logging in or signing up Industrial Hydraulics etmasih Download Post to : URL : Related Presentations : Share Add to Flag Embed Email Send to Blogs and Networks Add to Channel Uploaded from authorPOINT lite Insert YouTube videos in PowerPont slides with aS Desktop Copy embed code: Embed: Flash iPad Dynamic Copy Does not support media & animations Automatically changes to Flash or non-Flash embed WordPress Embed Customize Embed URL: Copy Thumbnail: Copy The presentation is successfully added In Your Favorites. Views: 745 Category: Science & Tech.. License: All Rights Reserved Like it (0) Dislike it (0) Added: May 25, 2012 This Presentation is Public Favorites: 1 Presentation Description Understanding Hydraulic Systems Comments Posting comment... Premium member Presentation Transcript Industrial Hydraulics: Industrial Hydraulics Understanding Hydraulic Systems E. T. MasihEnergy Transfer Systems: Energy Transfer Systems Aspects of basic Energy Transmission System as used by the Product / Process oriented industries. These classes of Energy Transmission Systems can be characterized by - Mechanical Rotary input in the form of - An input speed, N i (Constant or Variable) An input Torque, T i which is variable, responding to the instantaneous demand of the System.PowerPoint Presentation: Energy Transfer Systems 2. Mechanical output in two basic forms – Liner a. Output Linear velocity V o (Constant or Variable) b. An output force reaction, F o which can be . constant or variable, responding to the . instantaneous changes in load reaction. Rotary a. An output angular velocity, ω which can be . constant, N o (shown as speed N instead of ω o ) or . variable θ . b. An output torque reaction, T o which can be . constant or variable.PowerPoint Presentation: Energy Transfer System The Energy Transmission System is an interface between an input element such as Prime Mover & an output element such as LOAD Load Ni Ti ETS Vo Fo No To Energy Input Transducer Energy Output Transducer Energy Control Linear Rotary Vo Fo No To Source ETS ETS Pumps IC Engine Torque Converter Drive Gear Control Valves Transducers Pressure Switches Pressure Gauges Limit Switches Linear Actuator Rotary Actuator Limited Rotation Motors Ni TiPowerPoint Presentation: Energy Transfer System Partial Load Curve No Load Curve Full Load Curve ΔP Loss Load Pressure Max. Design Pressure Ideal Case M Vo. Fo No. To P1 Q1 P2 Q2PowerPoint Presentation: Energy Transfer Systems Practically there are four junction interfaces as shown below – Source – ETS Interface (Energy Input) Energy Input – Energy Control Interface Energy Control – Energy Output Interface ETS (Energy Output) – Load At every junction Interface transmission losses are incurred all along ETS. The Energy Transmission System is basically Load Oriented in nature.PowerPoint Presentation: Hydraulic systems essentially use positive displacement input – output devices such as Pumps, Actuators & Motors. Energy is transferred by means of potential energy changes in the fluid transfer medium. This is done by virtue of hydrostatic fluid pressure level differentials ( Δ P). The rate at which energy is transferred is a function of Flow Rate ( Q). These two variables – Pressure & Flow Rate are essentially independent of each other. Energy Transfer SystemsPowerPoint Presentation: Energy Transfer Systems There is s common misconception concerning Fluid Power Systems that a Positive displacement Pump generates pressure. It does not. A Hydrostatic Pump (Positive Displacement) transfer fluid at a controllable rate into system against an impedance (Total opposition to Fluid flow). In Hydraulic Systems resistance is offered by Pipe lines, Hoses, Fittings, Orifices and Flow Paths through Valving. It specifically means that in any Hydraulic System a Δ P loss is existing by default, which is calculated by the system designer.Design verses Analysis: Design verses Analysis Fluid Power Circuits & Systems can be considered from two viewpoints for better understanding – Design: Design of a circuit implies a synthesis of an Energy Transfer System to perform a specific task. Analysis: Analysis of a circuit implies the existence of a circuit to be analyzed with respect to