Siemens SIPROCESS GA700 Operating Instructions

The following example with four measuring ranges illustrates this:
Table 9-2 Selection of the reference gas
Measuring range Criterion for selection of the reference gas
17to22% O
2
The span of 17 to 22% O
2
is part of all measuring ranges. The physical zero point
may lie within this range. Air (20.95%O
2
%) is suitable as the reference gas.
15to25% O
2
0to25% O
2
0to100% O
2
Exception: If the smallest measuring span is ≥5% O
2
and the distance to the reference gas
amounts to no more than 16% O
2
, the physical zero point can also lie outside the measuring
range. The purity of the reference gas has to be appropriate for the measuring task.
9.4.1.2 ULTRAMAT 7
In an analyzer module without physically suppressed zero point, meaning with characteristic
initial value of zero, use nitrogen as the reference gas (purity 4.6).
In an analyzer module with a physically suppressed zero point, use an appropriate reference
gas. The concentration of the reference gas generally corresponds to the characteristic initial
value or, in special cases, the full-scale value or intermediate values.
In order to compensate for interference, the reference gas compartment can be subjected
to the puri󹪝ed sample gas of the measured component (absorber mode) or gas out of the
cylinder, which corresponds to the average interference gas composition.
9.4.2 Requirements for reference gas from the gas cylinder
The reference gas pressure must be 2000hPa above the sample gas pressure for su󹪟cient
measuring ability.
1. Use a reference gas line with the following characteristics at measuring spans of < 2% oxygen:
– Small cross-section, e.g. pipe diameter 2mm
– Made of metal, e.g., stainless steel
2. Flush the reference gas line thoroughly with reference gas before commissioning.
9.4.3 Introducing reference gas
• Set the 󹪞ow of sample gas and reference gas to the same level.
• Always introduce the reference gas before introducing the sample gas.
Commissioning
9.4OXYMAT 7 / ULTRAMAT 7: Introduction of reference gas
Wall-mounted device
128 Operating Instructions, 07/2023, A5E31930403-AB

Siemens SIPROCESS GA700 Specifications

General

Brand	Siemens
Model	SIPROCESS GA700
Category	Measuring Instruments
Language	English