The top edge of the bowl top has a retaining groove into which is inserted an oil-resistant rubber seal ring. This ring is a flat rubber washer, not an 0-ring. A discharge ring seats on top of this seal ring. The outer edge around the top of the bowl top is threaded to receive a coupling nut. The coupling nut screws down over the discharge ring, forcing the dis- charge ring down onto the rubber seal ring. This seal ensures that discharging water will flow up through the center of the discharge ring. The coupling ring, as previously stated, forces the bowl top down onto the top of the bowl shell, thus completing a seal. As the coupling ring is screwed downward, it forces the bowl top down onto the disk stack. This action compresses the disk stack and ensures that each disk will seat tightly on its adjacent disks. The space between each disk is thereby assured to be correct. To ensure correct tension on the disk stack, an aligning mark is stamped on the coupling ring and the bowl top. These two marks must be lined up when tightening the coupling ring. An indicating arrow and the word “OPEN’ are also stamped on top of the cou- pling ring. These marks show the direction of rotation to remove the coupling ring. CAUTION The coupling ring and coupling nut have left-hand threads. Four T-shaped slots are equally spaced around the outside/upper rim of the coupling ring. A special wrench engages these slots for removal or installation of the coupling ring. A discharge ring, seated on top of the bowl top, acts as a dam to maintain the proper line of separation between the water and the JP-5 within the bowl shell assembly. Each purifier is furnished with a set of seven dis- charge rings. The outside diameters of the discharge rings are the same. The inside diameters of the discharge rings are different. The inside diameter size is etched on each ring. The inside diameters range from 220 milli- meters to 250 millimeters in 5-millimeter increments (220, 225, 230, 235, 240, 245, and 250). The coupling nut locks the discharge ring in place. Like the coupling ring, the coupling nut also has an indicating arrow and the word “OPEN” stamped on its top. The coupling nut has four circular slots equally spaced around its outer edge. A special wrench en- gages one of these slots for removal or installation. Purifier Operations The operations described in this section deal with starting from two different conditions-with a clean bowl and with a dirty bowl. Regardless of the condition of the bowl, there are some preliminary steps to follow before starting the purifier. These steps are as follows: 1. Open the bowl cover. 2. Ensure the handbrake is in the OFF position. 3. Remove the two bowl shell lock screws. 4. Insert the two bowl shell lock screw plugs. 5. Turn the bowl by hand. If the bowl does not turn freely, investigate and correct the cause. 6. Check the level of oil in the oil sump. If the oil is at or below the red line, add sufficient oil to raise the oil level to the white line. 7. Close the bowl cover and engage and tighten the three handwheel cover clamps. 8. Engage the feed tube to the paring disk. 9. Ensure the seal water inlet hose is connected to the purifier seal water inlet valve. 10. Ensure the purifier sump tanks are empty. The following starting and stopping procedures are for transferring fuel from one port wing storage tank, through one transfer pump, through the port purifier, to one port wing service tank. Since transfer is from wing tank to wing tank within the same group of tanks, and on the same side of the ship, there is very little change to the list and trim of the ship. The starboard service tanks can be filled from starboard storage tanks in the same manner. But, the transfer- ring is accomplished by using only one transfer pump to pump into one purifier, since they both have the same capacity. Starting with a clean bowl is accomplished as follows: 1. Close the following valves: a. Sample connections. b. Purifier inlet valve. c. Purifier discharge valve. d. Purifier seal water inlet valve. 2. Open the following valves: a. Designated manifold tankside valve. 4-41