GAS SAMPLING BAGS
Gas Samples are conveniently moved in plastic bags. Gas bags with quick-connect fittings can be purchased, but they are needlessly expensive. A kitchen bag works just as well, and costs almost nothing. It is important that the bag be dry and contaminant-free. This always seems to be true of kitchen bags.
The easiest way to fill an air bag is by the “wind-sock” method. Open the bag and swing it laterally. Then close it with its tie or zipper. One needs an outlet on the bag to transfer the sample to an absorption cell. This can be a small length of plastic tubing that is taped into the corner of the bag. The tubing can be closed off with a clamp or stopper.
Air may be removed from a cell by a laboratory vacuum pump. The bagged air will then flow directly into the evacuated cell. If the cell has gas in it, rather than vacuum, the bagged air can be forced in by squeezing the bag. The gas can also be transferred from the bag to the cell by using the Gas Mega Syringe in its “pump mode”.
Infrared Analysis, Inc. supplies air bags with the requisite plastic tubing and a closure. Other plastic bags can be purchased at the grocery store. The plastic tube can be taped in by the user. A plastic clamp is the normal closure supplied with the bags. A nylon ball valve with double hose barb may be purchased and moved
from bag to bag.