Grundfos NKG Pumps
Spare Parts for NKG Range Pumps
Product Summary
Genuine and compatible spare parts for the Grundfos NKG long-coupled end-suction pump (ISO 2858), used across Australia for HVAC chilled and condenser water, district heating, water supply, irrigation and industrial process duties. Every NKG from the NKG 50-32-160 to the NKG 200-150-500 shares the same build (single impeller, replaceable wear rings, mechanical shaft seal and a bearing bracket coupled to a separate motor), so tick what you need and we’ll match the exact kit to your nameplate (e.g. NKG 125-100-200/219).
Spare Parts List
✓ Tick the parts you need. Grundfos NKG service kits are matched to pump size, impeller diameter, bearing design and shaft seal code, so your nameplate model is all we need to get them right. Not sure which items? Add a photo of the nameplate and we’ll work out the kit for you.
| Select | Wear / Service Item | Function & when to replace |
|---|---|---|
| Common Service Kits | ||
| Shaft Seal Kit | Mechanical shaft seal with its fitting parts, matched to your seal code (standard BQQE: rubber bellows, SiC/SiC, EPDM; cartridge, tandem, back-to-back seals and gland packing to order). Replace at the first sign of leakage. | |
| Impeller Kit | Impeller in cast iron or 316 stainless, trimmed to your diameter (e.g. /219), with its key, nut and washer. Replace if eroded, cracked or out of balance. | |
| Wear Ring Kit | Replaceable bronze wear rings that seal the impeller eye. Worn rings cost flow and head; renew them at any rebuild. | |
| O-ring & Gasket Kit | The O-ring between pump housing and cover plus plug seals, in EPDM or FKM. Renew whenever the pump is opened. | |
| Bearing Kit | Ball bearings and bearing seals for the bearing bracket, in the standard or heavy duty design on your pump. Replace if the bearings run hot, rough or noisy, or at a major overhaul. | |
| Other Core Parts | ||
| Shaft Kit | AISI 316 stainless pump shaft for your bearing bracket and pump size. Replace if scored at the seal seat, bent or worn at the bearing or impeller fit. | |
| Bearing Bracket | The complete bearing bracket that carries the shaft and bearings. The quickest fix when the bracket or shaft is damaged. | |
| Coupling | Flexible coupling (standard or spacer type) between pump and motor shafts. Replace the elements if worn, cracked or causing vibration. | |
| Coupling Guard | Guard and fasteners covering the coupling, sized to your pump and motor. | |
| Replacement Motor | Foot-mounted motor matched to your kW, frame and speed (2-pole 2900 rpm or 4-pole 1450 rpm). NKG is supplied bare shaft, so we confirm the motor from its own nameplate. | |
| Pump Housing | Cast iron volute casing with AS 2129 Table E flanges, matched to your pump size. Replace if cracked, badly corroded or eroded. | |
| Complete Replacement Pump | When a rebuild doesn’t stack up, we quote a like-for-like NKG (bare shaft, or base-up with motor, coupling, guard and base plate) from the model on your nameplate. | |
How we confirm the exact part: Grundfos NKG kits depend on pump size, impeller diameter, bearing design (standard or heavy duty), coupling type, material code and shaft seal code. Your nameplate carries all of it, in the model (e.g. NKG 125-100-200/219 A2-F-A-E-BQQE) and the product number. Tick the items above and add a nameplate photo, and we’ll confirm the correct part and price for your exact pump.
Models
Spare parts are available for every NKG size in the current Grundfos Australia range. In the model (e.g. NKG 125-100-200/219), 125 and 100 are the inlet and outlet sizes (DN), 200 the nominal impeller diameter and 219 the actual impeller diameter in mm.
