Reciprocating pumps – choose the most appropriate limitation for water supply use Which single statement best describes a commonly cited limitation of reciprocating pumps for potable water service?

Introduction / Context:
Reciprocating pumps are positive-displacement devices used for small to moderate discharges against high heads. In municipal practice, they are selected carefully because certain water qualities and operating conditions cause rapid wear or undesirable hydraulics.

Given Data / Assumptions:

• Potable water duty, not viscous chemicals.
• Typical reciprocating pump with valves and plungers.
• Focus on the most general limitation relevant to raw/treated water conveyance.

Concept / Approach:
Suspended grit and sand abrade valves, seats, and cylinders of reciprocating pumps, increasing maintenance and reducing reliability. Therefore such pumps are avoided for sediment-laden flows unless special protection is provided. Cost ratios (e.g., 4×) are not fixed, and pulsation is inherent rather than “perfectly steady.” Suitability for variable head depends on controls and is not an absolute limitation.

Step-by-Step Solution:
Identify what most directly limits service → sensitivity to sediment and abrasives.Reject exaggerated or non-general claims (fixed cost multiples, “perfectly steady” flow).Select the statement about unsuitability for sediment-bearing water.

Verification / Alternative check:
Manufacturer manuals recommend adequate straining/clarification ahead of reciprocating pumps and note accelerated wear with solids.

Why Other Options Are Wrong:

• (a) Not universally true; positive-displacement units can handle head variations with relief/bypass.
• (b) Cost factor is not a standard constant.
• (d) Opposite is true; flow is pulsating unless smoothed by air vessels.
• (e) Inapplicable because (c) is valid.

Common Pitfalls:
Ignoring the need for air vessels and surge control; using such pumps upstream of grit removal.

Final Answer:
They are not suitable for pumping water containing sediments