GRUNDFOS ¡ SOLAR SUBMERSIBLE PUMP ¡ 4 IN CENTRIFUGAL
SQFlex 4 in Centrifugal
4 in stainless steel centrifugal solar submersible pumps for low heads and large flow rates. Six models, 16 SQF-10 to 75 SQF-3, with the MSF 3 permanent-magnet motor and built-in AC/DC inverter, MPPT and dry-run protection. Runs on solar, wind, generator or grid power.
75 SQF-3: 75.5 GPM at 50 ft
25 SQF-7: 29.9 GPM at 100 ft
30-300 VDC or 90-240 VAC
1400 W Max Input
4 in Minimum Well
Built-In MPPT
4 in Dia x 32-40 in L
23.3-24.6 lb Net Weight
Overview
The SQFlex system is a reliable water supply system based on renewable energy sources, such as solar and wind energy, and incorporates an SQF submersible pump. Very flexible as to its energy supply and performance, the SQFlex system can be combined and adapted to any need according to the conditions of the installation site. Being designed for continuous as well as intermittent operation, it is suitable for water supply in remote locations.
The SQF pump range comprises two pump technologies: the helical rotor pump (3 in) for high heads and small flow rates, and the centrifugal pump (3 in and 4 in) for low heads and large flow rates. This listing covers: Centrifugal pump (4 in) for low heads and large flow rates. All pump types are in stainless steel AISI 304.
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Dry-running protection. A water level electrode on the motor cable, 12 to 24 in above the pump depending on pump type, measures contact resistance to the motor sleeve through the water. When the water level falls below the electrode the pump stops, and it restarts automatically five minutes after the level is back above it.
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Maximum Power Point Tracking (MPPT). The built-in microprocessor continuously optimizes the pump duty point to the input power available. MPPT is available for pumps connected to DC supply.
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Wide voltage range. Operates at any voltage from 30-300 VDC (100-300 VDC for 2500 W) or 90-240 VAC, which makes installation and sizing easy.
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Overload protection. Above the upper load limit the motor compensates by reducing speed; below minimum speed it stops, stays stopped for 30 seconds and restarts automatically. No extra motor protection is required.
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Overtemperature protection. A temperature sensor in the electronic unit stops the motor above 185 °F and restarts it once the temperature drops to 165 °F.
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Simple installation and service. Low weight, no motor starter or starter box, and a modular pump and motor design. The cable and the end cover with socket are fitted with screws so they can be replaced.
What Ships and What It Needs to Run
Included: the pump, supplied as a complete pump and motor with a 6 ft 7 in motor cable fitted with the water level electrode and socket, and a cable guard.
Power source required, ordered separately: a solar array sized to your head and daily water need (use the Solar Pump Calculator below), or any 30-300 VDC supply or 1 x 90-240 VAC supply, such as a generator, battery bank or the grid. No inverter or controller is needed to run the pump; MPPT is built in.
Optional controls: the Grundfos CU 202 control unit adds on/off control, a tank level switch input and alarms; the IO 101 switch box switches automatically to a backup generator. DC disconnects and other solar hardware are on our Grundfos solar pump system accessories listing.
Drop cable and splice kit: sized to your setting depth and the supply voltage, ordered separately.
Genuine Grundfos equipment, factory-new in original packaging â sold and supported by Watermain Supply, an independent industrial supplier.
Warranty
24 months from date of installation, but not more than 30 months from date of manufacture. In Grundfos's words, products are âwarranted to the original user only to be free of defects in material and workmanshipâ; the full terms are in the installation and operating instructions on the Data Sheet tab.
Specifications
| Specification |
Value |
| Supply to pump |
30-300 VDC, PE (100-300 VDC for the 2500 W motor) or 1 x 90-240 V -10 % / +6 %, 50/60 Hz, PE |
| Motor |
MSF 3 permanent-magnet motor with built-in electronic unit, stainless steel AISI 304 |
| Start / stop |
No limitation to the number of starts and stops per hour |
| Enclosure class |
IP68 |
| Motor protection |
Built into the pump: dry running by water level electrode, over- and undervoltage, overload, overtemperature |
| Pumped liquids |
Thin, clean, non-aggressive and non-explosive liquids without solid or long-fibred particles. pH 5 to 9 |
| Liquid temperature |
32 °F to 104 °F. The pump can run at free convection (about 0 ft/s past the motor) at maximum 104 °F |
| Sand content |
Maximum 50 ppm. A higher sand content considerably reduces the lifespan of the pump |
| Conductivity |
At least 70 microsiemens per cm |
| Installation depth |
The pump must be completely submerged. Maximum 500 ft below the static water table (220 psi) |
| Installation position |
Vertical or horizontal. Horizontal installation requires the water level electrode to sit at least 12 to 24 in above the pump so the dry-running protection works |
| Suction strainer |
16 SQF and 25 SQF: holes of 0.10 in diameter. 35 SQF, 45 SQF and 75 SQF: slots of 0.16 in x 0.80 in |
| Motor cable |
6 ft 7 in with water level electrode and socket |
| Operation through generator |
Generator output equal to motor input power P1 plus 50 %, and at least P1 plus 10 % |
Models & Performance â Will It Do What You Need?
