Pumps/pumping centrifugal pump installation

More pumps fail as a direct result of improper installation than any other single factor. The predominant reasons for these failures include starvation, caused by inadequate or inconsistent suction conditions distortion, caused by pipe strain or improper foundation and turbulent that results from piping or entrained gas problems. Centrifugal pump installation must follow Hydraulic Institute Standards, which provide specific guidelines to prevent these installation and performance problems. This chapter will address the fundamental requirements for proper installation. 

A centrifugal pump installed in a pipeline as conveying device is an excellent mixing device [39]. One or more stirrers can also be incorporated on the same shaft in a short pipe section ("in line blending ) [191, 587]. 

MICHELL VERTICAL THRUST BEARING FOR A CENTRIFUGAL PUMP. INSTALLED AT COHUNA ON THE MURRAY RIVER, VICTORIA, 1907... 

Pump Suction. The net positive suction head required (NPSHR) affects the resistance on the suction side of the pump. If it drops to or near the vapor pressure of the fluid being handled, cavitation and loss of performance occurs (13). The NPSHR is affected by temperature and barometric pressure and is of most concern on evaporator CIP units where high cleaning temperatures might be used. A centrifugal booster pump may be installed on a homogenizer or on the intake of a timing pump to prevent low suction pressures. 

A more economical alternative is found in a submersible pump where the pump, directly coupled with the prime mover, is slid into the tubewell through narrow pipes. Narrow pipes are easy to sink into rocky terrain or very deep water levels. They are less expensive and are easy to install due to the elimination of the need for a pump house. Once the unit is slid into the well it requires little maintenance. (See Figures 7.5-7.7.) Such pumps have a standard centrifugal multistage arrangement, and the motors are required to work under water or any other liquid. These motors have an exclusive application for submersible pumps. 

This system requires a pump with a best effieieney point (BFP) of 94 feet at 300 gallons per minute. If this is a eonventional industrial centrifugal pump with a BFiP of 94 feet, the shut-off head should be approximately 110 feet. And if the motor is a standard NFMA four pole motor spinning at about 1800 rpm, the diameter of the impeller should be approximately 10.5 inehes. If this pump were bought off the shelf from local distributor stock, it would probably be a 3 x 4 x 12 model end-suction centrifugal back pullout pump with the impeller machined to about 10.5 inches before installing the pump into the. system. And that s the way it is done. 

A strainer should be used in the pump suction line temporarily for a centrifugal pump and permanently for the rotary positive displacement pump. For the permanent installations, a Y-type strainer with an austenitic stainless strainer basket should be used. The cross-sectional... 

Karassik, I.J., Installation of Centrifugal Pumps, Chemical Processing Mar. 1989. 

Centrifugal pumps, as do most other mechanical equipment, generate dynamic forces that must be absorbed by their foundation. The foundation should have a mass that is at least five times that of the installed pump and driver. In addition, the pump assembly must be properly affixed... 

Very few pump installations follow Hydraulic Institute recommendations. A minority of installations fail to follow reasonable engineering practices or even common sense. Therefore, it should not be a surprise that centrifugal pump applications often exhibit chronic reliability and maintenance problems. 

Installation requirements for rotary positive-displacement compressors are similar to any rotating machine. Review the installation requirements for centrifugal pumps and compressors for foundation, pressure-relief, and other requirements. As with centrifugal compressors, rotary positive-displacement compressors must be fitted with pressure-relief devices to limit the discharge or inter-stage pressures to a safe maximum for the equipment served. 

You must install a centrifugal pump to transfer a volatile liquid from a remote tank to a point in the plant 500 ft from the tank. To minimize the distance that the power line to the pump must be strung, it is desirable to locate the pump as close to the plant as possible. If the liquid has a vapor pressure of 20 psia, the pressure in the tank is 30 psia, the level in the tank is 30 ft above the pump inlet, and the required pump NPSH is 15 ft, what is the closest that the pump can be located to the plant without the possibility of cavitation The line is 2 in. sch 40, the flow rate is 100 gpm and the fluid properties are p = 45 lbm/ft3 and (j, = 5 cP. 

Induction motors are the most frequent in use because of their simple and rugged construction, and simple installation and control. They are constant speed devices available as 3600 (two-pole), 1800, 1200, and 900 rpm (eight-pole). Two speed models with special windings with 2 1 speed ratios are sometimes used with agitators, centrifugal pumps and compressors and fans for air coolers and cooling towers. Capacities up to 20,000 HP are made. With speed... 

Centrifugal pumps serve the industries well, but can be involved in accidents even if they are correctly sized and specified, made of the correct materials, and properly installed. Three pump incidents follow. This first case history involves an explosive incident that occurred during maintenance to remove a defective pump. Incidents two and three occurred during operations. 

SAFETY AND MONITORING INSTALLATIONS ON HIGH-PRESSURE CANNED-MOTOR CENTRIFUGAL PUMPS... 

A typical Fenton s treatment installation requires facilities for storing and dosing chemicals (hydrogen peroxide, ferrous catalyst, acid and alkali for pH adjustment), a reaction tank, a settlement tank or centrifugal pump for solids removal and a UV-VIS lamp if photo-Fenton s is to be employed. The use of Fenton s and photo-Fenton s systems are likely to grow in use over the next decade as environmental legislation becomes more widespread, and as the systems become more efficient. 

Related Calculations. Use the procedure given here for any type of centrifugal pump where the similarity laws apply. When the term model is used, it can apply to a production test pump or to a standard unit ready for installation. The procedure presented here is the work of R. P. Horwitz, as reported in Power magazine [2]. 

Evaluate the pump chosen for the installation. Check the specific speed of a centrifugal pump using the method given in Example 6.20. Once the specific speed is known, the impeller type and approximate operating efficiency can be found from Fig. 6.12. 

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