Models & Key Specifications
| Size (in-out) | Casing sizes | Connections (in / out) | 2-pole (2900 rpm) | 4-pole (1450 rpm) |
|---|---|---|---|---|
| NKG 50-32 | 160, 200 | DN50 / DN32 | 160, 200 | 160, 200 |
| NKG 65-40 | 200, 250, 315 | DN65 / DN40 | 200, 250, 315 | 200, 250, 315 |
| NKG 65-50 | 160 | DN65 / DN50 | 160 | 160 |
| NKG 80-50 | 200, 250, 315 | DN80 / DN50 | 200, 250 | 200, 250, 315 |
| NKG 80-65 | 160 | DN80 / DN65 | 160 | 160 |
| NKG 100-65 | 200, 250, 315 | DN100 / DN65 | 200, 250, 315 | 200, 250, 315 |
| NKG 100-80 | 160 | DN100 / DN80 | 160 | 160 |
| NKG 125-80 | 160, 200, 250, 315, 400 | DN125 / DN80 | 160, 200, 250 | 160, 200, 250, 315, 400 |
| NKG 125-100 | 160, 200, 250, 315, 400 | DN125 / DN100 | 160, 200, 250, 315 | 160, 200, 250, 315, 400 |
| NKG 150-125 | 200, 250, 315, 400, 500 | DN150 / DN125 | 200, 250, 315 | 200, 250, 315, 400, 500 |
| NKG 200-150 | 200, 250, 315, 400, 500 | DN200 / DN150 | 200, 250, 315 | 200, 250, 315, 400, 500 |
All sizes: bare-shaft pump end (base-up versions with motor, coupling, guard and base plate on request), liquid temperature −25 °C to +120 °C (clean water / glycol), PN16, AS 2129 Table E flanges, standard shaft seal BQQE (others on request). Cast iron housing with cast iron or 316 impeller, 316 shaft, bronze wear rings. Standard bearings L10 17,000 h; heavy duty bearings L10 100,000 h.
Troubleshooting
Pump will not start
Likely cause: no supply, a tripped motor protection or fuse, or a seized pump. Action: check the supply and reset the protection; with the power isolated, turn the shaft by hand at the coupling. A pump that won’t turn needs inspection of the impeller, wear rings and seal.
Motor protection trips repeatedly
Likely cause: overload from running well right of the duty curve (low system resistance), a rubbing impeller, failing bearings or a phase fault. Action: check the voltage on all phases and the motor current; throttle to the duty point; inspect the impeller and bearings; confirm the impeller diameter suits the duty.
Low flow or head
Likely cause: worn wear rings or impeller, air in the pump, a blocked suction strainer or impeller, wrong rotation. Action: vent the pump and check the suction side; clean the strainer and impeller; confirm rotation; if output still falls short, replace the wear ring kit and impeller kit.
Noise or vibration
Likely cause: cavitation (insufficient NPSH), air in the pump, a damaged or out-of-balance impeller, worn bearings, worn coupling or misalignment, or pipe strain on the flanges. Action: check suction pressure and NPSH; vent the pump; inspect the impeller and bearings; check coupling alignment; support the pipework so the pump isn’t carrying it.
Leaking at the shaft seal
Likely cause: worn or damaged seal faces, often from dry running, abrasive particles or a seal material that doesn’t suit the liquid. Action: replace the shaft seal kit and renew the O-rings. Never run a NKG dry: the seal relies on the pumped liquid for cooling and lubrication.
Leaking at the pump housing
Likely cause: a perished O-ring between the pump housing and cover, a failed flange gasket, or a cracked housing. Action: fit the O-ring and gasket kit and tighten the housing bolts evenly to Grundfos specification; replace the housing if it is cracked.
Bearings running hot or noisy
Likely cause: worn bearings, too much or too little grease, coupling misalignment or excessive pipe load. Action: check alignment and lubrication; replace the bearing kit if the bearings are rough or noisy. Heavy duty bearing versions are available for demanding duties.
Request for Quotation
Selected Parts:
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Not sure which parts? Just send a photo of the nameplate or part below.