Blog posts tagged with 'positive displacement pump'

Air-operated double diaphragm (AODD) pumps are highly versatile, reliable devices widely used across various industries for handling viscous, abrasive, and shear-sensitive fluids. Powered by compressed air, these pumps use two diaphragms in a reciprocating motion to transfer liquid. With no need for electricity, these pumps offer a versatile option for hazardous and demanding environments.

AODDs: Basic Parts and Operation

1. Diaphragms: Located on either side of the pump, the diaphragms are flexible membranes typically made of materials like PTFE or rubber. 
2. Air Chamber: The air chamber (also known as the air valve chamber) is where compressed air is introduced to alternate between the two diaphragms. 
3. Inlet and Outlet Manifolds: The inlet manifold allows the fluid to enter the pump chamber, while the outlet manifold directs the fluid out of the pump after it has been moved by the diaphragms. 
4. Check Valves: Each diaphragm chamber has two check valves, one at the inlet and one at the outlet. These valves are responsible for directing fluid flow in a single direction. Typically a ball and seat style check valve.  
5. Valve Assembly (Air Valve): The air valve assembly, typically located in the center section of the pump, controls the distribution of compressed air to the diaphragms. 
6. Fluid Chambers: Fluid chambers are located on either side of the diaphragms. 
7. Exhaust Port: As compressed air pushes one diaphragm, the air on the opposite side is expelled through the exhaust port. This port vents the air used to move the diaphragms, and in some applications, exhaust air is collected or muffled to reduce noise.
8. Center Section: This is the core of the pump, housing the air valve and the air distribution system. 

 

 

How These Parts Work Together

When the pump starts, compressed air is directed into the air chamber behind one of the diaphragms, causing it to push outward and transfer fluid out through the outlet manifold. Simultaneously, the opposite diaphragm is pulled inward, creating suction in its fluid chamber, drawing in new fluid through the inlet manifold. The air valve then alternates the air supply to the other diaphragm, repeating the process. This alternating motion allows AODD pumps to handle viscous, abrasive, and shear-sensitive materials efficiently and reliably.

 

 

This design makes AODD pumps ideal for industries where the safe handling of various fluid types—especially in explosive or corrosive environments—is essential. 

 

Advantages of an AODD Pump

1. Corrosion Resistance

Advantage: Built with materials like PTFE, Viton, and Santoprene, AODD pumps can handle a wide variety of fluids, including those that are abrasive, viscous, corrosive, or contain solids.

Benefit: This versatility allows them to be used in many different industries and applications, from chemical processing to food and beverage production.

2. Self-Priming Capability

Advantage: AODD pumps are self-priming, meaning they can start pumping without needing to be filled with fluid first.

Benefit: This makes them ideal for applications where the fluid source is below the pump or where frequent starts and stops are required.

3. Ability to Run Dry

Advantage: AODD pumps can run dry without damage, unlike many other pump types. This means operating the pump without fluid moving through it.

Benefit: This is valuable in situations where the fluid supply may be inconsistent or may be interrupted. For example, you could use an AODD to pump out the contents of a barrel without needing to monitor the liquid level and shut off the pump immediately when the barrel is emptied to avoid damage to the pump. 

It should be noted that although an AODD pump can run dry, prolonged operation with no fluid can be hard on the diaphragms and other components. 

4. Safety 

Advantage: While not all AODD pumps are inherently explosion-proof, they are powered by compressed air and don’t require electricity, eliminating the risk of sparks.

Benefit: This generally makes them safe for use in hazardous environments where flammable or explosive materials are present, such as in the oil and gas industry. Always be sure to check that your pump and pump materials are compatible and designed for your application and environment.

5. Gentle Pumping Action

Advantage: The reciprocating diaphragm movement in AODD pumps produces a gentle, low-shear pumping action compared to other pump types. 

Benefit: This makes AODD pumps preferable for handling shear-sensitive fluids, such as emulsions, suspensions, and biological materials, without damaging them.

6. Easy Maintenance

Advantage: AODD pumps have relatively simple designs with few moving parts, making them easy to maintain and repair.

Benefit: Maintenance can typically be performed on-site without the need for specialized tools, reducing downtime.

