Grundfos Model Numbers Explained: What CR3-19 and CM5-5 Actually Mean

In a Grundfos CR or CM model number, the first number is the nominal flow rate in cubic metres per hour and the second is the number of impellers, or stages. So a CR3-19 is a 3 cubic metre per hour pump with 19 stages, and a CM5-5 is a 5 cubic metre per hour pump with 5 stages.

That single rule covers most of what people need. The rest of the code, the letters after the model and the eight digit number printed beside it, tells you materials, seals and exactly which part you are holding. This guide decodes all of it, with worked examples from the Grundfos pumps we stock.

How a Grundfos CR Model Number Is Built

Grundfos publishes a type key for the CR range. A full designation looks like CR 32-4-2 A-F-G-E-HQQE, and it reads left to right.

1. Range: CR, CRI, CRN or CRT. CR is cast iron and 304 stainless, CRI is all 304 stainless, CRN is 316 stainless, CRT is titanium. An E anywhere in the range name, as in CRE or CRNE, means an integrated variable frequency drive.
2. Nominal flow rate in cubic metres per hour. This names the family, it is not your actual duty point.
3. Number of impellers, which is the number of stages. More stages means more head at the same flow.
4. Number of reduced diameter impellers. This position only appears on CR 32, 45, 64 and 90.
5. Pump version, pipe connection, materials and rubber parts codes, one letter each.

6. Shaft seal code, four characters: seal type, rotating face, stationary face and secondary seal material. HQQE and BUBE are the ones you will see most.

Worked Examples

Here is what the model numbers on our best selling Grundfos pumps actually say.

Note that the flow figure is metric. Grundfos prints a rule of thumb on the CR nameplate sheet that you multiply cubic metres per hour by 5 to get US gpm, but the published nominal flows do not always follow it. A CR5 is listed at 30 gpm, not 25. Use the data booklet table when the number matters.

The Exceptions That Trip People Up

• Stages times ten: on CR and CRN 2, 4, 8 and 16, the second figure is the number of stages multiplied by ten, not the stage count itself.
• The 1s suffix: CR 1s, CRI 1s and CRN 1s use an undersize impeller on every stage. The s is not a typo.
• A slash figure: in a designation like CR 8-20/1, the /1 means the pump has fewer impellers than it has chambers.
• A trailing digit: on CR 32, 45, 64 and 90, a standalone figure at the end is the number of reduced diameter impellers. Those impellers are two thirds diameter, and Grundfos notes efficiency runs about 2 percent below the published curve.
• The letter after the model: an A, B, C or D on the nameplate after the type designation is the designated model, meaning the design generation. It is not an impeller trim.

Model Number vs Product Number

These are two different things, and mixing them up is the most common ordering mistake we see.

The type designation describes the pump: CR3-19, CM5-5. The eight digit number beside it, for example 97742685 on our CR3-19, is the Grundfos product number, and it identifies one specific build including motor, voltage and seal. When you order a replacement, quote both. If you only have one of them, the product number is the more precise.

How CM Model Numbers Differ

CM follows the same grammar with a shorter code. A full CM designation looks like CM 10-3 A-S-I-E-AQQE, where 10 is the rated flow, 3 is the stage count, and the letters cover version, pipe connection, materials, rubber parts and shaft seal.

• Version codes worth knowing: A is basic, O is self-priming to about 26 feet of suction lift, S is self-priming to about 13 feet.
• Materials: A is a cast iron inlet and outlet, I is 304 stainless, G is 316 stainless impellers and chambers.
• No reduced impeller position, and stage counts run far lower than CR. A CM25 is only built in 1 and 2 stages.
• The rated flow is a 50 Hz figure, so a US 60 Hz pump runs above the nominal flow printed in the name.

Reading It Off the Nameplate

On a CR the nameplate carries the type designation, the designated model letter and the product number as separate fields, alongside head, flow and motor data. Photograph the whole plate rather than copying one line, because the seal code and the product number are what pin down the exact spare.

If the plate is unreadable, the pipe size, stage count and motor HP will usually get you to the right family. From there our Grundfos collection and our comparison of CR vs CM pumps will narrow it down. We take the same approach with other brands: see how we decode Berkeley pump model numbers.

Final Thoughts

Grundfos model numbers look cryptic and are not. Flow first, stages second, then a string of letters describing what the pump is made of and how it seals.

Learn those two numbers and you can size, compare and reorder without opening a catalogue. Keep the eight digit product number for anything you actually buy, and if the duty point is the part you are unsure about, start with vertical multi-stage pumps or boiler feed pumps.

Frequently Asked Questions

What does the number after the dash on a Grundfos pump mean?

It is the number of impellers, which is the number of stages. A CR3-19 has 19 stages. The exception is CR and CRN 2, 4, 8 and 16, where that figure is the stage count multiplied by ten.

What does CR stand for on a Grundfos pump?

CR is the vertical multistage centrifugal range. CRI is the all 304 stainless version, CRN is 316 stainless and CRT is titanium. Adding an E, as in CRE or CRNE, means the pump has an integrated variable frequency drive on the motor.

Is the first number in a Grundfos model gallons per minute?

No. It is the nominal flow rate in cubic metres per hour. One cubic metre per hour is about 4.4 US gpm, so a CR10 is roughly 55 gpm nominal, not 10 gpm.

What does HQQE mean on a Grundfos pump?

It is the shaft seal code. The four characters give the seal type, the rotating seal face material, the stationary seal face material and the secondary seal material, in that order. Quote it when you order a seal kit.