Installing and connecting
3.3 Gas connections and internal gas routing
OXYMAT 64
24
Operating Instructions, 06/2008, A5E00880383-03
3.3
Gas connections and internal gas routing
3.3.1
Sample gas line
3.3.1.1
Gas connections
Sample gas inlet: clamping ring gland for pipe diameter 6 mm or 1/4".
Sample gas outlet: pipe couplings with pipe diameter 6 mm or 1/4".
A material suitable for the sampling gas must be selected for the inlet and outlet pipes.
3.3.1.2
Sample gas inlet pipe
The quality of the sample gas inlet pipe depends on the measuring task.
The smaller the O
2
concentration to be measured (below approx. 100 vpm O
2
), the higher
the requirements on the surface quality of the inlet pipe. Recommended is an inlet pipe
made of stainless steel with an internal electrolytically polished surface.
In addition, the number of pipe glands and other connecting elements should be kept as low
as possible. Glands are potential sources of leaks and possess cavities which only release
O
2
slowly, resulting in an slower rise in signal.
It should also be noted that steam has an influence on the quality of the measurement. It
adheres through adsorption on the surfaces of the parts wetted by the sample gas, and in
turn binds O
2
, which can also result in a slow rise in signal.
It is therefore recommendable to heat long inlet pipes to above 110 °C and to select a small
cross-section (internal diameter ≤ 2 mm).
3.3.1.3
Sample gas outlet pipe
If the sample gas is to flow into an exhaust line, use as short a line as possible or a transition
to a larger diameter to make sure that no flow resistance is produced in the exhaust line.