WATERAX BB-4® SERIES
High-pressure 4-stage fire pumps delivering up to 440 PSI and 106 GPM. The weapon of choice for Type 6 brush trucks, slip-on units, and demanding wildland firefighting operations.
40+ Years of Proven High-Pressure Performance
The WATERAX BB-4® series has been the weapon of choice for forest agencies and wildland firefighters for over 40 years. These high-pressure 4-stage centrifugal pumps deliver the pressure needed to operate very long hose lays and overcome pressure losses due to large elevation changes encountered in rugged wildland fire operations.
Available with 18-23 HP Briggs & Stratton Vanguard, 21 HP Honda GX630, or 25 HP Kubota diesel engines, BB-4 pumps deliver pressures up to 440 PSI and flows up to 106 GPM. The innovative quick-release clamp allows field replacement of pump ends in minutes without tools.
The 4-stage pump end on the BB-4 is identical to the pump end on the legendary MARK-3®, greatly reducing spare parts inventory and improving response to unexpected equipment damage. You can also quickly install a mid-range B2X™ pump end as needed for supply or structure firefighting.
Key Features
B2X-18 Performance
The 4-stage pump end is identical to the MARK-3®, reducing spare parts inventory. The quick-release clamp allows field replacement without tools, minimizing equipment downtime.
Maintenance-Free Bearings
Sealed ball bearings eliminate pump end greasing in the field. Combined with the blister-resistant mechanical rotary seal, BB-4 pumps deliver extended service life in demanding conditions.
Belt Drive System
Proven timing belt and pulley system with 1.88:1 speed increaser provides reliable, low-maintenance power transfer. Time-tested over 40+ years of field use by forest agencies worldwide.
Choose Your BB-4 Configuration
The BB-4 series offers multiple engine options to match your power requirements: Briggs & Stratton Vanguard (18 or 23 HP), Honda GX630 (21 HP), or Kubota diesel (25 HP). All models share the same proven 4-stage pump end.
BB-4-18 (18 HP Briggs & Stratton)
BB-4-18 Performance
Maximum Pressure: 440 PSI (30.3 BAR)
Maximum Flow: 104 GPM (394 L/min)
Maximum Head: 1,016 ft (310 m)
Pump Type: 4-stage centrifugal
BB-4-18 Flow at Pressure
At 150 PSI: 100 GPM (379 L/min)
At 250 PSI: 80 GPM (303 L/min)
At 350 PSI: 50 GPM (189 L/min)
BB-4-18 Configurations
BB-4-18V: Vehicle mount, vertical drive
BB-4-18VT: Vehicle mount with integral fuel tank
BB-4-18VX: Vehicle mount with exhaust primer
Weight: 153-165 lbs depending on configuration
BB-4-23 (23 HP Briggs & Stratton)
BB-4-23 Performance
Maximum Pressure: 440 PSI (30.3 BAR)
Maximum Flow: 106 GPM (401 L/min)
Maximum Head: 1,016 ft (310 m)
Pump Type: 4-stage centrifugal
BB-4-23 Flow at Pressure
At 150 PSI: 105 GPM (397 L/min)
At 250 PSI: 95 GPM (360 L/min)
At 350 PSI: 65 GPM (246 L/min)
BB-4-23 Configurations
BB-4-23V: Vehicle mount, vertical drive
BB-4-23VX: Vehicle mount with exhaust primer
BB-4-23PXTC: Portable with carry frame
Weight: 153-162 lbs depending on configuration
BB-4-21H (21 HP Honda GX630)
BB-4-21H Performance
Maximum Pressure: 440 PSI (30.3 BAR)
Maximum Flow: 106 GPM (401 L/min)
Maximum Head: 1,016 ft (310 m)
Pump Type: 4-stage centrifugal
BB-4-21H Flow at Pressure
At 150 PSI: 103 GPM (390 L/min)
At 250 PSI: 94 GPM (356 L/min)
At 350 PSI: 65 GPM (246 L/min)
BB-4-21H Configuration
BB-4-21H: Vehicle mount, horizontal drive
Engine: Honda GX630 twin-cylinder
Power: 20.8 HP @ 3600 RPM
Weight: 169 lbs
BB-4-D902 (25 HP Kubota Diesel)
BB-4-D902 Performance
Maximum Pressure: 395 PSI (27.2 BAR)
Maximum Flow: 106 GPM (401 L/min)
Maximum Head: 912 ft (278 m)
Pump Type: 4-stage centrifugal
Kubota D902 Engine
Engine: Kubota D902-E4B
Type: 3-cylinder, liquid cooled diesel
Power: 25 HP
Features: Fuel injected, low maintenance
BB-4-D902 Configurations
BB-4-D902V: Vehicle mount, vertical drive
BB-4-D902H: Vehicle mount, horizontal drive
FastWire: 14-pin connector standard
Listed: USFS Type 6 Fire Apparatus specs
Common Pump Specifications
All BB-4 models share these pump end specifications.
