MIL-HDBK-1027/4A
lines. Valves located under concrete slabs should be set in a pit having a
least dimension of five pipe diameters with a minimum of at least 10 inches
and fitted with a cover.
4) Recirculation Pattern. The normal recirculation pattern
should be 50% flow through the overflow or skimming system and 50% through
the main drains. The recirculation system must be designed with adequate
capacity such that 100% of the recirculation flow can pass through the
overflow or skimming systems and 100% through the main drains. Pool water
inlets should be located to produce uniform circulation of water through the
entire pool. Inlets should be capable of providing 100% shutoff for testing
of the piping system after the pool construction is complete. Provide one
inlet per 15 feet of pool perimeter. Flow through each inlet should be
adjustable. See Drains and Overflow/Skimming Devices for information on pool
water outlets.
5) Overflow/Skimming Devices. Total flow rate capacity of
overflow/skimming devices must be at least 100% of the required filter flow
for the recirculation system. Perimeter overflow gutters are preferred.
6) Drains. Two outlet drains should be provided at the
deepest section of the pool. The spacing between the drains should be a
minimum of 6 feet. Each drain should be large enough to empty the pool
completely in a maximum of 4 hours. Each drain's grate area must be such
that the maximum velocity of water passing through the grate not exceed 1.5
feet per second, even when flow is through only one drain. The openings in
the grating should be no larger than one-half of an inch wide.
d) Filtration. Filtration is required for the removal of
suspended particles and clarifying pool water.
1) Filter Type. High rate pressure sand filters with a flow
rate of 15 gpm per square foot of sand bed area are preferred. Diatomaceous
earth filters require special disposal of waste generated during backwashing
as well as respiratory protection. While cheaper from an initial cost
standpoint, cartridge type filters are labor intensive.
2) Accessories. A pressure gauge should be provided on the
inlet and outlet lines of each filter. A rate-of-flow indicator should be
provided on the outlet line of the filter system. Air-relief devices should
be provided at the highest point of each filter tank. An access manhole
should be provided near the top of each filter tank.
3) Backwashing. Backwashing of sand filters should be
automatically controlled. Automation will ensure complete cleaning in
multiple sand filter configurations and eliminate disruptions to training
schedules. Backwash water should discharge to waste. A sight glass should
be provided for viewing the clarity of backwash water.
e) Pool Water Heating. Swimming pools are normally designed for a
water temperature between 75 degrees F and 82 degrees Fahrenheit, with 80
degrees Fahrenheit being most desirable. Water survival training may
necessitate higher or lower temperatures. Investigate all training
techniques and procedures to ensure the pool's heating equipment is
appropriately sized and controlled for intended use. Calculations must
address the desired heat pickup time. A pressure relief valve should be
162
Previous Page
