We all know that a liquid filling machine is a kind of equipment that dispenses liquid/paste into bottles or other containers. In order to ensure that each bottle receives an equal amount of liquid/paste during the dispensing process, the filling machine will have a device or component specifically designed to measure. Common metering methods include gravity fillers based on time control, piston fillers based on volume control, and overflow fillers based on liquid level, and one is pump fillers based on pump control.
What is a Pump Filler?
A pump filling machine offers flexibility for a wide range of product filling from liquids to shampoo consistencies with the ease of simply entering the amount you want in the container. Since liquid bottle filling machines are positive displacement pumps, they are self priming and can draw product directly from the bulk source whether that be a tank, drum or other container. Pump liquid filling equipment is available from single head models, to 12 head or more head inline automatic machines.
How Does a Pump Filler Work?
Pump filling machines can measure liquids during the fill in two different manners, again depending on the project, pumps and goals of the fill. A time based fill on these machines simply allows the pump to run for a pre-set amount of time each cycle. Simple timers or a PLC will assist operators in setting the necessary times, and pump speed may be adjusted for more accurate fills as well. The second method used on these liquid fillers is referred to as a pulse based fill. The pulse based fill will measure the revolution or other movement of a pump component each cycle. For example, on a project using a gear pump, each pulse may be equivalent to a quarter turn of the gear, with 10 pulses completing the cycle. Either method will provide an accurate volumetric fill and for some products and projects either method may be used.
The core of the pump filling machine is which pump to use to form the automatic indexing system. Below we will learn more about the various pumps.
If you need to move liquid material from one place to another, you’re going to need a pump. Industrial pumps come in two different types: centrifugal pumps and positive displacement pumps. Each type has unique properties concerning efficiency, flow rate, viscosity, and pressure.
Centrifugal Pump VS Positive Displacement Pump
A centrifugal pump is used to move fluids by using rotational energy created by a motor or engine. The fluid enters the pump’s impeller across the rotating axis, where the spinning impeller pushes the fluid toward a scroll or diffuser. The fluids gain both velocity and pressure when being passed through the impeller.
A positive displacement (PD) pump moves a fluid by repeatedly enclosing a fixed volume and moving it mechanically through the system. Two or three spindles moving in opposite directions create the function of pumping, trapping, and displacing the liquid. The pumping action is cyclic and can be driven by pistons, gears, rollers, diaphragms or vanes.
Usually used in liquid filling machines are positive displacement pumps. Here are some of the benefits of using positive displacement pumps.
- Different viscosities — Positive displacement pumps can handle various levels of viscosity.
- Various pressures — This type of pump has the ability to operate at higher levels of pressure and flow without an impact on capacity.
- Consistent flow — A positive displacement pump can maintain a constant flow and speed.
- Don’t require sealing — These types of pumps do not have to be completely sealed.
Types of Pump Filling Machines
Although there are a wide variety of PD pump designs, the majority can be placed into two categories: reciprocating pump and rotary pump. The following is a partial list of common pump filling machines based on different types of pumps.
Reciprocating Pump Fillers
In a piston pump the piston slides within a tightly fit cylinder. When the piston retracts, the volume expands. Typically, a valve on the inlet opens, allowing fluid to enter into the pump as the volume expands. When the piston reverses, the volume contracts, and a valve on the outlet opens, allowing the fluid to exit the pump. How Does A Piston Filler Work?
A plunger pump operates in a nearly identical manner to a piston pump. The difference is that the plunger moves through a seal into the pump volume. The displaced volume of the plunger changes the fluid volume within the pump, leading to pumping action.
A diaphragm pump uses a flexible membrane (often called the diaphragm) that flexes inward and outward. The movement of the membrane changes the volume internal to the pump and, when coupled with valves, allows fluid to flow into and out of the pump. Diaphragm pumps are ideal for vacuum, air, and low pressure corrosive fluids.
Rotary Pump Fillers
External Gear Gump
An external gear pump consists of two interlocking gears supported by separate shafts (one or both of these shafts may be driven). Rotation of the gears traps the fluid between the teeth moving it from the inlet, to the discharge, around the casing. No fluid is transferred back through the centre, between the gears, because they are interlocked. Close tolerances between the gears and the casing allow the pump to develop suction at the inlet and prevent fluid from leaking back from the discharge side. Leakage or “slippage” is more likely with low viscosity liquids.
Internal Gear Pump
An internal gear pump operates on the same principle but the two interlocking gears are of different sizes with one rotating inside the other. The cavities between the two gears are filled with fluid at the inlet and transported around to the discharge port, where it is expelled by the action of the smaller gear.
In the case of the lobe pump, the rotating elements are lobes instead of gears. The great advantage of this design is that the lobes do not come into contact with each other during the pumping action, reducing wear, contamination and fluid shear.
Vane pumps use a set of moveable vanes (either spring-loaded, under hydraulic pressure, or flexible) mounted in an off-centre rotor. The vanes maintain a close seal against the casing wall and trapped fluid is transported to the discharge port.
Sometimes known as roller pumps, peristaltic pumps move fluid by using rollers to trap liquid in a flexible tube and move it from the inlet to the outlet. This design results in fluid contact only with the inside of the tube. This feature coupled with easy-to-replace tubing makes peristaltic pumps ideal for one-time use applications such as blood contact in a dialysis machine. How Does A Peristaltic Pump Filler Work?
How to Choose Pump Filler Machine?
In the packaging world, different products create different challenges. From bottle size and shape to custom labels and packing to change-over for different container sizes, each product packaged has its own unique traits. In turn, each liquid filler created for a specific product also has its own unique traits. Product viscosity will always play a part in choosing the correct liquid filler for your specific goods and thick viscosity products can create a unique challenge.
Whether filling your bottles using a time or pulse based method, pump filling machines are ideal filling machines for thicker products and some products that contain particulates. A time based filling method will simply fill by allowing the pump to run for the same length of time each fill cycle. A pulse based filling system will not utilize time, but will measure revolutions or movements of the pump. For example, a "pulse" on a gear pump would be a revolution or partial revolution of the gear. The type of pump used on the filling equipment will be determined by the product being filled.
Different pump types will be chosen to efficiently and accurately complete the fill. The gear pump referenced above will capture product between the teeth of the gears to direct it through the product pathway and to the waiting bottles. Lobe pumps, progressive cavity pumps and many others offer different methods of moving product. Some pumps offer advantages for certain filling projects. For example, the peristaltic pump uses rollers to move product through tubing without having the rollers actually contact the product, making this pump a good choice for sanitary projects or for filling numerous different products or flavors. No product contact parts aids in creating a sanitary process and simple tube changeover protects against contamination from product to product or flavor to flavor.
Generally, pump filling machines will be employed when a product requires some assistance with product flow. Thick products that do not flow freely and products with particulates require more than simple gravity to push the liquid through the product pathway. However, pump filling machines are not exclusive to thick products and can handle a wide range of liquids while providing an accurate fill by volume.
On all pump filling machines manufactured by VKPAK, the pump will be carefully chosen to match the characteristics of the current project. To learn more about pump fillers and additional pump options, or to discuss your own project with a packaging specialist, contact VKPAK.