Fresh Air Makeup Vent; Safety And Protective Devices; Table 20. Controlled Atmosphere Safety And Protective Devices - Carrier 69NT40-489-100 Series Operation And Service Manual

8.5 FRESH AIR MAKEUP VENT

The purpose of the vent is to provide ventilation for
commodities that require fresh air circulation and must
be closed when transporting frozen foods, or CA loads.
NOTE
The fresh air makeup vent must be closed for all
Controlled Atmosphere loads.
The fresh air makeup vent is also used to vent the
container prior to the door interlock system opening and
user entry, refer to section 10.7, page 113.

8.6 SAFETY AND PROTECTIVE DEVICES

System components are protected from damage by
safety and protective devices listed in Table 20. These

Table 20. Controlled Atmosphere Safety and Protective Devices

UNSAFE CONDITIONS
Excessive current draw on control
circuit
Excessive current draw by the
microprocessor
Excessive air compressor motor
temperature
Abnormal pressures in the CA
system
Abnormal temperature in the air
heater
T-305
devices monitor the system operating conditions and
open a set of electrical contacts when an unsafe
condition occurs.
The entire CA system will shut down if one of the
following safety devices open:
S
S
S
S
SAFETY DEVICES
Fuse (F3)
Fuse (F1 & F2)
Internal Protector (IP-AM) --
Automatic Reset
Pressure Relief Valve
High Air Temperature Switch
(HATS)
98
Control Contactor Fuse (F3)
Control Circuit Fuse (F1, F2)
Air Compressor Overload (IP-AM)
Circuit Breakers (CB-1 or CB-2) of the
refrigeration unit
DEVICE SETTING
Opens at 10 amps
Opens at 5 amps
N/A
Opens at 10.55 kg/cm@ (150 psig)
Opens at 82 ¦ 3 _C (180 ¦ 5 _F).
Closes at 70 ¦ 5 _C (158 ¦ 9 _F).