Solar pumps have no single duty point: flow rises with the power reaching the motor. Find the head the pump must add (depth to pumping water level, plus the rise to the tank, plus pipe friction), then read where the pump starts and what it delivers at mid-curve and at the end of its curve, where more power adds no more water at that head.
16 SQF-10 ¡ heads 100 ft to 230 ft ¡ 9 charted heads, 7 shown
| Head added |
Starts pumping at (W) |
Mid-curve GPM |
at input (W) |
End of curve GPM |
at input (W) |
| 100 ft (43 psi) |
135 |
15.6 |
770 |
21.8 |
1400 |
| 115 ft (50 psi) |
160 |
14.5 |
780 |
21 |
1400 |
| 150 ft (65 psi) |
220 |
12.1 |
810 |
18.9 |
1400 |
| 165 ft (72 psi) |
250 |
11 |
825 |
17.8 |
1400 |
| 180 ft (78 psi) |
280 |
10 |
840 |
16.6 |
1400 |
| 215 ft (93 psi) |
350 |
8 |
875 |
14.3 |
1400 |
| 230 ft (100 psi) |
380 |
7.3 |
890 |
13.2 |
1400 |
25 SQF-7 ¡ heads 35 ft to 165 ft ¡ 9 charted heads, 7 shown
| Head added |
Starts pumping at (W) |
Mid-curve GPM |
at input (W) |
End of curve GPM |
at input (W) |
| 35 ft (15 psi) |
60 |
29.8 |
720 |
39.6 |
1380 |
| 50 ft (22 psi) |
90 |
27.6 |
745 |
37.9 |
1400 |
| 80 ft (35 psi) |
155 |
21.2 |
780 |
32.7 |
1400 |
| 100 ft (43 psi) |
195 |
18 |
795 |
29.9 |
1400 |
| 115 ft (50 psi) |
220 |
15.8 |
810 |
27.2 |
1400 |
| 150 ft (65 psi) |
â |
8.8 |
710 |
21.3 |
1400 |
| 165 ft (72 psi) |
â |
7.6 |
735 |
18.7 |
1400 |
25 SQF-3 ¡ heads 7 ft to 50 ft ¡ 4 charted heads, 4 shown
| Head added |
Starts pumping at (W) |
Mid-curve GPM |
at input (W) |
End of curve GPM |
at input (W) |
| 7 ft (3 psi) |
25 |
31 |
370 |
40 |
720 |
| 15 ft (7 psi) |
45 |
28 |
380 |
37.9 |
715 |
| 35 ft (15 psi) |
90 |
22.7 |
400 |
32.9 |
715 |
| 50 ft (22 psi) |
â |
13.1 |
350 |
28.4 |
715 |
35 SQF-4 ¡ heads 15 ft to 115 ft ¡ 7 charted heads, 7 shown
| Head added |
Starts pumping at (W) |
Mid-curve GPM |
at input (W) |
End of curve GPM |
at input (W) |
| 15 ft (7 psi) |
35 |
44.8 |
570 |
58.1 |
1100 |
| 35 ft (15 psi) |
90 |
40.8 |
615 |
54.9 |
1140 |
| 50 ft (22 psi) |
160 |
36.9 |
680 |
51.4 |
1200 |
| 65 ft (28 psi) |
230 |
31.8 |
730 |
46.9 |
1235 |
| 80 ft (35 psi) |
305 |
25.7 |
770 |
41.3 |
1240 |
| 100 ft (43 psi) |
395 |
22.1 |
860 |
34 |
1210 |
| 115 ft (50 psi) |
495 |
11 |
715 |
19.2 |
940 |
45 SQF-3 ¡ heads 15 ft to 80 ft ¡ 5 charted heads, 5 shown
| Head added |
Starts pumping at (W) |
Mid-curve GPM |
at input (W) |
End of curve GPM |
at input (W) |
| 15 ft (7 psi) |
50 |
58.2 |
730 |
74.6 |
1410 |
| 35 ft (15 psi) |
120 |
51.8 |
760 |
69.2 |
1400 |
| 50 ft (22 psi) |
215 |
45.2 |
815 |
62.7 |
1405 |
| 65 ft (28 psi) |
315 |
36.5 |
850 |
55 |
1385 |
| 80 ft (35 psi) |
425 |
26.6 |
860 |
44 |
1295 |
75 SQF-3 ¡ heads 15 ft to 80 ft ¡ 5 charted heads, 5 shown
| Head added |
Starts pumping at (W) |
Mid-curve GPM |
at input (W) |
End of curve GPM |
at input (W) |
| 15 ft (7 psi) |
85 |
81.5 |
765 |
106 |
1440 |
| 35 ft (15 psi) |
205 |
66.4 |
835 |
92.6 |
1465 |
| 50 ft (22 psi) |
370 |
49.3 |
915 |
75.5 |
1460 |
| 65 ft (28 psi) |
545 |
36.2 |
1005 |
56.7 |
1460 |
| 80 ft (35 psi) |
765 |
18 |
990 |
30.9 |
1210 |
Points verbatim from the Grundfos Product Center curves for each model, at the heads Grundfos charts in its SQFlex data booklet 92552657 (North America, 60 Hz): the start point, the middle published point and the end of the curve. Input power is P1 at the motor, after cable losses. Mean values; Grundfos states a typical deviation of Âą15 %, not guarantee curves. A dash in the start column means the published curve at that head begins already pumping, at its first point. Every charted head and all nine points per head are in the curve images and on the Data Sheet tab; the Solar Pump Calculator sizes the array for your site.
