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Grundfos Unilift Submersible Pumps
Grundfos Unilift AP Wastewater Pump
Grundfos
Grundfos Unilift AP Wastewater Pump
- Price
- From $1,431.65
Grundfos Unilift AP12 Drainage Pump
Grundfos
Grundfos Unilift AP12 Drainage Pump
- Price
- From $1,101.12
Grundfos Unilift KP Submersible Pump
Grundfos
Grundfos Unilift KP Submersible Pump
- Price
- From $661.07
Grundfos Unilift Submersible Pumps
Grundfos Unilift
Submersible Drainage, Effluent & Sewage Pumps
Six stainless-steel submersible platforms on one chassis philosophy — KP and AP12 for drainage, AP35 and AP35B for effluent, AP50 and AP50B for domestic sewage. Solids handling from 0.4 in to 2.0 in, 60 Hz US models, stocked on the Gulf Coast with engineering-led sizing.
0.4–2.0 inSolids passage
140 GPMHighest range max flow
52 ftHighest range max head
115 & 230VSingle phase, 60 Hz
CSA C/USListing
Grundfos builds the Unilift range as vertical, single-stage submersible centrifugal pumps for free-standing installation or installation in a collecting tank. The range splits by what the liquid carries: KP and AP12 are drainage pumps with a semi-open impeller and 0.4 in passage; AP35 and AP50 are vortex-impeller pumps for effluent and sewage, passing 1.4 in and 2.0 in respectively; the AP35B and AP50B Basic models put the same hydraulics in a smooth steel-tube housing on a ring stand, with a horizontal outlet for auto-coupling installation. Enclosure class is IP68 across the range and the wet ends are stainless steel.
We stock the US 60 Hz models with NPT outlets and 25 ft cords — 115 V units with a NEMA 5 plug, 230 V units unplugged for hard wiring. Tell us the solids you have to pass, the lift, the run length and whether there is a water closet on the system, and we will size it. Compare the models below, or call 1-888.510.4036 and we will do it for you. Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial distributor.
The Grundfos Unilift Range
Grundfos walks the range in under three minutes — drainage, effluent and sewage duties side by side.
The Unilift Line
Three listings, six model families. Solids passage is the first decision and it is the one that cannot be fixed later.
Unilift KP
Compact 115 V drainage workhorse
0.4 inMax solids
65 GPMRange max flow
32 ftRange max head
1-1/4 inNPT top outlet
The smallest Unilift, for clean and slightly dirty water with the pump fully or partly submerged. A one-piece stainless sleeve, a single-curved impeller that resists fibre jamming, and guide vanes that lift sand grains into the flow instead of letting them pack the housing. Three motor sizes, all 115 V with a NEMA 5 plug on 25 ft of cable. The models we stock are the manual version — no float switch.
Key specifications
- KP 150, KP 250, KP 350 — 1/4, 1/3 and 1/2 HP nominal
- Liquid 32 to 122 degrees F; pH 4 to 9
- Max installation depth 30 ft below liquid level
- AISI 304 wet end, AISI 431 shaft; IP68, insulation class F
Best forFlooded cellars and buildings, emptying pools, tanks and vessels, domestic wastewater without toilet waste, agriculture, dairy and horticulture.
View Unilift KP
Unilift AP12
Portable or permanent drainage
0.4 inMax solids
140 GPMRange max flow
52 ftRange max head
1-1/2 / 2 inNPT vertical outlet
A heavier drainage pump built to be carried to the job and dropped in. Insulated handle on a one-piece stainless sleeve, clip-on inlet strainer that comes off by hand, and an internal riser pipe perforated to cool the motor. Semi-open backswept impeller with 0.4 in clearance; silicon carbide shaft seal with an oil chamber. Available manual or automatic with an integral float switch.
Key specifications
- AP12.40.04 at 115 V; AP12.40.08 and AP12.50.11 at 230 V
- Liquid 32 to 131 degrees F; pH 4 to 10
- Max installation depth 34 ft below water level
- AISI 304 housing and impeller, AISI 316 sleeve; IP68
Best forGroundwater lowering, drainage and surface-water collecting wells, emptying ponds and tanks, installer and light-industry use as a portable pump.
