AMT Replacement Diaphragms for Diaphragm Pumps

AMT replacement diaphragms for diaphragm pumps are available through Ken’s Distributing in rubber, neoprene, Buna/nitrile, and TPE compounds, with OEM-fit dimensions for AMT 2 inch and 3 inch diaphragm pump models used in construction dewatering, trench and pit pumping, municipal stormwater control, and industrial fluid transfer. Ken’s Distributing also stocks the neoprene check valve assemblies that work alongside the diaphragm to control one-way flow through AMT pumps.

Bulk pricing is available on orders of 15 units or more for contractors, distributors, and businesses managing multiple AMT pumps.

If you know your AMT pump model number, use the compatibility tables below to confirm the correct diaphragm part number and available material compounds for your specific unit.

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Available materials

Neoprene

Rubber

TPE

Neoprene

2″ AMT Replacement Diaphragm – Neoprene (Model 336)

3″ AMT Replacement Diaphragm – Neoprene (Model 335)

3″ AMT Replacement Diaphragm – Neoprene (No Holes)

Rubber

2″ AMT Replacement Diaphragm – Rubber (Model 336)

3″ AMT Replacement Diaphragm – Rubber (Model 335)

TPE

2″ AMT Replacement Diaphragm – TPE (Model 336)

2″ AMT Replacement Diaphragm – TPE (No Holes)

3″ AMT Replacement Diaphragm – TPE (Model 335)

3″ AMT Replacement Diaphragm – TPE (No Holes)

How AMT Diaphragm Pumps Work

Understanding the role of the diaphragm in an AMT pump helps clarify why material selection and correct fit matter as much as they do.

AMT diaphragm pumps in this category are single-diaphragm aluminum designs. A single diaphragm creates both the suction and discharge strokes inside the pump body, drawing fluid in on one stroke and pushing it out on the other. The diaphragm physically separates the air chamber from the liquid chamber, which protects the internal drive components from contact with the fluid being pumped.

The drive mechanism in these AMT pumps uses an oil-bath gearbox and needle plunger bearing to move the diaphragm through its stroke. A neoprene check valve assembly controls the direction of flow, ensuring fluid moves through the pump in one direction only.

Because the diaphragm is the primary wear component and the only barrier between the fluid and the drive mechanism, using a diaphragm in the correct material for the fluid being pumped directly affects both service life and pump reliability.

AMT 2 Inch Replacement Diaphragms

Compatible AMT 2 Inch Pump Models

The following AMT pump models use the 2 inch replacement diaphragm. Each pump in this series uses one diaphragm. Discharge connection is 2 inch NPT.

AMT Model	Engine or Motor
338Z-96	Hatz 1B30 Diesel
338G-96	Honda GX120
338L-96	LCT 280CC
338E-96	1.5 HP 115 VAC 60 Hz
338T-96	1.5 HP 3-Phase 208-230/460 VAC 60 Hz

2 Inch Diaphragm Part Number

Replacement diaphragm part number: 3380-300-00

This part number covers the 2 inch diaphragm dimension. The material compound is selected separately. Contact Ken’s Distributing to confirm current stock by compound for this part number.

Available Compounds for AMT 2 Inch Diaphragms

Rubber: General-purpose diaphragm for clean water and lightly sediment-laden water in standard dewatering applications. The most cost-effective option for AMT pumps handling water without chemical or hydrocarbon content.

Neoprene: Chemical and abrasion-resistant compound for construction dewatering, dirty water, and slurry applications. Better outdoor durability than rubber. The most commonly specified material for AMT pumps in active construction use.

Buna/Nitrile: Correct choice when the fluid contains oil, fuel, or hydrocarbon contamination. Rubber and neoprene will degrade rapidly in contact with petroleum-containing fluids. Specify Buna/nitrile for any AMT pump application involving oily wastewater or fuel-contaminated groundwater.

TPE: Premium long-life compound for AMT pumps in continuous-duty, high-cycle, or chemically demanding applications where rubber and neoprene require replacement more frequently than the operation can absorb. Higher per-unit cost than rubber or neoprene, typically justified by extended service intervals in demanding conditions.

2 Inch Check Valve Assembly

Check valve assembly part number: 3360-070-90 (neoprene)

The check valve assembly controls one-way fluid flow through the pump. Inspect the check valve assembly whenever the diaphragm is replaced. Worn or debris-fouled check valves reduce pump efficiency and can mask performance improvements after a new diaphragm is installed. Replace the check valve assembly if flow is erratic or the pump fails to hold prime after a diaphragm replacement.

Typical Applications for AMT 2 Inch Diaphragm Pumps

Small construction site dewatering and trench pumping
Pit dewatering in foundation and excavation work
Irrigation system water transfer
Light industrial fluid transfer in clean or lightly contaminated water applications

AMT 3 Inch Replacement Diaphragms

Compatible AMT 3 Inch Pump Models

The following AMT pump models use the 3 inch replacement diaphragm. Each pump in this series uses one diaphragm. Discharge connection is 3 inch NPT.

