water in the tank. Should this occur, it will be neces- sary to take a composite sample. A composite sample is one in which samples are taken from different levels in the tank and mixed to form one sample. This type sample is more repre- sentative than one taken from only top and bottom. The same type sampler used to take the bottom sample can be used to take a composite sample, simply by attaching a string to the upper part of the disk guide stem. The sampler can then be opened at various levels by giving a smart jerk on the string. Tanks found to be contaminated with entrained water must be allowed more settling time before transferring. RECEIVING JP-5 ABOARD The first significant replenishing operation ever performed at sea by the U.S. Navy was in 1899, when the U.S. Navy collier Marcellus, while towing USS Massachusetts, transferred coal to her. Since that time, many methods and procedures have been tried and abandoned. Those described in this section are the typical procedures currently used in the fleet. The actual rigging of the replenishing hose between ships is the responsibility of the deck department and is not discussed. The ABF is concerned with only the filling connection hookup and the procedures for receiving JP-5 aboard. The receipt of aviation fuel aboard carriers is a continuing problem in the fleet. This is due, in most part, to the hazardous nature of the fuel involved, and the ever increasing quantity required for our modern- day aircraft. Other factors of equal importance that also must be considered are the type and location of the operation, the time allotted, and the large number of personnel involved. Time is an ever important aspect in any refueling operation, but more so at sea. The entire Task Force is scheduled to be replenished on a given date, and each ship is allotted a maximum time for this purpose. Not only are ships in constant jeopardy of a fire or colli- sion during the replenishing operation, but they are also easy targets in the event of an attack. JP-5 fuel is comparatively safe (having a mini- mum flashpoint of 140 F) when in its stored state. But, this same fuel handled under high pressure is ex- tremely dangerous when released into the atmosphere in a fine mist or spray. Therefore, it should be treated accordingly, and every precaution should be taken to prevent the possibility of a fire or explosion when pumping this fuel. A replenishing operation from a tanker was chosen to be described here since it covers all phases of any refueling operation. The procedure for receiving JP-5 fuel aboard is basically the same for all class carriers. This section deals with the general procedures, equipment used, and the criteria for the acceptance or rejection of JP-5 fuel without reference to any particular ship. The rate of fuel received is increased by using a double-hose rig. Two hoses are suspended, one below the other, from a single span wire. With this rig, two kinds of fuel maybe received simultaneously at a single station, or one kind may be pumped through both hoses. Before receiving the tanker alongside, certain preparations are necessary to safely and efficiently ex- pedite the replenishing operation. Deballasting and Stripping Any ballasted JP-5 tanks should be deballasted and stripped as soon as possible after the date and time of the replenishing operation have been confirmed. This requirement will be rare but must be covered in this section. Obtain assistance from personnel in the engi- neering department. They will align the main drainage system as required and operate the main drainage educ- tors. The pump room or manifold operators align the tank stripping system as follows: 1. Unlock and open the main drainage cutout valve on the flood and drain manifold. (Relock manifold.) 2. Open the valves on the single-valved stripping manifold to the tanks to be deballasted. NOTE All tanks interconnected with one flood and drain manifold can be deballasted simulta- neously. Each eductor can deballast an average of 1,000 gpm when supplied with fire main pressure of about 150 psi. Because of the tremendous suction taken by the main drainage eductors, loss of suction on the tanks is most likely to occur before the tanks are completely emptied. When this occurs, realign the tank manifolds to use the tank stripping system as follows: 1. Close all valves in the single-valved stripping manifold. 4-62