LMI Two Dial B Series Chemical Metering Pump — 1.4 to 7.0 GPH, NSF 50/61/372, Standard and Chlorine-Handling Models

Manually Adjustable Diaphragm Metering Pump For Water Treatment, Sodium Hypochlorite Dosing, And Industrial Chemical Injection

The LMI Two Dial B Series is a solenoid-driven Liquifram™ diaphragm metering pump that injects measured amounts of chemical into water and process lines. Two control dials adjust stroke length and stroke speed for a 1000:1 turndown range. Available in standard and chlorine-handling (AutoPrime) configurations for municipal, industrial, and water treatment dosing.

Key Features of the LMI Two Dial B Series Chemical Metering Pump

• Two-dial manual control lets you adjust stroke length and stroke speed independently, giving a 1000:1 turndown range from 0.1% to 100% of rated output.
• Clear acrylic pump head shows the diaphragm moving on every stroke, so operators can confirm chemical flow at a glance without disassembling the pump.
• AutoPrime® off-gassing valve vents gas bubbles back to the supply tank on each stroke, preventing air lock when pumping sodium hypochlorite, calcium hypochlorite, or hydrogen peroxide (chlorine-handling models only).
• Four-function discharge valve (4FV) combines anti-siphon, back-pressure, priming, and check valve functions in one unit, removing the need for separate accessories at the injection point.
• Automatic over-pressure protection stops the Liquifram™ from pulsating when discharge pressure exceeds the pump's rating by more than 35%, eliminating the need for a separate pressure relief valve.
• NEMA 4X / IP65 enclosure handles outdoor installations and wet indoor environments, with full sealing against splashes, chemical spray, and dust.
• 115 VAC, 50/60 Hz electrical fits standard US and Canadian wall outlets, with a maximum 29-watt power draw at full speed and pressure. 230 V version available on request.
• Complete out-of-the-box kit includes the pump, foot valve with integral strainer, ceramic weight, injection check valve, four-function discharge valve, 16 ft (4.8 m) of chemical tubing, and the installation manual.

How to Choose: Standard vs. Chlorine-Handling

This is the most common question buyers have. Here's the plain-language answer.

What goes wrong with chlorine in a standard pump: Sodium hypochlorite (liquid chlorine bleach) slowly breaks down in your supply tank and releases tiny gas bubbles. Those bubbles get drawn into a standard pump head along with the chemical. Over time, the bubbles collect into an air pocket inside the pump. The pump keeps cycling, but no chemical comes out. This is called losing prime or air lock. You'll see the pump running, but your chlorine residual drops to zero.

How AutoPrime fixes it: The chlorine-handling pump head includes a fifth functional element called the AutoPrime valve, which sits on top of the liquid end. On every pump stroke, this valve vents the gas bubbles back to your chemical tank, so the bubbles never get a chance to collect inside the pump. The pump stays primed automatically, even sitting overnight.

Choose chlorine-handling models ("HI" suffix) for:

• Sodium hypochlorite (any concentration up to 12.5%, the NSF 50 test concentration)
• Calcium hypochlorite solution
• Hydrogen peroxide
• Any other chemical that releases gas in the supply tank

Choose standard models ("SI" suffix) for: alum, citric acid, coagulants, PAC, caustic soda, hydrochloric acid (NSF 50 tested up to 31%), scale inhibitors, polymers, and most other water treatment chemicals that don't off-gas.

Install Note for Chlorine-Handling (AutoPrime) Models

AutoPrime models work in both suction-lift and flooded-suction installations. For flooded-suction setups (chemical tank above the pump), the fluid level in the supply tank should not exceed 3 feet above the suction check valve. The AutoPrime valve continuously bleeds a small amount of fluid back to the supply tank, so excessive heat from a high tank can cause continuous overflow at that bleed line. For tanks higher than 3 feet above the pump, contact our team. We'll help you configure your installation correctly.

Specifications

Model Lineup

Quick guide on sizing: higher PSI models inject against pressurized water mains or process lines (typical municipal distribution runs 50–150 PSI). Lower PSI models handle gravity-fed or atmospheric systems. Higher GPH models handle larger flow streams or higher dosing rates.

Not sure which model fits your system? Contact our team with your flow rate, system pressure, and chemicals. We'll help you pick.

What's in the Box

Every B Series pump ships ready to install with 16 ft (4.8 m) of tubing total. Each kit includes:

• The B Series pump with attached power cord
• Foot valve assembly with integral one-piece strainer (sits in your chemical tank)
• Ceramic weight (keeps the foot valve vertical and submerged at the tank bottom)
• Injection check valve with 1/2" NPT male connection (installs where chemical enters your water or process line)
• Four-function discharge valve (4FV)
• Suction and discharge chemical tubing — 16 ft (4.8 m) total per pump, with compressing connections
• Installation and operation manual

Applications

The LMI Two Dial B Series handles chemical dosing in:

• Municipal water disinfection: sodium hypochlorite chlorination at small and mid-sized treatment plants
• Wastewater effluent disinfection: chlorine residual control at lift stations and treatment lagoons
• Cooling tower chemical treatment: biocide, scale inhibitor, and corrosion inhibitor feed
• Boiler water treatment: oxygen scavenger and pH adjustment dosing
• Drinking water systems: small community wells and booster stations (NSF 61 certified for potable contact)
• Industrial process water: alum, PAC, and coagulant feed for clarifier systems
• Chemical dosing skids: pH adjustment with caustic or hydrochloric acid feed

Certifications

The LMI Two Dial B Series carries the following certifications, listed individually because municipal and procurement buyers verify each one before purchase:

• cUL — Canadian electrical safety listing
• UL — US electrical safety listing
• NSF/ANSI 50 — rated for chemicals used in commercial water treatment (tested with 31% hydrochloric acid and 12.5% sodium hypochlorite per LMI's General Pump Manual)
• NSF/ANSI 61 — approved for use on potable drinking water systems
• NSF/ANSI 372 — lead-free compliant (≤0.25% weighted average lead) per the US Safe Drinking Water Act and corresponding Canadian requirements
• CE — European conformity for international installations

Why Choose the LMI B Series

The LMI B Series handles the chemistries Cleanflow customers run every day sodium hypochlorite, caustic, PAC, alum, and process acids at flow rates from 1.4 to 7.0 GPH with 1000:1 turndown. NSF 50, 61, and 372 certifications cover potable water and lead-free compliance. Cleanflow is a trusted LMI Milton Roy supplier across Canada and the USA, with liquid-end rebuild kits and accessories stocked.

Buy the LMI Two Dial B Series Chemical Metering Pump Online from Cleanflow

In stock and ready to ship from our Winnipeg warehouse, typically same- or next-business-day across Canada and the USA. Browse the full LMI Milton Roy chemical metering pump range at Cleanflow.