Grundfos CM is a close-coupled, end-suction horizontal multistage pump. It lies on its feet with threaded ports, so it installs where headroom rules out a vertical pump, and head comes from stacking stages rather than from a bigger impeller.
Two decisions make the part number. The drive: CM runs at fixed speed on a standard motor, CME has the frequency converter and a control panel built into the motor and holds a pressure setpoint on its own. The material grade: A is a cast iron head with an AISI 304 liquid path, I is all 304, G is all 316 — the grade for chloride-bearing water. The two choices are independent.
1 to 9 stages across the CM 3, CM 5 and CM 10 frames, cartridge shaft seals in AQQE or AQQV, NSF/ANSI 61 for drinking water contact.
All 344 published Grundfos part numbers, with the factory part number on every variant. Engineering-led sizing against the published curve — ask and we will quote the fixed-speed and variable-speed versions side by side.
Call 1-888.510.4036 or email sales@watermainsupply.com.
Grundfos CM 1-I Horizontal Multistage Pump, 304 Stainless Steel
Price
From $1,262.90
Grundfos CM / CME Horizontal Multistage Pumps
Grundfos · Horizontal Multistage
Grundfos CM / CMEHorizontal Multistage Pumps
One close-coupled, end-suction multistage pump end, offered two ways: CM on a fixed-speed motor, CME with the frequency converter built into the motor. Each in three material grades — cast iron with 304 internals, all 304, all 316.
344Part Numbers Listed
2Drive Options
3Material Grades
1–9Stages
1-888.510.4036Talk to a Person
CM is Grundfos’s horizontal multistage pump: close-coupled, end-suction, lying on its feet with threaded ports. Head comes from stacking stages rather than from a bigger impeller, so one compact footprint covers a wide pressure range — and where headroom is short or the pipe run is horizontal, it installs where a vertical pump will not.
Two decisions make the part number: the drive — CM at fixed speed or CME with the converter inside the motor — and the material grade, A, I or G. They are independent, so any material can be had either way. We list 344 published part numbers across 18 product pages, with the Grundfos part number on every variant, and offer engineering-led sizing against the published curve. Call 1-888.510.4036 or email sales@watermainsupply.com. Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial supplier.
Fixed Speed or Variable Speed
The first decision, and the one that changes the price and the panel. The material grade is a separate choice and is covered below.
Grundfos CM
168 part numbers20 models1–9 stages0.58 to 8.4 HP
The pump end on a standard NEMA C-face motor. It runs at one speed; you add a starter, and a drive later if the duty turns out to need one. Simplest machine, lowest purchase price, and the right answer whenever the flow is steady or a tank and a switch already control it.
Drive — standard NEMA C-face motor, one speed; a starter and any external drive are ordered separately
Material grades — CM-A (40 part numbers), CM-I (64 part numbers) and CM-G (64 part numbers)
Frames CM3, CM5 and CM10, 1 to 9 stages
Motor 0.58 to 8.4 HP, 115/230V 1Ph and 208-230/440-480V 3Ph
Cartridge shaft seal, AQQE and AQQV
Best forSteady-flow transfer, filtration and wash-down duty, tank filling, boosting behind a pressure tank.
Grundfos CME
176 part numbers20 models1–9 stages3/4 to 7-1/2 HP
The same pump end with a Grundfos MLE motor on top. The frequency converter and a graphical control panel are built into the motor, so the pump holds a pressure setpoint by varying its own speed rather than throttling against a valve. Nothing separate to buy, mount, wire or commission.
Drive — Grundfos MLE motor with the frequency converter and a graphical control panel built in; no separate VFD, panel or drive wiring
Material grades — CME-A (32 part numbers), CME-I (72 part numbers) and CME-G (72 part numbers)
Frames CM3, CM5 and CM10, 1 to 9 stages
Motor 3/4 to 7-1/2 HP, 200-240V 1Ph, 200-240V 3Ph and 440-480V 3Ph
Cartridge shaft seal, AQQE and AQQV
Best forConstant pressure against varying demand, any duty where a throttling valve would otherwise burn the excess, retrofits replacing a pump plus external VFD.
Material Grades
The second decision, and it applies the same way to CM and CME. Pick it on water chemistry, not on budget.
Grade
Build
Liquid path
Stages
CM SKUs
CME SKUs
A
Cast iron / 304
AISI 304 stainless (EN 1.4301); head cast iron
1–5
40
32
I
All 304
AISI 304 stainless (EN 1.4301); head stainless steel
1–9
64
72
G
All 316
AISI 316 stainless (EN 1.4401); head stainless steel
1–9
64
72
A — Cast iron / 304. Cast iron pump head with an AISI 304 stainless liquid path. The default, and the right one on treated municipal water, closed HVAC loops and general transfer.
I — All 304. All AISI 304 — nothing in the wetted path can rust and stain the water it is moving. Potable water where staining matters, food and beverage, wash-down.
G — All 316. All AISI 316. The molybdenum resists chloride pitting, which is the failure 304 has in salt-bearing water — softened, brackish, coastal or reverse osmosis.
