Three strokes at 120 degrees mean at least one plunger is always delivering, which reduces pulsation to a level a small damper handles, and the crankshaft loads largely balance. More cylinders smooth further but with diminishing returns against real added cost and complexity.

So the oil-lubricated mechanism never contacts the pumped liquid. Wear particles, abrasives and chemicals stay on the wet side and cannot reach the bearings and crankshaft, which is what allows the drive end to last far longer than the consumable fluid end and makes the pump economically rebuildable.

Ceramic-coated or solid ceramic for abrasive and high-pressure service, and stainless or plated steel for cleaner duty. Ceramic resists the abrasion that would otherwise score a plunger and then destroy packing rapidly, so it is standard wherever the fluid carries any solids.

Packing and valve life, since both are consumables working at full pressure on every stroke. The interval depends on pressure, speed, fluid cleanliness and temperature, and is usually established from experience on the specific duty rather than from a general figure.

Water jetting and hydrodemolition, industrial and vehicle cleaning, reverse osmosis feed, hydrostatic testing, misting and dust suppression, and agricultural spraying. The common requirement in all of them is continuous running at a set high pressure with reasonably clean liquid, which is the condition this pump is built to sustain for long periods.

Usually a small one, even with three cylinders. The residual pulsation is modest but still enough to fatigue pipework, disturb instruments and affect spray quality over time. A damper sized for the pump is inexpensive relative to the pipework it protects.

Most often incomplete cylinder filling from a restricted or inadequate suction, which lets the plunger hammer as the fluid catches up. It can also be worn valves or a failing bearing. Suction problems are by far the most common and are usually fixed by pipework rather than by the pump.