View Unilift AP12
Unilift AP35 & AP50
Vortex effluent and sewage
1.4 / 2.0 inMax solids
140 GPMRange max flow
49 ftHighest range max head
1-1/2 / 2 inNPT outlet
Four models on one listing. AP35 and AP35B pass 1.4 in for effluent, fibre-carrying laundry waste and domestic wastewater without toilet discharge. AP50 and AP50B pass 2.0 in, which brings toilet discharge into scope. All four use a stainless vortex impeller with a protective cap against long fibres, and all four are automatic with an integral float switch on 230 V.
Key specifications
- AP35 and AP50: free-standing, vertical outlet, liquid to 131 degrees F
- AP35B and AP50B: ring stand, 2 in horizontal outlet, liquid to 104 degrees F
- Spring-mounted wet end on the B models for quick dismantling
- Silicon carbide shaft seal; IP68, insulation class F
Best forSeptic and sludge-treating systems, laundry and light-industry effluent, viaduct and underpass drainage, and — on AP50 and AP50B — outdoor sewage installations below sewer level.
View Unilift AP35 & AP50
Unilift Models Side by Side
Every figure below is a published Grundfos range value for the 60 Hz US model. Maximum flow and maximum head are separate ceilings on the curve, not a duty point you can have at the same time.
| Specification | KP | AP12 | AP35 | AP35B | AP50 | AP50B |
|---|---|---|---|---|---|---|
| Duty class | Drainage | Drainage | Effluent | Effluent | Sewage | Sewage |
| Max solids | 0.4 in | 0.4 in | 1.4 in | 1.4 in | 2.0 in | 2.0 in |
| Toilet discharge | No | No | No | No | Yes, outdoor | Yes, outdoor |
| Range max flow | 65 GPM | 140 GPM | 79 GPM | 92 GPM | 140 GPM | 136 GPM |
| Range max head | 32 ft | 52 ft | 39 ft | 43 ft | 41 ft | 49 ft |
| Impeller | Semi-open | Semi-open | Vortex | Vortex | Vortex | Vortex |
| Outlet | 1-1/4 in NPT vertical | 1-1/2 or 2 in NPT vertical | 1-1/2 in NPT vertical | 2 in NPT horizontal | 2 in NPT vertical | 2 in NPT horizontal |
| Liquid temperature | 32–122 F | 32–131 F | 32–131 F | 32–104 F | 32–131 F | 32–104 F |
| pH range | 4 to 9 | 4 to 10 | 4 to 10 | 4 to 10 | 4 to 10 | 4 to 10 |
| Max install depth | 30 ft | 34 ft | 34 ft | 34 ft | 34 ft | 34 ft |
| Voltage, 1 phase | 115V | 115V or 230V | 230V | 230V | 230V | 230V |
| Level control stocked | Manual | Manual or automatic | Automatic | Automatic | Automatic | Automatic |
| Cord | 25 ft, NEMA 5 | 25 ft, NEMA 5 or no plug | 25 ft, no plug | 25 ft, no plug | 25 ft, no plug | 25 ft, no plug |
| Installation | Free-standing | Free-standing or portable | Free-standing | Ring stand, auto coupling | Free-standing | Ring stand, auto coupling |
| Motor poles | 2 | 2 | 2 | 2 | 2 | 2 |
| Enclosure | IP68 | IP68 | IP68 | IP68 | IP68 | IP68 |
Quick rule. Start with solids, not flow. A water closet anywhere on the system means 2.0 in passage and therefore AP50 or AP50B. No water closet but fibrous waste means AP35 or AP35B. Clean or lightly dirty water with nothing bigger than 0.4 in means KP for the small jobs and AP12 when you need the head or the flow. Choose a B model only when you are installing on an auto coupling and can live with the 104 degrees F limit.
Rated Performance
Grundfos publishes head-flow curves for these pumps but does not tabulate points from them, so no H-Q table appears here. What it does tabulate is the maximum discharge pipe run per model at a given lift, which is the question most installations actually turn on.