AMT Model	Engine or Motor
337G-96	Honda GX120
337H-96	Honda GX160
337L-96	LCT 280CC
337Z-96	Hatz 1B30 Diesel
337E-96	1.5 HP 115 VAC 60 Hz
337T-96	1.5 HP 3-Phase 208-230/460 VAC 60 Hz

3 Inch Diaphragm Part Number

Replacement diaphragm part number: 3370-300-00

This part number covers the 3 inch diaphragm dimension. The material compound is selected separately. Contact Ken’s Distributing to confirm current stock by compound for this part number.

Available Compounds for AMT 3 Inch Diaphragms

Rubber: Standard choice for AMT 3 inch pumps handling clean water or lightly sediment-filled water in construction and dewatering applications where chemical and hydrocarbon exposure is not a factor.

Neoprene: Tough, flexible, and abrasion-resistant compound for AMT 3 inch pumps in construction dewatering, wastewater transfer, and outdoor applications where rubber would degrade from weathering and ozone exposure over time.

Buna/Nitrile: Oil and fuel-resistant compound for AMT 3 inch pumps handling hydrocarbon-contaminated water on industrial, demolition, or environmental remediation sites. The correct specification when oil or fuel contact is present.

TPE: Premium compound for extended service life under abrasive slurry, chemical exposure, and continuous-duty operation in AMT 3 inch pump applications where rubber and neoprene replacement frequency is too high for the operation.

3 Inch Check Valve Assembly

Check valve assembly part number: 3354-070-90 (neoprene)

Replace the 3 inch check valve assembly when flow becomes erratic, when the pump fails to prime after a diaphragm replacement, or when physical inspection reveals wear or debris accumulation on the valve faces. Replacing the check valve assembly at the same time as the diaphragm on a high-hour pump is a practical maintenance step that prevents a second service call shortly after the diaphragm replacement.

Typical Applications for AMT 3 Inch Diaphragm Pumps

Large-volume construction dewatering on active job sites
Municipal bypass and stormwater control during utility maintenance
Industrial slurry and wastewater transfer
Higher-volume trench and excavation dewatering where the 2 inch pump capacity is insufficient

Selecting the Right Compound for Your AMT Diaphragm Pump

The single most important factor in AMT diaphragm selection is matching the compound to the fluid being pumped. The following framework covers the most common AMT pump applications.

Clean water, standard groundwater, light sediment: Rubber or neoprene. Choose rubber if cost is the primary consideration and the pump is not stored outdoors for extended periods. Choose neoprene if the pump operates or is stored outdoors, runs continuously, or handles slurry and sediment-laden water.

Concrete cutting slurry, construction wastewater, outdoor pump operation: Neoprene. The combination of abrasive fine particles and outdoor conditions favors neoprene over rubber for AMT pumps in construction use.

Oily wastewater, fuel-contaminated groundwater, petroleum-containing fluids: Buna/nitrile. Rubber and neoprene are not appropriate for hydrocarbon contact. Specify Buna/nitrile for any AMT application where oil or fuel is present in the fluid being pumped.

Continuous-duty, high-cycle operation, abrasive slurry, mild chemical exposure: TPE. When the pump runs for extended hours and the cost of frequent diaphragm replacement exceeds the cost difference between TPE and rubber or neoprene, TPE is the correct specification.

If your application does not fit cleanly into these categories, contact Ken’s Distributing with your AMT pump model and a description of the fluid being pumped. Our parts team can recommend the correct compound for your specific conditions.

How to Know When Your AMT Diaphragm Needs Replacement

AMT diaphragm wear typically shows up as gradual performance loss before a complete failure occurs. Catching wear early prevents debris from reaching the oil-bath gearbox and needle plunger bearing, which are more expensive to repair than the diaphragm itself.

Replace or inspect your AMT diaphragm when you observe any of the following.

The pump takes noticeably longer to prime than when the diaphragm was new
Discharge flow drops at full throttle without a change in suction conditions or discharge head
Air bubbles appear in the discharge stream, indicating the diaphragm is allowing air to bypass the liquid chamber
Visible cracking, surface stiffening, fabric exposure, or permanent deformation on the diaphragm face or edges during a physical inspection
Water appearing in the air chamber or at the air exhaust, indicating a diaphragm tear or pinhole failure
Pump vibration increases noticeably during normal operation

Inspect AMT diaphragms regularly as part of routine pump maintenance. Do not wait for a complete failure to replace the diaphragm. A failed diaphragm that continues to run can allow fluid to enter the gearbox housing, which converts a simple diaphragm replacement into a significantly more costly repair.

