LMI Pump Model Number Guide: C Series Code Explained

C92 1-363SI. The first time most people see that string, the only part they recognize is the "C." An LMI pump model number isn't complicated, though. This one has three sections: C92 is the drive, 1 is the voltage, and 363SI is the liquid end. Each section maps to a small table on the data sheet, so you just look it up.

An LMI pump model number is effectively a configuration list. One drive can take several liquid ends, and once the string is written down, control method, flow step, power and materials are all fixed. Spare parts are ordered by liquid end number later too. That's why reading the code is more useful than memorizing series names.

Let's read a C series code from left to right.

Section One of the LMI Pump Model Number: The Drive Code

The drive code at the front of every C series LMI pump model number has three parts: the letter C, one digit for control method, and one digit for output.

Control method is the second character

1: manual control, with stroke rate and stroke length both set by hand knobs;
7: instrument response/manual control, which adds the option to switch to external signal control;
9: grouped with 7, and the literature notes that the C9 can be programmed in strokes per hour for even lower output.

Manual and externally controlled C series pumps look almost identical, so the model is more reliable than appearance. The C series can accept external signals, and the catalog lists pulse multiply/divide, 4–20 mA and remote start/stop among the control options.

Output is the third character

The last digit of the drive section of the LMI pump model number sets flow and pressure. With standard liquid ends, the maximum flow and maximum injection pressure for each output code are:

0 (C10/C70/C90): 4.9 L/h, 20.7 bar;
1 (C11/C71/C91): 9.5 L/h, 10.3 bar;
2 (C12/C72/C92): 15.1 L/h, 6.9 bar;
3 (C13/C73/C93): 30 L/h, 4.1 bar;
4 (C14/C74/C94): 76 L/h, 1.7 bar.

There are also the C76, C77 and C78: 15.1 L/h at 12.1 bar, 38 L/h at 5.5 bar and 95 L/h at 2.07 bar respectively. They have more power but no UL or cUL listing.

So the C92 at the start means C9 control, output code 2, up to 15.1 L/h and up to 6.9 bar. When reading an LMI pump model number for selection, start with the third character. Strike out anything without enough pressure, then choose the control method from what's left.

Section Two of the LMI Pump Model Number: The Voltage Code

The middle digit gives voltage and plug type: 1 is 120 V with a US plug, 2 is 240 V with a US plug, 3 is 220–240 V with a DIN plug, 5 is UK, 6 is Australia/New Zealand, and 7 is Swiss.

On 220 V sites, choose a 220–240 V code and confirm the plug against the local socket. Get it wrong and the pump arrives unable to plug in, leaving you to swap the plug or use an adapter.

Section Three: The Liquid End Number

The liquid end number carries the most information in an LMI pump model number, and it's where most of the difficulty lies. Taking 363SI as the example:

The number 363 maps to a specific set of materials: PVDF head and fittings, ceramic balls, PVDF/PTFE check valves, size code 1.8;
Suffix S means it has the 4FV four-function valve;
Suffix I means tubing connections with 0.375 inch OD PE tubing.

Changing the suffix letters

The data sheet gives several substitutions. Replace I with P for 1/4 inch NPT male threads. Replace I with U for black UV-resistant tubing. Replace S with T for the 3FV three-function valve. Drop the S for no 4FV.

The 4FV mounts on the pump head as a diaphragm-type anti-siphon/pressure relief valve. It prevents siphoning and helps priming against pressure. The 3FV combines pressure relief, priming assist and line drain.

The size code must match the drive

Liquid ends come in size codes 0.9, 1.8, 3.0 and 6.0, and each drive only takes its matching size. The C92 uses 1.8 and the C94 uses 6.0, for example. A liquid end of the wrong size simply won't fit.

Liquid end numbers starting with D are AutoPrime liquid ends with three check valves. The top valve continuously returns a small amount of chemical to the tank, carrying gas out of the head. They suit chemicals that gas off, at the cost of slightly lower maximum flow. Numbers containing HV are high-viscosity liquid ends.

Four Checks Once You Can Read the LMI Pump Model Number

With the code decoded, checking has a clear direction:

Does the output code's pressure cover the injection point?
Will the liquid end material stand up to the chemical?
Is the connection tubing or rigid pipe?
Does the voltage code match the site supply?

Other Series Follow the Same Logic

The P+ and PD versions of the LMI pump model number are also built position by position, just with more positions. The P+ order is adjustment method, output, voltage, liquid end construction, size, material, head and function valve, then connection. The PD runs control code, output code, power code, liquid end code, and finally the inlet/outlet valve and connection code.

The approach carries across series, so once you can read one, the others come quickly. The exact meaning of letters and digits differs between series, though. Don't apply the C series table to a P+. Always use that series' own data sheet.

The usual mistakes are dropping a digit from the liquid end number or writing a US plug voltage code by accident. Finding out on delivery costs a lot of time. Reading the whole LMI pump model number back once before ordering takes a couple of minutes.

Conclusion

An LMI pump model number reads in three sections: the drive gives control method and output, the middle digit gives voltage, and the end gives the liquid end number and suffixes. The C series runs from 4.9 L/h at 20.7 bar to 95 L/h at 2.07 bar across several steps, with pressure falling as flow rises. Check each section against the data sheet before ordering and the choice will rarely go wrong.

FAQ

What's the difference between C10 and C70?

Flow and pressure are the same, 4.9 L/h at 20.7 bar. The C70 can switch to external signal control, while the C10 is manual only.

What's the minimum output?

With a standard liquid end at 1 stroke per minute and 10% stroke length, the C10 bottoms out at about 0.005 L/h. External control mode can go lower still.

Can I drop the S from 363SI in my LMI pump model number?

Yes. Without the S you get the version with no 4FV. But at low injection pressure or when dosing into an open tank, plan other anti-siphon and relief measures, or the flow will wander.

What's the maximum stroke rate?

The C series runs 1–100 strokes per minute, and stroke length should stay at 10% or more. For lower flow, reduce stroke rate first rather than shortening stroke too far.

Does the C series have drinking water certification?

The data sheet lists NSF/ANSI Standard 50 certification. Check the data sheet for which models and liquid ends it covers, and confirm item by item for drinking water projects.

To check whether a particular LMI model suits your duty, send the model, chemical and pressure through our contact page and we'll go through it section by section.

LMI Pump Model Number Explained: Decoding the C Series Position by Position