Page 378 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

13 Air Vessel - Few reciprocating pumps may have an air vessel; it helps to reduce the frictional head or
acceleration head.

Classification
1 Piston: Piston pumps generally are used where medium to high delivery pressures are required, such as for a
high-pressure flushing of vessel interiors and tanks. These can be obtained in multi cylinder form and can be
single or double acting
2 Plunger: Plunger pumps usually are used for metering or proportioning a fluid. Frequently, a variable speed
drive or stroke adjusting mechanism is provided to vary the flow as desired.

3 Diaphragm: Diaphragm pumps are invariably air driven and very compact, also no seals or packing is exposed
to the liquid being pumped, which makes them ideal for handling hazardous or toxic liquids. These often are
used for sump pump out.
4 Single-acting reciprocating pump: This has one suction valve and one discharge valve. When the piston is
moved backward, suction happens and when it moves forward, the delivery valve opens up to discharge the
liquid.
Double-acting reciprocating pump: Unlike a single acting pump, here there are two suction and delivery
valves. When the piston is moved forward or backward, with each stroke, both suction and expulsion happen
simultaneously. Thus it requires two inflow pipes and two outflow pipes. Some of the common applications of
these kinds of pumps are in Salt Water Disposal, Well Service, Descaling, Hydraulic Fracturing, and Oil & Gas
Pipelines.
5 Double - acting: These are double-acting pumps where steam, air, or gas is used to transmit power to the
liquid through the piston. The ratio of total steam force (steam pressure per unit area x area of the steam
piston) to total liquid force (pump head x area of the liquid piston) helps determine the efficiency with which the
pump produces pressure. They can operate at any point of pressure and flow, within a flexible range. Because
of these features, steam-driven pumps are mostly used in the refineries for pump-out service, with low NPSH
and the fluids used are hydrocarbons mostly with high viscosity and high temperature. National, Gardner
Denver, Oilwell, Gaso, and Wheatley are known as key manufacturers of such pumps.
6 Simplex, Duplex, Triplex, Quintuplex Pumps: Many reciprocating type pumps are simplex(one), duplex
(two), or triplex (three) cylinder. Duplex pumps are usually used where the two pumps can be used alternatively.
Such pumps are commonly used in oil-line pumping, mine de-watering, and chemical and petroleum products
transfer, but has many more applications. A triplex pump consists of three plungers, with the aim of reducing
the pulsation of a single reciprocating pump. Quintuplex pumps are designed with a gear case that assists in
a high-pressure task. Common applications of which are in cement slurries, sand-laden fluids, crude oil, acids,
mud, and other oil well-servicing fluids. Well known manufacturers for these types of pumps are National,
Gardner Denver, FMC, SPM, Oilwell, Kerr, Union, Gaso, Emsco, Aplex, and Wheatley.
7 Metering Pumps: A metering pump is usually used where the rate of flow of the liquid needs to be adjusted
in a specific time period. Most of the metering pumps are piston-driven and are called Piston pumps. Piston
pumps can pump at a constant flow rate against any kind of discharge pressure. Both Piston pumps and
Plunger pumps are reciprocating positive displacement pumps that use a plunger or piston to move fluid/
substance through a cylindrical chamber. Manufacturers such as Lewa, Watson Marlow, and Bredel offer
metering pumps at competitive prices.
Application of reciprocating pumps
• Vessel, pipe, tank, tube, condensate pipe, heat exchanger etc cleaning,
• Oil drilling, refineries, production, disposal, injections.
• Pneumatic pressure applications.
• Vehicle cleaning.
• Sewer line cleaning.

• Wet sandblasting
• Boiler feeding
• High-pressure pumps for the RO system (Reverse osmosis)
• Hydro testing of tanks, vessels, etc.

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CITS : Automotive - Mechanic Diesel - Lesson 129 - 131