ThermoFisher Scientific Ozone Primary Standard 49iQPS, Инструкция по эксплуатации

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Introduction
Principle of Operation
Thermo Scientific 49iQPS Instruction Manual 1-3
The 49iQPS operates on the principle that ozone (O
3
) molecules absorb
UV light at a wavelength of 254 nm. The degree to which the UV light is
absorbed is directly related to the ozone concentration as described by the
Beer-Lambert Law:
KLC


e
o
I
I
where:
K = molecular absorption coefficient, 308 cm
-1
(at 0°C and 1
atmosphere)
L = length of cell, 38 cm
C = ozone concentration in parts per million (ppm)
I = UV light intensity of sample with ozone (sample gas)
I
o
= UV light intensity of sample without ozone (reference gas)
Zero air is supplied to the 49iQPS through the zero air bulkhead and is
split into two gas streams, as shown in Figure 1–2 . One gas stream flows
through a pressure regulator to the reference solenoid valve to become the
reference gas (Io). The second zero air stream flows through a pressure
regulator, ozonator, and manifold to the sample solenoid valve to become
the sample gas (I). Ozone from the manifold is delivered to the
ozone
bulkhead. The solenoid valves alternate the reference and sample gas
streams between cells A and B every 10 seconds. When cell A contains
reference gas, cell B contains sample gas and vice versa.
The UV light intensities of each cell are measured by detectors A and B.
When the solenoid valves switch the reference and sample gas streams to
opposite cells, the light intensities are ignored for several seconds to allow
the cell to be flushed. The 49iQPS calculates the ozone concentration for
each cell and outputs the average concentration to the front panel display,
the analog outputs, and also makes the data available over the serial or
Ethernet connection.
Principle of
Operation