Available Options
Grundfos SQ – submersible pumps with constant speed and electronic protections
Grundfos SQ are fixed-speed submersible pumps designed for domestic water supply, small water supply systems, irrigation and tank applications. The pumps have built-in electronic protection, soft start, dry-running, overload, overvoltage, undervoltage and overheating protection, but do not offer variable speed like the SQE.
Main advantages of SQ
- Constant operating speed for reliable and predictable performance.
- Built-in frequency converter with soft start to reduce starting current.
- Dry running protection with automatic shutdown in the event of lack of water.
- Overvoltage and undervoltage protection (150–315 V).
- Overload protection with automatic speed reduction.
- Overheating protection with temperature sensor in the electronic unit.
- Upthrust bearing protection at low backpressure start.
- Floating impellers with tungsten carbide/ceramic bearings for sand resistance.
- Built-in check valve with spring.
- High efficiency of the pump and motor.
- Lightweight design for easy installation and handling.
- Suitable for installation in wells with a diameter of 3 inches (75 mm) or larger.
Applications
- Domestic water supply for single-family houses and villas.
- Small water supply systems for residential buildings and commercial properties.
- Irrigation of gardens, parks and agricultural areas.
- Tank applications – filling and emptying.
- Maintaining a constant water level in wells and pools.
- Pumping from one tank to another.
- Replacement of existing 4-inch submersible pumps in existing installations.
Suitable liquids
- Thin, clean, non-aggressive and non-explosive liquids without solid or long-fiber particles larger than grains of sand.
- pH value of the liquid between 5 and 9.
- Maximum sand content – 50 g/m³ (increased content reduces service life).
General technical characteristics
| Characteristics | Value |
|---|---|
| Pump type | Submersible pump with constant speed and electronic protection |
| Working fluid | Clean, non-aggressive water (pH 5–9) |
| Maximum sand content | 50 g/m³ |
| Liquid temperature range | 0–35 °C (Western, Central Europe and Asia-Pacific), 0–30 °C (North America) |
| Minimum flow velocity around the motor | 0.15 m/s for temperature up to 40 °C |
| Degree of protection | IP68 |
| Insulation class | F (155 °C) |
| Supply voltage | 1 × 200–240V, 50/60Hz |
| Motor speed | Constant speed (approx. 2900–3000 min⁻¹ at 50 Hz) |
| Output connection | Rp 1¼" (SQ 1, 2, 3), Rp 1½" (SQ 5, 7) |
| Cooling | From the pumped liquid through an internal circulation system |
| Engine protection | Built-in electronic protection against dry running, overvoltage, low voltage, overload and overheating |
| Impeller type | Floating impellers made of polyamide, reinforced with 30% glass fibers |
| Camps | Tungsten carbide/ceramic for each impeller |
| Management | Direct connection with pressure switch and pressure vessel, or via Pressure Manager (PM 1/PM 2) |
Installation
The SQ can be mounted vertically, horizontally or in any intermediate position, as long as the pump does not fall below the horizontal level of the motor. For horizontal mounting, it is recommended to use a flow sleeve to ensure sufficient flow velocity around the motor and prevent sand or mud clogging.
System with pressure switch and pressure vessel
SQ is controlled by a pressure switch and a pressure vessel. When a tap is opened, the pressure in the vessel drops and the pump starts with a soft start (approximately 3 seconds). When the tap is closed, the pump stops when the set output pressure (pcut-out) is reached.
System with Pressure Manager
Through the Pressure Manager (PM 1 or PM 2) the SQ can operate with or without a pressure vessel. The Pressure Manager provides automatic start/stop when a tap is opened and closed, with built-in dry-running protection and the possibility of manual reset.
Electronic protections
- Dry-running protection: Automatic shutdown in the event of lack of water. The pcut-out value is factory-set and ensures shutdown in the event of lack of water in the well.
- Overvoltage and undervoltage protection: Shutdown at voltage below 150 V or above 315 V. Automatic restart when returning to the permissible range.
- Overload protection: Automatic speed reduction in case of increased load. Shutdown at speed below 3000 min⁻¹.
- Overheating protection: A temperature sensor in the electronic unit switches off the motor at a critical temperature and restarts it automatically when it cools down.
- Upthrust protection: An upthrust bearing protects the pump and motor when starting with very low backpressure.
