Mono Merlin Pumps
Spare Parts for Merlin Range Pumps
Spare Parts List
Genuine and compatible spare parts for the Mono Merlin progressing cavity pump — a legacy small-industrial range (up to 60 m³/h and 10 bar, single or two-stage, pin-joint drive). Complete Merlin pumps are no longer built, but the parts that wear — stators, rotors, pin-joints, coupling rods and seals — remain available to keep your existing units running. The Merlin superseded the older D, MD, H and MH ranges — if you run one of those, we can help too.
Common Wear & Service Parts
✓ Tick the parts you need — the rotating parts and wear items are still supplied for the Merlin range. Not sure which, or need the exact spec? Add a photo of your pump nameplate and we’ll identify it for your model.
| Select | Wear / Service Item | Function & when to replace |
|---|---|---|
| Primary Wear — Pumping Element | ||
| Stator | The primary wear item — choose the elastomer (natural rubber / nitrile / Hypalon / neoprene) to suit your fluid. Replace with the rotor as a matched set when output drops. | |
| Rotor | Nitralloy or chrome-plated; replace as a matched set with the stator. | |
| Drive & Coupling (Pin-Joint) | ||
| Coupling / Connecting Rod | Transmits drive to the rotor; replace if worn at the joints. | |
| Pin-Joint Kit | Pins, bushes and sealing boots at each end of the rod — the classic Merlin wear point; replace as a set. | |
| Drive Shaft | Replace if scored or worn at the seal / bearing journals. | |
| Sealing | ||
| Mechanical Seal | For mechanical-seal builds — replace on leakage. (Tell us if your pump runs a packed gland instead.) | |
| Gland Packing Set | For packed-gland builds — repack set with lantern ring. | |
| Shaft Sleeve | Runs under the seal or gland; replace when grooved. | |
| Body & Consumables | ||
| Gaskets / O-Ring Set | Renew whenever the pump is opened for service. | |
| Bearings | Bearing-housing set on bareshaft units; replace on noise or play. | |
| Full Service Kit | Stator + rotor + pin-joints + seal/gland + gaskets as a matched set for a complete rebuild. | |
How we confirm the exact part: the current Mono manuals identify parts by exploded diagram only, so we quote genuine parts against your unit’s model & serial number. Tick the items above and add a nameplate photo — we’ll confirm the correct part, in the right size, material and stage, for your exact Merlin pump.
Models
Spare parts are available across the Merlin range in single- and two-stage builds. Find your model code on the pump nameplate.
Single-Stage
Two-Stage
Range & Specifications
| Model coding | Merlin build code (frame + build + stage) — your exact code is on the pump nameplate |
| Capacity | Up to 60 m³/h |
| Maximum pressure | Up to 10 bar |
| Stages | Single or two-stage |
| Drive | Pin-joint, self-priming |
| Body | Cast iron or stainless steel |
| Rotor | Nitralloy or chrome-plated |
| Stator options | Natural rubber, nitrile, Hypalon, neoprene or cast urethane (selected for the pumped fluid) |
| Sealing | Mechanical seal or packed gland |
| Availability | Rotating parts and wear parts supplied; complete pumps and new castings discontinued |
| Supersedes | Mono D, MD, H and MH ranges |
Troubleshooting
Pump will not run
Likely cause: overload tripped, no power, or a seized pumping element. Action: reset the overload and check the supply; turn the pump by hand to free it and check for a blockage.
Reduced or no output
Likely cause: worn stator and rotor, or a blocked suction / delivery line. Action: replace the stator and rotor as a matched set; clear any blockage and check for air leaks on the suction side.
Pump runs but will not prime or pump
Likely cause: worn stator / rotor, an air leak on the suction, or incorrect direction of rotation. Action: confirm rotation (see below), check the suction joints, and inspect the stator, rotor and coupling rod.
Noisy or vibrating
Likely cause: worn pin-joints, or starved suction. Action: inspect and replace the pin-joint kit and boots; slow the pump or improve the suction condition.
Leakage at the seal or gland
Likely cause: worn mechanical seal or gland packing, or a grooved shaft sleeve. Action: re-pack or adjust the gland, or replace the mechanical seal and the shaft sleeve.
Rapid stator / rotor wear
Likely cause: dry running, over-pressure, or abrasive fluid. Action: never run the pump dry; keep the duty within 10 bar and check for a blocked delivery line. Consider a harder-wearing stator elastomer for abrasive duty.
Direction of rotation (important)
Likely cause: supply phased for the wrong rotation. Action: confirm correct rotation before start-up — running a progressing-cavity pump in reverse can unscrew the rotor and coupling rod and cause damage.
Request for Quotation
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