its performance characteristics. Note: Design is a deductive process whereas Analysis is inductive.Classification of Circuits: Classification of Circuits Hydraulic Circuits are the main Building Block of any Hydraulic System. Hydraulic Circuits are Classified as follows – Functional a) Open Circuits b) Closed Circuits Control a) Open Loop Circuits b) Closed Loop Circuits 3. Flow Constant Flow Circuits b) Demand Flow CircuitsClassification of Circuits: Classification of Circuits Fluid Power Systems can be divided into two major groups Open-loop and Close-Loop from control point of view. Open-Loop System: There is no feed back mechanism in this system, the performance of the circuit are determined entirely by the characteristics of the individual components & there interaction. Closed-Loop System: In this system a feedback mechanism continually monitors system output, generating a signal proportional to the output & comparing it to command signal.PowerPoint Presentation: Classification of Circuits Fluid Power circuits are further divided into two groups - Constant Flow Circuits and Demand Flow Circuits. Constant Flow Circuits: In a typical Constant Flow Circuit the DC Valve bypasses fluid to tank when valve is in center thus unloading the pump to reservoir. Demand Flow Circuits: In this circuit a center closed DC valve is used along with an unloading valve and an Accumulator, pump is unloaded when the valve is in center.PowerPoint Presentation: Classification of Circuits Open Circuit Close Circuit Open Circuit Close Circuit Open Loop Circuits Constant Flow Demand Flow Different Open Loop Circuits Shown in the Block DiagramPowerPoint Presentation: Classification of Circuits Close Loop Circuits Constant Flow Demand Flow Open Circuit Close Circuit Open Circuit Close Circuit T T T T Different Closed Loop Circuits Shown in the Block DiagramConstant Flow Circuits: Constant Flow Circuits Fluid Power Circuits & Systems are broadly categorized as - Open Loop Circuits Closed Loop Circuits Open Loop Circuits are further subdivided as - Open Center Closed Center Open Center circuits are characterized as - Constant Flow CircuitsPowerPoint Presentation: Constant Flow Circuits Shown below is a Constant Flow Circuit with an Open Center Valve.PowerPoint Presentation: Constant Flow Circuits Characteristics of Constant Flow Following are the characteristics of Constant Flow Circuits Pump discharge pressure is a function of Load . resistance and must build from zero. Pump output is not determined by Actuator speed . requirements Actuators are sized to meet speed requirements as . a function of Pump output Sizing the actuator: Q p = A p . S/tDemand Flow Circuits: Demand Flow Circuits Closed center circuits are more accurately characterized as Demand Flow Circuits . Demand Flow Circuit require – Fixed displacement pump Closed center DC valve Accumulator Pump Unloading valve OR Variable displacement, Pressure compensated . Pump.PowerPoint Presentation: Demand Flow Circuits Fixed displacement pump Variable displacement, . Pressure Compensated pumpPowerPoint Presentation: Demand Flow Circuits Demand Flow Circuits are used when Load requirements are not constant but varying through the Work Cycle (Where Load velocity is changing) In Demand Flow Circuits either a fixes displacement pump, Center closed DC valve and an Accumulator is used to provide an arrangement to unload the pump when DC valve is in its neutral position or a Variable displacement, pressure compensated pump is used. Closed Center Circuits are characterized as - Demand Flow CircuitsPressure Compensated Pump: Pressure Compensated Pump Pressure Compensated Pumps are designed to reduce the wasted energy in the demand flow circuits. If in the demand flow circuit a Pressure Compensated Pump is used, then the compensator setting determines maximum circuit pressure. Pump output remains constant until the system reaches a given Set pressure, called Cutoff pressure . At this point the force acting on the compensator tend to exceed the force of the control spring that holds the swash plate at maximum anglePowerPoint Presentation: Demand Flow Circuits Pressure Flow Dead head Cutoff In demand flow circuit equipped with