The A build stops earlierA reaches 5 stages where I and G reach 9, so the tallest stacks on this range are stainless only. If the duty needs the head, the material decision is already made for you.
Quick ruleStart at A. Move to I when iron in the wetted path is the problem. Move to G when chloride is the problem. Paying for 316 on ordinary municipal water buys nothing; specifying 304 on softened water is how pumps pit.
CM and CME Side by Side
Same pump end, same frames, same stage counts, same seals. Everything that differs is above the pump.
CM
CME
Drive
Fixed speed, standard motor
Variable speed, converter inside the motor
External VFD needed for constant pressure
Yes
No
Control panel
Not supplied
Graphical panel on the motor
Material grades
CM-A, CM-I and CM-G
CME-A, CME-I and CME-G
Frames
CM3, CM5 and CM10
CM3, CM5 and CM10
Stages
1–9
1–9
Motor power
0.58 to 8.4 HP
3/4 to 7-1/2 HP
Supply voltages
115/230V 1Ph and 208-230/440-480V 3Ph
200-240V 1Ph, 200-240V 3Ph and 440-480V 3Ph
Shaft seal options
AQQE and AQQV
AQQE and AQQV
Models published
20
20
Part numbers listed
168
176
On the motor ratingsThe two ranges are quoted differently because they are different motors: CM uses standard motors whose US horsepower falls where the metric rating lands (0.58 to 8.4 HP), while the CME’s MLE motors are catalogued in nominal US sizes (3/4 to 7-1/2 HP). Compare the duty point, not the HP label.
Which is cheaperA CM costs less to buy. A CME costs less to run wherever the flow varies, and it removes a drive, a panel, its wiring and its commissioning from the job. On a steady-flow duty the CM usually wins; on constant-pressure duty against varying demand the CME usually does. Ask us to price both against your load profile.
Frames and Stages
The frame number is Grundfos’s nominal duty in cubic metres per hour, not a GPM rating — CM 3 is 3 m³/h, CM 10 is 10 m³/h. Head comes from the stage count, the second number in the model.
Frame
CM
CME
Material grades
CM3
3 listings
3 listings
A, I and G
CM5
3 listings
3 listings
A, I and G
CM10
3 listings
3 listings
A, I and G
We do not print a curve table hereGrundfos publishes a duty point per part number, and there are 344 of them across these two ranges. The published figures are on each product page. Boost in psi equals head in feet multiplied by 0.433; for a duty between two models, ask us to size it against the published Grundfos curve.
Sizing One Of These
Pressure first, then the limits. The curve is rarely the check that fails a job.
1 · Work Out the Boost You Actually Need
Required boost = target pressure at the fixture plus 0.433 psi for every foot of elevation above the pump plus friction loss through pipe, fittings and any filter minus the pressure already arriving at the inlet.
2 · Then Check the Limits That Decide the Fit
Six of them, below. The A build stops at 5 stages, which is the one that most often decides the grade for you.
Worked exampleA wash-down line wants 45 psi at the nozzle, 20 ft above the pump, with about 6 psi of friction through the hose and filter. The supply arrives at 30 psi. Required boost = 45 + (20 × 0.433) + 6 − 30 = 30 psi, which is 69 ft of head. Pick the stage count that delivers that at your design flow.
Chloride
Softened, brackish, coastal and RO water need the G build; ordinary municipal water does not. Send the analysis with concentration and temperature.
Stage count against grade
The A build stops short of the stainless builds. If the duty needs more head than it reaches, the material choice is already made.
Suction
Not self-priming, and it will not pull a lift. Flooded suction or a positive inlet, every time.
Drive
A CM needs a starter, and an external VFD if you want constant pressure. A CME needs neither. Neither includes a pressure tank or isolation valves.
Seal and liquid
AQQE (EPDM) is the water default; AQQV (FKM) is for liquids EPDM does not suit. Check the liquid temperature against the seal.
Orientation
CM lies horizontal on its feet. If you need more head than the range reaches, the vertical CR platform is the answer, not a taller CM.
Step up a model, not threeIf your duty sits above about 70% of a model’s maximum head, take the next stack up. It costs little and it is what keeps the pump off its end-of-curve for the life of the installation.
Selection Guide
Where each combination usually lands. A starting point, not a substitute for the duty point and the water analysis.
Application
Drive
Grade
Why
Constant pressure against varying demand
CME
A—I—G by water
The drive pays for itself wherever a valve would otherwise throttle.
Steady-flow transfer between tanks
CM
A unless the water says otherwise
Nothing varies, so nothing to vary the speed for.
Wash-down and cleaning lines
CME
I or G
Demand swings hard; stainless suits the environment.
Filtration and RO feed
CME
G
Permeate is aggressive despite being clean.
Boosting behind a pressure tank
CM
A
The tank and switch already do the controlling.
Potable water where staining matters
Either
I
No cast iron in the wetted path.
Softened, brackish or coastal water
Either
G
Chlorides pit 304.
