11
Note: Tubing lengths in these images
are not to scale.
2.7.3 Fresh Air Port Instructions
The Fresh Air Port is used to draw the fresh
air sample into the dock for instrument
processing. Check valves and/or fresh air
filters are required depending on how fresh
air is delivered to the dock. See the chart
below for specific requirements for your
setup. The fresh air filter is placed on the
Air Port at the dock to protect the dock from
contaminants. Check valves are used to
ensure the purity of external fresh air
sources when more than one dock is used.
Air Filter
at Dock
Check
Valve(s)
Single Dock in Fresh
Air
Yes N/A
Multiple Docks in
Fresh Air
Yes N/A
Single Dock w/Zero
Air Cylinder
No No
Multiple Docks
w/Zero Air Cylinder
No Yes
Single Dock w/Sealed
Fresh Air Conduit
Yes No
Multiple Docks w/
Sealed Fresh Air
Conduit
Yes Yes
Air Filter / Check Valve
Requirements Chart
Fresh Air Filter
Under normal circumstances, the IQ
Express Dock is located in a fresh air
environment and fresh air is drawn in from
the local environment. A filter is included
with the dock that is used to protect the
dock from contaminants that may
inadvertently enter the dock. The air filter
should be installed if the dock is drawing
fresh air from the immediate surroundings or
if it is drawing fresh air from an external
source via a sealed conduit. The fresh air
filter can be left off if the fresh air source is a
calibration cylinder.
Only one side of the
filter will screw into the
Air Port on the dock.
Providing Fresh Air in a
Contaminated Environment
If the IQ Express is to be located in a
potentially contaminated environment, fresh
air must be delivered to the Air Port on the
dock for use during instrument processing.
This can be accomplished either by using a
cylinder of “zero air” with a demand flow
regulator (option 1 below) or by plumbing
fresh air into the dock in a sealed conduit
from an outside location that has known
fresh air (option 2 below).
Performing the fresh
air calibration in a contaminated
atmosphere will lead to inaccurate and
potentially dangerous readings. Fresh
air containing 20.9% oxygen and no
contaminants must be provided to the IQ
Express Dock for instrument processing.
If fresh air is unavailable in the
immediate area, steps must be taken to
provide fresh air to the dock.
When a secondary fresh air source (either
gas cylinder or sealed conduit) is used with
two or more IQ Express Docks, a one-way
check valve must be placed in line between
the common section of the fresh air manifold