pressure compensated, variable displacement pump, compensator setting determines maximum circuit pressurePowerPoint Presentation: Demand Flow Circuits In demand flow circuit equipped with pressure compensated pump, the pump output is related to actuator speed requirements . t Flow Pump delivery Actuator Flow Cutoff Deadhead Pressure Deadhead Pressure t 0 t 1 t 2 t 3 0 t 0Flow Compensated Pumps: Flow Compensated Pumps In Flow Compensated Pumps a control Orifice senses the flow rate, the pressure drop across the orifice being proportional to flow rate as per the equation given below – Q = C d A 0 √2gΔP/γ Where C d = Discharge Coefficient . A 0 = Cross-sectional Area of Orifice neck . g = Acceleration due to gravity . ΔP = Pressure Differential . γ = Specific weight of the FluidPowerPoint Presentation: Flow Compensated Pumps Control Orifice As the equation indicates that pressure drop is a function of the square of the FLOW. The induced pressure drop is felt by the compensator control piston which adjusts pump output in proportion to flow. Simple Flow Compensated PumpFlow & Pressure Compensated Pumps: Flow & Pressure Compensated Pumps A B In this configuration a fixed orifice ‘A’ is used to sense flow rate, In addition, it has a second fixed orifice ‘B’, in the line to the spring end to the compensator. A pressure control valve regulates the pressure in the spring chamber end of the compensator. When pressure in this chamber matches that of the valve setting the valve opens & bypasses oil to tank, creating a pressure drop across orifice ‘B’, thus the total pressure differential imposed across the compensator piston is the sum of the two pressure drops. This value will exceed the pressure drop induced across orifice ‘A’ by flow alone.Fundamentals of Pressure Control: Fundamentals of Pressure Control The two control factors which effect energy transmission are PRESSURE & FLOW. The Pressure affects the potential energy LEVEL of the fluid in the SYSTEM. Pressure (P) is Force per unit area. The Flow control regulates the quantity of fluid passing a reference point per unit time. Flow rate (Q) is Distance moved per unit time. The product of Pressure & Flow rate is the POWER transferred by the fluid in the circuit.PowerPoint Presentation: Fundamentals of Pressure Control Force-Balance Concept Pressure Control Valves work on the principle of a hydraulic Force acting against a mechanical Spring. This is known as the force-Balance concept. It is essential to understand that when working with pressure controls, and for that matter, all Fluid Power components, we are dealing with mechanical devices. They all work on FORCE-BALANCE principle.PowerPoint Presentation: Fundamentals of Pressure Control Hydraulic force can be developed on one side of a control element (Poppet or Spool). The magnitude of the hydraulic force equals the product of Δ P across the element & the effective area of the element. F H = ΔP.A ΔP F H A If this hydraulic force were unopposed, the element would shift to wide open position and fluid will flow through the valve with low pressure drop. To achieve any degree of control a force must be applied on the opposite side.PowerPoint Presentation: Fundamentals of Pressure Control In Force-Balance concept there is a spring opposing the hydraulic force. The force exerted by the spring is expressed by - F s = K s .X s F H = ΔP.A F s = K s .X s ΔXs F Xs Where Fs is the force in lb, Ks is the spring constant in lb/in and Xs is the amount of spring compression in inches . The valve Pre-set value = Max. WP + (150 to 200 psi) pre-defined thumb rule This relationship translates to a minimum pressure drop, (ΔP), across the control element to bring the hydraulic force into equilibrium with the spring force.PowerPoint Presentation: Fundamentals of Pressure Control Two Pressure Control Modes are used in Fluid Power Circuits – Direct Control Mode: 1. Pressure Relief Valves – Maximum System (P) 2. Reducing Valves – Branch Pressure Control 3. Variable displacement pressure compensated . Pumps - Pressure Compensated Pumps control Energy . Level in demand flow circuits reducing wastage . of energyPowerPoint Presentation: Fundamentals of Pressure Control Secondary Control Mode: 1. Sequence Valves - To switch flow to a secondary . circuit when fluid pressure in primary circuit . reaches preset value 2. Counter Balance Valves – To switch flow when a . preset pressure has reached in the cylinder to . move the Overrunning Load 3. Unloading Valves – To bypass pump flow to . reservoir after system pressure has reached a . preset value. 