Milton Roy Metering Pump Models Explained: G Series, MAXROY, Milroyal and Primeroyal
Milton Roy metering pump models carry a lot of names: G, MAXROY, Milroyal, Primeroyal, mRoy, and the LMI brand on top. First-timers get lost quickly. Sort the Milton Roy metering pump models into four lines by drive type and pressure class, then look at flow within each line, and it all becomes clear. This overview is a map, not a model-by-model breakdown. Its job is to tell you which brochure to open.
Line One: Mechanical Diaphragm Milton Roy Metering Pump Models
These suit water treatment dosing from atmospheric pressure up to the teens of bar. Simple construction, easy maintenance.
G series GM/GB
Up to 1800 L/h per head and 12 bar discharge pressure, 10:1 turndown, ±1% steady-state accuracy, 3 m suction lift and fluid temperatures up to 60 ℃. Heads come in PVC, PVDF and 316 stainless, plus high-viscosity and slurry versions. Adjustment can be manual, electric or variable frequency, and a double-diaphragm head with rupture detection is available.
SDP smart digital series
Also a mechanical diaphragm design, up to 1800 L/h per head and 10 bar. It adjusts both motor frequency and stroke length, reaching 1000:1 turndown with ±1% steady-state accuracy from 1% to 100% of rated flow. It has a touch screen and Modbus RS485 as standard, which suits sites that need remote monitoring and a wide flow range.
MAXROY B series
Up to 1100 L/h and 10 bar, with a built-in relief valve against overpressure and a composite PTFE and elastomer diaphragm. It complies with API675 and can be multiplexed. The literature also lists special liquid ends for concentrated sulfuric acid, high viscosity and slurries.
Line Two: Hydraulic Diaphragm Milton Roy Metering Pump Models
These Milton Roy metering pump models come in when pressure and reliability demands go up. Hydraulic oil drives the diaphragm, allowing higher pressure at the cost of an oil circuit to maintain.
mRoy A/B
Built for continuous chemical feed, with a hydraulically actuated PTFE diaphragm, internal relief valve and oil-bath worm gear drive. Common on cooling towers, boilers, drinking water and industrial water treatment.
Milroyal B series
Up to 2616 L/h per head and 250 bar, designed and built to API675, with the MARS mechanical automatic refill system. Several units can be ganged, each adjusted separately.
Milroyal D series
Flow from 0.11 to 345 L/h and pressure up to 500 bar. Liquid end options include the M metal diaphragm, HPD hydraulic diaphragm and U and N plunger heads. Plunger stroke is 25.4 mm, fluid temperature up to 110 ℃, and up to 13 heads can be ganged. The first typical application in the literature is methanol and corrosion inhibitor injection at oil and gas wellheads.
Line Three: Primeroyal High-Pressure Process Pumps
This is the heaviest group among Milton Roy metering pump models, all designed to API675 for critical petrochemical and oil and gas service. The Primeroyal models step up by thrust and flow:
- PH: about 948 L/h, up to 690 bar;
- PK: about 2500 L/h, up to 930 bar;
- PL: about 4410 L/h, up to 1034 bar;
- PQ: about 8657 L/h, up to 1035 bar;
- PN, PR, PP: flows above 9683, 15659 and 15665 L/h respectively;
- Primeroyal X: built for ultra-high pressure at 1380 bar, with a metal double-diaphragm liquid end, mainly for chemical injection on offshore platforms.
These are upper limits for each Milton Roy metering pump model. No single pump hits maximum flow and maximum pressure at once. What a given liquid end delivers at a given pressure is in the data sheet for that model.
How a Milton Roy Metering Pump Model Number Is Built
Many Milton Roy metering pump models use a long product code, but there's a pattern. The first letters identify the series, followed by stroke speed or plunger diameter, motor, liquid end size and type, operating pressure, and then options. MAXROY codes start with MXB, Milroyal B codes with MBH, and later positions cover materials, connection type, diaphragm monitoring, number of valve balls and so on.
When reading a code, focus on the liquid end material and operating pressure. Those two decide what chemical the pump can handle and how much pressure it can push. Other options can be confirmed with the factory later.
One small tip: some Primeroyal data sheets exist in Chinese and some only in English. Don't skip a model just because you can't find it in one language.
Line Four: LMI Solenoid Milton Roy Metering Pump Models
LMI is Milton Roy's solenoid metering pump brand, focused on low flow.
The P+ series reaches 15.1 L/h and 17.2 bar, with adjustable stroke rate and stroke length, taking 4–20 mA or pulse. The B series reaches 17 L/h and 10 bar with 1.5 m suction lift. The D series reaches 90 L/h and 18 bar. EXCEL AD offers up to 1000:1 turndown. The C series has many models, from the C10 at 4.9 L/h and 20.7 bar to the C14 at 76 L/h and 1.7 bar. There's also EXCEL XR, which is really a mechanical diaphragm pump driven by a variable-frequency motor. It carries the LMI name, but don't treat it as a solenoid pump.
Narrowing Down Milton Roy Metering Pump Models Fast
With duty data in hand, filter the Milton Roy metering pump models with three questions.
How high is the pressure? Within 12 bar, start with the mechanical diaphragm pumps. Tens to hundreds of bar, look at Milroyal. Hundreds to over a thousand bar, Primeroyal.
How much flow? Up to a dozen or so liters per hour is mostly LMI. Tens to one or two thousand liters per hour, look at the G series, SDP and MAXROY. Larger flows go to Milroyal B and the big Primeroyal models.
Is there a standard requirement? If the project documents call for API675, choose only among series marked API675 compliant, such as MAXROY, Milroyal and Primeroyal.
Conclusion
The Milton Roy metering pump models boil down to one line: G, SDP and MAXROY for mechanical diaphragm, mRoy and Milroyal for hydraulic diaphragm, Primeroyal for ultra-high-pressure process duty, and LMI for low-flow solenoid. Use pressure and standards to pick the series, flow to pick the model, then confirm liquid end and materials on the data sheet. Published flow and pressure figures are series maximums, so real selection depends on your actual duty point.
FAQ
How are Milton Roy and LMI related?
LMI is Milton Roy's solenoid metering pump brand, centered on low-flow water treatment dosing. It complements Milton Roy's mechanical and hydraulic pumps.
Among the mechanical Milton Roy metering pump models, G series or SDP?
Their flow and pressure ranges are close. For a steady dose, the G series is enough. For widely varying flow with remote control and data logging, the SDP's 1000:1 turndown and touch screen fit better.
Is API675 always required?
No. Routine water treatment usually doesn't call for it. Petrochemical process injection points and projects whose documents specify it do.
Why does Milroyal D combine such low flow with such high pressure?
It's built for low-flow, high-pressure chemical injection, such as wellhead methanol and corrosion inhibitor. 500 bar is the series limit, and what you actually get depends on whether you choose a plunger, metal diaphragm or hydraulic diaphragm head.
Can I pick between Milton Roy metering pump models using the maximum figures?
No. The published limits are series maximums. Check the specific model's flow at your working pressure and leave margin.
Not sure which series your duty falls into? Gather flow, pressure and chemical and send them through our contact page. We'll match a model from the Milton Roy brochures with you.