This article is the third part of the following three-part series of articles:
Filtration and Drying Principles in Pneumatic Systems
Filtration Principles in Hydraulic Systems
Filtration Principles of Pneumatic and Hydraulic Systems: A Comparison Study
The filtration principles of pneumatic and hydraulic systems were given in the previous articles. The third part of the three-part series of articles on filtration principles in fluid power systems attempts to make a comparison of the filtration principles, as given in Table 1. A comparative study of the filtration principles would bring out the essential similarities as well as differences in the filtration principles and would provide an overall view of the subject matter.
Table 1 | A comparison of the filtration principles in pneumatic and hydraulic systems
| Parameter | Pneumatics | Hydraulics |
| Medium of energy transfer | Compressed air | Oil |
| Contaminants | Particles, moisture, oil, + | Particles, chemical contaminants, moisture, air, + |
| Effect of contaminants | Abrade surfaces Corrode internal parts Reduce functionality and service life of components | Abrade surfaces Corrode internal parts Reduce service life of oil |
| Cleanliness standards | ISO8573 | ISO 11171 & ISO4406 NAS1638 SAE AS4059 |
| Particle removal | Filters | Filters, Magnets |
| Moisture removal | Dryers, Filters | Vacuum dehydrator |
| Oil (air) removal | Coalescing filters Adsorption filters | Air bleeds Diffuser (Baffle screen) |
| Filter types | General purpose filters Coalescing filters Adsorption filters | Surface filters/ Depth filters Cartridge type/ spin-on Inline filters In-tank filters |
| Filter media | Sintered bronze/ polyethylene Borosilicate glass microfibres Activated carbon | Wire mesh Paper Synthetic |
| Filter locations | Intake Mainline Service line | Suction side Pressure side Return-line Offline |
Joji Parambath
Author, Fluid Power Educational Series Books
Pneumatic and Hydraulic Books authored by Joji Parambath
37 books in Paperback and Kindle eBook versions on the subjects of Pneumatics and Hydraulics, authored by Joji Parambath, have been published under Fluid Power Educational Series. Joji Parambath is a trainer in the field of Pneumatics, Hydraulics, and PLC, for over 25 years. All the books are available at Amazon marketplaces.
These books deal with pneumatic system components and circuits. The fundamentals required to understand the core topics are given initially. These books describe the topics on compressed air generation and contamination control, pneumatic actuators, and control valves, in detail. Further, these books present the maintenance, troubleshooting, and safety aspects of pneumatic systems. Many single-actuator pneumatic circuits are given in multiple positions. Many critical positions of pneumatic single-actuator circuits are given to make the reader understand the control circuits easily.
These textbooks deal with the components and circuits of hydraulic systems. The fundamentals required to understand the core topics are given initially. The book describes the topics on hydraulic fluids, filters, power packs (reservoirs, pumps, pressure relief valves) hydraulic actuators, directional control valves, flow control valves, pressure control valves, fluid conductors, and accumulators, in detail. Further, the book presents the maintenance, troubleshooting, and safety aspects of hydraulic systems.
These books explain the basic principles of hydrostatic transmissions. The concepts of open-circuit and closed-circuit HSTs are explained in the book. The topics also include configurations, advantages and disadvantages, and applications of HSTs.
These books enlighten the details of components required for load sensing systems. The operation of load sensing systems in their various operating modes is described in a simplified manner.
The book ‘Electro-hydraulic proportional valves’ explores the technology used in proportional valves. The book also describes the construction of electro-hydraulic proportional valve systems, the details of various types of control elements, characteristics, and applications of proportional valve systems.
The book ‘Electro-hydraulic servo valves’ describes the technology used in state-of-the-art servo valves. The book also describes the construction of electro-hydraulic servo valve systems, the details of various types of control elements, and the applications and characteristics of servo valve systems.
These books explain the functioning of solenoid valves and various electrical control components such as pushbuttons, electro-magnetic relays, limit switches, reed switches, proximity sensors, electronic timers, and counters. The development of many typical single-actuator and multiple-actuator electro-pneumatic and electro-hydraulic circuits are also separately explained in these books. Many circuits are given in multiple positions for a quick understanding of the working of each circuit.
And many more ….