7. Pumping of Solids and Slurries

Advantage: AODD pumps can easily handle fluids containing solids or slurries without clogging.

Benefit: This capability is crucial in industries like wastewater treatment, mining, and construction, where the fluid being pumped often contains particles or debris.

8. Simple Control

Advantage: The flow rate of AODD pumps can be easily adjusted by regulating the inlet air pressure without the need for complex controls.

Benefit: Common air regulators are all that is required to adjust the pump. A simple ball valve can be used to turn the pump on and off.

9. Suction Lift Capability

Advantage: AODD pumps can achieve significant suction lift (30 feet or more!), making them capable of drawing fluid from deep or difficult-to-access locations.

Benefit: This makes them useful in situations where the fluid source is located below the pump, such as in sump pits or underground storage tanks.

 

Specific AODD Pump Applications Across Industries

The unique design of AODD pumps allows them to fit into several different applications. Let’s examine some specific scenarios where an AODD pump can excel while other transfer pumps fall short.

Safe Transfer of Corrosive and Hazardous Fluids

In the chemical industry, AODD pumps are essential for safely transferring corrosive and hazardous substances. Their seal-less design significantly reduces the risk of leaks, enabling secure handling of acids, solvents, and aggressive chemicals.

Specific applications: AODD pumps with poly body and Teflon diaphragms can be used to pump high concentrations of phosphoric acid and Kynar body pumps with Teflon diaphragms can handle sulfuric acid. 

AODD Pumps in Food and Beverage Production

AODD pumps are widely utilized in the food and beverage sector to handle products like sauces, syrups, and beverages. Their mild pumping action preserves the quality and consistency of materials that can change in viscosity when agitated or stirred (creams, sauces, condiments, etc.).

Specific applications: There are also AODD pumps designed for handling large solids and slurries associated with the meat and poultry processing industries. These pumps are sanitary pumps designed for quick and easy cleaning. Typically featuring high-grade stainless-steel bodies.

Mining and Construction: Heavy-Duty AODD Pumps for Slurry and Dewatering

Mining and construction industries present unique and rugged applications. The need for dewatering dirty water and sludge where the contents and solids sizes are often varied and unpredictable. The right AODD pump can withstand tough environments. They are also portable and can run dry without damage, making them a reliable choice in these demanding fields.

Specific Application: Warren Rupp offers durable pumps with metal bodies (aluminum, cast iron, stainless). The Sandpiper Beast is a tough, clog-resistant pump designed to move fluids with debris up to 2 inches in diameter.

Petroleum Industry

In the oil and gas industry, AODD pumps move crude oil, gasoline, diesel, and other petroleum fluids. The pumps’ lack of electrical components provides explosion-proof safety, making them ideal for hazardous environments. 

AODDs are ideal for handling oils and hydraulic fluids of various weights making them a versatile option for fleet maintenance. 

Specific Applications: The Zeeline NS1040UL is a UL-rated AODD that will safely pump gasoline and diesel fuels up to 37 gallons per minute. 

AODD pumps also work excellent for handling waste oil. 

Car and Fleet Wash

Transferring different soaps, detergents, wax, and sealers requires a pump that can move the fluid without resulting in foaming. It also must handle a wide range of different chemical combinations and viscosities.  

Specific applications: This Yamada poly pump is versatile and has wide chemical compatibility for soaps, detergents, and other cleaning products. 

 

 

What Materials are AODD Pumps Made From?

AODD pumps are constructed from a variety of different materials. Different materials are used for the main components: the housing, check valve balls, seats, and diaphragms. 

The housing (or body) of an AODD pump consists of the fluid chambers and inlet/outlet manifolds. Common materials include:

• Aluminum: Lightweight and suitable for oils, coolants, and certain solvents but may corrode with acidic or abrasive fluids.
• Stainless Steel: Durable and resistant to corrosion, making it ideal for food, beverage, pharmaceutical, and certain chemical applications.
• Polypropylene: A cost-effective, lightweight plastic that resists a wide range of chemicals. 
• Kynar (PVDF): A chemically resistant plastic with excellent durability, often chosen for aggressive chemicals like acids and solvents.
• Cast Iron: Highly durable but susceptible to corrosion with certain chemicals. They are commonly used for demanding applications in construction and mining. 

