Key features
Calpeda builds the casing to EN 733 for main dimensions and performance, then adds sizes outside the standard to complete the range. Check the size against the standard before you assume a like-for-like swap.
The motor's extended shaft drives the impeller directly. No coupling, no coupling guard, and no pump-to-motor alignment to set or hold.
Standard build is a cast iron casing and lantern bracket. BNM puts the casing and lantern bracket in bronze CC480K, with a bronze impeller and an AISI 316 shaft.
A PN 10 casing is GJL 250 grey cast iron; the 16 bar rating uses GJS 400-15 ductile iron. Six sizes and the bronze version are 10 bar only.
Axial suction and radial delivery on top, PN 10-16 flanges. Delivery ports run DN32 to DN100 across the two-pole range.
Calpeda lists the NM EI and NM4 EI from 0.37 to 37 kW with the I-MAT converter on the motor, giving a 1,750–2,900 rpm control range on the two-pole units.
About the Calpeda NM
The Calpeda NM is a clean-water transfer and pressure pump. Calpeda puts it on water supply, on heating, air conditioning, cooling and circulation plant, on civil and industrial duties, and on irrigation. This is the general-duty end of the catalogue, not a process pump.
Start with the liquid. Calpeda rates the NM for clean liquids that are non-explosive and non-flammable, free of abrasives, non-aggressive to the pump materials, and carrying solids up to 0.2%. That 0.2% sits a long way below the 3–4% rule of thumb where you would normally move off centrifugal pumps altogether, and it is the number that decides whether this pump belongs on your duty. Grit will abrade the wet end. Fibre will bind on the impeller. If either is in the medium, ask us for a solids-handling pump and we will point you at one instead.
The close-coupled build is the other thing to weigh. Pump and motor are a single unit, which is compact and has nothing to misalign. The cost is that the motor is part of the pump: it carries an extended shaft rather than a standard motor frame, so a replacement motor comes from Calpeda. Where you want a standard motor on the front, Calpeda builds the same hydraulics as the NMS, on a bracket with a stub shaft and an integrated thrust bearing.
Most of what goes wrong with one of these was decided before anybody ordered it. Total suction lift is up to 7 m, and suction conditions are where the failures come back to: NPSHa has to beat NPSHr at the duty point, or you cavitate. The other half is margin stacking. The consultant adds a bit of flow, the contractor adds a bit of head, the installer adds a bit more, and a 3 kW duty ends up with an 11 kW motor running off the end of its curve for the next twenty years. Send us the real duty point and the pipework it sits in, not the one with the margins already on it.
How the Calpeda NM works
The Calpeda NM is a single-stage centrifugal pump. Liquid enters axially at the suction flange, the impeller throws it outwards, and the casing discharges radially from the top. The impeller sits on the motor's own extended shaft, and a carbon, ceramic and NBR mechanical seal keeps the liquid off it. Calpeda publishes the curves with tolerances to UNI EN ISO 9906:2012.
Reading the designation
Calpeda's own worked example is BNM(S)4 EI 32/16A/B. A leading B is the bronze version and no letter means cast iron. NM is the series, a following S is the stub-shaft version, and a 4 is the four-pole version, so a plain NM is the two-pole cast iron close-coupled pump. EI marks the I-MAT converter build. Then 32 is the delivery port diameter in millimetres, 16 the nominal impeller diameter, A the impeller size, and a trailing /B a revision. So an NM 40/20A/A has a DN40 delivery port on the 20 impeller. Matching an existing pump? Send the full designation and the serial number, both read off the nameplate.
Standards, efficiency and the nameplate
Main dimensions and performance follow EN 733, with additional sizes added to complete the range. Flanges are PN 10-16 to EN 1092-2. Motors are built to EN 60034-1 and EN 60034-30-1, insulation class F, IP 54, and suit converter operation; three-phase efficiency is IE2 up to 0.65 kW and IE3 from 0.75 to 55 kW. Supply is 230/400 V ±10% up to 3 kW and 400/690 V ±10% from 4 kW.
The pumps are declared under European Regulation No 547/2012, and Calpeda's index for the two-pole hydraulics gives a minimum efficiency index of MEI ≥ 0.4 against a benchmark of MEI ≥ 0.70 for the most efficient water pumps. Worth knowing before you specify one into a scheme with an energy target on it. The nameplate carries the type, the flow and head range, rated power, supply voltage, current, speed, duty, insulation class, weight, year of manufacture and serial number, along with the ESCC classification and the MEI figure.
Duty cycle and noise
Calpeda caps starts per hour by motor rating: 60 up to 2.2 kW, 40 up to 7.5 kW and 20 up to 30 kW. Maximum sound pressure runs 70 dB(A), 80 dB(A) and 85 dB(A) across the same bands. A float or pressure switch set to cycle the pump harder than that will cost you the seal, and the seal is the weak point in almost any pump. Never run it dry: the seal faces are lubricated by the liquid, and a few seconds without it is enough.
Variable speed, and the EI build
Calpeda offers the NM EI and NM4 EI from 0.37 to 37 kW with the I-MAT converter mounted on the motor. On the two-pole units the control range is 1,750–2,900 rpm, and the system runs in constant pressure, proportional pressure, constant flow, fixed speed or constant temperature mode. It protects against dry running, operation against a closed valve, system leakage, motor overcurrent, over- and undervoltage and current imbalance between phases. On a duty that varies, that beats throttling a fixed-speed pump on running cost.
