- Problem No 9 Fig 9 Centrifugal Pump Pumps Water From The Reservoir A To Reservoir B Difference Of Levels In The Reserv 1 (215.17 KiB) Viewed 49 times
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Problem No 9 Fig. 9 Centrifugal pump pumps water from the reservoir A to reservoir B. Difference of levels in the reservoirs is a: the highest point of the pipeline is elevated by b over the liquid level in the upper reservoir. Minor losses on suction line are as follows: Entrance from the reservoir to the pipe (K.=0.5), stock check valve with strainer, hinged disk (K=1.05), elbow 90°, gate valve. Minor losses on discharge line are as follows: swing check valve; gate valve; 90° elbow, entrance from the pipe to the reservoir (K) = 1.0). Table 9 Description of the pipeline Description of the pipeline Parameters Variant I 6 Difference of liquid levels in reservoirs a (m) 2.0 Elevation of the highest point b (m) 4.5 Length of suction pipe /, (m) 25 Diameter of the suction pipe d, (mm) 150 Length of discharge pipe 12 (m) 722 Diameter of the discharge pipe d, (mm) 80 Required capacity of the pump (m/h) 230 Temperature of the pumped water tº 87 Type of the pump (GRUNDFOS) NB/NK series 1. Select the pump, which will ensure required volumetric capacity Q. If the required flow rate cannot / ensured for the given type of pump (for example the hydraulic losses are too high), increase the pipes diameter so that the parameters can be reached. 2. Determine what will be the head H, efficiency 71 and power consumption N. 3. What should be pumps speed N in order to increase pumps volumetric capacity Q by 10%? 4. What should be the new diameter D, to get volumetric capacity decrease of 10%? Estimate the annular operation cost increase if the same capacity is ensured not by trimming of impeller but by throttling. Assume the pump is constantly working. 5. Which connection (serial or parallel) of the selected pumps in the given network will ensure bigger volumetric flow rate? 6. What will be the gage pressure at the highest point of discharge pipe (swing check valve; gate valve; and 90° elbow are in a fragment from the pump to the highest point)? 7. Find the allowable suction height (to ensure protection from cavitation).