6-20
T-268-07
raises stylus indicated temperature reading;
shortening shaft (clockwise) lowers stylus
reading. Then retighten set screw.
(b) Reset control at 0
_
C (32
_
F), start the
refrigeration unit and repeat accuracy check.
After temperature stabilization, recording
thermometer should be within 0.3
_
C (1/2
_
F)
limits.
3
4
1
2
5
6
1. Wind-up Key
2. Stylus
3. Set Screw
4. Pinion Shaft
5. Stylus Lifter
6. Bulb
Figure 6-19. Partlow Recording Thermometer
e. Replacing Recording Thermometer Element
(Bulb and Capillary)
The
element
is
mercury-filled
and
the
temperature-pressure of the element controls the stylus,
which moves across the chart in response to temperature
changes as sensed by the bulb located in the evaporator
supply air.
The element flange contains three O-rings. Care should
be taken to install the new element flange without
damaging the O-rings. It is possible for a mercury leak
to develop at the flange if O-ring damage occurs.
The stylus will continue to fall (container temperature
will actually be higher) if a leak develops in the flange,
capillary or bulb.
To replace the recording thermometer element:
1. Turn unit OFF and disconnect power source.
2. Remove upper back panel. Remove bulb clamps
securing bulb to unit.
3. Remove two flange screws from recording
thermometer and feed capillary and element
through the unit.
4. Push replacement bulb end and capillary through
the unit.
5. Fill slots with silastic (RTV432, Dow Corning).
6. Attach bulb clamps tightly to bulb.
7. Connect element flange to recorder making sure
hub of flange faces out to fit into the hole in
instrument case (recording thermometer).
8. Rezero the recorder. (Refer to sections 6.19.a.
through 6.19.d.)
9. Install inlet air grille and upper panel. Start unit and
check recorder calibration.
CAUTION
Capillary tubing may be bent, but never
sharper than 1/2” radius; extra care should
be taken when bending adjacent to welds.
The sensing bulb should never be bent, as
this will affect calibration.
6.20 SAGINOMIYA RECORDING THERMOMETER
NOTE
Do not overtighten chart nut after replacing
chart.
a. Battery
1. Open door and remove chart nut and platen.
2. Push voltage indicator test switch (item 2,
Figure 6-20). Replace battery if voltage indicator
points to the red or white zone.
b. Calibration
1. Install new chart on platen.
2. Place recorder bulb in ice bath (0
¦
0.2
_
C = 32
¦
0.35
_
F). (Remove rear upper panel to remove
bulb.) Leave bulb immersed in ice bath for
10
minutes.
3. After 10 minutes, rotate the chart by hand and check
the stylus indicated temperature. Do not touch
stylus during the checkout procedure.
