Grundfos 15 SQ Submersible Well Pump

SQ is a 3-inch diameter deep well submersible pump designed for pumping raw water in domestic water supply, and is suitable for both continuous and intermittent operation. Typical applications are domestic water supply, light commercial service, irrigation and tank applications. The pump fits 3 in and larger boreholes. SQ pumps feature a permanent-magnet motor combined with a Grundfos micro-frequency converter, giving soft start and integrated dry-run protection. SQ models operate at a constant speed much like conventional pumps; the difference is that SQ delivers the benefits of an electronically controlled permanent-magnet motor that cannot be achieved with a conventional induction motor. A simple 2-wire single-phase design means only an on/off switch is needed — no control box, starter box or capacitor.

The pumps are protected against dry running. A value of Pcut-out ensures cut-out of the pump in case of lack of water in the borehole, thus preventing a burnout of the motor. Pcut-out is factory-set. The integrated protection of all motors prevents damage in case the voltage moves outside the permissible range: the pump will cut out if the voltage falls below 150 V or rises above 315 V, and the motor is automatically cut in again when the voltage returns within range. Therefore no extra protection relay is needed. Exposure of the pump to heavy load causes the current consumption to rise; the motor automatically compensates by reducing the speed to 3000 rpm, and further overload will lead to stop. If the rotor is prevented from rotating, this is automatically detected and the power supply is cut out. Consequently, no extra motor protection is needed.

The pump design features floating impellers that are not fastened to the shaft. Each impeller has its own tungsten carbide / ceramic bearing, and the construction and materials ensure high wear resistance to sand for long product life. The hydraulic pump components are polyamide reinforced with 30 % glass fiber; the hydraulic design provides for high pump efficiency resulting in low energy consumption. Starting up a pump with very low counter pressure involves the risk of the entire impeller stack being lifted, also called upthrust, which may cause breakdown of both pump and motor. A top bearing protects both pump and motor against upthrust, thus preventing breakdown during the critical start-up phase.

A built-in check valve with spring and low weight mean the pump may be installed vertically, horizontally or in any position in between, but it must not fall below the horizontal level in relation to the motor. For horizontal installation a flow sleeve is recommended, to ensure sufficient flow velocity past the motor for cooling and to prevent the motor and electronic unit from being buried in sand or mud.

• Dry-run protection — factory-set Pcut-out stops the pump when the borehole runs short of water, preventing motor burnout.
• Overvoltage and undervoltage protection — cuts out below 150 V and above 315 V and restarts automatically when supply returns to range. No protection relay needed.
• Overload protection — the motor reduces speed to 3000 rpm under heavy load, stops on further overload, and cuts power if the rotor is blocked. No separate motor protection needed.
• Overtemperature protection — a temperature sensor in the electronic unit cuts the motor out when temperature rises too high and cuts back in once it drops.
• Soft start — reduces starting current and gives smooth, steady acceleration, minimising wear on the pump and avoiding overloading the mains at start-up.
• High starting torque — high locked-rotor torque of the permanent magnet motor combined with few pump stages, and the starting reliability holds up at low supply voltage.
• Protection against upthrust — a top bearing protects pump and motor against impeller-stack lift during the critical start-up phase.
• Floating impellers — not fastened to the shaft, each with its own tungsten carbide / ceramic bearing, for high wear resistance to sand.
• 2-wire single-phase design — no control box, starter box or capacitor.
• Built-in check valve with spring and a 2.68 in pump diameter, 2.91 in including the cable guard, for 3 in and larger wells.
• Stainless steel exterior — AISI 304 outlet chamber, pump sleeve, cable guard, shaft and motor housing.

• Domestic water supply in single-family dwellings and seasonal homes not connected to municipal waterworks
• Light commercial water supply and small waterworks
• Irrigation systems
• Tank applications — liquid transfer, emptying or filling a tank, pumping from one tank to another
• Pressure boosting and groundwater lowering

SQ is normally installed with a pressure switch and a pressure tank. Where constant pressure is wanted, the SQE version of the same hydraulics adds a variable-speed Smart Motor that works with the CU 302 control unit.

Type key. In 15 SQ05-70: 15 is rated gallons per minute, SQ is the type range (basic version, without communication), 05 is horsepower and -70 is total dynamic head in feet at rated flow.

Order by part number. 15 SQ05-70 — 96160146; 15 SQ05-110 — 96160147; 15 SQ07-150 — 96160148; 15 SQ07-180 — 96160149; 15 SQ10-220 — 96160150; 15 SQ10-250 — 96160151; 15 SQ15-290 — 96160152; 15 SQ15-330 — 93001423. The 1/2 HP models carry a second part number for the 100-115 V version: 15 SQ05-70 — 96160168; 15 SQ05-110 — 96160169.

Cable sizing. Maximum drop cable length in feet by copper wire size:

Accessories. SQ, SQE flow sleeve, complete — product number 98148594. SP, SQ, SQE wrench — 99588350. Cable kit, SQ SQE 14 AWG 5 ft NSF, motor model C — 97778332. The flow sleeve is recommended for horizontal installation and wherever the motor may be covered by sediment or sits below the well screen.