Food, beverage and light process
CME
I or G
304 unless the stream carries chloride or acid.
HVAC top-up and closed-loop make-up
CM
A
Treated, closed water — no case for stainless.
Retrofit replacing a pump plus external VFD
CME
Match the existing metal
One machine instead of two, and no drive panel to re-home.
Why This Platform
What the engineering actually buys you on an installation.
Close-coupled and horizontal
The pump lies on its feet with the motor bolted straight to it — no baseplate to grout, no coupling to align, and it fits where headroom rules out a vertical pump.
Head from stages, not size
Adding stages raises head at the same flow without changing the footprint, so a system can be re-tuned by changing the stack rather than the pump.
Three grades, one footprint
A, I and G share hydraulics and mounting. A specification can be upgraded on water-quality grounds without redrawing the pipe.
Drive optional, not bolted on
The same pump end is sold fixed-speed or with the converter inside the motor. The decision is a part number, not a different machine.
Cartridge shaft seal
Silicon-carbide faces in both seal options, replaced as a unit without setting faces by hand.
Threaded ports
No flange kit and no gaskets to source for a standard install.
NSF/ANSI 61
Certified for drinking water contact.
Every part number published
All 344 Grundfos part numbers across 18 listings, with the factory part number on every variant — so what you order is what the submittal says.
Buying These From Watermain Supply
Engineering-led sizing
Send the duty point and the water analysis and we will size it against the published Grundfos curve — including telling you when a smaller pump will do.
Fixed or variable, priced both ways
Ask and we will quote the CM against its CME equivalent so the drive decision is made on numbers rather than habit.
Multi-brand honesty
We sell more than one line. If a CM is not the right fit for your duty — including when a vertical CR is — we will say so.
The correct US build
60 Hz, US voltages, NSF/ANSI 61 where it applies. International variants of the same model carry different limits; we quote the US figure.
Everything on one order
Pump, seal kit, accessories and literature on a single purchase order and a single submittal package.
Parts and aftermarket
Genuine Grundfos seal kits and spares, quoted by part number against the pump you bought.
Questions We Get Asked
If yours is not here, call. Sizing conversations are the part of this we are good at.
What is the difference between CM and CME?
The drive. CM is the pump end on a standard fixed-speed motor; CME is the same pump end with a Grundfos MLE motor that carries a frequency converter and a control panel inside it. A CME holds a pressure setpoint on its own; a CM runs at one speed until something else switches it.
What do the A, I and G letters mean?
Material grade. A is a cast iron pump head with an AISI 304 stainless liquid path; I is all 304; G is all 316. The letter applies the same way to CM and CME, so the drive choice and the material choice are independent.
Do I need 316, or is 304 enough?
Chloride is the deciding factor. AISI 304 handles ordinary potable and process water indefinitely; it pits in salt-bearing water. Softened water, brackish or coastal supply, reverse osmosis permeate and most chemical dosing call for 316 — the G build. Send the water analysis with the chloride concentration and temperature.
How is this different from a CR?
Orientation and construction. CR is a vertical in-line pump that stands on a base with the ports on one centreline. CM lies on its feet, close-coupled and end-suction, with threaded ports. Where headroom is short or the pipe run is horizontal, CM is usually the easier install; where you need more head than CM reaches, CR is the answer.
Which seal, AQQE or AQQV?
Both have silicon-carbide faces; the last letter is the elastomer. E is EPDM, the default for water. V is FKM, for liquids EPDM does not suit. If you are pumping water, AQQE.
Will one of these lift water from a tank below the pump?
No. CM is not self-priming. It needs flooded suction or a positive inlet pressure.
Can I add a drive to a CM later?
Yes, an external VFD will run a fixed-speed CM, and that is a common retrofit. Whether it is cheaper than buying the CME depends on the panel, the cabling and who commissions it. Ask us to price both.
Why do the A models stop at fewer stages?
Grundfos publishes fewer stage counts in the cast-iron build than in the stainless ones. On this range A reaches 5 stages where I and G reach 9, so the tallest stacks are stainless only.
Are these certified for drinking water?
Yes — NSF/ANSI 61 for drinking water contact.
Can I run two in parallel?
A single pump runs on its own. Multi-pump staging is a packaged Grundfos system specified as a set, not two pumps wired together. Ask us if that is what the building needs.
Dimensional drawings, curve pages and a factory submittal package for a specific part number are available on request — email sales@watermainsupply.com with the part number.
Ready To Size One
Send the duty point, the inlet pressure and the water analysis. We come back with the part number, the curve page and a submittal package.
Specifications, dimensions and published duty points are Grundfos data and are subject to change without notice. Confirm against the current Grundfos documentation for your part number before ordering. GRUNDFOS, CM, CME, CR and MLE are trademarks of Grundfos Holding A/S, used here for product identification only. NSF and ANSI are trademarks of their respective organisations. Watermain Supply is a DBA of E4 Industrial LLC, an independent industrial supplier based in Houston, Texas.
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