4. Pressure SwitchPowerPoint Presentation: Fundamentals of Pressure Control Directly Operated Pressure Relief Valve Directly operated Relief valve is also known as Quick Acting pressure control valve. This valve operates over a pressure band (range), rather at one specific pressure. (Modulating Valve). This valve is not suitable for a Pump which is delivering large volumetric flow, beyond 25 LPM Pumps.PowerPoint Presentation: Fundamentals of Pressure Control Pilot Operated Pressure Relief Valve This is two-stage Pressure Relief Valve and it overcomes the disadvantages of Directly Operated Pressure Relief Valve. A small pilot piston is held on its seat by a relatively long, low gradient spring. The pilot piston has a small diameter, the hydraulic force acting on it is also small. This minimizes the cracking effects which are present in directly operated pressure relief valves.PowerPoint Presentation: Fundamentals of Pressure Control Pilot Operated Pressure Relief Valve cum Unloading Valve This is a three stage valve combining Pilot Operated Pressure Relief Valve with Pump Unloading Valve. This valve provide a direct interface between Pressure Control Valve and PLC. This valve is an essential Element of Modern Hydraulic Systems.PowerPoint Presentation: Fundamentals of Pressure Control A Pressure Switch is an electrical device operated by a pressure sensitive element such as bourdon tube or a bellows It can actuate a solenoid operated valve when a preset pressure is reached. This valve can unload a pump or switch to a secondary circuitFundamentals of Flow Control: Fundamentals of Flow Control Flow control deals with the rate of energy transfer which, in turn, is related to rate of fluid flow. There are three types of Flow Rates - Volumetric Flow Rate (Qv): This flow rate is expressed in units of in 3 /sec or min. Volumetric flow rate must be used to calculate the speed of piston rod (Load) Weight Flow Rate (Qw): This flow rate is expressed in units of lb/sec or min. Weight flow rate must be used to calculate power.PowerPoint Presentation: Fundamentals of Flow Control 3. Mass Flow Rate (Qg): This flow rate is expressed . in units of slugs/sec or min. (in CU measure) or . Kg/sec in SI units. Mass flow rate must be used in . calculating inertia forces during acceleration & . deceleration periods. The same control valves are used for all the three types of flow rates since they control the quantity of fluid that flows through the valve per unit of time. Flow through an orifice Q = C d A 0 √2gΔP/γ The control options are Area (A) or Pressure drop across ( ΔP)PowerPoint Presentation: Fundamentals of Flow Control There are basically two categories of flow regulators 1. Throttle Valves 2. Flow Control Valves Throttle valve are further divided into two categories Sharp Edged Orifice b) Restrictor (Fixed or Variable) Basic characteristic change in flow rate is negligible due to change in Viscosity Basic characteristic flow rate will change if Viscosity will changePowerPoint Presentation: Fundamentals of Flow Control Flow control valves are subdivide into seven categories - 1. Flow Regulator: A flow regulator consists of an . orifice which senses flow rate, as a pressure drop . across the orifice and a compensating piston . which adjusts to variations in inlet and outlet . pressuresPowerPoint Presentation: Fundamentals of Flow Control 2. Bypass Flow Regulator: In this flow regulator, flow excess of set flow rate returns to reservoir through a bypass port. Bypass Flow regulator returns excess flow from pump to tankPowerPoint Presentation: Fundamentals of Flow Control 3. Pressure compensated variable Flow Control: In this class of Flow Control a Pressure Compensator or Hydrostat is provided to adjust flow under changing load conditions. Load The compensator automatically adjusts to varying inlet & load pressures, maintaining essentially constant flow rate under these operating conditions to accuracies up to 5%PowerPoint Presentation: Fundamentals of Flow Control 4. Variable Flow Pressure & Temperature Compensate Flow Control Valve: This valve controls the change in flow rate due to the change in pressure & temperature. 