Franklin Electric FBSTF Series Frame Mount Self-Priming Pump

FBSTF Pump Manuals & Resources

Franklin Electric FBSTF Frame Mount Self-Priming Pump Overview

The Franklin Electric FBSTF Series is a range of frame-mounted, self-priming centrifugal pumps for irrigation, liquid fertilizer transfer, construction dewatering, and commercial or industrial water movement. Four pump-end models, FBSTF-1, FBSTF-2, FBSTF-3, and FBSTF-5, cover the manufacturer’s listed 1–5 HP drive ratings and 1-1/4-inch, 2-inch, and 3-inch threaded port configurations.

These pumps combine a cast iron volute, semi-open cast iron impeller, and independent bearing frame. The design suits installations where the power source is connected through an appropriately engineered belt or direct-drive arrangement rather than a close-coupled motor. Franklin Electric lists series capacities up to 250 GPM, heads up to 80 feet, a 120 PSI maximum working pressure, and a 200°F maximum liquid temperature. Actual duty-point flow depends on the selected model, drive speed, system head, and piping losses.

Key Features and Benefits

• Self-priming after initial filling: The pump is designed to re-prime during normal cycling when sufficient liquid remains in the casing. The casing must be filled before initial operation and whenever prime is lost.
• Semi-open cast iron impeller: Franklin describes the impeller as non-clogging and incorporates a blind-hole design to help protect the pump shaft. Confirm the suitability of any solids-laden liquid against the intended service conditions.
• Frame mount with separate drive: A heavy-duty bearing frame enables properly selected belt or direct-drive arrangements, with shaft alignment and drive guarding handled during installation.
• Cast iron volute with service openings: Ports allow access for priming, venting, and draining.
• Mechanical sealing: Manufacturer series literature specifies carbon/ceramic seal faces, FKM (Viton) elastomers, and stainless components. Individual service-seal part listings may use different material descriptions; confirm the installed seal by model and build date.
• Four available sizes: Select from FBSTF-1, FBSTF-2, FBSTF-3, and FBSTF-5 according to required flow, total dynamic head, power arrangement, and connections.

FBSTF Series Technical Specifications

FBSTF-1, FBSTF-2, FBSTF-3 and FBSTF-5 Ordering Information

Use the Franklin order number to identify the required pump-end model. The rating and port sizes below follow the manufacturer frame-mount catalog. A pump-end order is not an automatic guarantee that a motor, belt, coupling, base, or guard is included.

For selection help, provide your required GPM, total dynamic head, available drive speed and power, suction lift, fluid details, and existing connection sizes when requesting a quote.

How FBSTF Self-Priming Works

The FBSTF casing must be filled with the liquid to be pumped before initial startup. During normal operation, the self-priming arrangement helps clear air from the suction line and establish flow. If liquid is lost from the casing, the pump can lose prime and must be filled again according to the manufacturer instructions. Do not operate the pump dry.

Self-priming does not eliminate suction-lift, pipe-friction, air-leak or NPSH limitations. For liquid fertilizer transfer, Franklin’s owner’s manual discusses a vertical distance of up to 25 feet under suitable conditions, with elevation and friction losses taken into account. Treat that as a conditional installation reference, not a guaranteed lift in every system.

Common Applications

• Irrigation and agricultural transfer: Transferring water or compatible liquid fertilizer where a frame-mount pump matches the selected power arrangement.
• Construction dewatering: Moving water from suitable sumps and drainage areas, subject to solids content and suction conditions.
• Commercial and industrial water transfer: Tank-to-tank or other general liquid-transfer duties within the published pressure, temperature and materials limitations.
• Municipal or field applications: Pumping installations that require belt or direct-drive flexibility and the ability to re-prime following normal stops.

Before handling fertilizer or any chemically treated liquid, check seal and pump-material compatibility. The owner’s manual prohibits pumping flammable liquids. Avoid assuming that a semi-open impeller makes the pump appropriate for unrestricted abrasive slurries or large solids.

