Grundfos CM 3-A Horizontal Multistage Pump, Cast Iron / 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.

4 models are offered, from CM 3-2 to CM 3-5, covering 0.58 to 1.5 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 145 psi maximum operating pressure.

Where the cast iron sits. On the -A build the pump housing is cast iron and the impellers, shaft and chamber parts are AISI 304. That is what makes it the lowest-cost CM, and it is also why the maximum operating pressure is 145 psi rather than the 232 psi the all-stainless builds carry. On a potable system where iron pick-up matters, choose the -I build.

• Cast Iron / 304 Stainless Steel — cast iron pump housing with AISI 304 stainless internals.
• 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 approvals for drinking water contact.
• 145 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 194 °F.
• 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.

• General water transfer and pressure boosting on potable and clean water
• Irrigation and washdown duty where cost matters more than an all-stainless path
• Cooling and condenser water loops
• Light industrial process transfer

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.