Reciprocating Pump | Working of Single Acting Reciprocating Pump

SINGLE ACTING RECIPROCATING PUMP

If a reciprocating pump uses one side of the piston for pumping liquid, then it is known as a Single Acting Reciprocating Pump.

01 - SINGLE ACTING RECIPROCATING PUMP - TYPE OF RECIPROCATING PUMPS

Description

The main parts of a single acting reciprocating pump are discussed below.

1.Cylinder, Piston, Piston Rod, Connecting Rod and Crank

A single action reciprocating pump consists of a piston, which moves forwards and backwards inside a close fitting cylinder. The movement of the piston is obtained by connecting the piston rod to the crank by means of a connecting rod. The crank is rotated by an electric motor.

2.Suction Pipe and Suction Valve

Suction pipe is connected to the cylinder. Suction valve is a one way valve, i.e., non-return valve. It allows the liquid to flow in one direction only. That is, it permits the liquid from the suction pipe to the cylinder.

3.Delivery Pipe and Delivery Valve

Delivery pipe is connected to the cylinder. Delivery valve is also one non-return valve. It permits the liquid to flow in one direction only. That is, it allows the liquid from the cylinder to the delivery pipe.

Working Principle

In a single-action reciprocating pump, liquid acts on one side of the piston only. A single-acting reciprocating pump which has one suction pipe and one delivery pipe; It is usually placed above the liquid level in the sump.

01 - SINGLE ACTING RECIPROCATING PUMP - TYPE OF RECIPROCATING PUMP

1.Suction Stroke

When the crank rotates from IDC to ODC the piston moves towards right in the cylinder. This is called suction stroke.

Now, the volume covered by the piston within the cylinder increases. On the free surface of water in the sump, atmospheric pressure acts. Thus there is a pressure different at the two ends of the suction pipe which connects the sump and the cylinder. This pressure difference between the free surface and inside of the cylinder causes the flow of water from the sump into the cylinder through the suction valve, which is kept open.

During this stroke, the non-return valve at the delivery side will be closed by the atmospheric pressure existing in the delivery pipe. At the end of this stroke, the cylinder will be full of water, the piston reaches the right end, which is called outer dead centre since, the water is continuously sucked into the cylinder, this stroke is called suction stroke. At the end of this stroke, since the pressure in the cylinder is atmospheric, the suction valve is closed.

2.Return stroke or Delivery Stroke

When the crank rotates the piston from its extreme right position starts moving towards left in the cylinder. This is known as Return or Delivery Stroke.

The movement of piston towards left increases the pressure of the liquid inside the cylinder to a pressure more than atmospheric pressure. Therefore, the Suction valve closes the delivery valve opens. The liquid inside the cylinder is forced into the delivery pipe through the delivery valve. Consequently, the liquid is raised to the required height. The liquid is discharged at every alternate stroke.

Abrasives | Types of Abrasives

Abrasives

Abrasive is a hard material. It can be used to cut or wear away other materials. Small abrasive particles are used in grinding wheels. They are called abrasive grains. Abrasives may be classified into two types.

Natural abrasives

These are produced by uncontrolled forces of nature. These are found from mines. The following are the natural abrasives.

a. Sandstone or solid quartz

b. Emery

c. Corundum

d. Diamond.

Natural abrasives lack uniformity of properties and reliability has been largely replaced by manufactured or artificial abrasives.

Artificial Abrasives

These are manufactured under controlled conditions in closed electric furnace in order to avoid the introduction of impurities and to achieve necessary temperature for the chemical reaction to take place. These abrasives have better cutting properties and higher efficiency than natural abrasives. The various manufactured abrasives are

a. Aluminium oxide

b. Silicon carbide

c. Artificial Diamond

d. Boron carbide

e. Cubic boron nitride.

Aluminium Oxide

01 - ALUMINIUM OXIDE ABRASIVE - TYPES OF ABRASIVE

It is the crystalline form of aluminium oxide. This abrasive carries very hard and tough grains having sharp cutting edges. It is manufactured by fusing mineral Bauxide in an electric arc furnace mixed with coke and iron scrap. Here, iron scrap acts as a flux. After fusing, it is crushed, washed and treated with alkalis. Again, it is washed and finally, ground.

Aluminium oxide is tough and less brittle. It is used for grinding materials of high tensile strength like high speed steel, malleable iron, wrought iron etc.

Silicon Carbide

01 - BLACK SILICON CARBIDE - TYPE OF ABRASIVES

It is made from Silicon dioxide, coke, sawdust and salt. The ingredients are thoroughly mixed and heated in an electric furnace about 2000 C for 34 Hours. The mass under the action of intense heat fuses and the following chemical reaction takes place.

The silicon carbide mass is crushed, washed and treated with alkalis. It is again washed and finely ground into small particles. Silicon carbide is hard and brittle. It is used for grinding materials of low tensile strength like grey cast iron, brass, copper, aluminium etc. The common trade name for this abrasive is ‘Silicon carbide’ ‘Carborundum’ ‘Crystolon’ and ‘Electron’ etc. It is represented by the letter C.

In general, the physical properties of aluminium oxide are compared with silicon carbide as follows:

1. Silicon carbide is harder than aluminium oxide.

2. Aluminium oxide can withstand greater stresses than silicon carbide.

3. Aluminium oxide is tougher than silicon carbide.

Artificial Diamond

01 - ARTIFICIAL DIAMOND - TYPES OF ABRASIVE

Artificial diamond is a form of pure carbon which is mainly used for truing and dressing other grinding wheels for sharpening carbide tools, and for processing glass, ceramics and stone.

Boron carbide

01 - BORON CARBIDE - TYPE OF ABRASIVE

It is harder than silicon carbide but not as hard as diamond. It is produced from coke and boric acid at tremendously high temperatures in an electric furnace. Boron carbide is mainly used for grinding and lapping very hard metals, hard alloys, glass and jewels.

Cubic boron nitride

01 - CUBIC BORON NITRIDE - TYPES OF ABRASIVE

It is a never synthetic abrasive that is harder than either aluminium oxide or silicon oxide. It is a combination of boron and nitrogen. Boron Cutters, grinding tool-steel, punch-press dies, grinding some hardenable stainless steel and for internal grinding of all ferrous metals.