As soon as it indicates LIQUID, disconnect the AF filler valve (17), close the transfer tank pressure valve (21 ), close the converter vent valve (20), and then disconnect the converter vent line connector (16). If no other converters are to be serviced, empty the transfer tank, open fill line shutoff valve (10), and then the pressure buildup valve (21), if necessary, and observe the liquid level gauge (13). When the transfer tank is empty, close the pressure buildup valve (21) and then the fill line shutoff valve (10). Close all valves except the storage tank vent valve (5). The flow of LOX from the storage tank to the aircraft converter is done as follows and can be traced using figure 5-8. The flow of LOX from the storage tank to the transfer tank is by gravity. It first passes through the transfer fill line shutoff valve (10) to the transfer tank. During this pro-cess, the gaseous oxygen produced by cooldown of the tank is vented back to the storage tank through the vent line shutoff valve (11). Conditions of the transfer tank are monitored and indicated by pressure gauge (12) and liquid level gauge (13). When the transfer tank is filled to the desired level, as indicated by the liquid level gauge, valves (10) and (11) are closed. The converter lines are connected to the vent line connector (16) and filler valve (17). The filler valve is opened to allow the pressure in the converter and transfer tank to equalize. The transfer tank pressure buildup coil (PBU) is used to increase the pressure in the transfer tank to approximately 90 psig. This pressure is regulated by the pressure buildup valve (21) as required to maintain as high a pressure as possible during the servicing operation.

WARNING The rate of pressure buildup depends on the liquid level in the transfer tank. On a full tank, the pressure will build extremely fast because of the small amount of vapor space to be filled. Use extreme caution in building the pressure, and never allow the pressure to exceed 90 psig. If observation of the rate of pressure buildup indicates it will exceed 90 psig, open transfer tank vent valve (11) to relieve the excessive pressure into the storage tank. This will avoid the opening of the relief valve (14) and the resultant undesirable discharge of gaseous oxygen from the vent line.

LOX is now able to flow from the transfer tank into the converter. When the converter full indicator gauge (19) indicates full, the overflow is returned to the storage tank by passing through the converter vent line shutoff valve (20). The filler valve (17) is then removed, the transfer tank pressure buildup valve (21) is closed, vent valve (20) is closed, and then vent line connector (16) is disconnected. The preceding process is repeated until the storage tank is either empty or the maximum operating pressure, as indicated on storage tank pressure gauge (7), has been replaced.

MAINTENANCE.- Information and in-structions for maintenance of the TMU-70/ M storage tank are found in NAVAIR 19-25D-26. The Maintenance section is organized to provide information and instructions for the three levels of maintenance responsibility: organizational, intermediate, and depot. The capability of the using or supporting activity will be the limiting factor as to the level of maintenance that can be performed on the equipment. If maintenance of the equipment is beyond the assigned maintenance responsibility of the using or supporting activity, the next higher level of maintenance will perform the maintenance.

AMEs are only responsible for the organ-izational maintenance of LOX trailers, which include those functions normally performed in support of daily operations. Normal operational maintenance functions include inspection and preventive maintenance. Table 5-1 will assist you in understanding these functions.