INFICON HAPSITE Smart Plus Chemical Identification System - Manual (Page 440)

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HAPSITE Smart Plus Operating Manual
13.1.1 How the HSS Operates
The function of the HSS is to provide consistent partition of analytes between the
sample and the headspace, and to transfer a representative sample of the
headspace to the HAPSITE for analysis.
Figure 13-2 is a schematic of the gas flow system which accomplishes these
functions. The flow starts with the Nitrogen supply, at the upper left. This can be
from disposable canisters or from an external cylinder supply. The Nitrogen
pressure and flow are controlled by two pressure gauges, a shut-off valve (the
variable orifice valve) and a fixed restrictor. All the valves in this system are
operated under software control.
Figure 13-2 HSS Operation Flow Diagram
Two three-way valves direct the flow to either bypass the vial (in the position
shown) or purge through the vial. While a sample is being transferred to the
HAPSITE, the flow is directed through the long needle, below the surface of the
sample. The Nitrogen flow into the vial is approximately balanced by the
HAPSITE’s sample pump draw out of the vial. The headspace sample is
transferred to the HAPSITE while maintaining neutral pressure in the vial.
At the end of the analysis, if a Purge cycle is programmed, the operator is prompted
to insert the needle into a clean vial and acknowledge it by pressing RUN. Purge
is achieved by providing a flow of clean Nitrogen through the needle, heated line
and the sample path in the HAPSITE. This clean flow removes residual organics
N2 Canister
External Supply
HAPSITE
Transfer
Line
Supply Pressure Control Pressure
VSO Valve
VSO PCB
Fixed Restrictor
Headspace Oven