MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

14Unfortunately, none of these classification systems include thenumerous early devices, many of which are still utilized in developingcountries and are included in this paper. Therefore, it was necessary todevelop such an all-encompassingsystem which would be the basis forfurther discussion. Since all devices can be grouped under one of thetwo methods of increasing head (11 in Table 2.1)--positive displacementor kinetic --these are the two primary classes for the system shown inTable 2.2 and the basis for the breakdown of alldevices and discussionof their operation in Chapters 3 and 4. Within each of these two primaryclasses, Table 2.2 further suggests an arrangement of sub-classes, utilizingseveral of the criteria listed in Table 2.1.It should also be mentioned that the terminology used throughoutthis paper reflects either the most commonly used nomenclature whereseveral terms exist for the same device or characteristic, or the mostphysically correct nomenclature where currently popular terms are confusingor misused. This is further explained in the following section andChapters 3 and 4.2.2 General Terminology and TheorySeveral basic principles are common to all types of water liftingmethods. Before selecting a specific method or installation for a givensituation, several characteristics, e.g., head, discharge, and power,must be considered--see Section 5.2. These considerations apply equallyas well for the manually-operated devices such as the shadouf as for thehigh-speed centrifugal pump. Therefore, this section discusses the basicwater lifting parameters; head, discharge, power and efficiency as theyapply to allmethods.