Franklin Electric MH Multi-Stage Booster Pump

The MH is Franklin’s horizontal multistage booster: stages stacked in line to build pressure in a compact body, with the entire wet end in 300-series stainless steel. Franklin lists it for pressure boosting from city mains or private water systems, water transfer and circulation, lawn and crop irrigation, reverse osmosis, filtration, pressure washing, poultry houses, spray cooling, evaporative misters, aeration, wash-down, commercial water features and cisterns.

Three nominal flow ratings — 15, 30 and 45 GPM — each in several stage counts, which is how you buy pressure. A 15 GPM pump in 4, 5 or 6 stages gives 88, 111 or 135 psi of shut-off head at the same nominal flow.

The motors are industry-proven, UL 778 approved, indoor/outdoor rated square-flange two-compartment units, and the three-phase versions are inverter duty rated — which matters if this is going in front of a drive rather than a pressure switch.

The MH is a bare pump and motor assembly, supplied as a single unit. Franklin publishes no paired or staged configuration for this series; multi-pump operation is a function of the control you put in front of it.

Where the installation wants constant pressure or a second pump, Franklin builds that separately. The VersaBoost Pro is a complete constant-pressure system that links up to four units wirelessly in parallel, and the Inline Controls range turns a pump like this one into a demand-led system without a tank. For a larger commercial package, the Inline SpecPAK stages two to four pumps on one manifold.

All 300-series stainless wet end — Every wetted part in 300-series stainless, which is what lets the pump handle RO permeate, filtration duty and wash-down water rather than just clean municipal supply.

Carbon / ceramic mechanical seal — With FKM elastomers and 300-series stainless components.

Inverter duty rated, three phase — The three-phase motors are inverter duty rated, so the pump can sit in front of a VFD rather than only a pressure switch.

225°F fluid temperature — Maximum fluid temperature to 225°F / 107°C — well beyond domestic boosting, and the reason this pump turns up in process and spray-cooling work.

140 psi maximum working pressure — The casing rating. Incoming plus added has to stay below it.

10 ft suction lift — Capable of suction lifts up to 10 feet, which most multistage boosters cannot do at all.

Franklin publishes the MH as capacity at total head, so the tables below are the manufacturer’s own. Read down the head column you need and across to the model.

15 GPM nominal — operating range 8 to 25 GPM

30 GPM nominal — operating range 15 to 40 GPM

45 GPM nominal — operating range 25 to 60 GPM

The models below are tabulated as pressure added at flow (the manufacturer publishes these curves in that orientation):

15 GPM nominal, 1/2 HP — PSI boost at flow

15 GPM nominal, 3/4 HP — PSI boost at flow

30 GPM nominal, 3/4 HP — PSI boost at flow

70 GPM nominal — PSI boost at flow

90 GPM nominal — PSI boost at flow

Drawing from a tank or cistern — nothing arrives with pressure, so total head and pressure added are the same number. A 30FMH2S5 moving 38 GPM is making 130 ft, which is 56 psi.

Fed by a city main — the pump adds on top of what already arrives, and the head in these tables is what it adds. On a 40 psi main, a pump making 130 ft of head puts 96 psi into the building. Check that against the 140 psi casing rating and against local code before selecting.

Best operating range: 8 to 25 GPM on the 15 GPM models, 15 to 40 GPM on the 30 GPM, and 25 to 60 GPM on the 45 GPM. These are Franklin’s own published operating ranges, not derived figures. Below this range the pump recirculates internally, which causes vibration and premature seal wear. Above it, it cavitates and the motor draws past its rating. Most booster failures are pumps that were oversized for the building.

Shut-off head is the pressure at zero flow — a ceiling, not a working point. A dash means the pump will not deliver at that head. Figures are 60 Hz US data from the Franklin Electric RLC Surface catalog M5049, and the operating ranges are the bands Franklin prints on its own performance curves. Convert head to psi by multiplying feet by 0.433.

This model has no app or remote connectivity. It runs from its own controls and needs no network connection.