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The following is a summary of the steps required to
initiate a USDA Cold Treatment.
a. Pre-cool the container to the treatment
temperature or below.
b. The product should be pre-cooled to treatment
temperature.
c.
Latch in the USDA back-up battery box.
d. Probe calibration is achieved by ice bathing the
three
USDA
"Calibrate/Monitor Probes" function on a DOS based
portable computer or "Husky" interrogator.
calibration determines the three probe offsets.
e. The product is then loaded directly from the
pre-cooling storage area to the container so that the
product temperature does not rise.
f.
Placement of probes --- there are three probes
required for a USDA cold treatment procedure.
Sensor 1
Place in pulp of the product located next
to the return air intake.
Sensor 2
Place in pulp of the product five feet
from the end of the load for 40 ft. con-
tainers and three feet from the end of
the load for 20 ft. containers. This
probe should be placed in a center car-
ton at 1/2 the height of the load.
Sensor 3
Place in pulp of product five feet from
the end of the load for 40 ft. containers
and three feet from the end of the load
for 20 ft. containers. This probe should
be placed in a carton at a side wall at 1/2
the height of the load.
g.
To initiate USDA Recording begin the cold
treatment recording, connect the interrogator and select
the "Cold Treatment Initialization/Update" option.
h. Interrogation software is available for DOS
based personal computers which allow retrieval of trip
data from the DataCORDER memory.
Carrier service representative for details.
1.16
NITROGEN FEED (Optional)
The purpose of the option is to provide a way to inject
nitrogen into the air stream of the unit. This is done by
connecting a nitrogen line to the quick-connect on the
front of the unit, with a 1/4" nipple conforming to the
MIL-C-4109. The nitrogen can then be feed into the unit
with a maximum pressure of 35 PSI which gives a flow rate
of 19.2 CFM.
Do not use a nitrogen feed inlet pressure higher
then 35 PSI.
Revised 8-6-93
Downloaded from
ManualsNet.com
probes
and
performing
Contact a
WARNING
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NITROGEN FEED FLOW RATE
35
30
25
INLET
20
PRESSURE
(PSIG)
the
15
This
10
5
0
0
1.17
HUMIDISTAT (OPTIONAL)
The supply air must be in-range or humidistat
circuit will not energize.
The humidistat (Figure 1-2) is factory set at 70%
relative humidity (R.H.) and is designed to operate when
transporting a chill load (controller set above ---10_C
(+14_F) and is locked out when the controller is set
below ---10_C .
a. The humidistat will be in operation if:
1. Supply
illuminated).
2. Dehumidification control Code 32 is ON.
3. Controller is set above ---10_C (+14_F).
4. Container relative humidity reaches the 70%
R.H. setting of humidistat.
The above energizes the humidistat circuit
energize the heaters and heat light.
b. For testing purposes:
Beware of rotating evaporator fan when
conducting following test.
1. Remove the front evaporator fan motor #1
access panel (see Figure 1-1). The humidistat is located
behind this panel.
2. Set the controller set pointer within 2_C (3.6_F)
of container supply air temperature.
3.
Set the dehumidification control Code 32 to ON.
4. Turn the humidistat control knob until heaters
are energized (heat light ON) and then reset control to
70% R.H. Replace access panel and lockwire.
1-26
2
4
6
8
10 12 14 16 18
FLOW RATE (CFM)
NOTE
air
is
in-range
(in-range
WARNING
light
to
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