What Brand Is an LMI Metering Pump? Origin and Product Line Overview
Walk into a water plant, cooling tower room or pool plant room and you'll often see a small pump with a black body and a yellow panel, mounted next to a chemical tank, clicking away as it doses. That color scheme is pretty much LMI's signature. People often ask what brand an LMI metering pump is. In short, it's Milton Roy's electronic metering pump brand, built mainly around low-flow solenoid diaphragm pumps for water treatment.
Below we cover where it comes from, then sort the product line by use. Once it's sorted, matching your own dosing point is much faster than flipping through series one by one.
LMI Metering Pump Brand: Which Country?
The LMI metering pump is an American brand. The data sheets give an address in Pennsylvania, the copyright holder is Milton Roy, LLC, and Milton Roy is now part of the Ingersoll Rand group. So the LMI metering pump is from the US, with Milton Roy as its parent.
LMI's catalog says it has been in the metering pump business for more than 40 years and was first to offer a full line of electronic metering pumps and accessories. In China, LMI's Chinese literature is issued by Milton Roy's Shanghai company, which also handles parts and selection.
Four Groups in the LMI Metering Pump Range
The LMI catalog splits products into four groups by drive and use, which is far easier to remember than series names.
Solenoid-driven diaphragm pumps
This is the core of the LMI metering pump range. A solenoid pushes the diaphragm, so the design is simple with few moving parts. The common series:
- P+: up to 15.1 L/h, up to 17.2 bar, 1–240 spm, IP68 electrical connectors;
- PD: up to 7.6 L/h, up to 30.6 bar, with a color LCD on the enhanced version;
- C: up to 95 L/h, up to 20.7 bar, many models and plenty of control options;
- D: up to 90 L/h, up to 18 bar, 230 V single phase, about 100 W;
- B: up to 17 L/h, up to 10 bar, 230 V single phase, about 75 W.
In each line, the maximum flow and maximum pressure come from different models. Higher-flow models have lower pressure. The B and D series have ±2% steady-state accuracy and 1.5 m water column suction lift.
P+ and PD are two generations of the same idea. The P+ adjusts both stroke rate and stroke length, with stroke length from 30% to 100%. The PD is an upgrade of the P series that switches to constant stroke length and adjusts flow by rate, and its enhanced version adds a color screen, calibration assist and totalizer. We compare the two in detail in a separate article.
Motor-driven diaphragm pumps
For more flow than a solenoid LMI metering pump can give, there are two motor-driven mechanical diaphragm series, SD and SG. SD covers 2.6–435 L/h up to 12.1 bar, and SG covers 400–1136 L/h up to 10.3 bar. Both use a variable eccentric design for smooth output and accept 4–20 mA VFD control.
Smart control
EXCEL XR is a stepper-motor mechanical diaphragm pump covering 0.023–203 L/h up to 12 bar, with turndown above 1000:1 and ±1% steady-state accuracy. It has manual, enhanced and communication modes, supports Profibus DP and Modbus RTU, and offers a Chinese-language interface.
EXCEL AD is a solenoid pump that can also reach 1000:1 turndown, with an LCD interface.
Explosion-proof
The E7 series is an explosion-proof solenoid pump with a cast housing and polyurethane coating, UL and cUL certified, for hazardous areas and outdoor use.
Liquid Ends and Accessories
LMI metering pump liquid ends come in PVC, PP, PVDF, 316 stainless and acrylic, with tubing connections, threaded connections and high-viscosity designs. Matching material to chemical matters more than picking the series.
The accessory range is broad: calibration columns, flow indicators, flowmeters, pulse senders, tanks, valves and piping. There's also the RPM Pro Pac maintenance kit, which bundles parts and instructions for annual service. Keep one in stock and the job is easy.
Common Mistakes When Choosing an LMI Metering Pump
Plenty of people know what brand the LMI metering pump is and still trip up at selection. The most common mistakes:
- Looking only at maximum flow. Within a series, the output code with the most flow usually has the least pressure. The 15.1 L/h P+ model manages only 1.0 bar, nowhere near enough for a pressurized line.
- Assuming all liquid ends ship with the same parts. B and D series PP and PVC liquid ends include a PVC foot valve as standard. PVDF liquid ends don't, so a strainer has to be ordered separately.
- Ignoring suction lift. A solenoid pump moves a small volume per stroke, so suction lift is limited to begin with. Mount it much higher than the tank and it may not prime.
- Using a standard head on viscous chemicals. The C series has high-viscosity liquid ends marked HV. Thick chemicals need one.
Run through these before ordering and you'll avoid a lot of rework.
Picking From the LMI Metering Pump Line
Start with flow. Up to a dozen or so liters per hour, the P+, PD and B solenoid pumps are enough. Tens of liters up to nearly a hundred, look at C and D. Beyond that, move to the SD and SG motor-driven pumps.
Then pressure and control. For injection into a pressurized line, check the pressure for the chosen output code. To connect an online analyzer or PLC, pick a model with 4–20 mA or pulse input. For remote communication, look at EXCEL XR. For hazardous areas, go straight to E7.
So once you know what brand an LMI metering pump is, the real work is matching your duty to a specific series.
Conclusion
Back to the opening question: what brand is an LMI metering pump? It's Milton Roy's American metering pump brand, strongest in low-flow solenoid diaphragm pumps for water treatment, with motor-driven, smart and explosion-proof products as well. Select in this order: flow sets the group, pressure sets the model, control sets the configuration. Choose the liquid end by chemical, and buy accessories and maintenance kits together to make later service easier.
FAQ
Are LMI and Milton Roy the same company?
LMI is a Milton Roy brand, and the data sheets are copyrighted by Milton Roy, LLC. Think of it as two product lines under one company.
Which LMI metering pump series should I use for sodium hypochlorite?
Several solenoid series offer suitable liquid ends, so flow and material are what matter. Hypochlorite tends to gas off, so consider an AutoPrime liquid end or the PD enhanced version with StayPrime.
How much suction lift does a solenoid LMI metering pump have?
Solenoid pumps have limited suction lift. The B and D series literature gives 1.5 m water column. Ideally put the tank beside or above the pump.
Is there an LMI pump with a Chinese interface?
Yes. EXCEL XR's multilingual menu includes Chinese, which makes commissioning and routine checks easier for local operators.
Are spare parts easy to get?
LMI offers RPM Pro Pac maintenance kits matched to series and liquid end. Stock them according to your annual service plan.
If you need to pick a model from the LMI line, send the chemical, flow and pressure through our contact page and we'll match a series and liquid end with you.