5. Demand Compensated Flow Control: This valve allows the controlled flow rate into the primary circuit & bypasses the excess flow to secondary circuit. Secondary PrimaryPowerPoint Presentation: Fundamentals of Flow Control 6. Priority Valve: The Priority Valve supplies fluid at a set flow rate to the primary circuit. Should inlet or load pressure or both vary the primary circuit has priority over secondary circuit. Flow in excess of what required by the primary circuit bypasses to a secondary circuit at a pressure somewhat below that in primary circuit.PowerPoint Presentation: Fundamentals of Flow Control 7. Deceleration Valve: A deceleration valve is a modified 2-way, spring off-set, cam actuated valve used for decelerating a load driven by a cylinder. A cam attached to the cylinder or load gradually closes the valve. This provides a variable orifice which gradually decreases the load velocity by increasing back pressure in the cylinder.Direction Control Fundamentals: Direction Control Fundamentals Direction Control Valves are basically switching devices in Hydraulic Systems. The switching requirements can be in the following forms – 1. Start . . 2. Stop . . 3 Change Direction 1 2 3 In many of the control requirements only two switching positions are required and in hydraulic language it is called TWO Position, 2 Way Valve. Single Flow Path through two Ports P & A, ON/OFF control P APowerPoint Presentation: Direction Control Fundamentals In Hydraulic control valves two types of technologies have developed - 1. Spool Valve Technology 2. Poppet Valve Technology Spool Valves: Spool Valves provide multiple flow paths but they always LEAK. Poppet Valves: Poppet Valves provide a single flow path and they never LEAK. Poppet Valves are digital in nature.PowerPoint Presentation: Direction Control Fundamentals Direction Control Valves can be used in one of the two modes – Discrete Position or ON/OFF Control: In this mode the valve switches a stream of fluid through a proper flow path in a circuit at the proper time of a m/c cycle. Full Flow or No Flow. 2. Proportional Position (Step or Infinite Control) In this mode the valve which controls direction of flow can assume any of an infinite number of positions between valve’s minimum and maximum limits. Proportional direction control valves are capable of multifunction control strategies.PowerPoint Presentation: Direction Control Fundamentals DC Valves (Spool Valves) DC Valves are further classified by their number of positions and their center configuration – 1. Two Position Valves 2 1 2. Three Position Valves 2 1 3 P T A BPowerPoint Presentation: Direction Control Fundamentals DC Valve Spool Design Spool Land Groove Spool edges play an important role in controlling the fluid and that is why these edges are called controlling edges. Imagine that a spool is opening to provide flow, if this opening is sudden then NO-flow to FULL-flow or FULL Flow to NO Flow condition will appear quickly and this will cause a pressure shock (Pressure Surge). Pressure Shock = 3 to 4 times of Working Pressure Pressure shock can cause Seal failure, Pressure Gauge & Fitting Failure.PowerPoint Presentation: Direction Control Fundamentals t P Set Value Time for which PS appeared We can clearly observe that the pressure shock rises over and above the working pressure, taking this into consideration we must control the sudden rising pressure, the control is dependant on the following two factors – 1. Geometry of the Control Edge 2. Shift Speed of the SpoolPowerPoint Presentation: Direction Control Fundamentals How to Reduce the Magnitude of the Pressure Surge It is possible to reduce the effect of pressure surge by introducing the V-Shape grooves on the periphery of the Control Edge of the Spool and by limiting the shift speed of the spool itself. What actually we are trying is to increase the flow rate gradually between