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Technical Note No. 068
AQSync NOx Modules Leak Check
Date: 03/07/2025
Author: Luke Greenidge
Summary:
This procedure shows how to check the AQSync 405 (NOx) system for leaks.
Before starting, note the following locations in the AQSync as they will be referred to in
this tech note. The location of the “Detection and “Plumbing” modules, and Sample Inlet
are referenced below:
In addition, there are two versions of the Detection Module that have slightly different
plumbing.
Version 1 (with VSO valve):
Version 2 (without VSO valve):
Tools/Materials Needed
- (2) Short lengths of 1/8’’ (3mm) ID silicon tubing
- (3) Tubing plugs (large fastener, Y fitting with tubing, or other) *
*See step 1b for examples
Procedure
1) Install plugs. Turn off AQSync before proceeding.
a) For version 1 Detection Module: Remove the cover from the detection module. The lid
is held on by four thumb screws, two on each side. Use a short length of tubing to
connect the open port on the VSO to the needle valve. This plugs both outlets.
For version 2 Detection Module: Remove the cover in the same way. Use a plug or Y
fitting with tubing to plug the needle valve.
b) Detach NOx sample inlet line from side of the enclosure. Plug the inlet line with a
large fastener (diameter > 4mm), or Y fitting with tubing.
c) Remove the cover from the NOx plumbing module. There are four thumb screws, two
on each side. Disconnect the line from the exhaust breather vent (located in the top
left corner of the top module). Plug the inlet line with a large fastener (diameter >
4mm), or Y fitting with tubing.
d) Plug the output of the VSO in the back left corner of this module using a short length
of silicon with a fastener or Y fitting plug. This valve is located under the breather vent
in step c.
2) Turn on AQSync. Navigate to NOx parameters page. Parameters > NOx
a) The pump should pull a vacuum through the NOx modules. Check that the cell pressure
drops <300 mBar.
b) Pinch the “pulling” line from the round pump. The Cell Pressure will start to rise.
Check that it does not rise >25 mBar between readings. Readings are output every 5
seconds.
3) If the pressure is below 300mBar and does not rapidly increase when pinching line as
described in step 2, the modules have passed the leak test. Remove all plugs and
reconnect NOx inlet and Ozone flow meter line.
If the modules do not pass, turn off the AQSync and check for leaks. The most common
leak area is the orange Savilex filter housing and the fittings into this housing. Repeat
steps 1 and 2.
4) After the NOx modules pass the test in step 2-3, turn off the AQSync. Remove all plugs
and secure covers back on the modules.