The check valve balls are in direct contact with the fluid and must be resistant to the medium you are pumping. Common materials include:

• Santoprene: A thermoplastic elastomer with good chemical resistance, typically used for water-based fluids and certain chemicals.
• PTFE (Teflon): Highly resistant to chemicals, suitable for aggressive solvents, acids, and high-temperature applications.
• Nitrile (Buna-N): Good for petroleum and certain chemicals but less resistant to extreme temperatures.
• Viton: Excellent for high-temperature and a variety of chemical applications.

Seats create the sealing surface for the balls, and their material affects the pump’s fluid compatibility. Common seat materials:

• Polypropylene
• Stainless Steel
• Santoprene and Buna-N

Diaphragms are crucial in AODD pumps, as they directly handle fluid and pressure. The choice of diaphragm material influences chemical resistance, flexibility, and temperature tolerance.

• Santoprene: A flexible, durable option for a range of chemicals, commonly used in general applications.
• PTFE (Teflon): Excellent chemical resistance, suitable for aggressive fluids, and has a longer lifespan in abrasive applications. 
• Buna-N (Nitrile): Good for petroleum-based fluids and general applications but limited by lower chemical and temperature resistance.
• Hytrel: A thermoplastic polyester with good chemical resistance, flexibility, and durability for various industrial fluids.

 

AODD Pump Limitations

The AODD family is very versatile and offers unique benefits but there are some limitations:

Requires Continuous Air Supply

AODD pumps need a reliable, continuous supply of compressed air to function. In remote locations or applications where compressed air is not readily available, additional equipment (like air compressors) may be needed, adding to setup costs.

Efficiency and Air Consumption

AODD pumps rely on compressed air to operate, which can lead to high air consumption, especially when running at high flow rates or under heavy loads. This can increase operating costs.

Compared to other types of pumps (like centrifugal pumps), AODD pumps typically have lower energy efficiency. This can be a drawback in applications where energy efficiency is a primary concern.

If energy efficiency is a priority, Graco offers electric motor-driven double diaphragm pumps. This provides you with the benefits of an AODD with significantly lower (up to 80%) operating costs. 

Pulsing

The “back and forth” nature of the pumping operation can result in a pulsating flow. This can be mitigated with pulsation dampeners, but it may still not be ideal for applications requiring a steady, continuous flow.

Pressure

An Air-Operated Double Diaphragm (AODD) pump typically operates at a maximum pressure of around 100 psi, although certain specialty models can handle higher pressures. These pumps are generally not suitable for high-pressure applications that exceed their design limits. Most AODD pumps have a 1:1 pressure ratio, meaning the liquid discharge pressure matches the air inlet pressure. For example, if the air supply is set to 50 psi, the pump will produce a liquid discharge pressure of approximately 50 psi.

 

Ready to Choose the Right AODD Pump?

Explore our selection of Air-Operated Double Diaphragm (AODD) Pumps, tailored for a wide range of applications. Our team is ready to assist you in finding the perfect pump for your industry’s needs.

A sprayer's job is to distribute fluid over a designated area. No matter what type of sprayer at the center of the system is a pump. There are nearly endless different types of sprayers. They are built for several applications and require different types of pumps to deliver the flow characteristics necessary to complete those different spraying tasks.

At Dultmeier Sales, pumps are not just the center of a sprayer, they are at the center of our business. We sell, service, and support a wide variety of pumps for all types of sprayers. In addition, we prioritize understanding the different types, how they operate, and what pump works best on different sprayers.

In this guide, we will look at all the different types of pumps used on sprayers. We will examine how each pump operates and how they compare in terms of flow rate and pressure. In addition, we will offer real examples so you can see exactly how each pump is used. You'll be able to understand what type of sprayer pump will work for your application.

Different Types of Sprayer Pumps

While there are several variations of each type, the different pumps used on sprayers are centrifugal, roller, diaphragm, and piston pumps. Each pump is unique in its design and performance. Let's explore each type to understand how they operate and when to use them.

