Grundfos DMH Pumps
Spare Parts for DMH Range Pumps
Product Summary
Genuine and compatible spare parts for the Grundfos DMH hydraulically actuated piston diaphragm dosing pump, the heavy-duty pump used across Australia for high-pressure and continuous chemical dosing in water and wastewater treatment, mining, power generation and process industries. Every DMH 251 to 257 shares the same build (hydraulic oil chamber, diaphragm, suction and discharge valves, built-in relief valve), so tick what you need and we’ll match the exact kit to your nameplate (e.g. DMH 143-10 B-PVC/V/C-X-E1U3U3XEMAG).
Spare Parts List
✓ Tick the parts you need. Grundfos DMH 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 DMH service kit: suction and discharge valves, diaphragm and the oil drain plug gasket, matched to your pump size and head, gasket and valve ball codes. Fit it with fresh hydraulic oil at the service interval. | |
| Diaphragm Kit | Replacement diaphragm for your DMH size (251 to 257). Replace after a diaphragm leak, at the service interval, or if oil and chemical have mixed. | |
| Valve Kit | Complete suction and discharge valves with balls, seats and seals, standard or spring-loaded. The usual fix for lost prime, back-flow or inaccurate dosing. | |
| Hydraulic Oil | Grundfos-specified hydraulic oil for the DMH drive and hydraulic chamber, supplied in the volume for your pump size. Change it at every service and whenever the diaphragm is replaced. | |
| Complete Dosing Head | Fully assembled dosing head for your model and materials. The quickest fix for a cracked, chemically attacked or heavily scaled head. | |
| Other Core Parts | ||
| Motor | Replacement motor matched to your DMH model and supply, including PTC and EX variants where fitted. | |
| 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 DMH flows (up to 1150 l/h). | |
| Pressure Loading Valve | Holds a steady counter pressure on the discharge to stop siphoning and over-dosing. The DMH relief valve protects the pump, but a system relief valve is still recommended. | |
| Pulsation Damper | Smooths the discharge flow and protects long or rigid discharge pipework from pressure peaks. | |
| Connection Kit / Inlays | Union nuts, hose inlays, hose nipples, glue/weld adaptors and DN32 flange parts for the pump inlet and outlet. | |
| Complete Replacement Pump | When a repair doesn’t stack up, we quote a like-for-like DMH from the model on your nameplate. | |
How we confirm the exact part: DMH kits depend on pump size (251 to 257), dosing head material, gasket, valve ball and valve type. Your nameplate carries all of it in the type key (e.g. DMH 143-10 B-PVC/V/C-X-E1U3U3XEMAG: PVC head, V = FKM gaskets, C = ceramic balls, 1 = standard valves; PV = PVDF, T = PTFE, 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 DMH size in the current Grundfos Australia range. The first number on your nameplate (e.g. DMH 143-10) is the nominal flow in l/h; the second is the maximum pressure in bar. A “D” after the pressure marks a twin-head pump.
Models & Key Specifications
| Model | Pump type | Max flow (l/h) | Max pressure (bar) | Dosing head (AU range) |
|---|---|---|---|---|
| DMH 12-16 | 251 | 12 | 16 | PVDF |
| DMH 18-16 | 251 | 18 | 16 | PVDF |
| DMH 23-16 | 251 | 23 | 16 | PVDF |
| DMH 36-16 | 252 | 36 | 16 | PVDF |
| DMH 37-10 | 252 | 37 | 10 | PVDF |
| DMH 45-16 | 252 | 45 | 16 | PVDF |
| DMH 54-16 | 252 | 54 | 16 | PVDF |
| DMH 83-10 | 253 | 83 | 10 | PVDF |
| DMH 100-10 | 253 | 100 | 10 | PVDF |
| DMH 143-10 | 254 | 143 | 10 | PVC |
| DMH 213-10 | 254 | 213 | 10 | PVC |
| DMH 291-10 | 254 | 291 | 10 | PVC |
| DMH 270-10 | 255 | 270 | 10 | PVC |
| DMH 403-10 | 255 | 403 | 10 | PVC |
| DMH 550-10 | 255 | 550 | 10 | PVC |
| DMH 575-10 | 257 | 575 | 10 | PVC |
| DMH 880-10 | 257 | 880 | 10 | PVC |
| DMH 1150-10 | 257 | 1150 | 10 | PVC |
| DMH 1500-4 | 257 | 1500 | 4 | PVC |
AU range: PVDF heads with PTFE gaskets and ceramic balls (DMH 251–253); PVC heads with FKM gaskets and ceramic balls (DMH 254–255) or glass balls (DMH 257). Manual stroke length control (20:1, 5–100% scale), built-in pressure relief valve and diaphragm protection. Motors: 0.06–0.09 kW (251–252), 0.18 kW (253), 0.55 kW (254–255), 1.1 kW (257). Flow figures at 50 Hz.
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; 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 at a longer stroke length, and fit spring-loaded valves or a deaeration arrangement back to the tank.
Diaphragm leak or chemical in the hydraulic oil
Likely cause: a ruptured diaphragm, letting chemical and oil mix. Action: stop the pump, flush the dosing head, fit the spare parts kit and change the hydraulic oil. Pumps with leak detection (PVCL, PVL heads) alarm before damage spreads.
Built-in relief valve opening, pressure too high
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 confirm the duty suits the model. Do not raise the relief valve setting above the pump rating.
Dosing rate low or drifting
Likely cause: worn valves, low or aerated hydraulic oil, siphoning, or too little pressure across the head. Action: check the oil level and condition, fit the valve kit, and install a pressure loading valve if the discharge pressure is low.
Oil leak or noisy drive
Likely cause: a worn drain plug gasket or shaft seal, low oil, or worn drive parts. Action: top up or change the hydraulic oil, renew the drain plug gasket, and have the drive inspected if noise continues.
Motor trips or will not start
Likely cause: a supply or phase fault, overload from excessive counter pressure, or a failed motor. Action: check the supply and motor current, confirm the discharge pressure, and replace the motor if it has failed.
Request for Quotation
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Not sure which parts? Just send a photo of the nameplate or part below.