Operating instructions

TM 11574A-OI
2-48
Figure 2-15. Autotransformer.
LEGEND
1. Dual Voltage Modular Autotransformer
2. Circuit Breaker (CB-2) 230V
3. 460 VAC Power Receptacle
b. Adjusting Fresh Air Makeup Vent
. The purpose of the fresh air makeup vent is to provide
ventilation for commodities that require fresh air circulation. The vent must be closed when
transporting frozen foods. Air exchange depends on static pressure differential, which will vary
depending on the container and how the container is loaded.
Two slots and a stop are designed into the disc for air flow adjustments. The first slot allows for a
0 to 30% air flow and the second slot allows for a 30 to 100% air flow. To adjust the percentage
of air flow, loosen the wing nut and rotate the disc until the desired percentage of air flow matches
with the arrow. Tighten the wing nut. To clear the gap between the slots, loosen the wing nut
until the disc clears the stop. Figure 2-17 gives air exchange values for an empty container.
Higher values can be expected for a fully loaded container.
For 60Hz operation multiply curves by 1.2
Figure 2-16. Make Up Air Flow Chart.