Centrifugal Pumps

• Pump Family: Centrifugal
• GPM Range: 0 to 500+
• PSI Range: 0 to 150

Centrifugal pumps use an impeller to move water or other fluids by using centrifugal force. They are known for their ability to move high volumes of liquid at relatively low pressure. The most common centrifugal pump type used on a sprayer is a straight centrifugal pump. Self-priming pumps can be used, but a straight centrifugal pump is typically more efficient and capable of developing higher operating pressure.

A self-priming pump is capped at about 40-60 PSI depending on the specific pump. The straight centrifugal pumps designed for use on sprayers can produce well over 100 PSI. They are intended to accommodate the high travel speeds of self-propelled sprayers combined with the expanded operating ranges of modern sprayer nozzles.

Common Centrifugal Sprayer Pump Applications

• Agricultural Spraying: Boom sprayers, fertilizer toolbars, boomless sprayers, fertilizer delivery on planters.
• Turf and Landscape: Golf course sprayers, sports field sprayers, large acreage sprayers.
• Industrial Uses: Salt brine trucks and trailers, water trucks for dust control.

Advantages of Centrifugal Sprayer Pumps

• High Volume Output: Centrifugal pumps can handle large volumes of liquid, making them suitable for applications requiring substantial flow rates.
• Durability: These pumps are robust and can handle abrasive and corrosive chemicals, making them versatile for various spraying tasks.
• Simplicity: The design is straightforward, which makes maintenance and troubleshooting easier compared to more complex pump types.
• Cost-Effective: Generally, centrifugal pumps are less expensive to manufacture and maintain, providing a cost-effective solution for many users.

Disadvantages of Centrifugal Sprayer Pumps

• Low pressure: Centrifugal sprayer pumps have lower pressure capabilities compared to some other types of pumps like piston or diaphragm pumps. While centrifugal pumps can move high volumes of liquid, they do so at relatively low pressures.
• Cannot Run Dry*: Running a centrifugal pump without fluid can cause significant damage to the pump. A centrifugal pump requires fluid in the pump case to lubricate the seal. *There are lubricated seals or "wet" seal centrifugal pumps that can run dry.

Centrifugal Pump Drive Types

• Hydraulic
• PTO
• Belt Driven
• Engine Driven

Parts of a Centrifugal Sprayer Pump

• Impeller: The heart of the pump, which is responsible for imparting kinetic energy to the liquid. The design and size of the impeller significantly affect the pump's performance.
• Casing: Encases the impeller and directs the flow of liquid. It also helps convert kinetic energy into pressure energy.
• Seal: Prevents leaks and maintains the pump's integrity by keeping the liquid within the system.
• Suction and Discharge Ports: Inlet and outlet points through which the liquid enters and exits the pump.

You can find a more detailed examination of centrifugal pump components and how they affect the performance of a pump in this guide to centrifugal pumps for fertilizer.

View All Centrifugal Pump Options

 

Roller Pumps

• Pump Family: Positive Displacement
• GPM Range: 2 to 60
• PSI Range: Up to 300
• Applications: Small and medium-sized boom sprayers, turf sprayers

Roller pumps use rollers inside a cylindrical housing to move liquid. As the rollers rotate, they create a vacuum that draws liquid in and then pushes it out. Roller pumps are very common on 3-point sprayers crop and turf boom sprayers, because they are self-priming, develop consistent pressure, and are less expensive compared to other types of sprayer pumps.

A roller pump is part of the positive displacement pump family. This means that a consistent volume of fluid is delivered with each cycle (in this case shaft revolution), regardless of the discharge head in the system. Simply put, you can spray at 60 psi if you want because the pump overcomes the restriction in the system. With a centrifugal pump, the system restriction will affect your operating pressure much more.

The larger roller pumps can produce about 50-60 GPM, limiting the size of the sprayer they can be used on. A roller pump can be repaired but the standard cast iron housings do have a limited life span. Friction eventually wears the pump housing to a point where the pump will no longer work efficiently.

To combat the wear and corrosion of agrochemicals and fertilizers, there are Ni-resist and Silvercast pump housings that last much longer than the standard cast iron roller pumps.

Advantages

• Pressure Output: Capable of producing consistent and generally higher pressure than a centrifugal pump.
• Self-Priming: Can draw liquid from a lower level, making them easy to start and use.
• Compact Design: Small and easy to integrate into different spraying systems.
• Can Be Reversed: Many roller pump models can be reversed so you can drive it either clockwise or counterclockwise. Consult the manual of your specific pump for details.
• Cost: Less expensive compared to other sprayer pump types. Especially when PTO driven since it does not require an engine or hydraulic motor.

