VICI 120 Dynacalibrator - Manual (Page 10)


A Note on Wafer Devices
Wafer devices have only a small permeable window, or wafer, so perme-
ation rates are typically an order of magnitude lower than rates for tubular
devices. The Model 120 is supplied with a 1/4" ID x 3.5 cm length of PTFE
tubing to be used as a spacer with VICI Metronics wafer devices. The
spacer fits on the non-permeating end of the stainless steel wafer device
body and lifts the device off the bottom of the permeation chamber and into
the region of most accurate temperature control.
Wafer devices should be inserted spacer end first, with the wafer side facing
up to allow the permeant gas to be released into the carrier flow down-
stream of the wafer body.
If you’re using a wafer device in a Dynacalibrator with a Teflon chamber, you
may find it difficult to remove the device from the chamber. In that situation,
a useful trick is to invert the Dynacalibrator and allow the device to slide out
by itself. This will not damage the device nor the Dynacalibrator.
CAUTION: Wafer devices are heavy and can damage a
glass permeation chamber if they are carelessly dropped
into the chamber. Use the forceps provided for careful
placement of the wafer device in the chamber.