Specifications
| Type | Close-coupled single-stage end suction centrifugal, axial suction, radial delivery on top | |
|---|---|---|
| Liquid handled | Clean liquids, non-explosive and non-flammable, free of abrasives and non-aggressive to the pump materials | solids content up to 0.2% |
| Flow rate | up to 240 m³/h | two-pole, 50 Hz |
| Total head | up to 93.8 m | two-pole, 50 Hz |
| Power rating | 0.55–22 kW | three-phase, two-pole |
| Speed | approx. 2,900 rpm | 2-pole, 50 Hz |
| Maximum working pressure | up to 16 bar | 10 bar on NM 32/12, 32/16, 32/20, 40/25, 50/20, 50/25 and the bronze version |
| Liquid temperature | -10°C to +90°C | |
| Ambient temperature | up to 40°C | |
| Total suction lift | up to 7 m | |
| Duty | Continuous | |
| Connections | Flanges PN 10-16 to EN 1092-2 | |
| Delivery port sizes | DN32 to DN100 | |
| Pump casing | Cast iron GJL 250 to EN 1561 for PN 10; cast iron GJS 400-15 to EN 1563 for PN 16 | |
| Lantern bracket | Cast iron GJL 200 to EN 1561 | |
| Impeller | Cast iron GJL 200 to EN 1561; brass CW617N to EN 12167 on 32/12, 32/16, 32/20 and NM 40/20 | |
| Shaft | Chrome-nickel steel 1.4305 to EN 10088 (AISI 303) | |
| Mechanical seal | Carbon / ceramic / NBR | |
| Bronze version (BNM) | Casing and lantern bracket in bronze CC480K to EN 1982, bronze impeller, AISI 316 shaft | |
| Motor | Two-pole three-phase induction, insulation class F, IP 54, suitable for converter operation | |
| Motor efficiency | IE2 up to 0.65 kW, IE3 from 0.75 to 55 kW | EN 60034-1 and EN 60034-30-1 |
| Voltage | 3~230/400 V ±10% up to 3 kW; 3~400/690 V ±10% from 4 kW | |
| Starts per hour | 60 up to 2.2 kW, 40 up to 7.5 kW, 20 up to 30 kW | |
| Sound pressure | 70 dB(A) up to 2.2 kW, 80 dB(A) up to 7.5 kW, 85 dB(A) up to 30 kW | maximum |
| Ecodesign | MEI ≥ 0.4, declared under Regulation (EU) No 547/2012 | |
| Test tolerances | UNI EN ISO 9906:2012 | |
| On request | Other voltages, AISI 316 impeller on 32 to 80 sizes, 60 Hz, IP 55, special mechanical seal, IE4 motors, single-phase NMM to 1.8 kW, counter-flanges | |
| Finish | Supplied fully painted |
Send us the flow, head, medium and site conditions and we will size the NM against your duty point, or tell you if a different pump suits it better. If you are replacing an existing unit, photograph the nameplate and send the model and serial number with the enquiry.
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Frequently asked
What is the difference between the Calpeda NM and the NMS?
The motor coupling, not the ports. Both are flanged and both follow EN 733, but on the NM the motor has an extended shaft connected directly to the pump, while the NMS uses a bracket built for standard motors, with a stub shaft and an integrated thrust bearing. The NM runs to 22 kW and IP 54, the NMS to 75 kW at two poles and IP 55.
What liquids can a Calpeda NM handle?
Clean liquids that are non-explosive and non-flammable, free of abrasives and non-aggressive to the pump materials, with a solids content up to 0.2%. Liquid temperature is -10°C to +90°C on the standard build. Anything abrasive or fibrous wants a different pump.
Is the Calpeda NM an EN 733 pump?
Its main dimensions and performance follow EN 733, and Calpeda adds sizes outside the standard to complete the range. Flanges are PN 10-16 to EN 1092-2. Check the specific size against the standard before treating a swap as dimensional like-for-like.
What does NM 40/20A/A mean?
NM is the series, 40 is the delivery port diameter in millimetres, 20 is the nominal impeller diameter, A is the impeller size and the trailing /A is a revision. A leading B would make it bronze, an S after NM would make it a stub-shaft NMS, and a 4 would make it the four-pole version.
What flow and head does the Calpeda NM cover?
Up to 240 m³/h and up to 93.8 m at 50 Hz on the two-pole range, on motors from 0.55 to 22 kW. No single pump does both ends; the smallest size is the NM 32/12F at 0.55 kW. Calpeda publishes 60 Hz data separately.
Can I get a Calpeda NM with a variable speed drive?
Yes. The NM EI carries Calpeda's I-MAT converter on the motor, from 0.37 to 37 kW, with a 1,750–2,900 rpm control range on the two-pole units and constant pressure, proportional pressure, constant flow, fixed speed and constant temperature modes.
Is there a bronze version of the Calpeda NM?
Yes, the BNM. The pump casing and lantern bracket are bronze CC480K to EN 1982, with a bronze impeller and an AISI 316 shaft. Maximum working pressure on the bronze version is 10 bar.