Part Two - - Controlled Atmosphere System; Introduction; Figure 55. Basic Schematic For The Ca System - Carrier 69NT40-489-100 Series Operation And Service Manual

PART TWO - - CONTROLLED ATMOSPHERE SYSTEM

DANGER
THE DANGER STATEMENTS MUST BE
STRICTLY ADHERED TO. REFER TO CON-
TROLLED ATMOSPHERE (CA) SAFETY
SECTION LOCATED IN THE SAFETY SUM-
MARY, SAFETY-1.
DANGER
HAZARDOUS ATMOSPHERE INSIDE
LOW OXYGEN INSIDE CONTAINER CAN CAUSE DEATH

7.1 INTRODUCTION

The Carrier Transicold
atmosphere system extends cargo life and reduces
cargo degradation by providing precise management of
the gases in the atmosphere surrounding the cargo. The
system reduces the amount of oxygen and carbon
dioxide in the cargo atmosphere by replacing them with
nitrogen. Also, when high concentration of carbon
dioxide is required, the system has the ability to monitor
and inject it from a customer supplied cylinder. Provision
is made for connection of the cylinder at the outside or
inside of the container.
1
2 4
3
13
12
11
TO CONTAINER
1. Ambient Air
2. Filter
3. Accumulator
4. Compressor
5. Heater
6. Nitrogen Separator
7. Oxygen Solenoid
Valve
8. Gas Mixture Released
i t At h

Figure 55. Basic Schematic for the CA System

INTRODUCTION
Everfresh controlled
5
2 6
7
10 9
8
9. Carbon Dioxide
Sensor
10.
Oxygen Sensor
11. Carbon Dioxide
Solenoid Valve
12. Regulator
13. CO Cylinder
2
SECTION 7
The basic controlled atmosphere (CA) system consists
of an air compressor, filters, accumulator, air heater and
nitrogen separator. The system is also fitted with oxygen
and carbon dioxide sensors to provide concentration
level information to the controller. An oxygen solenoid
valve is supplied to allow ambient air into the container.
The carbon dioxide injection equipment consists of the
customer supplied cylinder with regulator and a
controller operated
description of the system is provided in section 8.4
page, 96.
Operation of the system is managed by a separate
controlled atmosphere microprocessor. Once the CA
Controller is set at the desired level of gas
concentration, the unit will operate automatically to
maintain specified levels of oxygen (O
dioxide (CO ).
2
Main power (at nominal 460 volt) and control power(at
18 and 24 volts AC) is supplied from the refrigeration
system power.
LOW OXYGEN LEVELS INSIDE CONTAIN-
ER. VENTILATE CONTAINER BEFORE EN-
TERING. STAY AWAY FROM DOORS WHILE
VENTING.
The unit requires installation of a door interlock system
on the rear doors of the container. Verification of this
installation (a visual inspection during pre-trip) is a
necessary precaution prior to CA operation of the unit.
Once the oxygen sensor detects an oxygen level
BELOW a safe level (19.8%), the CA Controller
energizes the door interlock solenoid to prevent
entrance into the hazardous atmosphere of the
container.
IT IS THE RESPONSIBILITY OF THE OPER-
ATOR TO ENSURE THAT THE REAR CON-
TAINER DOORS AND DOOR HANDLES ARE
PROPERLY CLOSED PRIOR TO CA SYS-
TEM USAGE. THE DOOR INTERLOCK SYS-
TEM MAY NOT SECURE THE DOORS UN-
LESS THE
PROPERLY.
Certain temperature and mechanical conditions must
be met before the CA system is allowed to operate. The
temperature controller monitors these conditions and
provides a signal to the CA controller once operation is
allowed. If at anytime the Temperature Controller
detects a change in any of the required conditions, it will
deactivate the CA system. See Section 9.
87
solenoid valve. A
) and carbon
2
DANGER
DANGER
HANDLES ARE CLOSED
detailed
T-305