Burks GNB6-1-1/2-6.25 Bronze Fitted Base Mount Centrifugal Pump
The Burks GNB6-1-1/2-6.25 is a base mounted, end suction centrifugal pump built for plants that move a lot of liquid and expect the pump to keep doing it for years. It pairs a close grain cast iron casing with an enclosed bronze impeller trimmed to 6.25 inches, giving you a bronze fitted build that handles water, condensate, and mild process liquids without the corrosion headaches of an all iron wet end. Liquid enters through a 2 inch NPT suction and leaves through a 1-1/2 inch NPT discharge, a combination that suits transfer, booster, and recirculation duties across a wide slice of the flow curve.
Because this is a frame mounted design rather than a close coupled one, the pump runs in its own grease lubricated bearing frame and connects to a separately sized motor through a flexible coupling. That separation is the whole point: you can re-motor the unit, change speeds, or service the bearings without disturbing the hydraulic end. The radial split casing and back pull-out arrangement let a technician pull the rotating assembly straight out the back while the casing stays bolted to the piping, which turns a seal change from a half-day plumbing job into routine maintenance.
Sealing is handled by a self-adjusting mechanical seal with a carbon face running against a ceramic seat, backed by a bronze shaft sleeve that protects the steel shaft from wear at the seal area. The impeller is dynamically balanced for smooth, low vibration running, and a bronze casing wear ring keeps internal clearances tight so efficiency does not fall off over the service life. Whether it lands in a commercial boiler room, a food plant washdown loop, a car wash, an irrigation skid, or a cooling water circuit, this pump is a straightforward, serviceable workhorse rather than a specialty machine.
Key Features
- Enclosed bronze impeller, 6.25 in diameter, dynamically balanced for vibration free operation
- Bronze fitted construction with close grain cast iron casing
- Radial split casing with back pull-out design for servicing without breaking piping
- Self-adjusting mechanical seal with carbon face and ceramic seat
- Bronze shaft sleeve protecting the steel shaft through the seal area
- Bronze casing wear ring to maintain running clearances and efficiency
- Grease lubricated ball bearings with wide spacing for solid shaft support
- Stud mounted casing assembly for positive alignment and multiple discharge rotation positions
- Frame mounted design allowing independent motor sizing and re-motoring
- Factory tested to Hydraulic Institute standards
Applications
- General industrial water transfer and recirculation
- Commercial and institutional heating and cooling loops
- Boiler feed and condensate return service
- Process water and mild chemical circulation
- Plant and equipment washdown systems
- Car wash and vehicle cleaning systems
- Cooling tower and chiller loop circulation
- Irrigation and agricultural water supply
- Booster service for building and process water lines
- OEM skid and packaged system builds
Specifications
- Model: GNB6-1-1/2-6.25
- Brand: Burks
- Pump type: End suction, base mount centrifugal
- Discharge port size: 1-1/2 in NPT
- Suction port size: 2 in NPT
- Impeller diameter: 6.25 in
- Impeller type: Enclosed
- Impeller material: Bronze
- Casing material: Cast iron
- Adapter material: Cast iron
- Casing wear ring material: Bronze
- Shaft material: Steel
- Shaft sleeve material: Bronze
- Seal type: Self-adjusting mechanical seal
- Seal materials: Carbon / ceramic / stainless steel / Buna-N
- Maximum liquid temperature: 225 °F (107 °C)
- Casing working pressure: 200 PSI
- Maximum inlet pressure: 100 PSI
- Seal pressure rating: 150 PSI
- Design speed: 3500 RPM nominal at 60 Hz
- Mounting: Frame mounted with independent bearing frame
- Drive: Flexible coupling to separately mounted motor
Frequently Asked Questions
Q: Is the GNB6-1-1/2-6.25 sold with a motor already attached?
A: No. It is a frame mounted pump, so the bare pump runs in its own bearing frame and is coupled to a motor that is selected and sized separately. This is what allows the same pump to be matched to different horsepower or speed requirements later on.
Q: What does "bronze fitted" actually mean on this pump?
A: Bronze fitted describes a build where the casing and adapter are cast iron while the wetted rotating parts, the impeller, wear ring, and shaft sleeve, are bronze. It gives better corrosion resistance in the moving components than an all iron pump without the cost of an all bronze wet end.
Q: Can the discharge be rotated after the pump is installed?
A: Yes. The casing assembly is stud mounted, which allows the discharge to be positioned in several rotational orientations to match the piping layout, and alignment is maintained when the assembly is repositioned.
Q: Does the impeller have to stay at 6.25 inches?
A: The 6.25 in trim defines this specific model within the GNB6 family. Other diameters are offered as separate part numbers in the same series, so a different duty point is usually met by selecting the matching model rather than modifying this one.
Q: Can the seal be replaced without unbolting the pump from the system piping?
A: Yes. The back pull-out arrangement lets the rotating element and seal be withdrawn from the rear of the pump while the casing remains connected to the suction and discharge lines.
CLRMarine