the two Ports by increasing the spool opening slowly thus accelerating the load in a controlled manner. T A P B TPowerPoint Presentation: Direction Control Fundamentals Direction Control Valve in a Circuit Using a 2/2 Solenoid operated DC valve we can achieve a digital control of a Hydraulic cylinder. Four numbers of 2/2 solenoid operated valves are arranged in a fashion as shown in the figure, now switching through electrical current is possible by a PLC to provide a precise digital control Arranging digital valves into a hydraulic integrated circuit allows them to accomplish the same functions as discrete spool-type valves while retaining the advantages of digital valves.PowerPoint Presentation: Direction Control Fundamentals Direction control through a 4/3 Solenoid operated, Center Closed DC Valve. This particular valve is a multi-flow path valve with two solenoids to provide forward and reverse movement of the cylinder, unlike the previous example in which digital functions are possible with Four solenoids. Advantage: Single hardware element Easy to maintainPowerPoint Presentation: Direction Control Fundamentals A single DC valve with one Sequence valve can control Two Cylinders in a sequence. This circuit does not solve the problem of controlling the pressure of a branch circuit. That means if cylinder one is to be operated at higher pressure and cylinder two is to be operated at much lower pressure then it would not be possible by this circuitPowerPoint Presentation: Direction Control Fundamentals Controlling Branch Pressure By introducing a pressure reducing valve we can easily control the branch pressure, because a reducing valve will close whenever require pressure is reached in the branch.Electro Hydraulic Valves: Electro Hydraulic Valves Proportional Position Valves (Step or Infinite Control) Proportional Position valves are divided into two specific classes - 1. Proportion Solenoid Control (Open/Closed Loop . Valves) 2. Torque Motor Control Servo (Closed Loop Control) In the first category valve is essentially controlled by electric signal coming from a controller but using a Proportional Solenoid (Open or Closed Loop) In the second category valve is controlled by a Torque motor and feedback system (Only Closed Loop)Proportional Position Proportional Solenoid Control Valves: Proportional Position Proportional Solenoid Control Valves In manually operated discrete position valves Operators started combining Switching and Flow Control simultaneously to achieve very small movements very precisely the action was given a special name which was called “Feathering” Valve Switching: Forward Neutral Reverse Neutral This is called FEATHERING This is a very quick ActionPowerPoint Presentation: Proportional Position Control Electrical Solenoid used in conventional valves provide a constant force to pull or shift the spool to its full limit, it means either full flow is delivered into the load or no flow is delivered. 2.5 to 3 Volts & 24 Volts. Voltage applied is constant Current is also constant so force to shift is a constant. T A P Full Flow or NO Flow ON – Off ControlPowerPoint Presentation: Proportional Position Control Proportional Solenoid: Proportional Solenoids are spatially designed solenoids which provide FORCE proportional to the command signal. Feedback from LVDT +10 V -10 V Current to the Proportional Solenoid comes from the Current Amplifier which is proportional to the command voltage but Voltage is 24 Volt constant. The command voltage of 1mV can be translated to 1mAmp through the current Amplifier.PowerPoint Presentation: Proportional Position Control Proportional Solenoids can be divided into two categories – 1. Stroke Solenoids 2. Force Solenoids Previous study shows that spool itself can cause inaccuracies due to the following 1. Spool Inertia 2. Sticktion 3. Hysteresis To overcome these mechanical draw backs of the spool LVDT is introduced to improve upon inaccuracies and enhance degree of control.Fundamentals Of Filters & Filtration : Fundamentals Of Filters & Filtration Function Filters are an essential component of every hydraulic system. Their function is to remove particle contaminants from the hydraulic fluid, which reduce