Grundfos DMX Pumps
Spare Parts for DMX Range Pumps
Product Summary
Genuine and compatible spare parts for the Grundfos DMX motor-driven mechanical diaphragm dosing pump, used across Australia for set-and-forget chlorination, coagulant, pH and chemical dosing in water and wastewater treatment, mining and industry. Every DMX 221 and DMX 226 uses the same wet-end build (diaphragm, suction and discharge valves, dosing head), so tick what you need and we’ll match the exact kit to your nameplate (e.g. DMX 50-10 B-PVC/E/C).
Spare Parts List
✓ Tick the parts you need. Grundfos DMX kits are matched to the dosing head material and pump size, 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 | ||
| Spare Parts Kit | The standard DMX service kit: suction and discharge valves with the diaphragm, matched to your pump size and head, gasket and valve ball codes. Fit it at the service interval or whenever output drops off. | |
| Diaphragm Kit | Replacement PTFE-coated diaphragm for your head size. Replace if chemical shows at the leakage hole or at the service interval. | |
| Valve Kit | Complete suction and discharge valves with balls, seats and seals. The usual fix for lost prime, back-flow or inaccurate dosing. | |
| Complete Dosing Head | Fully assembled dosing head for your model and materials. The quickest fix for a cracked, chemically attacked or heavily scaled head. | |
| Drive Lubricant Kit | Grundfos lubricant for the DMX drive, used when the gear and eccentric are serviced or the diaphragm return parts are renewed. | |
| Other Core Parts | ||
| Motor | Replacement motor, 3-phase or 1-phase, matched to your DMX model and supply. | |
| Injection Unit | Injection unit at the dosing point, stopping back-flow into the discharge line. Replace if scaled, blocked or leaking. | |
| Foot Valve | Foot valve with strainer for the end of the suction line, sized for DMX flows (up to 460 or 1150 l/h). | |
| Pressure Relief / Loading Valve | Pressure relief valve to protect the pump and discharge line, or a pressure loading valve to hold a steady counter pressure and stop siphoning. | |
| Pulsation Damper | Smooths the pulsing discharge of a mechanical pump and protects the line, especially on long or rigid discharge pipework. | |
| Connection Kit / Inlays | Union nuts, hose inlays, hose nipples and glue/weld adaptors for the pump inlet and outlet (G5/8, G5/4 or G2). | |
| Complete Replacement Pump | When a repair doesn’t stack up, we quote a like-for-like DMX from the model on your nameplate. | |
How we confirm the exact part: DMX kits depend on pump model (221 or 226), head size, dosing head material, gasket and valve ball. Your nameplate carries all of it in the type key (e.g. DMX 50-10 B-PVC/E/C: PVC head, E = EPDM gaskets, C = ceramic balls; V = FKM, G = glass) 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 DMX size in the current Grundfos Australia range. The first number on your nameplate (e.g. DMX 50-10) is the nominal flow in l/h; the second is the maximum pressure in bar.
Models & Key Specifications
| Model | Pump type | Max flow (l/h) | Max pressure (bar) | Connection |
|---|---|---|---|---|
| DMX 16-12 | 221 | 16 | 12 | G5/8 |
| DMX 27-12 | 221 | 27 | 12 | G5/8 |
| DMX 50-10 | 221 | 50 | 10 | G5/8 |
| DMX 115-3 | 221 | 115 | 3 | G5/4 |
| DMX 132-10 | 226 | 132 | 10 | G5/4 |
| DMX 199-8 | 226 | 199 | 8 | G5/4 |
| DMX 280-8 | 226 | 280 | 8 | G5/4 |
| DMX 321-6 | 226 | 321 | 6 | G5/4 |
| DMX 460-6 | 226 | 460 | 6 | G5/4 |
| DMX 525-3 | 226 | 525 | 3 | G2 |
| DMX 765-3 | 226 | 765 | 3 | G2 |
All AU range models: PVC dosing head with EPDM or FKM gaskets; ceramic valve balls, glass on the DMX 525-3 and 765-3. Manual stroke length control (10:1, 10–100% scale). DMX 221: 0.09 kW motor, glass-fibre reinforced gear housing. DMX 226: 0.37 kW motor, aluminium gear housing. Flow figures at 50 Hz; IP65 motors, 3-phase or 1-phase.
Troubleshooting
Pump runs but does not dose
Likely cause: air in the dosing head, a dry or blocked foot valve, worn or dirty valves, or a blocked injection unit. Action: prime the pump with the discharge open to atmosphere; clean the foot valve strainer; check the injection unit; if output does not return, fit the valve kit.
Air lock or gassing (sodium hypochlorite, peroxide)
Likely cause: outgassing chemical collecting in the dosing head. Action: keep the suction line short and flooded where possible, run the pump at a longer stroke length and higher speed, and fit a deaeration (vent) arrangement back to the tank.
Chemical at the leakage hole (diaphragm leak)
Likely cause: a ruptured or fatigued diaphragm, often from running against excessive pressure. Action: isolate the pump, flush the dosing head and fit the spare parts kit. Do not keep running: chemical can reach the drive behind the diaphragm.
Pressure too high, line or pump knocking
Likely cause: a closed or blocked discharge line, a seized injection unit, or counter pressure above the pump rating. Action: check discharge valves are open, clean or replace the injection unit, and fit a pressure relief valve. A pulsation damper reduces peaks on long lines.
Dosing rate inaccurate or too high
Likely cause: worn valve balls and seats, siphoning through the pump when the discharge is lower than the tank or under suction, or too little pressure across the head (under 1 bar). Action: fit the valve kit and install a pressure loading valve.
Noisy drive or motor overheating
Likely cause: worn gear or eccentric parts, lack of lubricant, a phase fault, or running against excessive pressure. Action: check the supply and motor current, confirm the counter pressure, and have the drive inspected and re-lubricated; replace the motor if it has failed.
Leaking at the dosing head or connections
Likely cause: loose dosing head screws, perished seals, or damaged union nuts and inlays. Action: fit the spare parts kit, torque the head screws evenly and replace damaged connection parts.
Request for Quotation
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Not sure which parts? Just send a photo of the nameplate or part below.