MIL-HDBK-1003/6
Page
Section 4
HTW HEATING PLANTS
4.1
General Requirements . . . . . . . . . . .
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4.2
Definitions . . . . . . . . . . . . . . . .
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4.2.1
High Temperature Hot Water (HTW) Systems .
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4.2.2
Medium Temperature Hot Water (MTW) Systems
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4.2.3
Low Temperature Water (LTW) Systems . . . .
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4.3
Types of Systems . . . . . . . . . . . . .
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4.3.1
Recommended . . . . . . . . . . . . . . . .
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4.3.2
Not Recommended . . . . . . . . . . . . . .
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4.4
System Water Velocities . . . . . . . . . .
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4.5
Types of Distribution Circuits . . . . . .
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4.5.1
Direct-Supply, Single-Circuit . . . . . . .
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4.5.2
Direct-Supply, Radial . . . . . . . . . . .
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4.5.3
Direct-Supply, Reverse-Return . . . . . . .
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4.5.4
One-Pipe Loop-Main . . . . . . . . . . . .
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4.5.5
Primary and Secondary Distribution Systems
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4.6
Hot Water Generators . . . . . . . . . . .
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4.6.1
Types . . . . . . . . . . . . . . . . . . .
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4.6.2
Design . . . . . . . . . . . . . . . . . .
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4.6.2.1
Maximum Pressure Drop through Generator . .
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4.6.2.2
Steam Space . . . . . . . . . . . . . . . .
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4.6.2.3
Tube Design . . . . . . . . . . . . . . . .
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4.6.2.4
Equalization of Flow through Tube Circuits
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4.6.2.5
Furnace Design . . . . . . . . . . . . . .
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4.6.2.6
Blowdown . . . . . . . . . . . . . . . . .
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4.7
Efficiency . . . . . . . . . . . . . . . .
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4.8
Pressurization . . . . . . . . . . . . . .
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4.8.1
Acceptable Pressurization Methods . . . . .
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4.8.1.1
Saturated Steam . . . . . . . . . . . . . .
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4.8.1.2
Inert Gas . . . . . . . . . . . . . . . . .
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4.8.2
Unacceptable Pressurization Methods . . . .
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4.8.2.1
Elevated Tank . . . . . . . . . . . . . . .
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4.8.2.2
Hydraulic Pump Arrangement . . . . . . . .
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4.8.2.3
Weighted Plunger Arrangement . . . . . . .
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4.8.2.4
Pressurization of the Boiler Drum . . . . .
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4.8.2.5
Combination Inert Gas and Steam
Pressurization System . . . . . . . . . .
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4.8.2.6
Air Pressurization System . . . . . . . . .
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4.8.3
Advantages and Disadvantages of Steam and
Inert Gas Systems . . . . . . . . . . . .
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4.8.3.1
Steam Pressurization Advantages . . . . . .
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4.8.3.2
Steam Pressurization Disadvantages . . . .
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4.8.3.3
Inert Gas Pressurization Advantages . . . .
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4.8.3.4
Inert Gas Pressurization Disadvantages . .
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4.9
Expansion Vessels . . . . . . . . . . . . .
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4.9.1
Purpose . . . . . . . . . . . . . . . . . .
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4.9.2
Sizing . . . . . . . . . . . . . . . . . .
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