GRUNDFOS · BM BOOSTER MODULE
BM 3 — 4 in Booster Module
Grundfos BM 3 booster module: a submersible multistage pump and motor sealed inside a stainless steel pressure sleeve, installed in-line to add pressure to a pressurized feed. 7 models, 1 to 5 1/2 HP, 3 x 440-480V, 4 in sleeve, 3 material versions.
298-1,133 ft (129-490 PSI) Max Boost · 20.6 GPM Max
1-5 1/2 HP
440-480V 3Ph
4 in Module
Victaulic-Type In-Line Connections
1,199 PSI Max Operating Pressure
Max Inlet 725 PSI
IP66
70.6-137 lb Weight
Overview
The BM 3 puts a Grundfos submersible pump and motor inside a stainless steel sleeve with inlet and outlet connections, so the whole unit sits in the pipe run and boosts an already pressurized flow. It is built for reverse osmosis feed and other high-pressure boosting duties. The motor is liquid-filled and cooled by the pumped water passing through the sleeve.
- 7 BM models, 1 to 5 1/2 HP, 3 x 440-480V
- BM: 304 stainless steel, NBR rubber; BM-N: 316 stainless steel, NBR rubber; BM-NE: 316 stainless steel, FKM (Viton) rubber
- 42 mm (1 1/4 in) Victaulic-type (PJE) couplings, straight-through or with elbow
- Maximum operating pressure 1,199 PSI; maximum inlet pressure 725 PSI (Grundfos data)
What Ships and What It Needs to Run
Included: the BM module: pump and motor in the stainless steel sleeve, with terminal box; motor filled with the standard glycol/water mixture (Grundfos price list).
Motor protection and starter required, ordered separately. Grundfos data lists external thermal protection and direct-on-line starting.
Mating couplings and pipe for the Victaulic-type connections, valves, power supply and disconnect: sized to your system and ordered separately.
Demineralized water: a demineralized-water motor fill is a Grundfos factory option at extra cost; ask us before ordering.
Genuine Grundfos equipment, factory-new in original packaging — sold and supported by Watermain Supply, an independent industrial supplier.
Warranty: 24 months from date of installation, but not more than 30 months from date of manufacture (Grundfos limited warranty). Grundfos repairs or replaces its own product; costs of removal, installation and transportation are not covered, and products sold but not manufactured by Grundfos carry their own manufacturer’s warranty.
Specifications
| Specification |
Value |
| Pressure boost range at zero flow |
298 to 1,133 ft (129 to 490 PSI) |
| Motor power range |
1 to 5 1/2 HP |
| Supply |
3 x 440-480V, 60 Hz |
| Starting |
Direct-on-line (Grundfos data) |
| Sleeve diameter |
4 in |
| Connections |
42 mm (1 1/4 in) Victaulic-type (PJE) couplings, straight-through or with elbow |
| Maximum operating pressure |
1,199 PSI (82.7 bar), Grundfos data |
| Maximum inlet pressure |
725 PSI |
| Liquid temperature |
up to 104 °F |
| Enclosure |
IP66 |
| Material versions |
BM: 304 stainless steel, NBR rubber; BM-N: 316 stainless steel, NBR rubber; BM-NE: 316 stainless steel, FKM (Viton) rubber |
Models & Performance — Will It Do What You Need?
Find the pressure boost you need at your flow and pick the first model that reaches it; the module adds this to the inlet pressure. Boost at flow in PSI, one row per model.
BM 3A-10 to BM 3A-38 · 7 models
| Model (HP) |
0 GPM (Shut-off) |
4 GPM |
10 GPM |
15 GPM |
20 GPM |
| BM 3A-10 (1 HP) |
129 |
122 |
110 |
93 |
63 |
| BM 3A-14 (1 1/2 HP) |
181 |
171 |
155 |
131 |
89 |
| BM 3A-18 (2 HP) |
232 |
219 |
197 |
166 |
112 |
| BM 3A-24 (3 HP) |
310 |
294 |
264 |
224 |
152 |
| BM 3A-28 (4 HP) |
361 |
344 |
313 |
270 |
198 |
| BM 3A-32 (4 / 5 1/2 HP) |
411 |
390 |
357 |
310 |
225 |
| BM 3A-38 (5 1/2 HP) |
490 |
466 |
428 |
373 |
273 |
Pressure the module adds to its inlet pressure at each flow, in PSI, rounded down (feet = PSI × 2.31). Shut-off is read from the Grundfos curve at zero flow. Flow columns are read from the Grundfos 60 Hz curve for each model (water at 68 °F), digitized and rounded down, at 20%, 50%, 75% and 100% of 20 GPM, the last regular flow every curve in this listing reaches; the curves end at 20.6 GPM. Full Grundfos curves are in the product images.
Before You Buy — The Limits That Decide the Fit
| Check |
What decides the fit |
| Duty point |
The model’s boost at your flow plus the inlet pressure must give the outlet pressure you need; the table shows the boost alone. |
| Inlet pressure |
The inlet pressure must stay within 725 PSI, and inlet plus boost within 1,199 PSI. |
| Material |
Pick the version that suits the pumped liquid: 304 (BM), 316 (BM-N), 316 with FKM rubber (BM-NE) or the high-alloy R version (904L, duplex sleeve); ask us if unsure. |
| Liquid temperature |
up to 104 °F. |
| Power |
3 x 440-480V supply; other voltages on request from Grundfos. |
| Cooling |
The pumped liquid cools the motor; never run the module dry or against a closed outlet. |
Applications
Reverse osmosis and desalination feed and boosting, pressure boosting in water supply and industrial process systems, washing and cleaning systems (Grundfos BM booster module applications).
Materials of Construction
| Component |
Material |
| BM version |
304 stainless steel pump and sleeve, NBR rubber |
| BM-N version |
316 stainless steel, NBR rubber |
| BM-NE version |
316 stainless steel, FKM rubber |
