5
a SUMMA® canister is electropolished, using a polishing procedure (devel-
oped by Molectrics) that enriches the nickel and chromium surface and makes
it more inert than untreated stainless steel. The new generation of sampling
canister is typified by the SilcoCan™ canister. Like the SUMMA® canister, the
SilcoCan™ canister is made of stainless steel, and the interior is electropol-
ished, but in an additional step - Siltek® treatment - an inert layer is chemical-
ly bonded to the interior surface. Siltek® treatment makes the surface inert not
only for relatively inactive organic compounds, but also for compounds that
are reactive with metal surfaces, such as sulfur-containing compounds. Thus,
surface deactivation for SilcoCan™ canisters exceeds that for SUMMA® canis-
ters.
Canister Valve
The valve on a sampling canister must be of high quality, with the following
characteristics: leak integrity, a metal seat (to eliminate offgassing of seat com-
ponents into the sample and memory effects in the seat material), stainless
a
plus 1
story
Barry was asked to build and test 20 air sampling
canisters, for shipping the same day at 11:30am.
He worked nonstop, until the canisters were
assembled, quality checked, and packaged for
shipment, ensuring a customer had the canisters
in time for an important project.
Barry Spicer, Jr.,
Restek Performance Coatings Technician
Figure 4
A flow controller will maintain a constant sample
flow despite changes in canister pressure or environmental
temperature.
Figures 4 and 5 courtesy of Veriflo Corp., a division of Parker Hannifin Corp.
Temperature Effects
Figure 5
A flow controller will maintain a constant sample flow
until it is unable to maintain a stable pressure differential across
the critical orifice.
Differential Pressure Response
