When the pumps are joined in series then | Agrigyan

• ISSS Soil Particle Size Classification:
• According to the International Society of Soil Science (ISSS) standards:
• Coarse sand: $2.0\text{ mm}$ to $0.2\text{ mm}$
• Fine sand: $0.2\text{ mm}$ to $0.02\text{ mm}$ ($0.02 - 0.2\text{ mm}$)
• Silt: $0.02\text{ mm}$ to $0.002\text{ mm}$
• Clay: $\lt 0.002\text{ mm}$
• USDA Comparison: USDA classifies very fine sand as $0.1 - 0.05\text{ mm}$ and silt as $0.05 - 0.002\text{ mm}$.
• Conclusion: Fine sand diameter ranges from 0.02 to 0.2 mm (Option 2).

Correct option: (2) 0.02 to 0.2mm

• Centrifugal Pumps in Series Operation:
• Pumps in Series: The discharge outlet of the first pump is piped directly into the suction inlet of the second pump.
• Discharge ($Q$): The mass flow rate passes sequentially through both pumps; hence total discharge remains equal to that of a single pump ($Q_{\text{total}} = Q_1 = Q_2$).
• Total Head ($H$): Each pump imparts its individual pressure head to the flowing liquid; thus heads add algebraically ($H_{\text{total}} = H_1 + H_2$).
• Pumps in Parallel: Discharge doubles while head remains constant.
• Conclusion: Only delivery head increases (Option 3).

Correct option: (3) only delivery head increases