Maximum combined pipe run — drainage models
Vertical lift down the left; the figure is the longest combined vertical plus horizontal Schedule 40 PVC discharge run Grundfos allows for that model at that lift.
| Vertical lift | KP 150 | KP 250 | KP 350 | AP12.40.04 | AP12.40.08 | AP12.50.11 |
|---|---|---|---|---|---|---|
| 4–5 ft | 400 ft | 775 ft | 950 ft | 1000 ft | 2700 ft | 3000 ft |
| 8–10 ft | 250 ft | 625 ft | 800 ft | 950 ft | 2250 ft | 2700 ft |
| 12–15 ft | 100 ft | 450 ft | 625 ft | 700 ft | 1900 ft | 2400 ft |
| 16–20 ft | — | 300 ft | 500 ft | 400 ft | 1750 ft | 2100 ft |
| 22–25 ft | — | 75 ft | 175 ft | 200 ft | 1250 ft | 1700 ft |
| 26–30 ft | — | — | 100 ft | 75 ft at 27 ft | 1000 ft | 1200 ft |
| 35 ft | — | — | — | — | 750 ft | 800 ft |
| 40 ft | — | — | — | — | 350 ft | 500 ft |
| 45 ft | — | — | — | — | 75 ft | 300 ft |
| 50 ft | — | — | — | — | — | 100 ft |
KP figures are published at 4, 8, 12, 14, 16, 20, 22, 24 and 26 ft; AP12 figures at 5, 10, 15, 20, 25, 27, 30, 35, 40, 45 and 50 ft. Rows are banded to fit one table — work from the exact figures in the data booklet before committing a long run.
Maximum combined pipe run — effluent and sewage models
| Vertical lift | AP35.40.08 | AP35B.50.08 | AP50.50.11 | AP50B.50.11 |
|---|---|---|---|---|
| 5 ft | 1250 ft | 1500 ft | 1750 ft | 2200 ft |
| 10 ft | 1000 ft | 1200 ft | 1250 ft | 1900 ft |
| 15 ft | 750 ft | 800 ft | 1000 ft | 1500 ft |
| 20 ft | 500 ft | 500 ft | 750 ft | 1000 ft |
| 25 ft | 250 ft | 175 ft | 500 ft | 750 ft |
| 26 ft | — | 75 ft | — | — |
| 30 ft | 150 ft | — | 250 ft | 450 ft |
| 32 ft | — | — | 75 ft | — |
| 35 ft | 50 ft | — | — | 100 ft |
Read it as a guide, not a guarantee. Grundfos states these overviews are intended as a guide and accepts no liability for installations that do not comply with them. If a non-return valve is fitted, deduct roughly 0.6 ft of head from the vertical length. Measure the vertical height of the discharge pipe from the pump stop level.
Head on this page is quoted in feet, as Grundfos publishes it. Multiply feet of head by 0.433 to convert to psi. For a duty point at a specific flow, request the manufacturer curve for the model — we will pull it from Grundfos and send it with the quote.
Sizing & Best Practices
The method Grundfos publishes for these pumps, in the order the decisions actually get made.
1. Establish system capacity in GPM
Count the water fixtures on the system and total their fixture-unit values — a bathroom group with a flush-tank water closet is 6 units, with a direct flush valve 8; a washing machine is 2; a kitchen sink is 2, or 3 with a garbage disposal. Convert the total to GPM on the fixture-unit curve, using the flush-valve line or the flush-tank line depending on which dominates the building.
2. Add up total dynamic head
Total dynamic head is static head plus friction loss. Static head is the vertical lift in feet from the minimum water level in the basin to the highest point in the discharge piping. Friction loss comes from the pipe run and every fitting on it — a 2 in swing check valve alone is worth 17.2 equivalent feet of pipe, a 2 in 90-degree elbow 5.2 ft. The friction tables for both pipe and fittings are in the data booklet.
3. Check the discharge velocity, not just the size
The line has to carry solids, which means a minimum velocity of 2 ft/s. That sets a floor on flow for each pipe size: 9 GPM through 1-1/4 in, 13 GPM through 1-1/2 in, 21 GPM through 2 in, 30 GPM through 2-1/2 in and 46 GPM through 3 in. Oversizing the discharge pipe is the commonest way to build a line that clogs.
4. Size the basin off run time
Pumpable volume equals GPM multiplied by run time, and run time must be at least two minutes or short cycling will take the service life out of the pump. At 50 GPM that is 100 gallons of pumpable volume. The basin also has to let the float swing freely, and the bottom of the basin inlet should sit at least 24 in above the basin floor.
5. Decide simplex or duplex
Local plumbing codes usually settle it. Most commercial installations run duplex — not for the capacity, but for the standby that many municipalities require on public-health grounds. Simplex is generally adequate residentially.
Sizing rule of thumb. If the calculated total dynamic head lands past 70 percent of a model’s maximum head, step up a model. A pump running near shut-off moves very little water, and on a wastewater line low flow means settled solids.
Which Unilift Do You Need?
