Hale Q Series Muscle - Manual (Page 19)

19 MUSCLE (Midship) Pumps Installation, Operation, and Maintenance Manual
p/n: 029-0020-63-0
Introduction 
2 Introduction
2.1 DESCRIPTION
Hale single-stage and two-stage Midship MUSCLE Pumps cover a range of capaci-
ties from 750 Gallons Per Minute (GPM) (3,000 Liters Per Minute, LPM) up to 2,250
GPM (9,000 LPM). Hale single and two-stage pumps are designed to mount on the
chassis rails of commercial and custom apparatus. The pump is driven from the
truck’s main driveline.
Various models of the single-stage muscle pumps and one model of the two-stage
muscle pump are offered. The use and position on the apparatus determines the
model selected as well as the drive unit. Flow capacities (or rates) are shown in
Appendix H: “Midship Flow Rates” on page 199, located at the back of this manual.
2.2 PRINCIPLE OF OPERATION
Centrifugal Force
Hale pumps are centrifugal pumps that operate on the principle
of centrifugal force created by a rapidly spinning disk. (See Fig-
ure 2-1: “Centrifugal Force - Rotating Disk.”)
As the disk rotates, it throws water from the center toward the
outer circumference of the disk. The velocity at which the water
travels from the center directly relates to the diameter of the
disk and the speed of rotation.
When water is confined in a closed container, such as the
volute (pump body), the velocity of the water is converted to
pressure that rises to a level dependent on the speed of rota-
tion.
There are three interrelated factors that regulate the perfor-
mance of a centrifugal pump:
 SPEED (RPM) If the speed of rotation increases with flow held constant, fluid
pressure increases.
 PRESSURE If pressure changes with speed held constant, the flow, measured in
gallons or liters per minute (GPM/LPM), changes inversely; if pressure increases,
flow decreases. Pressure is measured in pounds per square inch (PSI) or pascals
(kPa).
Figure 2-1: Centrifu-
gal Force - Rotating
Disk