Air and oxygen can be introduced into the medium through the ring sparger and the flow
rate is controlled by a needle valve located on the right hand side of the control cabinet
(Fig. 4).
Percentage of oxygen introduced into the medium can be determined manually by the user.
For high density culture, 100% of oxygen can be applied.
Oxygen can be introduced into the medium automatically through D.O. cascade system.
When DO2 loop is in PID mode and "2 GAS" is in "DO" mode, oxygen will be introduced
automatically into the inlet gas flow to maintain the set percentage of the D.O..
When DO2 loop is in PID mode, agitation loop is in DO mode and 2-Gas is in AgO2DO
mode, oxygen can also be introduced automatically into the medium after agitation speed
reaches its maximum setting value, yet the dissolved oxygen is still lower than the set point.
1.7 pH CONTROL
pH is controlled in the range of 2.00-12.00 ( 0.01). The pH is sensed by a glass electrode.
Control is maintained by PID controller which operates two peristaltic pumps, connected to
acid and base addition ports (Fig. 5). Available as an option is the ability to provide control
with a deadband of 0.1 about a setpoint (see switch 2 settings at the end of section 2.6).
This will provide for only allowing the pumps to be activated when you are either 0.1 pH
units above or below the setpoint chosen.
1.8 D.O. CONTROL
D.O. is controlled in the range of 5-95% ( 1%). It is sensed by the D.O. electrode and
control is maintained by the PID controller which can change the speed of agitation and the
percentage of oxygen in aeration.
The D.O. probe used on BioFlo 3000 can be Phoenix polarographic or Ingold
polarographic (Fig. 6, 7).
1.9 FOAM CONTROL
Foam is controlled during batch fermentation by the antifoam probe which is located in the
headplate. The controller operates the antifoam addition pump that adds chemical
defoamer into the vessel (Fig. 8).
1.10 EXHAUST SYSTEM
The exhaust gases pass into the exhaust condenser where moisture is removed and returned
to the vessel. The air remaining passes into the 0.2 m exhaust filter (Fig. 9).
1.11 SAMPLING SYSTEM
1.11.1 System I
This system has a sampler which is attached to a sampling tube extending to the lower
portion of the vessel. The sampler has a rubber suction bulb to facilitate collection of
representative samples without contamination. A 25mL screw cap container serves as a
reservoir (Fig. 10).
1.11.2 System II
This system consists of a sample line and a peristaltic pump. Use "ON/OFF" mode of the
M1217-0050 5
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