INFICON HAPSITE Smart Plus Chemical Identification System - Manual (Page 468)

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HAPSITE Smart Plus Operating Manual
Open the SituProbe front door and press the FLUSH switch. The SituProbe will
increase the temperatures of the heated zones and actuate valves to Nitrogen flush
all sample pathways. This process will continue until the the FLUSH switch is
pressed a second time or the system runs out of Nitrogen gas. The system should
be flushed for a minimum of at least one hour to as long as overnight, depending
on the level of contamination. An installed Nitrogen gas canister will provide
approximately two hours of flush time. A bulk Nitrogen cylinder is recommended for
a longer flush times.
14.10 Operating Tips
14.10.1 Reducing Background
Operator judgment is the first and best means of reducing background and
carryover contamination in the SituProbe.
14.10.1.1 Sampling Precautions
Avoid immersing the probe into an organic phase indicated by a sheen on the
surface of the water phase. Alternatively, try locating a less contaminated sampling
area or collect a sample from below the surface with a separate sampling vessel.
In addition to the analytes of interest, consider all VOCs that may be present in the
water sample.
14.10.1.2 Expected Concentration
Select a Loop or Concentrator method based on detection limit requirements.
Prepare and analyze standards within the concentration operating range of the
SituProbe/HAPSITE configuration.
When using a Concentrator method, set an appropriate ConcFill event time for the
expected VOC concentration range and detection limit requirements. Collecting on
the Concentrator for longer than required will unnecessarily emphasize
background interference.
Analyze clean water blanks on a regular basis to purge the system and monitor the
background level for use in interpreting sample data.
14.10.2 Nitrogen Usage
The Nitrogen supply to the SituProbe is only consumed during sample analysis.
There is no Nitrogen usage between sample runs. Nitrogen is consumed during
headspace creation, sample purging, and dry purge events. The operator has
control over the timing of the last two events. The sample purging events consume
the most nitrogen because the flow rate must exceed the HAPSITE sample pump
flow rate. Nitrogen sample purge usage can be managed in two ways: