Dosing pump

Dosing pump are precision instruments. This type of pump has to inject a certain amount of volume during an impulse. Another important aspect of the pump is that it has to transport the liquid with great accuracy. The pulsing plunger or diaphragm pump are pumps that suit the requirements of a dosing pump. These pumps are provided with a control system making the effective impulse length of the diaphragm adjustable. Sometimes, the cycle rating can also be adjusted.

The most important requirement of this pump is that the impuls of the liquid flow has to be very accurate and repeatable. The amount of liquid in an impuls can only have a difference of 1%. With repeatable we mean that with every impuls, the same amount of liquid is being pumped.

The principle of the dosing pump can be compared with the working of the heart. When we compare the functioning of the human heart with the dosing pump, we find some amazing simularities:

  • Capacity will adapt to the requirements of the system
  • Adjustable for changing pressures and capacities
  • Oscillating and pulsating principle
  • Suction and pressure valves
  • Leakfree
  • Built in safety system
  • Solid construction, which requires little maintenance
  • Is able to pump two different liquids synchronically
  • All "system" parts are dependant on the dosing pump

    It would be ideal if the dosing pump is able to pump a large number of different sorts of liquids. Liquids that are toxic, dangerous, corrosive, abrasive and liquids that contain solid parts.

    To meet up to these requirements, the manufacturers have developed a few model-dosing pumps, which can be divided into different categories like:

  • Capacity
  • Suction-pressure and discharge-pressure
  • Capacity
  • Motor
  • Control mechanism
  • Environment conditions

    Electrical driven dosing pump

    The electromagnetically driven dosing pump can handle capacities up to 30 liters. A magnet is being used, to get the diaphragm in motion. At the same time the diaphragm moves, a spring is being tensed. When the magnetic impuls ends, the diaphragm is pushed by the spring back, creating an increase of volume in the pump chamber. The liquid is then sucked into the empty space.

    When the pump is driven this way it only has one moving part, the magnet. This kind of pump can handle pressures up to 16 bar. The pump isn't suitable with greater capacities and higher pressures, since the magnet has te be out of proprtion large, which eliminates it's effectiveness.

    An important advantage is the ability to control the pump. There are two control mechanisms which can be adjusted, separately from each other.

  • The controllable impuls-length of the magnet.
  • The impuls frequency from the electro magnet

    The magnetic driven pump is constructed out of two modules. The magnetic driven part with the mechanic and electronic control parts, and the dosing part which is constructed with different types of material. The magnet driven part and the electronic control device are placed in a plastic pump house, strengthened with glassfiber. This solid material is light-weighted and waterproof. The protection-rate is IP65. This construction is important, because dosing pumps are often used in moisturized and aggressive environments.

    Mechanical driven dosing pump

    The mechanical driven diaphragm dosing pump is applied at capacities greater than 30 liters and with pressures up to 12 bar. When the pump is constructed with a smaller engine that can handle capacities up to 500 liter has a electromotor. Using the spiralspring, the suction impuls is activated, pushing the plunger on to the eccenter This way the contact with the eccenter remains intact.

    This systeem is suitable to handle suction heights up to 6 meters. At higher suction heights and high-viscous liquids, the system is driven by a krik mechanism. Because of the vertical construction of the worm the electronic engine can also be placed vertical. This way, the used space of the pump will be significant smaller than when the pump is horizontal placed.

    The diaphragm, from the smaller magnetically driven pump, is also used for the mechanic diaphragm pump. With a larger vulcanized core, the pump is able to have very precise impulses. Except for a few diaphragm diameters, the manufacturer also offers about 4 delay mechanisms. The pump then has impuls-frequenties from 144, 120, 96 and 72 available.

    Hydraulic diaphragm dosing pump

    The hydraulic balanced diaphragm pump combines the advantages from the mechanical diaphragm pump and the plunger diaphragm pump. The plunger doesn't get any contact with liquid, and the diaphragm is driven by the hydraulics. The controllable plunger is constructed within a cylinder. The cylinder is connected with the supply-tank, which contains the hydraulic liquid. The plunger has the same controls as the mechanical driven dosing pumps. By setting the plunger in motion, a certain amount of liquid is being displaced. The plunger uses the hydraulic liquid to set the diaphragm in motion. This causes the product-liquid to be pushed towards the outlet-side. The diaphragm keeps the product-liquid and hydraulic-liquid separated. The strain on a diaphragm is narrowed to a minimum, since the pressures on both sides of the diaphragm are equal and divided over the entire surface of the diaphragm.