Franklin Electric FMIH Series Hydraulic Driven Self-Priming Pump

FMIH 40 Pump Manuals & Resources

The Franklin Electric FMIH Hydraulic Self-Priming Pump is a heavy-duty centrifugal pump engineered for agricultural irrigation, construction dewatering, mining, and water truck applications where tractor or equipment hydraulic power is the available drive source and self-priming capability combined with high solids tolerance is required. Handling mud, sand, and silt up to 10% by volume through a semi-open cast iron impeller, featuring a replaceable wear plate for extended service life, and driven by a 7/8-inch SAE B-fit hydraulic spline shaft, the FMIH delivers the combination of self-priming performance and hydraulic drive flexibility that remote field applications demand. At Ken’s Distributing Company, we stock the FMIH and can help you confirm hydraulic motor compatibility and spline fit before you order.

What Is the Franklin Electric FMIH Series Hydraulic Driven Self-Priming Pump?

The FMIH is Franklin Electric’s hydraulic driven self-priming centrifugal pump, representing the intersection of three capabilities that remote agricultural and industrial applications need: self-priming operation, high solids tolerance, and hydraulic motor drive compatibility. The designation FMIH identifies this as Franklin Electric’s frame mount self-priming pump series in the hydraulic driven configuration, making it the hydraulic powered equivalent of the electric motor driven FMIT Series and the gas engine driven FMIG Series.

The hydraulic drive approach is particularly practical in agricultural settings where a tractor with auxiliary hydraulic outputs is already on site. Rather than running a generator for an electric pump or managing a separate gas engine, the FMIH connects directly to the tractor hydraulic circuit through the 7/8-inch SAE B-fit spline shaft and a compatible hydraulic motor. The tractor becomes the power plant, the FMIH delivers the water flow, and the entire setup runs without electrical power or fuel management for a separate engine.

Kendisco is an authorized Franklin Electric distributor. Every FMIH ordered through Ken’s Distributing Company is a genuine Franklin Electric product with full manufacturer support and genuine replacement parts availability when service is needed.

Technical Specifications

Volute Material: Cast Iron

Impeller Type: Semi-Open Cast Iron

Solids Handling: Mud, sand, and silt up to 10% by volume

Seal: Carbon/Ceramic faces, FKM elastomers, 300 Series Stainless Steel

Bearing Frame: Heavy duty with sealed bearings, keyed stainless steel shaft

Wear Plate: Replaceable

Hydraulic Spline: 7/8-inch B-Fit spline shaft

Mounting Orientation: Horizontal

Connection Type: Threaded FNPT suction and discharge

Rotation: Clockwise facing the shaft

Order Information

How the FMIH Hydraulic Drive System Works

The FMIH connects to a hydraulic motor through the 7/8-inch SAE B-fit spline shaft. The hydraulic motor in turn connects to the tractor or equipment auxiliary hydraulic circuit. When the tractor’s hydraulic pump pressurizes fluid through the motor, the motor shaft rotates and drives the FMIH pump shaft and impeller through the spline connection.

The SAE B-fit designation is an important specification to understand before ordering. SAE B refers to the involute spline profile used for the shaft connection between the hydraulic motor and the driven equipment. The 7/8-inch diameter with the B-fit profile matches a specific range of hydraulic motors used with tractors and equipment in the agricultural and construction sectors. Confirm that your hydraulic motor uses a 7/8-inch SAE B-fit spline before ordering the FMIH to ensure a direct connection without adapters.

The flow rate and pressure output from the FMIH depend on the RPM delivered by the hydraulic motor, which is determined by the hydraulic flow rate from the tractor auxiliary circuit. Most modern tractors with auxiliary hydraulic outputs include a flow control valve that allows you to vary the hydraulic output, giving you indirect speed and flow control over the pump without additional electronic controls.

Construction Details

Cast Iron Volute with Service Ports

The FMIH volute is cast iron with dedicated tapped ports for priming, venting, and draining. The priming port allows the initial housing fill before first startup. The venting port bleeds air from the housing during priming. The drain port provides complete housing drainage for winterizing and storage without disconnecting installed piping or hose connections. Cast iron construction provides the durability needed for continuous-duty operation in agricultural and construction field environments.

