Carrier 69NT40-511-1 Operating And Service Manual

Also see for 69NT40-511-1: Operation and service

Contents

SECTION 22-13 T-268-072.5 UPPER FRESH AIR MAKEUP VENTThe purpose of the fresh air makeup vent is to provideventilation for commodities that require fresh aircirculation. The vent must be closed when transportingfrozen foods or controlled atmosphere loads.Air exchange depends on static pressure differential,which will vary depending on the container and how thecontainer is loaded. The chart below gives air exchangevalues for an empty container. Higher values can beexpected for a fully loaded container.02550751001251501752002250 10 20 30 40 50 60 70 80 90 100AIRFLOW(CMH)2-3/8 ”PERCENT OPENT-BARZERO EXTERNAL STATIC PRESSURE, 50HZ POWERFor 60HZ operation multiply air flow values from curve by 1.2a. Full Open or Closed PositionsMaximum air flow is achieved by loosening the wingnut and rotating the disc to the maximum open position(100% open). The closed position is 0% air flow.Two slots and a stop are designed into the disc for airflow adjustments. The first slot allows for a 0 to 30% airflow, and the second slot allows for a 30 to 100% airflow. To increase the percentage of air flow, the wingnut must be loosened, and the disc rotated until thedesired percentage of air flow matches with the arrow onthe disc. Tighten the wing nut. To clear the gap betweenthe slots, loosen the wing nut until the disc clears thestop, and rotate the disc for the second slot.The operator may also increase or decrease the air flowvolume to meet the required air flow by aligning thearrow on the disc with the percentage of desired air flowmarked on the supplied label (see Figure 2-1).2.6 LOWER FRESH AIR MAKEUP VENT(Optional)The purpose of the lower fresh air makeup vent is toprovide ventilation for commodities that require freshair circulation. The vent must be closed whentransporting frozen foods.Air exchange depends on static pressure differential,which will vary depending on the container and how thecontainer is loaded. The chart across gives air exchangevalues for an empty container. Higher values can beexpected for a fully loaded container.a. Full Open or Closed PositionsThe air slide is supplied with two adjustable air controldiscs. The fresh air makeup can be adjusted for 15, 35,50 and 75 cubic meters per hour (CFM). The air flow hasbeen established at 60 Hz power, and a 2 1/2 inch T bar,with 15 mm (0.6 inch) H2O external static above freeblow.Maximum air flow is achieved by loosening the hexnuts and rotating each disc to the maximum openposition (100% open). The closed position is 0% airflow.The operator may also adjust the openings to increase ordecrease the air flow volume to meet the required airflow.NOTEThe main air slide is in the fully closed positionduring reduced air flow operation.a. Air Sampling for Carbon Dioxide (CO 2) LevelLoosen hex nuts and move the cover until the arrow onthe cover is aligned with the “atmosphere samplingport” label. Tighten the hex nuts and attach a 3/8 hose tothe sampling port.If the internal atmosphere content has reached anunacceptable level, the operator may adjust the discopening to meet the required air flow volume toventilate the container.