LMI Dosing Pump B Series vs D Series: Flow, Pressure and Power Compared

The B and D series are two yellow LMI dosing pump lines that look almost identical on a shelf, and both use model numbers that run 11, 12, 13 and so on. If you are trying to pick an LMI dosing pump from one of these two lines, the fastest way is to put the two data sheets side by side. One line covers small flows, the other covers medium flows, and pressure and power change with them.

Below we go through it in the order we use when checking a customer's duty: headline figures first, then each model, then the details people tend to miss.

The Headline Numbers for Each LMI Dosing Pump Line

The first block on each data sheet gives the series limits:

• B series: up to 17 L/h, up to 10 bar, about 75 W;
• D series: up to 90 L/h, up to 18 bar, about 100 W.

A lot is shared. Both are solenoid-driven mechanical diaphragm pumps with a PTFE-faced Hypalon diaphragm. Both run on 230V 50Hz single phase. Both quote steady-state accuracy of ±2% of rated flow across 10%–100% of the range, and both list suction lift as 1.5 m of water column. Flow can be set anywhere from 0–100% whether the pump is running or stopped, and stroke length can be adjusted by hand while it runs.

So the choice between the two comes down to which flow and pressure band your duty falls in. The power difference is small. Either LMI dosing pump runs on an ordinary single-phase supply, so you normally don't need a dedicated circuit, just the right voltage at the socket.

B Series LMI Dosing Pump: Three Models, Up to 17 L/h

The B series LMI dosing pump table has only three rows:

1. B-11, B-71, B-91: 0.06–6 L/h, maximum pressure 10 kg/cm²;
2. B-12, B-72, B-92: 0.095–9.5 L/h, maximum pressure 7 kg/cm²;
3. B-13, B-73, B-93: 0.17–17 L/h, maximum pressure 3.5 kg/cm².

The pattern is obvious: the more flow a model delivers, the less pressure it can handle. B-13 has the most flow and only 3.5 kg/cm², so check the line pressure before you put it on a pressurized injection point. The first two models use 3/8"×1/4" connections, B-13 uses 1/2"×3/8", and the plastic version weighs about 5.5 kg.

D Series LMI Dosing Pump: Four Models, Up to 90 L/h

The D series performance table has four rows:

• D-11, D-71, D-91: 0.1–12 L/h, maximum pressure 9 kg/cm²;
• D-12, D-72, D-92: 0.15–17 L/h, maximum pressure 7 kg/cm²;
• D-13, D-73, D-93: 0.25–35 L/h, maximum pressure 4 kg/cm²;
• D-14, D-74, D-94: 0.6–90 L/h, maximum pressure 1.5 kg/cm².

All four use 1/2"×3/8" connections, so moving up or down a size rarely means re-piping. D-11 and D-12 weigh about 8.5 kg, D-13 and D-14 about 9 kg. This LMI dosing pump is noticeably bigger than the B, so leave room for it when you plan a wall mount or bracket, using the outline dimensions on the data sheet.

Ask About That 18 bar Figure

The front page of the D series sheet says "up to 18 bar", yet the highest pressure in the four-row table is 9 kg/cm². The weight table also lists a D-10, D-70 and D-90 that has no flow or pressure row. Our reading is that the high-pressure model was left out of the performance table, but that is an inference. If your project needs high pressure, get the supplier to confirm the rating of the exact model in writing before you rely on the headline number.

What the 1, 7 and 9 Mean in an LMI D Series or B Series Model

The B and D data sheets state only one thing about the middle digit: the "9" models are automatic-control pumps, for example accepting a 4…20 mA signal. What separates the 1 and 7 models isn't spelled out on these two sheets. Don't borrow decoding rules from another LMI series. Ask when you request a quote, especially if the pump has to talk to a PLC or an online analyzer.

The last digit is the flow size. Within one size, the 11, 71 and 91 versions share the same flow and pressure; only the control differs.

LMI Dosing Pump Liquid Ends Are the Same on Both

Both series offer PP, PVC and PVDF liquid ends. Balls are ceramic, seals are TEFLON and tubing is LDPE. PP and PVC liquid ends come with a PVC valve body, PVC foot valve and PVC check valve. On PVDF the valve body and check valve are PVDF, but there is no foot valve, so a strainer has to be ordered separately.

A common site problem: someone orders an LMI dosing pump with a PVDF head, the pump arrives with a bare suction line, sludge from the bottom of the drum gets pulled in and a check valve sticks. Put the strainer on the same order and save a trip.

Working Backwards From the Injection Point

This is how we usually size an LMI dosing pump:

1. Work out the maximum dose in L/h and add a margin;
2. Take the actual pressure at the injection point and find the models that can beat it;
3. From those, pick the one whose range covers your dose without running near the bottom of the dial all the time.

A typical case: you need about ten-odd liters an hour and there is some back pressure. B-13 has the flow but only 3.5 kg/cm². D-11 gives 9 kg/cm² and up to 12 L/h, so it is often the safer pick. On the other hand, if you only need a few liters and pressure is low, B-11 is plenty, with lower power draw and a lighter body.

Don't forget suction lift. Each LMI dosing pump in these two lines lists only 1.5 m of water column, so put the pump next to the tank or below the liquid level. We have seen plenty of sites mount the pump on a bracket above the drum. It looks tidy, but every drum change means priming again, and operators eventually move the pump down to the floor.

Conclusion

The B and D LMI dosing pump lines are two sizes of the same design. The B series has three models up to 17 L/h for small doses; the LMI D series has four models up to 90 L/h for medium doses. On both data sheets the higher-flow models have lower pressure, so match the injection pressure to a specific model rather than the headline figure. For high pressure, confirm the D series high-pressure model with the supplier first. For automatic control, choose a "9" model. With a PVDF liquid end, order a strainer.

FAQ

B-13 and D-12 both reach 17 L/h. Which should I choose?

It depends on pressure and space. B-13 tops out at 3.5 kg/cm² and D-12 at 7 kg/cm², so with back pressure go for D-12. With very low pressure and a need for a lighter unit, B-13 works.

Which LMI dosing pump model takes a 4…20 mA signal?

Choose a "9" model such as B-91 or D-92. The data sheet states the "9" models are automatic-control pumps, so tell the supplier your signal type when ordering.

Can D-14 inject into a pressurized line?

Only if the pressure is very low. D-14 has the most flow but its table rating is just 1.5 kg/cm², which suits open tanks or near-atmospheric injection points.

Can I change the flow while the pump is stopped?

Yes. Both data sheets say flow can be set from 0–100% whether the pump is running or stopped, and stroke length can be adjusted by hand while it runs.

My chemical gasses off. Is a B or D series LMI dosing pump suitable?

It can work, but plan for venting. Mount the pump near the liquid level, purge air from the head at start-up and keep lines short. If the chemical gasses off heavily, mention it at the selection stage so the liquid end can be checked.

Not sure which size fits your duty? Send us the chemical, dose rate and injection pressure through our contact page and we will pick a model with you.