Semi-Open Cast Iron Impeller with 10% Solids Tolerance

The semi-open cast iron impeller is the hydraulic heart of the FMIH’s solids handling capability. The single-shroud semi-open geometry provides large flow passages that allow mud, sand, and silt up to 10% by volume to pass through without clogging the impeller. This quantified solids tolerance is what makes the FMIH practical for real-world agricultural water sources, construction site groundwater, and mining site drainage where the pumped water carries suspended material that would clog a standard enclosed impeller.

Replaceable Wear Plate

The replaceable wear plate sits between the impeller and the volute, maintaining the critical running clearance that determines pump efficiency. In applications with abrasive water carrying sand and silt, this clearance gradually increases as the wear plate erodes. When efficiency drops below acceptable levels, the wear plate is replaced as a single service component, restoring the original clearance and efficiency without replacing the entire pump end. This is the same wear plate design used in the FMIT electric motor driven and FMIG gas engine driven versions of this pump family, reflecting the shared design philosophy across the FM series.

FKM Mechanical Seal

The carbon and ceramic mechanical seal faces with FKM (Fluoroelastomer) elastomers and 300 Series stainless steel hardware provide the chemical and temperature resistance needed for agricultural applications involving fertilizer solutions and mildly aggressive water chemistry. FKM elastomers outperform standard BUNA or Nitrile in these conditions, extending the seal service interval in agricultural field use.

Hydraulic Bearing Frame

The heavy-duty bearing frame uses sealed bearings and a keyed stainless steel shaft designed for hydraulic motor connection through the 7/8-inch B-fit spline. Sealed bearings resist contamination from the field and agricultural environments where dust, moisture, and crop debris are constant factors. The keyed stainless shaft connection to the impeller provides a secure, corrosion-resistant interface throughout the pump’s service life.

Applications and Industries

The FMIH serves applications where tractor or equipment hydraulic drive is the available power source and self-priming capability with high solids tolerance are both required.

• Agricultural Irrigation: Tractor-connected field irrigation from ponds, canals, and open water sources is the primary application for the FMIH. The tractor already on site provides the hydraulic power. The FMIH handles the silt and organic debris common in agricultural water sources through its 10% solids tolerance impeller. The self-priming design manages the repeated start-stop cycles of irrigation schedules automatically. This is the cleanest, most integrated hydraulic pump solution for agricultural irrigation without electrical infrastructure.
• Remote Field Water Transfer: Moving water between storage tanks, ponds, and distribution points in remote fields where running electrical power lines is impractical and a tractor is available as the power source.
• Construction Dewatering: Skid steer and excavator hydraulic outputs can power the FMIH for dewatering excavations and trenches on construction sites before permanent electrical service is established. The self-priming capability handles unattended overnight dewatering reliably.
• Water Truck Service: Equipment trucks with hydraulic systems use the FMIH for on-board pumping where the vehicle hydraulic circuit provides the drive power. The threaded FNPT connections and clockwise rotation match standard water truck plumbing configurations.
• Mining: Remote mining site water management using equipment hydraulic circuits where electrical power distribution to the pump location is impractical. The 10% solids tolerance handles the demanding water quality of active mining operations.
• Municipal: Emergency pumping and water transfer using municipal vehicle hydraulic systems where self-contained portable pumping capacity is needed quickly without electrical hookup.
• Light Industrial: Industrial facilities with hydraulic-equipped equipment use the FMIH for portable water transfer and site dewatering without dedicated electrical pump circuits.

