Pump selection for water supply: low discharge, high head, low maintenance; delivery need not be continuous; high rotational speed is not necessary. Which pump suits best?

Introduction / Context:
Selecting a pump depends on discharge, head, energy source, maintenance, and operational continuity. Some devices convert a portion of a larger low-head flow into a smaller high-head discharge using hydraulic principles rather than electric motors.

Given Data / Assumptions:

• Low discharge required.
• High delivery head required.
• Low maintenance preferred.
• Continuous delivery is not essential.
• High rotational speed is not required (or unavailable).

Concept / Approach:
A hydraulic ram (hydram) uses water hammer from a drive flow to lift a fraction of the water to a higher elevation. It has few moving parts, needs no external power (other than a fall in the drive supply), and delivers intermittently in pulses, matching the stated requirements better than conventional pumps.

Step-by-Step Solution:
Match low discharge–high head: hydraulic ram lifts a small fraction to high head.Maintenance: minimal due to simple construction (check valves, air chamber).Continuity: delivery is pulsating/intermittent — acceptable per problem statement.Speed: no rotating machinery is necessary.Therefore select hydraulic ram.

Verification / Alternative check:
Where a reliable fall and source flow exist, hydrams run for years with minimal attention; widely used in rural water supply.

Why Other Options Are Wrong:

• Reciprocating pump: high head possible but demands prime mover, higher maintenance, and typically continuous operation.
• Centrifugal pump: better for moderate head, higher discharge, requires power and continuous operation.
• Air-lift and jet pumps: need compressors or motive fluid; efficiency and maintenance do not match the constraints.

Common Pitfalls:
Confusing “intermittent delivery acceptable” with a requirement for continuous flow; ignoring the need for a driving head for hydram operation.

Final Answer:
Hydraulic ram