AMI Analyzer Manual
Expanded Installation Procedure
12
5. Connect the sample line with ¼” stainless steel tubing.
Use stainless tubing only to connect the sample to the analyzer. Other materials are either not robust
enough or in the case of plastics, allow oxygen to enter the sample via diffusion. Normally ¼” tubing is
adequate unless the sample run is very long and the source pressure low – in this case you may have to use
wider tubing.
You should have some kind of blocking valve on the sample port. If you use a Demister, use at least a half
inch ball valve at its base.
6. Turn the Sample/Span/Off valve to the Off position.
The Sample/Span/Off valve is to the lower right of the grey faceplate above. This valve contains a Flow
Control (metering valve) in its center. If you turn the Sample/Span/Off valve to the off position, it will stop
either sample or span gas from flowing into the analyzer – but the exhaust is still connected to the
atmosphere so when you have a sensor in the analyzer it is not sealed off by this valve. At this point in this
procedure you shouldn’t have the sensor in place yet. Don’t use the metering valve to shut off the flow (as
it is a fine adjustment valve)!
7. Pressurize the sample line to line pressure (1 – 150psig).
The exact pressure doesn’t matter – we want enough so that you can easily see leaks in the following step.
8. Leak check every fitting and weld from the analyzer inlet to the sample tap.
Use a liquid soap solution such as “Snoop™” or similar. Don’t spray it on! You are looking for little bubbles
that appear after a while, indicating a leak. Even the tiniest leak will allow oxygen to enter the gas stream,
no matter what the pressure inside the line is. Check absolutely every possible source including welds,
valve packing, and fittings both around the tube and the nut, and anything else that might leak.
Oxygen can get into the gas stream because you are dealing with diffusion of molecules, not the flow of
water. To an oxygen molecule, 3000psig of gas still has enough spaces between its molecules that it looks
like zero pressure. People often don’t understand this until Mother Nature teaches them about it the hard
way. So at this point, be absolutely sure that you don’t have any leaks.
9. Connect the vent line to outside, running slightly downhill all the way.
Particularly if the analyzer and gas is warmer than the environment, any water vapor in the gas will tend to
condense in the vent line. If the line runs uphill, or has a low point, water will collect and potentially freeze,
stopping the flow. If the sample gas is flammable, the vent must go to a safe area.
Also take precautions that insects don’t make nests in the exhaust line. You may need some sort of a grill
over it.
10. Adjust the sample flow to approximately 1 SCFH with the Flow control valve located in the middle
of the Sample/Span/Off valve.
The Flow Control Valve is the metering valve in the middle of the Sample/Span/Off valve. It is a sensitive
needle valve – so don’t try to use it to shut off the flow. Turn the main valve to the OFF position for this.
