Carrier 69NT40-541-306, Операция и обслуживание

Страница: 52 / 154

T-354 4–16
4.6.11 USDA Cold Treatment
Sustained cold temperature has been employed as an effective post-harvest method for the control of Mediterra-
nean and certain other tropical fruit flies. Exposing infested fruit to temperatures of 2.2

C (36

F) or below for spe-
cific periods results in the mortality of the various stages of this group of insects.
In response to the demand to replace fumigation with this environmentally sound process, Carrier has integrated Cold
Treatment capability into its microprocessor system. These units have the ability to maintain supply air temperature
within one-quarter degree Celsius of setpoint and record minute changes in product temperature within the Data-
CORDER memory, thus meeting USDA criteria. Information on USDA is provided in the following subparagraphs
A. USDA Recording
A special type of recording is used for USDA cold treatment purposes. Cold treatment recording requires three
remote temperature probes be placed at prescribed locations in the cargo. Provision is made to connect these
probes to the DataCORDER via receptacles located at the rear left-hand side of the unit. Four or five receptacles
are provided. The four three-pin receptacles are for the probes and fifth, five-pin, receptacle is the rear connection
for the Interrogator. The probe receptacles are sized to accept plugs with tricam coupling locking devices. A label
on the back panel of the unit shows which receptacle is used for each probe.
The standard DataCORDER report displays the supply and return air temperatures. The cold treatment report dis-
plays USDA #1, #2, #3, and the supply and return air temperatures. Cold treatment recording is backed up by a
battery so recording can continue if AC power is lost.
B. USDA Message Trip Comment
A special feature is incorporated which allows the user to enter a USDA (or other) message at the head of a data
report. The maximum message length is 78 characters. Only one message will be recorded per day.
4.6.12 USDA Cold Treatment Procedure
The following is a summary of the steps required to initiate a USDA Cold Treatment:
a. Calibrate the three USDA probes by ice bathing the probes and performing the calibration function with
the DataReader or a personal computer. This calibration procedure determines the probe offsets and
stores them in the controller for use in generating the cold treatment report. Refer to the Data Retrieval
manual 62-10629 for more details.
b. Pre-cool the container to the treatment temperature or below.
c. Install the DataCORDER module battery pack (if not already installed).
d. Place the three probes. The probes are placed into the pulp of the fruit (at the locations defined in the fol
lowing table) as the product is loaded.
e. To initiate USDA Recording, connect the personal computer and perform the configuration as follows:
1. Fill in ISO header information.
2. Add a trip comment if desired.
3. Configure for five probes (s, r, P1, P2, P3).
4. Configure for one-hour logging interval.
5. Set the sensor configuration at USDA.
6. Configure for two byte memory storage format.
7. Perform a trip start.
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-foot containers,
or three feet from the end of the load for 20-foot containers. This probe should be
placed in a center carton at one-half the height of the load.
Sensor 3
Place in pulp of product five feet from the end of the load for 40-foot containers or
three feet from the end of the load for 20-foot containers. This probe should be
placed in a carton at a side wall at one-half the height of the load.