Compressed Air Distribution, Treatment, and Hydraulic Systems
Distribution Network
The distribution network is the set of pipes that leads compressed air to all the elements of the pneumatic circuit. This network starts from the deposit and guarantees the pressure and air velocity at all points. The pipes of the distribution network must have a diameter that ensures compliance with these conditions. The diameter of the pipe is a function of:
- Velocity of air circulation
- Pressure loss
- Working pressure
- Length of conduction
- Existing bottlenecks along the conduction
All these factors are closely interrelated. For example, when velocity increases, the pressure drop also increases. The air velocity is usually between 6 and 10 m/s, and the pressure drop should never be greater than 0.1 bar. To calculate the pipes, there are many tables and diagrams that usually give an approximate diameter of the required pipe. Calculating the diameter is often very complicated, especially in a large pneumatic system. All the above factors must be considered, as well as future expansion of the circuit, increases in the pace of work, pipes, etc.
Often, a network of steel pipes and their linkages are made by welding, and this procedure provides more watertightness and lower cost. However, welding has the problem of oxidation. For this reason, connections with fittings of different types (cone or olive ring) and of different materials (steel or plastic) are also commonly used. Other pipes are made of plastic material, which are used in small sections and at low pressures, although their price is very high. Two fundamental elements of the distribution network are the tank, always present in all circuits, and accumulators.
Treatment of Compressed Air
For all the elements of a pneumatic circuit to work properly, it is necessary to remove impurities. To achieve clean air, it is necessary to use a range of assistive devices, such as:
- Filters, which are placed at strategic points of the circuit.
- Separators, which remove oil particles from the lubrication circuit that pollute the air.
- Condensation collectors, whose mission is to eliminate water particles that are moving in the air.
If this air conditioning process is not carried out, different faults can occur in the circuit. Some of the most common problems are:
- Rapid wear of stiff joints
- Valve malfunction
- Oil deposits
- Clogged mufflers
- Excessive moisture in the air filter
On the other hand, if the moisture in the air is high, the consequences for the pneumatic system could be:
- Corrosion in pipes, drums, and other components.
- Increased wear and expensive maintenance due to corrosion.
- Disposal of the basic lubrication layer of some components.
- Impaired valve connection function, causing significant disruption in operation.
- Fouling and damage to places where compressed air has direct contact with sensitive goods.
Pascal’s Principle
Pascal’s Law: Pressure applied to a confined fluid is transmitted entirely in all directions and exerts equal forces on equal areas, these forces acting normally to the walls of the container.
Pascal’s law explains why a full water bottle will break if a plug is introduced into the chamber. Since the liquid is practically incompressible, and transmits the pressure applied to the entire container cap, the result is a force over an area considerably larger than that of the stopper. So it is possible to break the back of the bottle by pushing the plug with a moderate force.
Recalling that pressure is the distribution of force between the surface:
and using the bar as a unit of pressure, the force on the bottom surface of the bottle will be the product of pressure x surface (F = pS).
Hydraulic Operation
Components of a hydraulic system:
- Electric motor
- Pump
- Regulation and transport elements
- Working elements
- Control elements
Operation:
- The default engine-powered electric pump allows rotation.
- The pump is responsible for generating the working pressure and flow required for the working items. In this sense, we can say that it performs a similar function to the compressor in pneumatic circuits.
- Some components, such as the pressure tank, filter, pressure gauge, and safety valves, must accompany the pump to ensure operation.
- Transport elements, pipes, and fittings are responsible for conducting the fluid to the point of consumption.
- Finally, the working elements are the actuators (cylinders). For both the motor and other components to function properly at the right time, regulation and control elements are needed.