TM 5-4220-225-142-15. Overbottom Pressure Requirements. The normal method of determining console operating pressure has beenderived by adding 60 psig and 100 psig to depth pressure for 300 and 600-ft. hoses, respectively. However, there will beinstances of limited compressor capability at the diving platform. Minimum compressor, or manifold pressure demandshave been formulated to reduce overbottom pressure requirements while retaining the ACFM flow obligation.The formula for the 300-ft. hose is:(diver's depth (FSW) x .50) + 42 = minimum manifold pressure (psig)The formula for the 600-ft. hose is:(diver's depth (FSW) x .62) + 42 = minimum manifold pressure (psig)Figure 2-10 is a graphic display of these formulas plotted in a straight line. There may be a small variation betweenformula results and graphic interpolation. In such cases, the greater pressure will be used. Figures 2-11, 2-12, and 2-13are graphic displays of the flowmeter Capsuhelic gage readings for constant air supply pressures at depth. Figure 2-11shall be used to determine the essential flowmeter gage readings (inches of H20) when a desired flow of 6 ACFM isrequired by the diver, utilizing the adjustable helmet supply valve. To find the proper flowmeter gage reading, locate thediver's depth (FSW) on the graph. If the depth is not exact, use the next greater depth represented on the graph. Followthe depth line up to the known constant manifold pressure (psig) line. If manifold pressure is not exact, use the nextlowest pressure. To find the desired flowmeter reading (inches of H20), follow this intersection point (depth and pressure)to the left margin of the graph. These flowmeter Capsuhelic gage readings from the graph should always be rounded upto the next half-tenth (0.05) inch of H20 as an additional diver safety factor. Topside may instruct the diver to adjust thehelmet supply valve until the flowmeter gage readout is at the desired setting. Figures 2-12 or 2-13 shall be used if flowrates of 4 ACFM or 2 ACFM are desired.2-16. Doffing Procedures. The MK12 SSDS is most easily doffed in the sequence given in Table 2-5, DoffingProcedures. Doffing the bottom (drysuit) configuration consists of all the listed steps. Doffing the neckdam configurationconsists of the steps marked by asterisk (*).2-43

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