Auxiliaries. PUMPS

Exercise 1. Read and learn the following words and expressions:

Exercise 2. Read and translate the text

Marine Pumps

On board ship, pumps are used for a number of services. Pumps feed water to the boilers, draw condensate from the condensers, supply sea water to the fire-main, circulate cooling water for the main and auxiliary engines cooling system, coolers and condensers, empty the bilges, transfer fuel oil, pump in and out ballast water, dis­charge fuel oil to the burners and fuel injection valves, circulate lube oil to bearings and gears of the propulsion plant components.

Every pump has a power end, which may be a steam turbine, a reciprocating engine or an electric motor, and a liquid end where the liquid enters and leaves the pump.

The suction head means the pressure of the liquid entering the pump, or the difference in the level of liquid with respect to the level of the pump on the suction side. The discharge head means the pressure of the liquid leaving the pump, or the level of liquid with respect to the level of the pump on the discharge side.

Most marine pumps are of reciprocating, rotary, centrifugal, or jet type.

The reciprocating pump moves liquid or gas by means of a piston or plunger which goes back and forth or up and down within a cylinder containing a suction valve and a discharge valve. An adjustable relief valve is fitted to the discharge chamber to protect the pump and piping against excessive pressure.

All rotary pumps work by means of rotating parts, which trap the liquid at the suction side and force it through the discharge outlet. Classification of rotary pumps is generally made according to the type of rotating elements: screw, gear, vane, axial-plunger rotary pumps. Rotary pumps are particularly used for pumping oil and other heavy, viscous liquids.

The centrifugal pump utilizes the throwing force of a rapidly revolving impeller. The liquid is drawn in at the center of the impeller and is discharged at the outer rim of the impeller. Centrifugal pumps are widely used on board ship for pumping, no viscous liquids. Fire pumps usually are single stage, double suction, volute type either turbine-driven or motor-driven centrifugal pumps. Main feed pump is a high­-speed, multistage, turbine driven, horizontal or vertical pump.

Jet pumps, unlike other types of pumps, use the Venturi effect to move fluid from one location to another, it means that the fluid is drawn into the pump passing through a constricted section. While passing through the constricted section the fluid’s pressure decreases, while the fluids velocity increases resulting in an increase in kinetic energy that allows fluid to flow.

There are many brands and models of jet pumps available, with some models offering pump capacity of up to a thousand gallons per hour. When choosing these pumps, the first thing should be paid attention to is how much water flow is required.

Exercise 3. Answer the following questions:

1. What is the most often used type of pumps in ships? 2. Where are the pumps to be found? 3. What is the function of the pumps? 4. What does the pump consist of? 5. Is it good when the liquid seeps through the packing? 6. Is impeller keyed onto the shaft? 7. How is the shaft protected against liquid? 8. What should be head of the pump be? 9. If the pump does not deliver water, will you check the casing? Should it be full of liquid? 10. What is recommended to do during long standing still periods?

Exercise 4. Give Russian/English equivalents.

· Steam turbine powered vessel; to handle fresh water; vertical shaft unit; pump casing, coupling; suction nozzle and discharge nozzle; secured by means of studs; grease lubricator; operating features; power requirements; discharge chamber; packing;

· высота всасывания, односекционный, лопастный насос, захватывать, набивка, труба, уплотнительное кольцо, заглушка, мощность, приемное сопло, фланец, предотвращать, корпус, муфта, крылатка, вертикальный агрегат.

Exercise 5. Look through the following information and then make the translation of the part B.