Question

The pumping system shown below consists of a suction pipe of length 3m and diameter 80mm; delivery pipe of length 6m and diameter 80mm; 4 elbows, each with a loss coefficient of k = 0.3; total static lift = 6m; tank entry and exit loss coefficients 0.5 and 1.0, respectively; suction and delivery pipe friction factor f = 0.007Darcy. A Robuschi 150-500 pump rotates at 1470 rpm and the desired flow rate is a minimum of 200 m3/h. Complete the following tasks: 1. Draw the system curve as described above on the Roubuschi pump curve data sheet supplied. Work in increments of Q 50m3/h starting at 0 (7-point curve) 2. Would you advise the client to select the ?400 or ?460 impeller? Give two reasons for your answer. If the ?400 impeller is used: Assume: • the gauge pressure in the suction tank at 115 kPa, • the vapour pressure of the water at its average operating temperature at 20C • suction height as 1.5 m. 3. Is the pump likely to cavitate? Support answer with a NPSH calculation approach. 4. Describe two steps that could be taken to reduce the likelihood of cavitation.

          The pumping system shown below consists of a suction pipe of length 3m and diameter 80mm; delivery pipe of length 6m and diameter 80mm; 4 elbows, each with a loss coefficient of k = 0.3; total static lift = 6m; tank entry and exit loss coefficients 0.5 and 1.0, respectively; suction and delivery pipe friction factor f = 0.007Darcy. A Robuschi 150-500 pump rotates at 1470 rpm and the desired flow rate is a minimum of 200 m3/h.

Complete the following tasks:

1. Draw the system curve as described above on the Roubuschi pump curve data sheet supplied. Work in increments of Q 50m3/h starting at 0 (7-point curve)

2. Would you advise the client to select the ?400 or ?460 impeller?
Give two reasons for your answer.

If the ?400 impeller is used:

Assume:
• the gauge pressure in the suction tank at 115 kPa,
• the vapour pressure of the water at its average operating temperature at 20C
• suction height as 1.5 m.

3. Is the pump likely to cavitate? Support answer with a NPSH calculation approach.

4. Describe two steps that could be taken to reduce the likelihood of cavitation.

The pumping system shown below consists of a suction pipe of length 3m and diameter 80mm; delivery pipe of length 6m and diameter 80mm; 4 elbows, each with a loss coefficient of k = 0.3; total static lift = 6m; tank entry and exit loss coefficients 0.5 and 1.0, respectively; suction and delivery pipe friction factor f = 0.007Darcy. A Robuschi 150-500 pump rotates at 1470 rpm and the desired flow rate is a minimum of 200 m3/h.

Complete the following tasks:

1. Draw the system curve as described above on the Roubuschi pump curve data sheet supplied. Work in increments of Q 50m3/h starting at 0 (7-point curve)

2. Would you advise the client to select the ?400 or ?460 impeller?
Give two reasons for your answer.

If the ?400 impeller is used:

Assume:
• the gauge pressure in the suction tank at 115 kPa,
• the vapour pressure of the water at its average operating temperature at 20C
• suction height as 1.5 m.

3. Is the pump likely to cavitate? Support answer with a NPSH calculation approach.

4. Describe two steps that could be taken to reduce the likelihood of cavitation.

Added by Brett G.

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