FBSTF Pump Selection and Installation Considerations

• Choose by duty point, not HP alone. Size against the manufacturer performance curve using your required flow, total dynamic head and actual operating speed.
• Match the piping. FBSTF-1 uses 1-1/4-inch ports; FBSTF-2 and FBSTF-3 use 2-inch ports; FBSTF-5 uses 3-inch ports. Size the suction line to minimize air pockets and friction loss.
• Mount and align the drive carefully. Follow the drive manufacturer’s instructions for coupling or pulley alignment, guarding, base rigidity, and permitted operating speed.
• Prime before starting. Fill the casing through the priming opening and confirm that suction connections are airtight. Never use the pump dry to test motor rotation.
• Protect against freezing. Drain the pump and piping according to the owner’s manual when frost exposure is expected.
• Check installed components before replacement. Some seal plates, transmission heads, gaskets and O-rings vary with manufacturing date; do not assume all FBSTF variants share service parts.

FBSTF Replacement Parts and Exploded View

Use the exploded-view figure numbers to identify the correct component. The table below follows Franklin Electric’s current frame-mount catalog and includes all four FBSTF models. Always cross-check model and manufacture date before purchasing replacement parts.

Current-Catalog Materials and Repair Parts

Important seal clarification: Franklin’s series features specify FKM elastomers, while the catalog’s replacement mechanical-seal row describes Buna. These are separate published descriptions. Confirm the correct seal part and material for your pump, application, and production date before ordering.

Pre-May 2019 and Older Part References

Some older FBSTF units use a different seal plate, transmission head, or gasket arrangement. The discontinued/older references below are preserved for parts identification, not represented as guaranteed substitutes for current production components.

FBSTF Dimensions

The manufacturer dimensions below are in inches and are intended for estimation and preliminary layout. Verify the final pump and drive assembly dimensions before fabrication.

FBSTF Performance Curves

Use the performance curve for your chosen FBSTF model to check flow and head at the intended operating speed. A maximum series flow value does not represent the flow available at the maximum series head. The catalog curve is labeled for a nominal speed of 3,600 RPM; the owner’s manual includes performance figures based on 3,450 RPM, so compare data at a consistent speed.

For official reference, see the Franklin Electric FBSTF Series product page, which links to the current catalog and owner’s manual.

Frequently Asked Questions About the Franklin Electric FBSTF

Is the FBSTF a frame-mount or close-coupled pump?

The FBSTF is a frame-mount centrifugal pump. Its bearing frame supports a separate drive connection. It should not be described as close-coupled.

Which FBSTF model has 3-inch suction and discharge connections?

The FBSTF-5, order number 90253004, has 3-inch NPT suction and discharge connections. FBSTF-2 and FBSTF-3 have 2-inch ports, and FBSTF-1 has 1-1/4-inch ports.

Does the FBSTF need to be primed?

Yes. Fill the casing before initial operation and whenever prime is lost. Under appropriate conditions, the self-priming design allows subsequent normal starts without repeating the initial fill. Never run the pump dry.

Can the FBSTF be used to transfer liquid fertilizer?

Franklin’s owner’s manual identifies liquid fertilizer transfer as a suitable application under its specified conditions. Confirm the chemical formulation, wetted-material and seal compatibility, suction conditions, and all applicable safety precautions first. Never use the pump for flammable liquids.

What is the maximum working pressure and temperature?

Franklin’s frame-mount catalog lists a maximum working pressure of 120 PSI and maximum liquid temperature of 200°F for the FBSTF series. An application still must satisfy the selected model’s performance curve and other operating limits.

Are all FBSTF replacement parts interchangeable?

No. Different models and production dates can use different casings, impellers, shaft seals, transmission heads, and gaskets. Provide the pump model, figure number, existing part number and approximate manufacture date before ordering a replacement.

How does the FBSTF differ from the FMIT frame-mount pump?

Both are Franklin Electric frame-mount self-priming centrifugal pump families. The FMIT offers different pump sizes and published solids-handling details; compare the specific model curves, suction requirements, and materials instead of treating the two series as interchangeable.

Related Franklin Electric Pumps and Parts

• Franklin Electric FMIT frame-mount self-priming pumps
• Franklin Electric FBSE close-coupled self-priming pumps
• Franklin Electric FBSEF close-coupled self-priming pumps
• Franklin Electric pump replacement parts

Request a Quote for an FBSTF Pump or Repair Part

Ken’s Distributing Company can help identify the FBSTF pump end or replacement component for your job. Include the FBSTF model and order number when requesting price and availability. For pump selection, also provide your target GPM, head, drive details and liquid type. Call 303-699-7845 or use the quote form on this product page to discuss your requirements.