Selection by application. Call with the solids, the lift and the run length for an engineering-led pick.
| Application | Solids to pass | Recommended | Notes |
|---|---|---|---|
| Flooded basement, pool or tank emptying | 0.4 in | KP 150 / KP 250 / KP 350 | 115 V with a plug; manual, so it runs while energised. Add a float switch or level control for unattended duty. |
| Groundwater lowering, construction dewatering | 0.4 in | AP12.40.08 / AP12.50.11 | Highest head in the drainage group. 230 V, wired in on site. |
| Surface-water collecting well, roof and yard drainage | 0.4 in | AP12.40.04 | 115 V with a plug; available manual or automatic. |
| Laundry, light industry, fibre-carrying effluent | 1.4 in | AP35.40.08 | Vortex impeller with an anti-fibre cap; vertical 1-1/2 in NPT outlet. |
| Effluent on an auto coupling in a permanent pit | 1.4 in | AP35B.50.08 | Ring stand and horizontal 2 in outlet. Liquid limit drops to 104 degrees F. |
| Septic and sludge-treating system effluent | 1.4 to 2.0 in | AP35B.50.08 or AP50.50.11 | Step to AP50 if a water closet discharges anywhere on the system. |
| Domestic sewage with toilet discharge, outdoor pit | 2.0 in | AP50.50.11 | The 2.0 in passage is the requirement, not a preference. Outdoor installation only. |
| Sewage on an auto coupling, deep pit, long run | 2.0 in | AP50B.50.11 | Highest head of the sewage pair at 49 ft; 2200 ft of run at 5 ft lift. |
Grundfos does not list any Unilift model for domestic wastewater with toilet discharge in an indoor pump installation. If the pit is inside the building, ask us for a different platform.
What Makes Unilift Different
The design decisions that show up as fewer callbacks.
Stainless throughout
Sleeve, housing, strainer and impeller in AISI 304, sleeve in AISI 316 on AP12 and AP35/AP50, shaft in AISI 431 on KP. There is no painted cast iron to shed into an effluent pit.
Vortex impeller with a fibre cap
On AP35, AP35B, AP50 and AP50B the impeller sits back from the flow path and carries a protective cap so long-fibered material does not wrap and deposit on it. That is what lets a 2 in solid pass without a grinder.
Sand-shedding guide vanes
On KP, guide vanes in the housing lift sand grains into the liquid flow instead of letting them settle. Sand is what kills small drainage pumps.
Cooling riser pipe
AP12, AP35 and AP50 run an internal riser pipe perforated with holes that move liquid past the motor. The motor stays cool without a jacket.
Silicon carbide shaft seal
A mechanical bellows seal and a lip seal with an oil chamber between them, silicon carbide faces. On the B models the chamber holds 2.7 fl.oz. against 2 fl.oz. on the standard housings.
Spring-mounted wet end
On AP35B and AP50B the ring stand, pump inlet and housing fasten to the motor with four springs. Servicing the impeller does not mean unbolting the pump from the coupling.
Built-in thermal protection
Single-phase Unilift motors carry thermal overload protection internally. The motor stops on overload and restarts when it has cooled; no external motor protection is required.
Adjustable float swing
On the automatic models, the free cable length between the float and the handle sets the start-stop difference. Longer cable means fewer starts and a bigger level swing; minimum free length is 4 in.
Spares & Service Kits
Grundfos publishes service kits by model for the whole Unilift family — shaft seals, impellers, inlet parts, cable sets and float switches.
Kits are ordered against the pump model and serial number, not the range, because the wet-end parts differ between the standard and Basic housings. Send us the nameplate and we will identify the right kit. The Grundfos service kit catalogue for UNILIFT AP, APB, APG, CC and KP is available here, and the full 60 Hz data booklet is here.
Genuine Grundfos spare parts available by model and serial number; contact us for the correct kit.
Why Source Grundfos Unilift from Watermain Supply
Gulf Coast Stock
Held in Houston and shipped from here. US 60 Hz models with NPT outlets and the right cord and plug for the voltage, not international variants pulled from an overseas warehouse.
Engineering-Led Sizing
Send the solids, lift, run length, fixture count and voltage. You get a sized selection against the Grundfos data, not a part number pulled off a shelf list.
Multi-Brand Perspective
If Unilift is not the right fit — an indoor sewage pit, a grinder duty, a continuous-duty application — we will say so and quote the one that is.