Disadvantages

• Wear and Tear: Rollers wear out, especially when used with abrasive chemicals.
• Limited Flow Rate: Not suitable for applications requiring high flow rates.
• Maintenance: Regular maintenance is required to ensure optimal performance.
• Limited Lifespan: Wear and corrosion can increase the Internal clearance between the pump housing and rollers to the point that the pump no longer works effectively.

Drive Types

• PTO
• Belt Driven
• Electric Motor
• Gas-Engine

Parts of a Roller Pump

• Rollers: The moving parts inside the pump that create suction and discharge action.
• Rotor: Holds the rollers in place and drives their motion.
• Housing: Encases the rollers and rotor, providing a sealed environment for the liquid to move through.
• Shaft: Driven by PTO or motor and spins the rotor.
• Seals: Prevents leaks and maintains the integrity of the pump system.

Check out the Different Roller Pump Options

 

12-Volt Diaphragm Pumps

• Pump Type: Positive Displacement
• GPM Range: 1 to 5
• PSI Range: Up to 100+
• Applications: ATV/UTV sprayers, spot sprayers, small boom sprayers, low-volume chemical transfer

12-volt diaphragm pumps are very common and versatile. They are used on small sprayers because they are easy to power with a battery and relatively low in cost. These pumps work well with a wide variety of agrochemicals, cleaners, and other liquids, especially when diluted. They are self-priming, and they can run dry.

One standout benefit of the 12-volt sprayer pump is the demand switch. This feature shuts the motor off when you close a valve on the discharge side of the pump. When the valve is closed, the pressure increases, tripping the demand switch and shutting off the motor.

The most common application of this is when you are spot-spraying with a trigger wand or spray gun. When you pull the trigger, your pump turns on, when you release the trigger, the pump stops. This conserves your battery life and prolongs the life of the pump as it only runs when needed.

A 12-volt diaphragm pump can be used on smaller boom sprayers. However, they may only be able to work on booms with about 5-10 tips depending on the size of the nozzles that you use.

Advantages

• Portability: Lightweight and easy to transport, ideal for portable sprayer setups.
• Self-Priming: Can draw liquid from a lower level, making them easy to start and use.
• Low Power Consumption: Efficient operation with low electrical power requirements.
• Chemical Resistance: Can handle a variety of chemicals without damage.
• Demand Switch: The pump only runs "on demand", when you pull the trigger or open the valve to spray.
• Low-Cost: Very affordable compared to other pump types.

Disadvantages

• Limited Flow Rate: Maximum flow rates are about 5 GPM.
• Pressure Limitations: Maximum pressure is lower compared to other positive displacement pumps.
• Pump Life: The pump motor and other components do not have the same lifespan as other pump types. Parts can be replaced but the cost and time to repair may be nearly as much as a new pump.

Drive Types

• 12-volt Electric Motor
• This pump type is also available with 24-volt and 115-volt motors

Parts of a 12V Diaphragm Sprayer Pump

• Diaphragm/Wobble Plate: This assembly is driven by the motor; it has an eccentric bearing that causes it to "wobble" and this motion creates the suction to pull liquid into the pump and force it out.
• Check Valves: let fluid flow into the pump and stop it from going back out of the inlet port.
• Pump Housing: Contains the wobble plate and check valve assembly, and serves as the pump chamber where the liquid is pulled into the pump and forced out.
• Motor: Powers the movement of the wobble plate.

View 12-Volt Pump Options.

 

Large Diaphragm Pumps

• Pump Type: Positive Displacement
• GPM Range: 3-100+
• PSI Range: Up to 725
• Applications: Tree spraying, turf sprayers, fertilizer applicators

Large diaphragm pumps use multiple diaphragms and chambers to move large volumes of liquid at high pressures. These pumps are the preferred tool for long-range or vertical spraying such as tree spraying. The combination of high-flow rate and high pressures, when combined with the right sprayer gun and nozzle, results in a stream of liquid that can be propelled 50 feet or more in the air.

