Hardware Manual 3–1
3 - H
2
S SCRUBBER
Scrubber Life
The scrubber contains material that gradually loses its scrubbing/drying ability
with use. The lifetime of the material depends on how much H
2
S flows through
the scrubber (gas composition) and how often (switching frequency). Thus,
scrubber lifetime is specific to each application.
The SpectraSensors H
2
S analyzer predicts the remaining scrubber capacity by
using the actual H
2
S concentration measurements and dry cycle durations to
calculate how much cumulative H
2
S has been removed by the scrubber.
Scrubber lifetimes have been simulated for typical natural gas and fuel gas
applications. As shown in Figure 3–1, under normal operating conditions, a 2”
scrubber in a natural gas application with an average H
2
S concentration of
4 ppmv will last many years, whereas a 3” scrubber in a fuel gas application
with an average H
2
S concentration of 100 ppmv would be expected to last
approximately 190 days.
As an added precaution on H
2
S systems, a scrubber efficiency indicator is
mounted at the outlet of the scrubber, as shown in Figure 3–2 and Figure 3–3.
The powder material in the scrubber efficiency indicator changes color from
turquoise to dark grey if there is any analyte breakthrough, as shown in Figure
3–4.
Alternatively, regular validation of the system with an appropriate gas standard
will indicate when the scrubber needs to be replaced.
H
2
S scrubbers and scrubber indicators contain Copper (II) Oxide
[CAS# 1317-38-0] and basic cupric carbonate [CAS# 12069-69-
1], which are harmful if swallowed and toxic to aquatic organisms.
Handle with care and avoid contact with the internal substances.
Due to the chemical properties of the process samples, care must
be taken to repair or replace components with proper materials of
construction. Maintenance personnel should have a thorough
knowledge and understanding of the chemical characteristics of
the process before performing maintenance on the system.
When specifying gas standards, make sure the background gas is
that specified or a mix that closely resembles the contents of the
process stream and if possible, have the gas standard certified to
better than the specified precision of the analyzer.
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