tailieunhanh - Mechanical Science HandbooksMechanical Science Handbooks 10000 Part 12

Tham khảo tài liệu 'mechanical science handbooksmechanical science handbooks 10000 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Pumps DOE-HDBK-1018 1-93 CENTRIFUGAL PUMP OPERATION Centrifugal Pump Operation Summary Cont. Pump runout is the maximum flow that can be developed by a centrifugal pump without damaging the pump. The greater the head against which a centrifugal pump operates the lower the flow rate through the pump. The relationship between pump flow rate and head is illustrated by the characteristic curve for the pump. Centrifugal pumps are protected from dead-heading by providing a recirculation from the pump discharge back to the supply source of the pump. Centrifugal pumps are protected from runout by placing an orifice or throttle valve immediately downstream of the pump discharge and through proper piping system design. Rev. 0 Page 17 ME-03 POSITIVE DISPLACEMENT PUMPS DOE-HDBK-1018 1-93 Pumps POSITIVE DISPLACEMENT PUMPS Positive displacement pumps operate on a different principle than centrifugal pumps. Positive displacement pumps physically entrap a quantity of liquid at the suction of the pump and push that quantity out the discharge of the pump. EO STATE the difference between the flow characteristics of centrifugal and positive displacement pumps. EO Given a simplified drawing of a positive displacement pump CLASSIFY the pump as one of the following a. Reciprocating piston pump e. Moving vane pump b. Gear-type rotary pump f. Diaphragm pump c. Screw-type rotary pump d. Lobe-type rotary pump EO EXPLAIN the importance of viscosity as it relates to the operation of a reciprocating positive displacement pump. EO DESCRIBE the characteristic curve for a positive displacement pump. EO DEFINE the term slippage. EO STATE how positive displacement pumps are protected against overpressurization. Introduction A positive displacement pump is one in which a definite volume of liquid is delivered for each cycle of pump operation. This volume is constant regardless of the resistance to flow offered by the system the pump is in provided the capacity of the power .