5
a SUMMA® canister is electropolished, using a polishing procedure (devel-
opedbyMolectrics) that enriches thenickel andchromium surfaceandmakes
it more inert than untreated stainless steel. The new generation of sampling
canister is typifiedby 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-
lybonded to the interior surface.Siltek® treatmentmakes the surface inertnot
only for relatively inactive organic compounds, but also for compounds that
are reactivewithmetal surfaces, such as sulfur-containing compounds. Thus,
surfacedeactivation for SilcoCan™ canisters exceeds that for SUMMA® canis-
ters.
CanisterValve
The valve on a sampling canistermust be of high quality, with the following
characteristics: leak integrity, ametal seat (to eliminateoffgassingof seat com-
ponents into the sample and memory effects in the seat material), stainless
a
plus1
story
Barrywas asked to build and test 20 air sampling
canisters, for shipping the same day at 11:30am.
Heworked nonstop, until the canisterswere
assembled, quality checked, and packaged for
shipment, ensuring a customer had the canisters
in time for an important project.
Barry Spicer, Jr.,
Restek PerformanceCoatingsTechnician
Figure4
A flow controllerwillmaintaina constant sample
flowdespite changes in canister pressureor environmental
temperature.
Figures 4 and 5 courtesy of Veriflo Corp., a division of Parker Hannifin Corp.
TemperatureEffects
Figure5
A flow controllerwillmaintaina constant sample flow
until it isunable tomaintaina stablepressuredifferential across
the critical orifice.
DifferentialPressureResponse
