Electric Diaphragm Pump
An electric diaphragm pump is a type of reciprocating positive displacement pump which uses an electric drive and flexible diaphragm to draw in and expel liquids through the pump body. The diaphragms are flexible membranes that can deform inwardly and outwardly to suck in and pump out the liquid from a casing. The design of the electric diaphragm pump is similar to the Air operated diaphragm pump with the only difference being the use of an electric motor to provide the mechanical energy needed for pumping action. The design of the electric diagram pump is such that it can run with single or double diaphragms configurations depending on the application. However, the electric diaphragm pump is the most common design of an electric diaphragm pump. Electric diaphragm pumps are widely used in applications where leakage is not tolerated because the pumped liquid is either highly corrosive or hazardous to the environment. The electric diaphragm pumps have high operational efficiency and unlike their air-operated counterparts, they only have minor pulsation; hence they do not need a costly pulse dampener. The electrically operated diaphragm pumps are often small in construction and can produce a mechanical force of between 60 and 100 PSI.
Figure: Electric diaphragm pump
In the external configuration, the electric diaphragm pump consists of a highly efficient electric motor, which powers the pump. The electric motor offers the advantage of a low-cost energy supplier, simple maintenance, and minimal chances of fluid leakage. The internal configuration of the pump consists centric cam system, two flexible membranes, liquid chambers, inlet, and outlet valve. The centric cam system is located at the center of the pump and its main function is to convert the rotational motion of the motor shaft to linear movement, which drives the diaphragms in a back-and-forth motion.
Working principle of electrically diaphragm pump
The center section of the electric diaphragm pump is fitted with an eccentric cam system that converts the circular motion of the motor shaft into linear motion of the shafts, attached to each of the diaphragms, so that the diaphragms are pushed and pulled from the left to right. Due to this back-and-forth motion, one diaphragm is pushed to discharge the liquid out of its chamber through the outlet manifold, while the other diaphragm is pulled to draw liquid into its chamber via the inlet manifold. When the cam changes over, the chamber that was filled with liquid in the previous cycle empties through the outlet manifold and the other chamber is filled with liquid via the inlet manifold. This cycle is repeated over and over creating a pumping cycle with a smooth changeover that minimization pulsation in the pump discharge.
Characteristic of electric diaphragm pump
- The electric diaphragm pump is powered by an electric drive
- Electric diaphragm pumps have good suction lift properties
- The pumps have excellent dry running capabilities
- The efficiency of an electric diaphragm pump can be as high as 97%
- Electric diaphragm pumps are self-priming pumps
- capacity to handle viscous, corrosive, abrasive, and toxic fluid. They come with a viscosity chart to help manage pump setting, to prevent under-sizing
- The membrane acts as a wall separating the pump fluid from the sensitive pump components
- Electric diaphragm pumps demonstrate excellent operational properties
Types of electric diaphragm pumps
The electric diaphragm pump has two different styles.
The demand style is the primary style of an electric diaphragm. This style contains fixed force switches to regularly and accurately switch the pump ON and OFF depending on the force settings. This kind of pump is also called the demand pump or demand and delivery pump. The operation principle of the demand pump is based on sensing pressure changes in a system and reiterating by delivering the liquid. The pump starts its operation when liquid is demanded and transfer the liquid from a storage tank to the desired location. A good application of the electric demand diaphragm pump is in toilet flushing. When the toilet is flushed, the demand pump will detect a pressure drop, through a solenoid valve, and will be activated. So long as the toilet is flushing and using water, the demand pump will deliver water into the flushing bucket. When the toilet has completed flushing and the water demand ceases, the demand pump automatically shuts off. Demand pumps are also used for faucet turning and many other applications involving the transfer of fluid.
The second style is known as the bypass style. In the bypass style, the pump operation depends on whether the outlet valve is closed or open, rather than on the force settings. If the outlet valve is open, the pump will continue to operate regardless of the magnitude of force applied to the system. If the outlet valve is closed, the pump’s internal flow stops.
Advantages of electric diaphragm pump
- High operational efficiency
- Excellent and superb output
- Maximum reduction of pulsation
- Electric diaphragm pumps have a smooth operation hence minor pulsation in the pump discharge.
- Low operation and maintenance cost
- Electric diaphragm pumps do not stall under pressure
- Electric diaphragm pumps are Energy savings
The Electric diaphragm pump has less energy requirement compared to Air operated diaphragm pump
- Application versatility
The electric diaphragm pumps come in a wide range of designs to suit the need of ultimately any type of industrial application.
- The electric diaphragm pump has an excellent self-priming ability
Conventional pumps such as the lobe pump, magnetic drive pumps, centrifugal pumps require regular priming to prevent damage to maintain the pumping process and to prevent damage to internal components
- Can run dry
An electric diaphragm pump can run dry for a long time without experiencing any operational issues or damage to its components. This is because the pump has no internal seals or moving parts that require lubrication.
- Less noisy- Compared to the air operate d diaphragm pumps, the electric diaphragm pumps are less noisy because the operation does not involve venting of air from the diaphragms.