Before You Buy â The Limits That Decide the Fit
| Check |
What to confirm |
| Well size |
4 in or larger casing |
| Supply |
30-300 VDC or 1 x 90-240 VAC, on the same two wires plus earth |
| Setting |
Fully submerged, no deeper than 500 ft below the static water level |
| Water |
Clean water, pH 5 to 9, 32°F to 104°F, sand up to 50 ppm, conductivity at least 70 microsiemens per cm (the dry-run electrode needs it) |
| Horizontal install |
Keep the water level electrode 12 to 24 in above the pump so the dry-run protection works |
| Generator backup |
Generator output at least the motor input power plus 50% (minimum plus 10%) |
Materials
| Pump component |
Material |
EN/DIN |
AISI |
| Valve casing, valve cup |
Stainless steel (cast on 35, 45 and 75 SQF) |
1.4301 |
304 |
| Valve seat |
NBR (16, 25 SQF) ¡ NBR-FKM (35, 45, 75 SQF) |
â |
â |
| Neck ring |
NBR / TPU (16, 25 SQF) ¡ TPU / PPS-FKM (35, 45, 75 SQF) |
â |
â |
| Bearing |
NBR (16, 25 SQF) ¡ LSR / FKM (35, 45, 75 SQF) |
â |
â |
| Washer for stop ring |
Carbon / graphite HY22 in PTFE mass |
â |
â |
| Chamber |
Stainless steel |
1.4301 |
304 |
| Impeller |
Stainless steel |
1.4301 |
304 |
| Inlet interconnector |
Cast stainless steel |
1.4308 |
CF8 |
| Strainer |
Stainless steel |
1.4301 |
304 |
| Shaft complete |
Stainless steel |
1.4057 |
431 |
| Strap |
Stainless steel |
1.4301 |
304 |
| Cable guard |
Stainless steel |
1.4301 |
304 |
4 in centrifugal pumps; Grundfos publishes one table for 16 SQF-10 and 25 SQF-3 and one for 35 SQF-4, 45 SQF-3 and 77 SQF-3, combined here.
| Motor component |
Material |
EN/DIN |
AISI |
| Stator with sleeve, rotor |
Stainless steel |
1.4301 |
304 |
| Stop ring |
PP |
â |
â |
| Shaft end |
Stainless steel |
1.4401 |
316 |
| Thrust bearing, stationary |
Stainless steel / carbon |
1.4401 |
316 |
| Bearing plate with radial bearing |
Silicon carbide |
1.4301 |
304 |
| Thrust bearing, rotating |
Stainless steel / aluminium oxide Al2O3 |
1.4401 |
316 |
| Filling plug |
Silicone (LSR) |
â |
â |
| O-ring, shaft seal |
NBR |
â |
â |
| Top cover |
PPS |
â |
â |
| Thrust-bearing housing |
Stainless steel |
1.4408 |
316 |
| Four screws (M4) |
Stainless steel |
1.4401 |
316 |
MSF 3 motor, 500-3600 rpm.
Salt content. Resistance of the stainless steel to chloride, for a pumped liquid of pH 5 to 9:
| Stainless steel |
Chloride content |
Liquid temperature |
| AISI 304 (1.4301) |
0-300 ppm |
Below 104 °F |
| AISI 304 (1.4301) |
300-500 ppm |
Below 86 °F |
For additional protection, for instance where chloride exceeds 500 ppm, Grundfos offers sacrificial zinc anodes: outside-mounted anode 99722879 with fastener set 99812400 (fitted diameter 4.9 in, minimum borehole 5 in; usually two anodes), or bottom-mounted anode kit 99599098 with four threaded rods, which adds 2.2 in to the pump length and keeps the minimum borehole at 3 in.
