The gas mixture that provides optimum growth conditions for anaerobic
bacteria is an 85/5/10 mixture of N2/CO2/H1. Regulations in some
locations do not permit mixtures containing 10% hydrogen. In these
locations, a mixture containing 5% to 7% hydrogen is recommended.
Note
If a 5% or less mixture of H
2
is used, an auxiliary
desiccant/palladium dryer may be required to maintain proper anaerobic
conditions.
s
Install two-stage pressure regulators with dual indicating gauges at the
cylinder supply outlets for both the nitrogen and mixed gas supplies.
If the cylinders are to be stored in another room, manual shut-off valves
should be installed.
Low stage pressure gauges on both tanks should be adjusted between 10
and 15 PSIG.
To ensure a constant supply of both gases, it is recommended that the
operator keep extra tanks of both gases on the premises.
• Nitrogen: A “high purity” grade nitrogen, with a minimum purity of
99.99%, maximum moisture 3 ppm, is recommended.
• Tri-mixture (anaerobic gas): Component gases are recommended to be
of a “high purity grade”, the final gas mixture should result in less than
10 ppm O
2
.
The Anaerobic and Nitrogen gas supply fittings are located on the
plumbing panel on the back of the unit. Refer to Figure 1-2. Securely
attach a vinyl line from the main source of Anaerobic and Nitrogen gas to
each appropriate serrated fitting. If a metal line is to be used, the serrated
fitting can be removed and the desired 1/8 MPT fitting can be added.
Note
Gas supplies are connected one way for start-up and another way for
normal operation to save gas costs on initial start-up.
s
1-4
Anaerobic System
Thermo Scientific
Section 1
Installation and Start-Up
Connect the Gas
Supplies
Gas Recommendations
To Connect the Gas
Supplies
