5.7 Cleaning and Adjusting the Humidity Steam
Generator, P/N 505087
Depending upon the quality of water used in the humidifi-
cation system, it may be necessary to clean the humidity gener-
ator and immersion heaters every 2 to 3 months.
Materials Required:
6-foot stepladder
Flat and Phillips screwdrivers
Clamp-on style Ammeter
Laboratory disinfectant
Siphon, sponge, & cleaning materials
1.
Remove all contents from the incubator, shut it off, and
disconnect the power.
2. Turn off the valve supplying the sterile distilled water.
3. From the stepladder, remove the eight Phillips screws
securing the top of the incubator cabinet.
4. When the steam generator has cooled, remove the four
thumbscrews.
The internal temperature of the
steam generator is hot enough to boil
water. Make certain sufficient time is
given to allow the unit to completely
cool before removing the top.
5. Lift the top off of the steam generator and lay it to the
side taking care to not crimp the copper capillary tube.
6. Siphon all of the water out of the steam generator and
clean it with a good quality laboratory detergent and dis-
infectant. Do not use any type of chloride cleaner. A
bristle brush may be needed for stubborn rust and scale.
Also clean the inside of the standpipe using a test tube
brush. Siphon and sponge the wash water out of the
boiler. Repeat cleaning with soap and water as neces-
sary.
7. Carefully pry off the brass top of the float control reser-
voir. Clean and disinfect it and the connecting tube
between the reservoir and the steam generator being
careful to not damage the float assembly.
8. Clean the two heater elements and the part of the copper
capillary tube attached to them.
9. When all surfaces are clean, rinse with sterile distilled
water until all soap and disinfectant are removed.
10. Open the distilled water valve and allow the reservoir to
fill. Measure the water level. The limit is three inches,
plus or minus one-quarter of an inch. The water level is
raised and lowered by carefully bending the float arm.
When set, replace the cover.
11. Replace the top of the steam generator and alternately
tighten the four thumbscrews to evenly compress the
rubber gasket.
a. Checking the Steam Generator Safety
Thermostat Calibration
1. Turn the slotted rheostat shaft of the temperature control
on the back of the steam generator fully clockwise.
2. Remove all tools and cleaning materials from the top of
the incubator. Reconnect power to the unit and turn it
on.
3. Set the RH level to 100% and open the incubator door.
This will cause the heaters in the steam generator to be
continuously energized.
The next step requires working in the
top section of the incubator where
high voltages are present. This should
only be done by qualified persons.
Models 3940 and 3949 _____________________________________________________________________________Service
5 - 3
Figure 5-2
float
valve
float
float
arm
capillary
tube
rubber
gasket
standpipe
Figure 5-3