the service life of system components through abrasive wear. The following text contains practical information on the rating, sizing and selection of hydraulic filters, fluid cleanliness standards and fluid condition analysis.PowerPoint Presentation: Fundamentals Of Filters & Filtration Filter sizing & Selection The primary consideration when sizing a filter is the pressure drop across the filter element, the magnitude of which should be kept as small as possible. Pressure drop is influenced by - Media type & area Particle blocking size Efficiency rating Fluid viscosity Flow ratePowerPoint Presentation: Fundamentals Of Filters & Filtration Filter manufacturers publish graphs that plot pressure drop against flow rate of a given viscosity for each filter (area) size and rating. The fluid cleanliness level required by a particular type of hydraulic system largely determines the particle blocking size and efficiency rating of the filter chosen, given table can be used for guidance. Before confirming filter selection, check that the pressure developed by the system at the chosen filter location is within the manufacturers maximum pressure limit.PowerPoint Presentation: Fundamentals Of Filters & Filtration Filter Rating Hydraulic filters are rated according to the size of particles they remove and the efficiency with which they remove them. Beta Ratio Filter efficiency is defined according to International Standard ISO 4572, commonly referred to as "multi-pass test" and expressed as Beta Ratio or rating (β) for a given size (χ). The Beta ratio value is derived as follows – β x = Number of particles of size χ μm downstream of the filter Number of particles of size χ μm upstream of the filterPowerPoint Presentation: Fundamentals Of Filters & Filtration Beta efficiency is derived as follows – % = No. of particles of χ upstream - no. of particles of χ downstream Number of particle of size χ upstream Filter Efficiency Efficiencies of β ratio Values β % β % β % 2.0 50.00 5.8 82.76 52.2 98.084 2.4 58.33 16.0 93.75 75.0 98.67 3.0 66.66 17.4 94.25 100.0 99.0 4.0 75.00 32.0 96.875 173.0 99.42PowerPoint Presentation: Fundamentals Of Filters & Filtration Absolute and Nominal Rating Absolute: A filter that is rated as Absolute has an efficiency of 98% or better at a specific μm size of the filter. Nominal: A filter that is rated as Nominal has an efficiency of between 50% & 95% at a specific μm size of the filter. Fluid Cleanliness Level Fluid cleanliness can be defined as ISO, NAS, or SAE standards. ISO 4406 defines contamination levels using a dual scale numbering system.PowerPoint Presentation: Fundamentals Of Filters & Filtration The first number refers to quantity of particles over 5 μm per 100 ml of fluid and the second number refers to the number of particles over 15 μm per 100 ml of fluid. For example, a cleanliness level of 15/12 indicates that there are between 2 14 and 2 15 particles over 5 μm and there are between 2 11 and 2 12 particles over15 μm per 100 ml of fluid.PowerPoint Presentation: Fundamentals Of Filters & Filtration Type of System Minimum Recommended Cleanliness level Minimum recommended Filtration level ISO 4406 NAS 1638 SAE 749 Silt sensitive 13/10 4 1 2 μm Servo Valves 14/11 5 2 3 - 5 μm High Pressure (250 - 400 bar) 15/12 6 3 5 - 10 μm Normal Pressure (150 - 250 bar) 16/13 7 4 10 - 12 μm Medium Pressure (50 - 150 bar) 18/15 9 6 12 - 15 μm Low Pressure (< 50 bar) 19/16 10 - 15 - 25 μm Large Clearance 21/18 12 - 25 - 40 μm βχ > 75PowerPoint Presentation: Fundamentals Of Filters & Filtration Filter Elements There are two main components of filter elements – The first is the design of the filter element Second is the type of media that is used Depth Filter Media Inside the element, the filter media can vary in thickness, pleat depth and pleat concentrationPowerPoint Presentation: Fundamentals Of Filters & Filtration Media Color Media color can indicate the type of fibers used in the media. For example, Donaldson hydraulic filters are generally equipped with either white (synthetic material) or natural brown (paper or cellulose material) media Media Color Inside Filter Canister Varies According to Manufacturer.PowerPoint Presentation: