_i. Storage._ Fuels may be used immediately after preparation. If the blend contains crankcase oils, the fuel should be fired as soon as practicable after filling. Other liquid blends may be stored indefinitely until required for use. For storage precautions see Paragraph 40. The storage drums also should be kept tightly closed to prevent loss of gasoline through evaporation and to prevent moisture from entering the fuel. If stored in the open, the drums should be laid on their sides so that rain water will not collect adjacent to the bungs. An unrusted and undamaged 16-gage or 18-gage drum has sufficient strength to withstand the internal vapor pressure of the fuel. 37. FILLING BY POURING. [Illustration: Fig 28. Filling fuel tanks by pouring. Any clean container may be used. A funnel may be improvised.] (Fig 28) This method is the simplest and quickest for liquid fuel, but it may be too slow for some thickened fuels. The procedure is as follows: _a._ Stand the tank group on the ground or a platform. If the tank group is not connected to the gun group, lock coupling plug in tank coupling. (Par 70) _b._ Using a 1-3/4-inch wrench, unscrew the filling plug and the safety-head plug. _c._ Inspect interior of tanks to see if clean and free from foreign matter. If not clean, flush with gasoline. _d._ Using an improvised funnel, fill to within 2 inches of the top of both plug openings. This allows sufficient void. The tanks will then contain approximately 4 gallons of fuel. _e._ Wipe the fuel-tank plug seats and the plug threads with a clean, dry cloth. (Fig 29) If plug has a tendency to freeze to seat, lubricate (Par 49 _b_) before screwing in the filling and safety-head plug assemblies. Tighten with wrench. [Illustration: Fig 29. Wiping plug seat.] _f._ Wipe any spilled fuel from weapon. 38. FILLING BY FORCE PUMP. A force pump, if available, may be installed with a short length of pipe in the top opening of a drum of fuel for filling flame-thrower fuel tanks. Keep working parts of pump clean. 39. FILLING BY BLOWING. Thickened fuel may be readily forced into the fuel tanks of flame throwers by the use of extremely low pressures of compressed air or nitrogen. Flame thrower fuel filling kit E6 or equivalent may be used. When equipment is available, filling by blowing is more efficient for filling large numbers of flame throwers with thickened fuel. Pouring or pumping are more time-consuming, depending on the consistency of the gel. The consistency may vary among batches even when the same proportion of thickener is used. The amount of moisture in the fuel seems to cause this variation. The precautions listed in Paragraph 40 should be observed. [Illustration: Fig 30. Blowing thickened fuel into fuel tanks by use of cylinders of compressed air or nitrogen.]