SERVOMEX SENSING TECHNOLOGIES INSIDE THE Chroma
PROTECTING YOUR GAS PURITY
THE SERVOPRO Chroma OFFERS VERSATILE ANALYSIS OPTIONS FOR MEDICAL GASES
The Chroma’s Thermal Conductivity
Detector (TCD) consists of an electrically
heated Wheatstone bridge in a
temperature-controlled cell. Helium
is passed over the reference arm of
the bridge and the column effluent
passes over the sample arm of the
bridge. When the column effluent is
helium carrier gas, the heat loss from
the sample arm of the bridge matches
the heat loss from the reference arm.
When an analyte elutes, this affects the
thermal conductivity of the effluent
and will change the heat loss from the
sample arm of the bridge, and hence
its electrical resistance. This change is
measured as a signal.
Gas Chromatography (GC) is an
exceptionally accurate method of separating
gas mixtures, measuring concentrations
down to parts-per-billion (ppb) levels.
It is well suited for use in high-purity
processes such as medical gas purity
analysis since, unlike most gas analysis
techniques, the measurement is made
once the sample has been separated
rather than within the sample.
By circulating a gas sample, the individual
gases are separated using an inert
carrier gas, such as helium or argon. This
mobile phase flows through a tubular
column, where the component gases are
separated due to their interaction with
the stationary phase.
The gas content is quantified by a
detector at the column outlet measuring
the retention times of specific molecules
as they bind to the column material at
different rates.
Each gas type elutes after a different
retention time in the column. Gas types
are identified by the order in which they
elute from the column.
SERVOPRO Chroma
One of the most versatile gas monitoring
solutions available, the SERVOPRO
Chroma can be optimized for medical gas
purity applications.
Medical gases are strictly regulated under
the same rules as medicinal drugs, with
official measurement methods and purity
levels set at acceptable concentrations.
A customizable mainframe analyzer based
around Gas Chromatography technology,
the Chroma is capable of utilizing
Servomex’s advanced Plasma Emissions
Detection (PED), Flame Ionization
Detection (FID) and Thermal Conductivity
(TCD) sensing technologies.
For medical gas applications, the Chroma
uses TCD to provide a nitrogen assay and
OVERVIEW
MEASURES:
carbon dioxide (CO 2 ) impurity analysis
in nitrous oxide (N 2 O). The Chroma also
delivers impurity analysis of carbon
monoxide (CO) in CO 2 and N 2 O through
FID with a methanizer.
The Chroma nitrogen assay measurement
meets the European Pharmacopeia’s
required concentration limit of greater
than 99.5% purity (the US National
Formulary requirement is slightly less
stringent at 99%).
The European Pharmacopeia required
concentration limit for CO 2 impurity is
less than 300 parts per million (ppm) and
for CO impurity is less than 5ppm – the US
National Formulary requires a gas detector
tube for these measurements. One of the
most compact and powerful trace analyzers
available to the market, the Chroma is
rack-mountable for easy integration into a
medical gas analysis system.
It is a standalone device that does not
require third-party software and is
designed to be easy to operate, with an
intuitive user interface and integrated
software providing access to all functions,
measurements and system status.
The Chroma has separate 4-20mA
outputs for each measurement,
ensuring peak impurity values and
chromatogram signals.
Comprehensive digital and analog
communications options deliver
flexible operation, with internet and
Ethernet connectivity for remote
control and monitoring via a network
or web browser.
APPLICATIONS
• Medical gas production • Hydrogen purification plants
Trace H 2 , O 2 , N 2 , Ar, CH 4 , CO, CO 2
and NMHC • Medical gas verification • Specialty gas laboratories
• Air separation plants • Semiconductor plants
BACKGROUND GASES: • Argon purification plants • Helium liquefaction plants
H 2 , O 2 , N 2 , Ar and He, CO 2 and N 2 O • Cryogenic truck loading station
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GC process conditions can be varied to
suit a variety of applications. The column
temperature may be altered, as can the
carrier gas flow rates, sample loop size
and the dimensions of the column itself.
FLAME IONIZATION
DETECTOR
The Flame Ionization Detector (FID) sensor
works on the principle of detecting ions
formed in the combustion of organic
compounds in a sample, producing charged
molecules that cause electrical conduction
between two electrodes. The ions are
attracted to a collector plate and induce
a current upon hitting the plate. The FID
measures this conduction and produces an
output which is directly proportional to the
concentration of Total Hydrocarbons (THC)
in the sample. Using a methanizer, this
technology can be also used to measure
very low concentrations of CO.
Based on reliable, sensitive Gas Chromatography techniques, the Chroma offers configurable sensor options that provide
best-in-class solutions for a range of trace gas applications. This accuracy and analytical capability is fully supported by
Servomex’s expert applications knowledge for Purity and Specialty Gas processes. It can also be incorporated into our custom-
designed system solutions.
Talk to our team today: servomex.expert/contact-us
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