Straight About Limits
These pumps are not designed for continuous operation and we will tell you that before you buy, not after. The solids rule, the temperature limits on the B models and the indoor-installation exclusion are on this page for the same reason.
Account Terms Available
Net-30 for qualified contractor, property-management and municipal accounts.
Parts & Aftermarket
Service kits, seals, impellers and float switches by model and serial, so a pump in a pit stays a repair rather than a replacement.
Frequently Asked Questions
The questions that come in by phone before an order goes out.
Which Unilift passes toilet discharge?
Only the 2.0 in models — UNILIFT AP50 and AP50B. Grundfos is explicit: if the building has a water closet of any kind, the pump must pass 2.0 in solids. AP35 and AP35B pass 1.4 in, which covers effluent and laundry waste but not toilet discharge. KP and AP12 pass 0.4 in and are drainage pumps.
What is the difference between AP35 and AP35B?
Housing and outlet. AP35 is the free-standing pump with a clip-on inlet strainer and a 1-1/2 in NPT vertical outlet. AP35B uses a smooth steel-tube housing on a ring stand with a 2 in NPT horizontal outlet, which suits auto-coupling installation. The B model also carries a lower liquid temperature limit, 104 degrees F against 131 degrees F, and its wet end is spring-mounted to the motor for quick dismantling.
Do these pumps come with a float switch?
It depends on the model. The three KP models we stock are the manual version with no level switch. AP12 is available either way — one manual and three automatic. Every AP35, AP35B, AP50 and AP50B we stock is automatic with an integral float switch.
What voltage do they run on?
KP is 115 V single phase with a NEMA 5 plug on 25 ft of cable. AP12 splits: the 1/2 HP models are 115 V with a NEMA 5 plug, the 1 HP and 1.5 HP models are 230 V with 25 ft of cable and no plug. Every AP35 and AP50 model is 230 V single phase, 25 ft of cable, no plug. The 230 V units are wired in on site.
Can a Unilift run continuously?
No. Grundfos states the KP and AP pumps are not designed for continuous operation. On the B models specifically, a pump fitted with a float switch is designed for intermittent duty: with the motor not fully submerged it must not run more than 5 minutes in any 30-minute period.
How deep can they be installed?
Maximum installation depth below water level is 34 ft for the AP range and 30 ft for KP. During operation the inlet strainer on KP, AP12, AP35 and AP50 must always be completely covered by liquid; on the B models it is the pump housing that must stay covered.
How do I size the basin?
Pumpable volume equals flow rate multiplied by run time, and the run time must be at least two minutes to avoid short cycling. At 50 GPM that is 100 gallons of pumpable volume. The basin also has to be wide and deep enough for the float to swing freely, and the bottom of the basin inlet should sit at least 24 in above the basin floor.
What discharge pipe size should I use?
Large enough to match the outlet, small enough to keep the line self-cleaning. Grundfos requires a minimum flow velocity of 2.3 ft/s through the discharge pipe: roughly 12 GPM in a 1.38 in inner diameter pipe, 15 GPM at 1.61 in, and 24 GPM at 2.067 in Schedule 40 PVC. Oversizing the pipe drops velocity and lets solids settle.
Do I need a duplex system?
Local plumbing codes usually decide. Most commercial installations are duplex, not for the extra capacity but for the standby that many municipalities require on public-health grounds. A simplex system is generally adequate for residential — check the local code before you commit.
Are Unilift pumps stainless steel?
Yes, throughout the wet end. On KP the sleeve, housing, suction strainer, impeller, guide vanes and stator housing are AISI 304 with an AISI 431 shaft. On AP12, AP35 and AP50 the housing, riser pipe and impeller are AISI 304 with an AISI 316 sleeve. On the B models the parts of the motor unit in contact with liquid are AISI 316, with a polycarbonate ring stand.
Ready to Size Your Unilift?
Send us the solids you have to pass, the lift from pump stop level, the discharge run and size, the fixture count and the voltage available. We will respond with a sized selection, the service kit that matches it and lead time.
Technical data on this page is taken from Grundfos US 60 Hz product literature (UNILIFT KP, AP data booklet 96900036 12.25) and is subject to change by the manufacturer. Confirm against the current installation manual and pump curve before specifying.
Grundfos and UNILIFT are trademarks of their respective owners, used here for product identification only.
Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.
Grundfos and UNILIFT are trademarks of their respective owners, used here for product identification only.
Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.
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