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CONTROLLED
ATMOSPHERE SYSTEM
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What is Controlled Atmosphere? Controlled Atmosphere:
The control of the chemical composition of the
atmosphere surrounding a commodity by thecontinualaddition or removal of gases.
Modified Atmosphere:
The one time surrounding of a commodity with
a mixture of calibrated gases prior to shipment.
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CA History
Apple
Storage
19981950 1966 1987
Modified
Atmosphere
Controlled
Atmosphere
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History
5 units
19971987 1992 1994
Series 1
25 units
Series 2
107 units
Series 3
Production
starts
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Gas Composition
Nitrogen 78%
Oxygen 21%
Carbon
Dioxide .03%
Nitrogen 96%
Carbon
Dioxide 2%
Oxygen 2%
Normal Atmosphere Typical Desired Atmosphere
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Respiration
Oxygen
21% +Sugar CarbonDioxide
Heat
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Reduces Respiration
O2
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Respiration and OxygenRespiration
0%
25%
50%
75%
100%
125%
2 4 6 8 10 12
% Oxygen
Rate
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Effects on Produce
Reduces respiration Ethylene production retarded
higher natural sugar content.
Retards senescence (ripening / aging) associated softening and compositional changes.
Alleviates certain physiological storage disorders.
Retards some pathogens and consequential decay.
Provides insect control.
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Retards Senescence
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Insect And Pathogen Control
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Ethylene - C2H4
Produce generated ripening hormone
Accelerates senescence - plant breakdown
Diluted by adding nitrogen
Absorbed naturally by potassium permanganate
Scrubber available from CTD
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Controlled Atmosphere Benefits Permits longer tree ripening
Better product quality at final destination
Less spoilage during transport
Broader range of cargo can be shipped
Permits extended post harvest shipping and
storage times
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15 - 19% O2- Co-ordination impaired
12 - 14% O2- Perception and judgement impaired
10 - 12% O2- Performance failure, poor judgement- Onset of Cyanosis
8 - 10% O2- Mental failure, unconsciousness
6 - 8% O2- 100% fatal after 8 minutes exposure
4% - Coma in 40secs, convulsions, death
SAFETY
Modified and Controlled Atmosphere
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Never assume the atmosphere is safe
Vent before entering 20 minutes minimum
Remain clear of open doors Remain clear of air vents
Even if safe yesterday
Work in pairs when entering
Modified Atmosphere Controlled Atmosphere Units
SAFETY DETAILS
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Integrated within CTDs proven reefer unit
Utilizes membrane separator technology
Operates anywhere without additionalsupport technicians or trucks
No schedule delays waiting for service
No additional usage charges or fees
System Features
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Creates and accurately maintains :
Oxygen 1 to 21%
Carbon Dioxide 0 to 25%
Automated Pretrip checks:
Integral safety lock
Internal oilless air compressor Membrane protected by two filters
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Uses the Micro-Link 2 controller
Easy to use
Identical operation logic Possesses self diagnostics
Built in alarm indicators
Requires only software change
Uses same keypad and display (except for text)
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High N2 output reduces leakage requirements
Improves pulldown times.
CA uses the Reefer Datacorder.
Design uses common parts to minimize spares Low weight :
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Carry out Reefer PTI test
Carry out Air Leakage Test
Carry out CA PTI Attach Ethylene Scrubber (If required)
Set Reefer Temperature Set point
Set O2 and CO2 Set point
General Operation 1
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Attach CO2bottles internally (If required)
Pick and pack premium cargo
Fit rear door curtain
Start Reefer and CA units
Attach external CO2bottles (If required)
Ensure temperature pulls down
Ensure CA starts and pulls down
General Operation 2
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N2
O2 CO2
CO2O2COCO22
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Overview
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Membrane Oxygen permeability (polymer specific)
Selectivity - The ratio of oxygen to nitrogen
permeability (polymer specific)
Surface area
Pressure differential across the membrane wall
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Safety Door Lock
Locks when O2 is less than19.8%
Unlocks when O2 is greater than 20.3%
Has manual override
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Safety Door Lock
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The operator inputs O2 and CO2 setpoints.
The system compares to actual levels.
Then uses one of three modes
Nitrogen addition
Oxygen addition
Null
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The nitrogen mixes with existing box atmosphere
Creating a slight positive pressure
Compensates for normal box leakage.
Continues until the set points are achieved
Unit into Null mode
External CO2 is required if CO2 respiration is low
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Successful Shipmentsr uct Fr m To R esults
Beans Dakar Rotterdam Good
Melons Dakar Rotterdam Good
Tomatoes Morrocco Montreal Good
Pineapples Ghana Rotterdam Very Good
Bananas Gen. Santos Hong Kong Excellent
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CA is not a panacea
Control is paramount
Preparation and packaging controlled
Temperature controlled
Atmosphere controlled
CA Cannot improve produce
Decreases senescence rate Not all product is equal
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