Keep engine air intake filters clean to maintain sufficient induction of air.
Q1. An electric motor is what part of a pump?
Q2. Excessive rubbing or wear is a result of what condition caused by improper belt tension?
Q3. Before starting a diesel engine, you must complete what type of inspection?
Q4. Whatfeature is the difference between agasoline and a diesel engine?
LEARNING OBJECTIVE: Identify specific types of pumps and the operation and maintenance procedures for each; identify methods used for installing piping, valves, and the maintenance of stuffing box, packing, and mechanical seals in pumps; and identify the methods used for the maintenance of internal pump components.
A Utilitiesman is required to work with pumps of many shapes and size. Some of the primary uses of pumps are as follows:
To supply feedwater to boilers
To deliver fuel oil to oil-fired boilers To circulate coolants and lubricants in internal combustion engines
To supply chemical feed in water purification systems,
To lift water from cells and distribute it throughout a system
To discharge sewage into setting tanks or mains.
The principles of pump operation, the principle of suction force, the types of valves used in pump operation, the different types of pumps, pump installation, and safety precautions that a Utilitiesman has to know to operate and maintain the various types of pumps used today are discussed in this section.
Pumps are used to move any substance that flows or can be made to flow. Most commonly, pumps are used to move water, oil, and other liquids; however, steam and other gases are also fluid and can be moved with pumps, as can molten metal, sludge, and mud.
A pump is a device that uses an external source of power to force fluid to move from one place to another. A pump develops no energy of its own; it merely transforms energy from the external source (steam turbine, electric motor) into mechanical kinetic energy, which is manifested by the motion of the fluid. This kinetic energy is then used to do work. For example. to raise liquid from one level to another, as when water is raised from a well. Other examples are to transport liquid through a pipe, as when oil is moved through an oil pipeline; to move liquid against some resistance, as when water is pumped to a boiler under pressure; or to force liquid through a hydraulic system, against resistance. Every pump has a POWER END, whether it is a steam turbine, a reciprocating steam engine, a steam jet. or some type of electric motor. Each pump also has a FLUID END, where the fluid enters (suction) and leaves (discharges) the pump.
The addition of energy to a liquid by a pump usually. results in an increase in pressure, which is generally referred to as HEAD. In pump operation, you should know that there are four types of head-net positive suction head, suction head, discharge head, and total discharge head. The definition of each of the types of head is as follows:
The NET POSITIVE SUCTION HEAD (NPSH) is the suction pressure minus the vapor pressure expressed in feet of liquid at the pump suction. This type of head pressure is commonly referred to as NPSH.
The SUCTION HEAD on a pump means the total pressure of the liquid entering the pump. In a de-aerating feed tank operating under saturated conditions. the suction head of the feed booster pump equals the NPSH plus the auxiliary exhaust pressure.
The DISCHARGE HEAD means the pressureof liquid leaving the pump or the level of liquid with respect to the level of the pump on the discharge side.
The TOTAL DISCHARGE HEAD is the net difference between the suction head and the discharge head.
NOTE: When positive, suction head is usually expressed in feet of water. When negative, it is expressed in inches of mercury.
When a pump operates below the level of a liquid, its suction end receives the liquid under a gravity flow. When the pump is located above the level of the liquid being pumped, the pump establishes a vacuum at theContinue Reading