T-292
4-2
Units may be equipped with a Vent Position Sensor
(VPS). The VPS determines the position of the fresh air
vent and sends data to the controller display.
0
30
60
90
120
150
180
210
240
0
10 20 30 40 50 60 70 80 90 100
AIR
FLOW
(CMH)
1-
!
/
2
”
PERCENT OPEN
50HZ
T-BAR
2-
%
/
8
”
3”
T-BAR
T-BAR
0
40
80
120
160
200
240
280
0 10 20 30 40 50 60 70 80 90 100
AIR
FLOW
(CMH)
1-
!
/
2
”
PERCENT OPEN
T-BAR
2-
%
/
8
”
3”
T-BAR
T-BAR
60HZ
Figure 4-2 Make Up Air Flow Chart
4.3.2 Lower Fresh Air Makeup Vent
a. Full Open or Closed Positions
Maximum air flow is achieved by loosening the wing
nuts and moving the cover to the maximum open
position (100% position). The closed position is 0% air
flow position.The operator may also adjust the opening
to increase or decrease the air flow volume to meet the
required air flow.
b. Reduced Flow for Fresh Air Makeup
On some models the air slide is supplied with two
adjustable air control disks. The fresh air makeup can be
adjusted for (15, 35, 50 or 75) cubic meters per hour
(CMH). The air flow has been established at 60HZ
power and 2 1/2 inch T bar and with 15mm (.6 inch) H2O
external static above free blow.
Loosen the hex nut and adjust each disk to the required
air flow and tighten hex nut.
NOTE
The main air slide is in the fully closed position
during reduced air flow operation.
NOTE
Model 69NT40-454 has a special air makeup
cover with a maximum air flow (100% open) of
80CMH (47CFM).
c. Adjustment
The air slide is supplied with two adjustable air control
discs. The fresh air makeup can be adjusted for 15, 35,
50 and 75 cubic meters per hour (CFM). The air flow has
been established at 60 Hz power, and a 2 1/2 inch T bar,
with 15 mm (0.6 inch) H
2
O external static above free
blow.
NOTE
The main air slide is in the fully closed position
during reduced air flow operation.
d. Air Sampling for Carbon Dioxide (CO
2
) Level
Loosen hex nuts and move the cover until the arrow on
the cover is aligned with the “atmosphere sampling port”
label. Tighten the hex nuts and attach a 3/8 hose to the
sampling port.
If the internal atmosphere content has reached an
unacceptable level, the operator may adjust the disc
opening to meet the required air flow volume to ventilate
the container.
4.4 CONNECT WATER-COOLED CONDENSER
The water-cooled condenser is used when cooling
water is available and heating the surrounding air is
objectionable, such as in a ship’s hold. If water cooled
operation is desired, connect in accordance with the
following subparagraphs.
4.4.1 Water--Cooled Condenser with Water Pres-
sure Switch
a. Connect the water supply line to the inlet side of con-
denser and the discharge line to the outlet side of the
condenser. (See Figure 2-5.)
b. Maintain a flow rate of 11 to 26 liters per minute (3 to 7
gallons per minute). The water pressure switch will
open to de-energize the condenser fan relay. The
condenser fan motor will stop and will remain stopped
until the water pressure switch closes.
c. To shift to air-cooled condenser operation,disconnect
the water supply and the discharge line to the water-
cooled condenser. The refrigeration unit will shift to
air-cooled condenser operation when the water pres-
sure switch closes.
4.4.2 Water-Cooled Condenser with Condenser
Fan Switch
a. Connect the water supply line to the inlet side of con-
denser and the discharge line to the outlet side of the
condenser. (See Figure 2-5.)
b. Maintain a flow rate of 11 to 26 lpm (3 to 7 gpm).
c. Set the condenser fan switch to position ”O”. This will
de-energize the condenser fan relay. The condenser
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Summary of Contents for 69NT40-531 Series
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