical system arrangement for sample stream switching with the Sample
Sequencer. Optional boards and customer-supplied equipment are shown for clarification.
Figure 4 illustrates a typical system arrangement for sensor switching with the Sample Sequencer.
Optional boards and customer-supplied equipment are shown for clarification.
Modes of Operation
The Sample Sequencer has three programmable modes of operation:
BATCH - For analyzers that take a sample "bite" (or batch), produce an analytical result
and then provide a contact signal output, in typically one to 20 minutes.
CYCLE - For any continuous analysis (conductivity, dissolved oxygen, pH and sodium).
Note
If using the Sample Sequencer with a Hach analyzer, See Appendix D.
SENTRY Equipment Corp • P. O. Box 127 • Oconomowoc, WI 53066 • 262/567-7256 • FAX: 262/567-4523
Web: www.sentry-equip.com • e-mail: sales@sentry-equip.com
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