492 MOLESWORTH'S POCKET-BOOK
COLD-WATEK AND FEED PuMPS.
Q = Cuffe feet of water required per hotse-power
per minute.
8 — Stroke of pump in inches.
N — Number of strokes per minute.
H — Horse-power of the engine.
D = Diameter of pump = a/H Q 2200
,, SN ’
The cold-water pump usually = diameter of
cylinder x 0*8 when stroke = | stroke of engine;
The cold-water pump usually = diameter of
cylinder x 0’42 when stroke = J stroke Of engine.
Velocity of water in pump-passages should not
exceed 500 feet per minute. Pump-valves should
not be of less area than | area of the pump.
Feed-pumps for High-pressure Engines :
Diameter = diameter of cylinder when
pump’s stroke = stroke of the engine.
Diameter = | diameter of cylinder when
stroke of the engine.
Diameter = | diameter of cylinder when ’th
stroke of the engine.
Feed-pumps for Condensing Engines:
Diameter = diameter of cylinder when J
stroke of the engine.
Diameter - | diameter of cylinder when |th
stroke of the engine.
INJECTION WATER.
Q = Quantity of water required per nominal
horse-power in cube feet per minute.
T - Temperature of the steam in degrees Fahr.
Q = T x 00304.
For temperature of steam, see Table.
Approximately 0*8 cube foot, or 5 gallons are
required per nominal horse-power per minute.