fuel vapors are present and this reading is the correct percentage of inertness. Upon the completion of all analysis, turn the ana- lyzer off and purge the vapor absorber in a normal room atmosphere. Connect the aspirator hose and bulb to the outlet (top) of the vapor absorber and operate the aspirator bulb for three minutes. Maintenance The batteries have a useful life of about 100 hours. When the current adjustment rheostat does not bring the indicating needle to 150 milliamps on the scale, the batteries should be replaced. After every 50 analysis, examine the calcium chloride and replace it if it is glazed or hard. Also, the activated carbon should be reactivated or replaced after every 50 analysis. As with all equipment main- tenance, refer to the technical manual and MRCs for the correct procedures. C02 FLOODING SYSTEM Carbon dioxide is stored in steel cylinders at pres- sures from 700 to 1,000 psi, depending on variations in temperature. At these pressures, about two-thirds of the cylinder’s contents is in liquid form. As gas is released through the opened cylinder valve, the pres- sure is gradually lowered until all the COZ turns into gas. Thus, the contents of COZ in the cylinder will expand about 450 to 500 times in volume when it is released. When fully charged, the large-size cylinders contain 50 pounds of COZ. Carbon dioxide is used for the protection of, and firefighting in, the gasoline pump room, motor room, access trunk, and fuel filter rooms, Carbon-dioxide cylinders are located in motor rooms and in compart- ments on the second deck directly above the filter rooms. The CO~ release valves on the cylinder are operated by a cable, with cable pull boxes located at three places. The cylinder valves are thus opened, but they cannot be closed. Spare COZ cylinders are carried aboard. The COZ emergency fire-extinguishing system for fuel pump rooms, motor rooms, access trunks, and filter rooms is similar on all ships. Carbon-dioxide cylinders, located inside each of the motor rooms, are connected by piping to the fuel pump room, motor room, and access trunks. The other four are spares. The cylinders release carbon dioxide into the piping when operated by any of the pull boxes. A pull box is located inside the fifth-deck access trunk, the fire-pumproom and on the starboard side of the hangar deck across from the MOGAS- pumproom access. The emergency pull box is watertight and has a metal cover with a rubber gasket held by friction clutches on the rim. Under the cover is a glass plate labeled with instructions for using the pull box. Also under the glass plate is a pull handle connected through a cable and pulley to a cylinder valve on the carbon dioxide cylinder head. To operate the pull box, release the friction catch to allow the cover plate to drop, break the glass and pull out the handle until the red portion of the pull cable can be seen. After a 15-second delay, released carbon dioxide gas flows through the piping to the fuel spaces, where it is discharged through diffusing horns and spreads as a smothering blanket, eventually filling the compart- ment. Connections from the carbon dioxide-cylinder distribution lines allow carbon dioxide to operate two pressure switches. Pressure from the carbon dioxide throws electric switches to actuate a carbon-dioxide warning bell in the space, a visual alarm outside the space at the access, and to stop the exhaust ventilation system fan motors. Stoppage of the ventilation system will cause operation of an audible and visible alarm. RECEIVING GASOLINE ABOARD When gasoline is to be taken aboard, there are certain preparations to be made. First, establish the amount of gasoline to be received. The maximum allowable capacity required onboard will be 95% at sea or at anchor and 80% when the ship is alongside a pier. Gasoline is received aboard ship through the starboard main deck filling connections. Equipment required at the filling connection is as follows: Swabs Rubber bucket Empty 5-gallon safety can Tool box with non-sparking tools Sample bottles Ground wire A portable funnel and a portable 2 1/2-inch hose connection 6-19