SQWP30 PRO
Water pump SQWP30 PRO
Gets water off the site, fast.
View detailsSIMAQ School · Calculator
Site dewatering
To choose a water pump, add the suction lift, the discharge head and the hose friction loss: that total head has to stay below the pump's rated head, with at least 2 m of margin. The 3″ SQWP30 PRO delivers up to 30 m³/h and lifts up to 13 m total head, and the 4″ SQWP40 PRO up to 40 m³/h and up to 16 m. They are separate maximums: near the maximum head, flow drops. Neither draws more than 8 m, so keep the pump close to the water.
The pump that “won't pull” is almost never broken. It's fighting a total head nobody calculated.
01
Head, not litres
A pump is rated by the total head it can overcome: the lift from water to pump, the rise from pump to outlet, and what friction eats along the way. Nameplate flow only happens when that sum is zero.
02
The suction ceiling
No pump “pulls” water: the atmosphere pushes it. At sea level that pressure holds a column of about 10 m, and in practice friction leaves you 7 or 8. Above that no surface pump works — you move it down.
03
Diameter rules
Friction loss falls with the fourth power of diameter. Going from 2″ to 3″ cuts it about sevenfold. That's why a big pump on narrow hose delivers less than a small one on the right hose — and hose is cheaper than pumps.
04
Cavitation
Choke the suction — narrow hose, clogged strainer, too much lift — and pressure drops so low the water boils cold. The bubbles collapse against the impeller and pit it. That rattling sound isn't wear, it's an install error.
How to set it up right
Strainer suspended, short suction hose at port diameter, pump close to the water and the discharge as direct as possible.
Run your case
Move the four variables of your job and the calculation tells you which SIMAQ pump holds up, with how much margin, and what to fix if it falls short.
Hose diameterThis decides almost everything: friction falls with the fourth power of diameter.
SQWP30 PRO
Enough3″ · 30 m³/h · max head 13 m
- Static head
- 9.0 m
- Friction loss
- 1.8 m
- Total head
- 10.8 m
- Margin
- +2.2 m
SQWP40 PRO
Enough4″ · 40 m³/h · max head 16 m
- Static head
- 9.0 m
- Friction loss
- 3.0 m
- Total head
- 12.0 m
- Margin
- +4.0 m
The SQWP30 PRO works with 2.2 m of margin.
Losses use Hazen-Williams (C = 120, sound site hose) at each pump's rated flow. Old hose, extra couplings or tight bends make it worse — which is why margin matters.
Practice
Pump out the trench yourself
Pick the pump, the hose and where it goes, then start it: watch the water drop, the pump curve with its operating point, and how long it takes. At the end, all 6 combinations side by side.
…
The four recurring mistakes
Narrow suction hose
Whatever was lying around. The number-one cause of cavitation and of pumps returned “faulty”.
Strainer resting in the mud
It sucks solids, clogs, and starves the suction. Suspend it, don't drop it.
Starting without priming
The casing must be full of water. Running dry burns the mechanical seal in minutes.
Long runs out of habit
Every metre of hose is head the pump must beat. A shorter route outperforms a bigger pump.
The pumps
SIMAQ water pumps
FAQ
What people ask most
How do I choose a water pump for the jobsite?
Add the suction lift, the discharge head and the hose friction loss: that total head must stay below the pump's maximum head, with at least 2 m of margin. With that number you choose between the 3″ SQWP30 PRO (13 m) and the 4″ SQWP40 PRO (16 m).
What's the difference between the 3″ and 4″ pumps?
The 3″ SQWP30 PRO delivers up to 30 m³/h and lifts up to 13 m total head, with a 6.5 HP Loncin engine. The 4″ SQWP40 PRO delivers up to 40 m³/h and up to 16 m, with a 9 HP Loncin engine. They're separate maximums: the higher the lift, the lower the flow. Both draw suction up to 8 m.
How high can a water pump draw?
A surface pump won't draw more than about 8 m: the atmosphere only pushes water about 10 m in theory and friction eats the rest. If the water is deeper, move the pump down closer to it.
Why does my pump sound like it's full of rocks?
That's cavitation: the suction is choked by narrow hose, a clogged strainer or too much lift. Use suction hose the same diameter as the pump port and keep the strainer suspended, not in the mud.
Do I have to prime the pump before starting?
Yes: the casing must be full of water. Running it dry burns the mechanical seal in minutes.
Does a wider hose help?
Yes, a lot: friction loss falls with the fourth power of diameter, and going from 2″ to 3″ cuts it about sevenfold. Before looking for a bigger pump, upsize the hose and shorten the run.
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