Dh Operation - NuAire NU-5800 Operation And Maintenance Manual

8.0 DH Operation

The Incubator is designed to provide a sterile, constant temperature, constant CO
for optimum growth of tissue cell cultures and other organisms requiring this precise environment. To operate the Incubator
properly, the following parameters must be reviewed, carefully set, and/or prepared.
8.1 Sterility
The chamber environment is not selective. The growth environment is applied equally to all microorganisms (specimens
and contaminates) within the chamber. Therefore, before placing any cultures in the Incubator, the shelves and sidewall
top plenums should be sterilized. The interior sidewalls, top, bottom, door, as well as the gasket should be wiped clean
with a 70% solution of isopropyl alcohol or other disinfectant compatible with the chamber construction, to remove any
contamination. Use mild detergent to clean the exterior of the Incubator.
8.2 Humidity
Humidification of the Incubator chamber is achieved through the process of water evaporation (vapor water pressure) from
a stainless steel water pan placed on the bottom of the chamber. Materials of different thermal resistance (e.g., glass,
plastic) do not offer sufficient thermal recovery and are not recommended for water pan usage. Although some metals
offer better thermal coefficients than stainless steel, dissimilar metals cause electrolysis in the acid atmosphere (carbonic
acid) and should never be used, or placed within the chamber.
Use only distilled or mineral-free water, no purer than 1 mega ohm, in the stainless steel pan. The water should be
changed at least once a week. FLOODING THE BOTTOM OF THE INCUBATOR IS NOT RECOMMENDED since it is difficult to
change the water weekly and almost always necessitates the use of chemicals, which are not recommended and may
damage the stainless steel. Also, it promotes condensation on the inner walls because it steals the natural convection, heat
flow through the inner chamber and condensation points occur.
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Note: ABSOLUTELY NO CHLORINATED OR HALOGEN MATERIALS ARE TO BE USED IN THE CHAMBER.
Humidity recovery to 90% of original level will occur in 20-40 minutes on average after a 15-second door opening with a
water pan surface area of 120 square inches (774.2 sq. cm). Contamination in the water pan may be avoided by adding a
small amount of copper sulfate to the water pan after each Incubator decontamination. NOTE: Please contact the copper
sulfate manufacturer to determine the proper amount of copper sulfate that should be added to the water pan.
Condensation on the glass door, walls, top, or bottom of the chamber indicates an incorrect balance of door and front
perimeter heat. Both the door and front perimeter heaters operate on a duty cycle. A good starting point for these duty
cycles is the default setting for the door & perimeter heaters in a room ambient temp of 22°C (72°F) at a temperature set
point of 37.0°C. The fresh airflow that the air pump delivers to the chamber has been preset at the factory. If condensation
starts forming on the sides or back wall in the chamber, the number and length of air injections into the chamber can be
increased. (See section 8.8.1.2 for instructions.) To alleviate the condensation, increase the airflow. To increase RH in the
chamber reduce the airflow. If airflow is decreased, some condensation may be unavoidable. The port plug with breather
hole must be used on the back port.
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Note : DO NOT SEAL THE OPENING IN THE PORT PLUG EXCEPT WHERE INSTRUCTED TO DO SO.
THIS IS A PRESSURE RELIEF FOR THE CHAMBER DURING THE HEATED CYCLES.
OM0211
Rev 3 March 2013
Page 18 of 48
level and naturally humidified atmosphere
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