Galvanic Applied Sciences ProTech903W, Руководство по эксплуатации

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Revision 1 25 9/10/2019
triggering of high concentration alarms, as stray light could make the system report that it was
analyzing a much higher concentration gas than it actually is.
2.7 Sample Flow Related Components
The system contains a number of components that control the flow of the sample and
condition it
It is essential to have a consistent flow rate because the concentration reading is dependent
on sample flow rate. The higher the flow rate, the more sample gas comes into contact with
the sensing tape in a given period time, and thus the faster reaction and higher concentration
reading.
2.7.1 Rotameter
The rotameter is a device that controls and indicates the flow rate through the system. It is
mounted on the right side of the 903W enclosure.
2.7.2 Power Vent (Eductor)
The power vent (eductor) produces a positive pressure at the exhaust while allowing the
analyzer vent to remain at ambient pressure. An eductor is shown in Figure 2-1.
Figure 2-10: Eductor
The eductor has two purposes:
• Changes in ambient pressure can affect the results produced by the system. If the system
is inside a building where there is a fluctuating static pressure in comparison to the outside
ambient pressure, the power vent will eliminate any influence on the tape staining.
Static pressure changes inside the building are normally caused by building vent fans
coming on and off which will change the differential pressure across the sample chamber.
Pressure can also be affected by a strong wind blowing across the vent. When this happens,
a slight change in the pressure of the sample between the tape and the sample chamber
occurs.
The slight change in differential pressure across the tape can cause a reduction in the seal
between the tape and the sample chamber, resulting in poorly shaped stains that give poor