Isolating Switch. A switch intended for isolating an electric circuit from its source of
power. It has no interrupting rating and it is intended to be operated only after the circuit has
been opened by some other means.
Listed.* Equipment, materials, or services included in a list published by an organization
that is acceptable to the authority having jurisdiction and concerned with evaluation of
products or services, that maintains periodic inspection of production of listed equipment or
materials or periodic evaluation of services, and whose listing states that either the
equipment, material, or service meets appropriate designated standards or has been tested
and found suitable for a specified purpose.
Manual Transfer Switch. A switch operated by direct manpower for transferring one or
more load conductor connection from one power source to another.
Maximum Pump Brake Horsepower. The maximum brake horsepower required to drive
the pump at rated speed. The pump manufacturer determines this by shop test under
expected suction and discharge conditions. Actual field conditions can vary from shop
Net Positive Suction Head (NPSH) (hsv). The total suction head in feet (meters) of liquid
absolute, determined at the suction nozzle, and referred to datum, less the vapor pressure of
the liquid in feet (meters) absolute.
Open Motor. A motor having ventilating openings that permit passage of external cooling
air over and around the windings of the motor. Where applied to large apparatus without
qualification, the term designates a motor having no restriction to ventilation other than that
necessitated by mechanical construction.
Pump, Additive. A pump that is used to inject additives into the water stream.
Pump, Foam Concentrate. See definition of Pump, Additive.
Pump, Gear. A positive displacement pump characterized by the use of gear teeth and
casing to displace liquid.
Pump, In-Line. A centrifugal pump whose drive unit is supported by the pump having its
suction and discharge flanges on approximately the same centerline.
Pump, Piston Plunger. A positive displacement pump characterized by the use of a piston
or plunger and cylinder to displace liquid.
Pump, Positive Displacement. A pump that is characterized by a method of producing flow
by capturing a specific volume of fluid per pump revolution and reducing the fluid void by a
mechanical means to displace the pumping fluid.
Pump, Rotary Lobe. A positive displacement pump characterized by the use of a rotor lobe
to carry fluid between the lobe void and the pump casing from the inlet to the outlet.
Pump, Rotary Vane. A positive displacement pump characterized by the use of a single
rotor with vanes that move with pump rotation to create a void and displace liquid.
Pumping Water Level. The level, with respect to the pump, of the body of water from
which it takes suction when the pump is in operation. Measurements are made the same as with the static water level.
Service.* The conductors and equipment for delivering energy from the electricity supply
system to the wiring system of the premises served.
Service Equipment.* The necessary equipment, usually consisting of a circuit breaker or
switch and fuses, and their accessories, located near the point of entrance of supply
conductors to a building, other structure, or an otherwise defined area, and intended to
constitute the main control and means of cutoff of the supply.
Service Factor. A multiplier of an ac motor that, when applied to the rated horsepower,
indicates a permissible horsepower loading that can be carried at the rated voltage,
frequency, and temperature. For example, the multiplier 1.15 indicates that the motor is
permitted to be overloaded to 1.15 times the rated horsepower.
Shall. Indicates a mandatory requirement.
Should. Indicates a recommendation or that which is advised but not required.
Standard. A document, the main text of which contains only mandatory provisions using
the word “shall” to indicate requirements and which is in a form generally suitable for
mandatory reference by another standard or code or for adoption into law. Nonmandatory
provisions shall be located in an appendix, footnote, or fine-print note and are not to be
considered a part of the requirements of a standard.
Static Water Level. The level, with respect to the pump, of the body of water from which it
takes suction when the pump is not in operation. For vertical shaft turbine-type pumps, the
distance to the water level is measured vertically from the horizontal centerline of the
discharge head or tee.
Total Discharge Head (hd). The reading of a pressure gauge at the discharge of the pump,
converted to feet (meters) of liquid, and referred to datum, plus the velocity head at the
point of gauge attachment.
Total Head (H), Horizontal Pumps.* The measure of the work increase per pound
(kilogram) of liquid, imparted to the liquid by the pump, and therefore the algebraic
difference between the total discharge head and the total suction head. Total head, as
dete atmospheric pressure. Total suction lift, as determined on test, is the reading of a liquid
manometer at the suction nozzle of the pump, converted to feet (meters) of liquid, and
referred to datum, minus the velocity head at the point of gauge attachment.
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