Instruction manual

120-00004 REV A 10/6/2011 4000 DIGITAL MANUAL PAGE 13
3.2 Sample Bag Calibration & Pressurized Cylinder
Calibration
Whatever the source of calibration gas, the recommended method
is to collect the gas in the proper sample bag, which is then
attached to the analyzer INLET. The calibration gas is drawn from
the proper sample bag through the sensor. An exception to the
use of a sample bag is for those gases, which are reactive with, or
chemisorbed by the bag itself (e.g. Chlorine, Hydrazine). Teflon®
or Tedlar® bags are suitable for H
2
S, SO
2
, NO and NO
2
. Several
bag materials are suitable for CO. Contact the Factory for
recommendations.
The sample bag method is the factory-recommended method for
calibration. Since an internal pump is used, the same flow rate
conditions during the sample and the calibrate modes are
assured, eliminating errors due to flow rate differences. For most
applications, using a bag is the simplest procedure.
A regulated pressurized certified cylinder fitted with a tee-manifold
(fig. 6) and unrestricted vent is a good procedure in place of the
sample bag, as long as the flow rate of the gas exceeds that of the
sample pump.
Pressurized
Ceritified gas
Minimum flow
rate 1.4 liters per
minute
To Interscan
Analyzer inlet
To Ambient pressure or
Vacuum not to exceed 3
inches of water.
(fig. 6)