Grundfos CM 3-I Horizontal Multistage Pump, 304 Stainless Steel

Horizontal, multistage centrifugal pump with the motor close-coupled to the pump end and the suction port on the end of the pump. Unlike the vertical CR range, the CM sits on its feet on a horizontal base, which suits a plant room where headroom is short and floor space is not.

The CM 3 frame is rated at 16.4 GPM. The family number is Grundfos’s nominal duty in cubic metres per hour, not a GPM figure — size the pump from the rated head table below, not from the model number.

8 models are offered, from CM 3-2 to CM 3-9, covering 0.58 to 3.4 HP on NEMA close-coupled motors. Adding stages raises head at the same flow without changing the footprint. Connections are 1 in NPT female suction and discharge, and the pump is rated 232 psi maximum operating pressure.

Why 304 rather than cast iron. The -I build has no cast iron in the liquid path, so there is no iron pick-up into the water and no rust bloom on a system that sits idle. It is also rated 232 psi against the 145 psi of the cast-iron -A build. Where chlorides are present, step up to the -G build in 316.

• 304 Stainless Steel — AISI 304 stainless throughout the liquid path.
• Horizontal close-coupled build — motor and pump end on one shaft, on feet, so no coupling alignment and no separate baseplate to grout.
• Multistage hydraulics — head is set by stage count at a fixed frame flow, so the duty point is chosen without oversizing the motor.
• Cartridge-format shaft seal — AQQE or AQQV, replaced without setting the seal by hand.
• WRAS, ACS, NSF61, UBA approvals for drinking water contact.
• 232 psi maximum operating pressure on this material build.
• 1 in NPT female suction and discharge — threaded, so no companion flanges to order.

• AQQE — EPDM. Carbon against silicon carbide with an EPDM O-ring. The standard water seal: potable water, hot water and glycol. Mineral oils need AQQV.
• AQQV — FKM. Carbon against silicon carbide with an FKM O-ring, for mineral oils, fuels and liquids that attack EPDM. Note that FKM carries the lower temperature ceiling of the two.

• AQQE — −4 °F to 248 °F on CM 3-2, CM 3-3, CM 3-4, CM 3-5, CM 3-6, CM 3-7.
• AQQE — −4 °F to 194 °F on CM 3-8, CM 3-9.
• AQQV — −4 °F to 194 °F.

In the Grundfos type key the final letter is the rubber: E = EPDM, V = FKM. The seal is a specification decision, not a preference — it changes the published temperature limit.

• Potable water boosting and transfer where iron pick-up is unacceptable
• Food, beverage and light process duty
• Boiler feed and condensate return
• Filtration, softening and light treatment skids
• Cooling and process water on clean, low-chloride supplies

Each part number is a complete pump: pump end, close-coupled motor and shaft seal, factory assembled and tested. The suction and discharge connections are NPT female threads, so no companion flanges or couplings are needed.

Motor starters, variable frequency drives, pressure sensors, pressure tanks, base plates, foundation bolts and isolation valves are not included. These are fixed-speed pumps; for integrated variable-speed control see the CME range.

Select the HP and voltage, then the model, then the seal. Each combination is a distinct Grundfos part number, listed in the table above and shown in the SKU of the selected variant.

The picker shows only the combinations Grundfos publishes.