Features and Benefits

• Hydraulic Drive for Tractor Integration: Connects directly to tractor or equipment auxiliary hydraulic circuits through the 7/8-inch SAE B-fit spline. Turns the tractor into the pump power source, eliminating the need for electrical power, a generator, or a separate gas engine at the pump location.
• Self-Priming After Initial Fill: Cast iron volute with tapped priming, venting, and draining ports. Fill once through the priming port before first startup. The self-priming design handles every subsequent restart automatically without manual intervention during normal operation.
• 10% Solids Tolerance by Volume: Semi-open cast iron impeller rated for mud, sand, and silt up to 10% by volume. A specific, measurable capability that makes the FMIH practical for real-world agricultural, construction, and mining water sources that carry suspended material.
• Replaceable Wear Plate: Maintain pump efficiency by replacing the wear plate alone rather than the entire pump end when running clearances wear from abrasive solids. Significantly extends the service life of the pump in high-solids applications at lower cost than full pump end replacement.
• FKM Mechanical Seal: Better chemical and temperature resistance than standard BUNA or Nitrile elastomers. Appropriate for fertilizer solutions and the mineral-rich water chemistry common in agricultural irrigation sources.
• Sealed Bearings for Field Conditions: Sealed bearings resist contamination from dust, moisture, and crop debris in agricultural and construction environments where open bearing configurations would fail prematurely.
• Keyed Stainless Steel Shaft: Corrosion-resistant shaft connection to both the impeller and the hydraulic drive spline. Stainless steel resists the chemical and moisture exposure inherent in field agricultural service.
• Threaded FNPT Connections: Standard pipe thread connections on suction and discharge ports are compatible with common hose and pipe fittings used across agricultural and industrial installations. No special fittings or adapters required for standard connection configurations.
• Clockwise Rotation: The FMIH40 rotates clockwise when facing the shaft. Standard rotation for most hydraulic motor configurations used with SAE B-fit connections.
• Horizontal Mounting: Designed for stable horizontal installation on a skid, trailer, or mounting frame. The horizontal orientation provides a stable operating platform that manages vibration and maintains consistent hydraulic drive alignment during operation.

FMIH vs. FMIT vs. FMIG: The FM Self-Priming Pump Family Compared

The FMIH, FMIT, and FMIG share the same core pump end design philosophy: semi-open impeller, replaceable wear plate, FKM mechanical seal, and high solids tolerance. The difference between them is the drive source. Here is a direct comparison to clarify which one belongs in your application.

If a tractor or hydraulic-equipped equipment is already at the job site and you want the simplest, most integrated pumping solution without a separate engine or electrical hookup, the FMIH is the right choice. If electrical power is available and the pump will be in a fixed location, the FMIT makes more sense. If neither electrical power nor hydraulic equipment is available at the pump location, the FMIG gas engine version provides fully independent operation. Call Ken’s Distributing at 303.699.7845 and we will help you choose the right configuration for your installation.

Installation and Compatibility

• Hydraulic Motor Spline Confirmation: The FMIH uses a 7/8-inch SAE B-fit spline shaft. Confirm that your hydraulic motor uses a matching 7/8-inch SAE B-fit spline before ordering. The spline dimensions are not interchangeable between B-fit and C-fit configurations without an adapter.
• Rotation Direction: The FMIH40 rotates clockwise when facing the shaft. Confirm that your hydraulic motor output shaft rotates clockwise in your intended mounting orientation. Incorrect rotation direction reduces flow significantly and can damage the pump over time.
• Hydraulic Flow Rate: Match your tractor’s auxiliary hydraulic output flow rate to the operating range of your hydraulic motor. Too little hydraulic flow results in the pump running below its performance curve. Too much flow can overspeed the hydraulic motor and pump beyond their design limits. Consult your hydraulic motor specifications and tractor operator manual for hydraulic output capacity.
• Mounting Orientation: Install the FMIH in the horizontal position. Use a stable skid or mounting frame with appropriate isolation to manage vibration from the hydraulic drive.
• Initial Priming: Fill the pump housing through the tapped priming port before the first startup. Bleed air through the venting port during fill. After the initial fill, the self-priming design handles subsequent restarts automatically.
• Suction Line: Connect to the threaded FNPT suction port. Keep the suction line short and direct. Install a foot valve at the water source to maintain liquid in the suction line between pump cycles and improve self-priming reliability. Ensure all suction connections are fully air-tight to prevent air ingestion that would disable the self-priming system.
• Discharge Line: Connect to the threaded FNPT discharge port. Match your pipe or hose diameter to the discharge connection size. Install a check valve on the discharge side to prevent backflow when the pump shuts down.
• Wear Plate Inspection: Inspect the replaceable wear plate at regular service intervals, particularly in high-solids applications. Replace when clearance between the impeller and wear plate exceeds the manufacturer specification to maintain rated pump efficiency.
• Mechanical Seal Protection: Never run the FMIH dry. The carbon and ceramic seal faces require liquid for lubrication and cooling at all times. Dry running even briefly causes immediate, irreversible seal damage.
• Winterizing: Use the drain port to completely empty the pump housing before freeze conditions or extended storage. Water left in the cast iron housing can cause cracking when it freezes.