Pump End Specifications
Pump Construction
Type: Detachable 4-stage centrifugal
Body & Diffusers: Anodized corrosion-resistant aluminum
Impellers: 3.67" diameter, anodized aluminum
Pump Shaft: Stainless steel
Max Allowable Pressure: 600 PSI (41.4 BAR)
Pump Connections
Intake: 2" Male NPSH
Discharge: 1-1/2" Male NPSH
Priming Port: 1-1/2" Male NPSH
Clamp: Hand-tight quick-release (no tools needed)
Drive: Timing belt & pulley, 1.88:1 ratio
Seals & Bearings
Bearings: Maintenance-free sealed ball bearing
Pump Seal: Blister-resistant carbon seal face, silicon carbide seat
Ratings: ISO 9 and NFPA 1906 Medium Pressure
Special Feature: Pump separates completely from engine/speed increaser
Priming Options
Guzzler Hand Primer
Type: Diaphragm, reliable & lightweight
Lift: 12 ft (16 ft with foot valve)
Volume: 0.44 quart per stroke
Construction: Aluminum handle, composite body
Shipped: Loose with hardware & 6 ft hose
Exhaust Primer
Type: Venturi (mounted to exhaust primer muffler)
Construction: Brass venturi, aluminum exhaust valve
Operation: Remote mount push/pull cable
Vacuum: Minimum 17 in-Hg
Electric Primer
Type: 12 VDC piston vacuum pump
Lift: 25 ft (7.6 m)
Vacuum: 22 in-Hg
Max Current: 105 amps
Weight: 8.1 lbs with mounting plate
Applications
BB-4 pumps are designed for professional wildland firefighting operations where high pressure is essential to overcome terrain challenges.
Type 6 Brush Trucks & Slip-On Units
The BB-4 has been the pump of choice for Type 6 brush trucks for over 40 years. Vehicle-mount configurations with FastWire connectors integrate seamlessly with WATERAX control panels.
Long Hose Lays
High pressure output up to 440 PSI enables water delivery over extended distances. The 1,016 ft maximum head overcomes pressure losses from friction and elevation changes in rugged terrain.
Tandem & Parallel Pumping
Strong enough to serve as a source pump for tandem and parallel pumping operations. Connect multiple BB-4 pumps in series for extreme pressure, or in parallel for increased flow.
High-Elevation Firefighting
The 23 HP model is ideal for pumping at high altitudes where engine power loss is a concern. High pressure provides accuracy in flow trajectory for structure protection.
Documents & Resources
BB-4-21H Data Sheet
Official WATERAX BB-4-21H Honda specifications, performance curves, and technical drawings.
BB-4-23V Data Sheet
Official WATERAX BB-4-23V Briggs & Stratton specifications, performance curves, and technical drawings.
BB-4-D902 Data Sheet
Official WATERAX BB-4-D902 Kubota diesel specifications and technical drawings.
Owner's Manual
Complete operating instructions, maintenance procedures, parts breakdown, and safety guidelines for all BB-4 models.
Shop Parts
Genuine WATERAX replacement parts ensure your pump delivers reliable performance season after season. From pump bodies and impellers to suction covers, mechanical seals, and shaft assemblies—we stock the components you need to maintain and service your pump.