Video of Diaphragm Pump on Skid Sprayer:

Diaphragm pumps can also be used on boom sprayers or fertilizer boom sprayers. While they don't offer the same flow rates as a centrifugal pump of similar size, they can be a good option for sprayers or applicators when the fluid being sprayed is too thick or viscous for a centrifugal pump.

Advantages

• High-Pressure Output: Capable of producing very high pressures
• Durability: The flexibility of the diaphragm offers good resistance to a wide range of abrasive and viscous fluids.
• Chemical Resistance: Can handle a variety of chemicals without damage.

Disadvantages

• Cost: More expensive to purchase and maintain compared to smaller pumps.
• Complexity: More complex design requires more safeguards and proper installation. Troubleshooting can be more complicated than with other pump types.
• Maintenance: The diaphragms and pump oil must be changed periodically, typically every 500 hours or 3 months of use.

Drive Types

• Engine Driven
• Hydraulic Driven

Parts of a Diaphragm Sprayer Pump

• Diaphragms: Multiple flexible membranes that move to create suction and discharge action.
• Check Valves: Control the flow of liquid into and out of the pump chambers.
• Pistons: Push and pull the diaphragms to create the necessary suction and discharge, driven by the crankshaft.
• Crankshaft: Driven by the engine or motor, rotation of the crankshaft drives the pistons
• Gear Box: Allows diaphragm pumps to be directly driven by a gas engine at about 3600 rpm.
• Regulator/Control: Serves as the relief valve and provides pressure adjustment. Also directs flow from the pump outlet to different sprayer features such as spray gun, agitation, etc.

View All Diaphragm Pump Options

 

Piston Pumps

• Pump Type: Positive Displacement
• GPM Range: Approx 1 to 68
• PSI Range: Up to 120
• Applications: Fertilizer application on toolbars or planters.

A piston pump is more common for fertilizer application than it is for pesticide/herbicide application. They do not offer the flow rates needed for large boom sprayers, and they are not as forgiving to solids or abrasion as diaphragm pumps. However, they excel at delivering fluid accurately and consistently.

This pump works by using pistons to create a reciprocating motion that draws liquid into the pump chamber on the suction stroke and then pushes it out on the discharge stroke. This mechanism allows the pump to generate consistent flow.

There are piston pumps that are designed for high pressures (1000 psi +), but the piston pumps used for agricultural applications are geared to precision. They are often ground-driven, which makes them the simplest option for automatic rate control. A ground-driven piston pump does not require flow meters or regulating valves for automatic rate control. As you speed up or slow down the pump delivers the precise amount needed to maintain your application rate.

These pumps are also available with hydraulic motors and PWM valves. This allows you to control the speed of the pump with a rate controller and flow meter.

Advantages

• Accuracy: The pump pushes a consistent amount of fluid with each stroke, especially important when applying fertilizers.
• Durability: Robust construction for long-lasting performance in harsh environments.
• Priming: Excellent ability to prime offers flexibility when mounting the pump on a sprayer, toolbar, or planter.
• Easy to Service: The NGP piston pumps are designed to be field repaired. The check valves can be quickly removed and cleaned or replaced as needed.
• Self-Adjusting: A ground-driven piston pump automatically adjusts to your speed, delivering the precise amount needed without flow meters or regulating valves.

Disadvantages

• Cost: More expensive than other pump types that deliver similar flow rates
• Complexity: More complex pumps with many components.
• No solids: Requires filter prior to the inlet to protect check valves and pistons from damage.

Drive Types

• Ground Drive
• Hydraulic

Parts of a Piston Sprayer Pump

The piston pumps used for fertilizer application are more complex pumps than some of the other fertilizer pumps. They feature several components but these are the main ones:

• Plunger: Reciprocating action of piston rod and plunger draws in liquid and pushes it out.
• Check Valves: Control the flow of liquid into and out of the cylinders.
• Crankcase: Houses connecting rod and crankshaft

See all the Piston Pump Drive Options Here

 

Key Takeaways

The type of pump used on a sprayer can have a drastic effect on the performance. Understanding the different types of sprayer pumps and their attributes will ensure you have the best tool for your application. The Dultmeier Sales team has decades of experience and can provide you with insights and guidance in selecting and troubleshooting your sprayer pump.