Replacement Parts and Service

The replaceable wear plate is the most important maintenance component for preserving FMIH efficiency in abrasive water applications. The FKM mechanical seal is the primary wear item at the shaft seal point. The frame mount design allows the pump end to be accessed for service without disturbing the hydraulic drive connection or the mounting base, making field service practical in agricultural and remote settings.

Ken’s Distributing Company carries genuine Franklin Electric FMIH replacement parts including replaceable wear plates, FKM mechanical seals, and semi-open cast iron impellers. When service components are needed, call us at 303.699.7845 and we will identify the correct part by model number and get it shipped fast to keep your operation running.

Browse our Franklin Electric replacement parts and repair kits for the FMIH Series and all other Franklin Electric pump lines.

Frequently Asked Questions

What does FMIH stand for in Franklin Electric pump naming?

FMIH refers to Franklin Electric’s frame mount self-priming centrifugal pump series in the hydraulic driven configuration. It is the hydraulic powered version of the FM self-priming pump family, sharing the same semi-open impeller, replaceable wear plate, and high solids tolerance design as the electric motor driven FMIT and gas engine driven FMIG Series.

What hydraulic motor spline does the FMIH use?

The FMIH uses a 7/8-inch SAE B-fit spline shaft for connection to the hydraulic motor. This spline specification matches a specific range of hydraulic motors used with agricultural tractors and construction equipment. Confirm that your hydraulic motor uses a 7/8-inch SAE B-fit spline before ordering to ensure a direct connection without adapters.

Is the FMIH pump self-priming?

Yes. After filling the pump housing through the tapped priming port for the first startup, the FMIH self-priming design handles every subsequent restart automatically. The cast iron volute includes tapped venting and draining ports for air bleeding during initial commissioning and complete drainage for winterizing.

How much solids can the FMIH handle?

The semi-open cast iron impeller is rated for mud, sand, and silt up to 10% by volume. This makes the FMIH practical for real-world agricultural, construction, and mining water sources that carry suspended material without the clogging that would stop a standard enclosed impeller pump.

What is the replaceable wear plate on the FMIH and when should it be replaced?

The wear plate maintains the running clearance between the impeller and the volute that determines pump efficiency. Abrasive solids gradually erode this clearance during normal operation in sandy or silty water. When pump flow and efficiency drop noticeably from original performance levels, inspecting and replacing the wear plate is the first corrective maintenance step. Replacing the plate alone is far less expensive than rebuilding the entire pump end and restores original efficiency.

Can I control the flow rate on the FMIH?

Yes, indirectly. The FMIH flow rate depends on the RPM delivered by the hydraulic motor, which is controlled by the hydraulic flow rate from the tractor auxiliary circuit. Most tractors with auxiliary hydraulic outputs include a flow control valve that allows you to vary the hydraulic output, giving you practical control over pump speed and flow without additional components.

Can I get FMIH replacement parts from Kendisco?

Yes. Ken’s Distributing Company carries genuine Franklin Electric FMIH replacement parts including replaceable wear plates, FKM mechanical seals, and semi-open cast iron impellers. Call 303.699.7845 for availability and fast shipping on all FMIH service components.

Related Products

• View the Franklin Electric FMIH branded model page for additional specifications
• Compare with the Franklin Electric FMIT electric motor driven self-priming pump
• Compare with the Franklin Electric FMIG gas engine self-priming pump for engine-driven applications
• See the XS Series hydraulic driven centrifugal pump for non-self-priming hydraulic applications
• Shop Franklin Electric replacement parts and repair kits for all series

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