AMT Diaphragm Installation and Maintenance

Installation

Confirm that the replacement diaphragm part number and material compound match your AMT pump model before installation. Using the part numbers listed above for your specific AMT model eliminates dimensional fitment issues.

Torque the cover plate bolts evenly in a cross pattern to ensure uniform sealing pressure across the diaphragm face. Uneven torque creates localized stress on the diaphragm edges and accelerates wear at the sealing perimeter.

Inspect the check valve assembly at every diaphragm replacement. Worn or dirty check valves that are left in place after a diaphragm replacement will limit the performance improvement from the new diaphragm.

Maintenance

Inspect AMT diaphragms every 500 to 1,000 operating hours in standard construction and dewatering use. Pumps handling abrasive slurry or running continuously should be inspected more frequently.
Flush the pump after handling sediment-laden, oily, or chemically active fluids. Allowing these materials to dry inside the pump accelerates wear on the diaphragm, check valves, and internal surfaces.
Do not run AMT diaphragm pumps dry. Dry running removes the fluid that cushions and lubricates the diaphragm during its stroke and accelerates wear, particularly on rubber compounds.
Store pumps out of direct sunlight when not in use to slow UV and ozone degradation on rubber and neoprene diaphragms.

Bulk Pricing for AMT Replacement Diaphragms

Contractors, distributors, rental companies, and businesses operating multiple AMT diaphragm pumps can access bulk pricing on orders of 15 units or more. Bulk pricing is available across all four material compounds and both the 2 inch and 3 inch diaphragm sizes.

Ken’s Distributing also offers blanket order programs for organizations that need a reliable, year-round supply of AMT replacement diaphragms without the risk of stockouts between orders.

Contact Ken’s Distributing with your AMT pump model, diaphragm size, material preference, and estimated annual volume for bulk pricing and blanket order program details.

Other Diaphragm Pump Brands We Support

Ken’s Distributing carries replacement diaphragms for all major diaphragm pump brands used in North American construction, industrial, and municipal markets. If you operate other pump brands alongside your AMT units, the following pages cover diaphragm replacements for each brand.

CH&E Replacement Diaphragms
Magnum Replacement Diaphragms
Mud Hog Replacement Diaphragms
Wacker Replacement Diaphragms
Gorman-Rupp Replacement Diaphragms
Multiquip Replacement Diaphragms
Riverside Replacement Diaphragms
Tsurumi Replacement Diaphragms

For diaphragm selection by material rather than brand, see the material-specific pages below.

Rubber Replacement Diaphragms
Neoprene Replacement Diaphragms
Buna/Nitrile Replacement Diaphragms
TPE Santoprene Replacement Diaphragms

Frequently Asked Questions About AMT Replacement Diaphragms

How do I find the right AMT diaphragm for my pump?

Locate your AMT pump model number on the pump tag and match it to the compatibility tables above. The 2 inch models use part number 3380-300-00 and the 3 inch models use part number 3370-300-00. If your model number is not listed or you cannot locate the pump tag, contact Ken’s Distributing with a description of your pump and we will confirm the correct part.

What material diaphragm does my AMT pump need?

The correct material depends on what the pump is handling. Rubber or neoprene for clean water and standard construction dewatering. Buna/nitrile for oily wastewater or fuel-contaminated groundwater. TPE for continuous-duty, high-cycle, or chemically demanding applications. The material selection guide above covers the most common AMT pump applications in detail.

Do AMT 2 inch and 3 inch pumps use the same diaphragm?

No. The 2 inch AMT pump models use part number 3380-300-00 and the 3 inch models use part number 3370-300-00. The dimensions are different and the parts are not interchangeable. Always confirm the part number against your specific AMT pump model before ordering.

Should I replace the check valve assembly at the same time as the diaphragm?

It is good practice to inspect the check valve assembly every time the diaphragm is replaced. If the pump is high-hour or if flow has been erratic, replacing the check valve assembly at the same time as the diaphragm avoids a second service call shortly after the diaphragm replacement. The check valve part numbers are listed above for both the 2 inch and 3 inch AMT pump series.

Can I upgrade from rubber to neoprene or TPE on my AMT pump?

Yes. The AMT diaphragm part numbers listed above are dimension-based, and the material compound is a separate selection within the same part number. Switching from rubber to neoprene or TPE does not require any pump modification. Contact Ken’s Distributing to confirm compound availability for your specific AMT model before ordering.

Is bulk pricing available for AMT replacement diaphragms?

Yes. Orders of 15 units or more qualify for bulk discount pricing. Blanket order programs are also available for contractors and distributors who need a consistent annual supply. Contact Ken’s Distributing with your pump model, size, material, and estimated volume for pricing details.

Do you ship AMT replacement diaphragms to Canada?

Yes. Ken’s Distributing ships AMT replacement diaphragms to all 50 U.S. states and Canada. Contact us for shipping details on large or bulk orders.