Disadvantages of electric diaphragm pump
- Electric diaphragm pump cannot be used for flammable liquid because of the possibility of producing a spark
- Can only run when there is a supply of electricity
- Relatively expensive as compared to the other types of diaphragms pumps
- Electric diaphragm pump has more components compared to the air operated diaphragm pump
Applications of Electric diaphragm pump
Electric diaphragm pumps are used extensively in various industries including the following
- Food industry
In this industry, the electric diaphragm pump is used to:
- processing dairy and Beer products
- unloading raw material
- Transfer shear-sensitive liquid products
- Additive injection
- Chemical process
Here, the electric diaphragm pump is used to perform many activities including:
- Transfer corrosive, abrasive, and toxic chemicals
- loading and unloading tankers, totes, and barrels
- Batching or dosing chemicals
- Filter presses
- To produce the required flow and pressure for spraying and cleaning tasks.
- Unloading raw materials
- Pulp and paper
- The electric diaphragms pumps are used to transport printing ink, resin solutions, adhesives, and glue
- Also used for bulk transfer
- Water treatment and sewage treatment
- The electric diaphragm pump is used to transfer solid laden media
- Dosing acidic or alkali chemicals for water treatment
- As utility pumps
- Filter press
- Surface conditioning
- An electric diaphragm pump is used for replenishing chemicals in plating and metal finishing tanks
- Offloading corrosive as well as solid laden waste
- Agitating cleaning solutions
- Circulating liquid to avoid sedimentation
- Filtration (when critical purification is required for high-quality parts)
- The electric diaphragm pump applies in dewatering sites and quarries
- Transferring solvents for separating minerals from ore
- pumping abrasive slurries and sludge mixtures
- moving fuels for vehicles and equipment
- Electric diaphragm pumps are used as feed pumps for spray guns
- Also used to flush/clean paint line with solvents
- To transfer, dispense and dose paint, ink, and dyes
Electric diaphragm pump troubleshooting
The pump fails to operate
- The electric motor of the pump blown (check; replace)
- A shortcoming in electric motor wiring; broken wires, loose connections (fix the loose connections or broken wires)
- open circuit breaker or blown out fuse (replace fuse/ close circuit breaker)
- Ball valve wedged into seat due to excessive pressure (install pressure relief valve)
- The electric diaphragm motor’s dispensing valve is clogged (Reduce pressure and clear the valves)
- Diaphragm breakdown (replace the diaphragm)
- Dirt in the pump chamber (clean dirt from the chambers)
Liquid leaking from the electric diaphragm pump
- The diaphragms of the electric diaphragm pump are ruptured (replace the diaphragm and ensure regular maintenance to prevent this from occurring)
- The electric diaphragm pump has a loose side housing (tighten the tire rods, screws)
- Damaged O-rings on manifolds (check and replace)
- fault in the pipe network
Electric diaphragm pump cycles but does not prime
- The inlet fittings or manifolds of the electric diaphragm pump are too loose (Tighten)
- The electric pump has some worn-out check valves (replace the balls)
- Suction or discharge valved fully or partially closed (ensure suction and discharge valves are open)
- The electric diaphragm pump has a clogged inlet or outlet (inspect and clean)
- The speed of the electric diaphragm pump is too high leading to cavitation before priming (reduce the inlet pressure of air)
premature failure of the pump’s diaphragm
- Extremely long periods of dry running
- Excessive pressure on the suction side (raise the pump or place it on top of the tank to reduce pressure
- Cavitation (Enlarge pipe diameter on the suction side of the pump or move closer to the product)
- Poor selection of diaphragm materials at manufacturing
- Poorly install or Incorrect diaphragm plates (check the manufacturer’s guide on the correct installation and right plates)
- Regular use of too high pressure on the suction side at the initial startup (Normalize starting the electric diaphragm pump at the pressure level as recommended by the pump manufacturer)
Electric diaphragm pump showing Unbalanced cycling
- Excessive suction lift (fill the chambers with liquid to prime the pump)
- pumped fluid in the exhaust air muffler
- Air leakage on the suction side
- Obstructed check valves (dislodge the obstruction in the check valve pocket)
This article covers the electric diaphragm pump, operation mechanisms, applications, and disadvantages and disadvantages. The article also discusses the troubleshooting issues related to the electric diaphragm pump together with the possible solution to such issues.
The electric diaphragm pump is a type of positive displacement pump that uses two flexible membranes, which are pushed and pulled using an electric motor drive, to draw in expel the liquid through the pump. The pump design has two main styles known as the Demand and Bypass electric diaphragms pump styles. Generally, electric diaphragm pumps are applied to transfer a variety of viscous, corrosive, and abrasive liquids in various industries including chemical, food and beverage, mining, oil and gas, water/sewage treatment plants, and paper and pulp industries.
Electric diaphragm pumps offer numerous advantages including high operation efficiency, ability to run dry, self-priming ability, compact design, and low operational and maintenance costs. Compared to the air-operated diaphragm pumps, the electric diaphragms pumps are less noisy, can operate with minimal pulsation, and have lower energy requirements. However, the electric diaphragm pump cannot be used for highly flammable liquid and submerged applications. Some of the major limitations of this pump include the need for electricity to operate and the high initial installation cost. The benefits of electric diaphragm pumps outweigh the limitations and the pumps are considered a reliable and efficient way of moving liquids in many industrial applications.