Component materials
Grundfos SQ is built from high-quality materials that ensure long service life, resistance to sand and corrosion, and high efficiency.
| Component | Material (SQ) | Material (SQ-N) |
|---|---|---|
| Pump (impellers, diffusers) | Polyamide reinforced with 30% glass fibers | Polyamide reinforced with 30% glass fibers |
| Pump housing | Stainless steel EN 1.4301 / AISI 304 | Stainless steel EN 1.4401 / AISI 316 |
| Shaft | Stainless steel | Stainless steel |
| Impeller bearings | Tungsten Carbide / Ceramics | Tungsten Carbide / Ceramics |
| Motor housing | Stainless steel EN 1.4301 / AISI 304 | Stainless steel EN 1.4401 / AISI 316 |
| Rotor | Asynchronous motor with short-circuited rotor | Asynchronous motor with short-circuited rotor |
| Stator | High efficiency copper coils | High efficiency copper coils |
| Electronic unit | Built-in frequency converter with soft start and electronic protections | Built-in frequency converter with soft start and electronic protections |
| Check valve | Built-in check valve with spring | Built-in check valve with spring |
| Cable | Submersible cable 1.5 m with plug for direct connection | Submersible cable 1.5 m with plug for direct connection |
Advantages of materials
- Polyamide with 30% glass fibers: High strength, low weight and resistance to abrasive sand.
- Tungsten carbide/ceramic: Exceptional wear resistance of impeller bearings, extending service life in sandy water.
- Stainless steel AISI 304: High corrosion resistance for standard clean water applications.
- Stainless steel AISI 316 (SQ-N): Increased corrosion resistance for aggressive environments, contaminated waters and applications with a high chloride index.
- Asynchronous motor: Reliable and proven design for constant speed with high efficiency.
- Built-in frequency converter: Soft start to reduce starting current and protect against electrical anomalies.
Approvals and certificates
Grundfos SQ has the necessary safety and quality approvals and certificates that guarantee reliable operation in domestic, commercial and industrial applications.
Major approvals
- CE marking: The pump meets the requirements of European directives for safety, health and environmental protection.
- UL approval: Compliance with Underwriters Laboratories standards for North America (for specific versions).
- ISO 9906:2012 Grade 3: Hydraulic performance tested according to the international pump standard.
- EN 60335-2-41: Safety standard for submersible pumps for wastewater and water supply.
Why are approvals important?
- Health and Safety: Approvals ensure that the pump meets strict safety and reliability standards.
- Regulatory compliance: The use of approved products is mandatory in many countries for installations related to water supply.
- Trust and quality: Certified products have passed rigorous testing and meet high quality standards.
- UL approval: Ensures compliance with North American safety standards and allows the pump to be used in the USA and Canada.
Comparison of SQ models
Grundfos SQ is available in several series according to nominal flow rate – SQ 1, SQ 2, SQ 3, SQ 5 and SQ 7. Each series includes several models with different maximum head. The SQ-N versions are made of stainless steel AISI 316 for aggressive environments.
| Series | Nominal flow rate | Maximum head (approx.) | Output connection | Applications |
|---|---|---|---|---|
| SQ 1 | 1 m³/h | 35–155 m (SQ 1-35 to SQ 1-155) | Rp 1¼" | Small domestic installations with low flow and high head |
| SQ 2 | 2 m³/h | 35–115 m (SQ 2-35 to SQ 2-115) | Rp 1¼" | Standard domestic installations with moderate flow and pressure |
| SQ 3 | 3 m³/h | 30–105 m (SQ 3-30 to SQ 3-105) | Rp 1¼" | Larger domestic and commercial installations with high flow rates |
| SQ 5 | 5 m³/h | 15–70 m (SQ 5-15 to SQ 5-70) | Rp 1½" | Large installations, irrigation and water supply systems |
| SQ 7 | 7 m³/h | 15–40 m (SQ 7-15 to SQ 7-40) | Rp 1½" | Industrial applications and large water supply systems with very high flow rates |
Which model to choose?
- SQ 1: Suitable for small domestic installations with low flow rates (up to 1 m³/h) and high head – for example deep wells for single-family houses.
- SQ 2: Universal model for standard domestic installations with moderate flow rate (up to 2 m³/h) and head – the most commonly used choice for water supply to single-family houses and villas.
- SQ 3: For larger domestic and commercial installations with high flow rates (up to 3 m³/h) – residential buildings, small commercial properties and irrigation of larger areas.
- SQ 5: For large installations with very high flow rates (up to 5 m³/h) – irrigation of parks and agricultural areas, water supply systems for residential complexes.
- SQ 7: For industrial applications and large water supply systems with maximum flow rate (up to 7 m³/h) and moderate head.
Difference Between SQ and SQE
- SQ: Submersible pumps with constant speed, electronic protections (dry running, overvoltage, overload, overheating), soft start, control via pressure switch and pressure vessel or Pressure Manager. Lower price, suitable for standard applications without the need for variable speed.
- SQE: Electronically controlled variable speed pumps (3000–10700 min⁻¹), constant pressure capability with CU 300/CU 301, two-way communication with Grundfos GO Remote, higher energy efficiency, higher price.
The technical specifications are in accordance with the provided Grundfos SQ technical catalogue. Please check the specific product number, voltage, cable length, version (SQ or SQ-N) and compatibility with control devices (pressure switch, Pressure Manager) before ordering.