Fundamentals Of Filters & Filtration How Depth Filter Media Removes Particles As the fluid flows through the media, winding its way through the depths of the layers of fibers, the contaminant in the fluid is captured by the media fibers and the fluid becomes cleaner and cleaner.PowerPoint Presentation: Fundamentals Of Filters & Filtration Synthetic vs. Cellulose Media The differences between synthetic and cellulose (paper-based) media can be seen in the close-up photos from the scanning electron microscope in which the media mat is magnified hundreds of times Synthetic Filter Media has Smoother, Finer, Rounded Fibers that Create Less Resistance to Flow.PowerPoint Presentation: Fundamentals Of Filters & Filtration Selecting an Element When purchasing a new filter or selecting a replacement element, it is important to first answer some basic questions about the application. Where will the filter be used? What is the required cleanliness level (ISO code) of . the system? What type of oil is being filtered? Duty-cycle and flow issues? Pulsating flow or Smooth Flow?PowerPoint Presentation: Fundamentals Of Filters & Filtration NO Yes Optimum Trade-off Decide on Filter Housing option Manufacturer’s Model Code Manufacturer’s stated sensitivity for components Specify Required Cleanliness in Circuit branches Decide on Filter Location Determine Initial Contamination Level in Reservoir Estimate Contaminant Ingression rate, Bypass and upstream Contamination Level Calculate the Minimum Beta Ratio required for Stated Cleanliness Levels Decide on Filter Media to be used Decide on Filter Housing, Style & Size Evaluate cost benefit Trade-off Environmental Variables How to Select Filter for Hydraulic SystemPowerPoint Presentation: Fundamentals Of Filters & Filtration Working components such as cylinders often create wide variations in flow, also called pulsating flow, which is problematic for filters. On the other hand, dedicated off-line filtration (also called kidney loop) can be designed to produce a consistent flow which often leads to much better cleanliness levels with the same efficiency filtration. Filters used in applications with steady, continuous flow can last longer. Filters that must endure cycles of pulsating flow at higher pressures fail early. The lower the micron size rating of a filter, the more often it needs to be changed because it is trapping more particles. Measuring & Managing Contamination : Measuring & Managing Contamination Most existing methods of defining solid contaminant quantities are based on the supposition that all such contaminants have a similar distribution of particle size This may be true of natural contaminants, which have been circulated in a system, subjected to crushing in pumps and to separation in Filters. To allow for such changes in distribution the profile is defined by two numbers indicating respectively, the number of solid particles above 5 µm and 15 µm per 100 ml sample of fluid.PowerPoint Presentation: Measuring & Managing Contamination In order to keep the number of ranges to a reasonable minimum and still ensure that each step is meaningful, a step ratio of two has been used; table-1 shows how each quantity has been allocated to a range number. The Procedure used is as follows - Using a 100 ml sample, first count all the particles above 5 µm and allocate a range number from the right hand column. Next sum all the particles above 15 µm and again allocate a range number as with the 5µm count.PowerPoint Presentation: Measuring & Managing Contamination The allocation of range of number in the ISO S.C. Code System to particle count is shown in Table-1 Number of Particles per 100 ml, More than up to. 15 µm & above 5 µm & above Range Number Number of Particles per 100 ml, More than up to. 15 µm & above 5 µm & above Range Number 8 M 16 M 24 2 K 4 K 12 4 M 8 M 23 1 K 2 K 11 2 M 4 M 22 500 1 K 10 1 M 2 M 21 250 500 9 500 K 1 M 20 130 250 8 250 K 500 K 19 64 130 7 130 K 250 K 18 32 64 6 64 K 130 K 17 16 32 5 32 K 64 K 16 8 16 4 16 K 32 K 15 4 8 3 8 K 16 K 14 2 4 2 4 K 8 K 13 1 2 1 M: Million: K: ThousandPowerPoint Presentation: Measuring & Managing Contamination For example Table-2 shows the result of a typical Millipore particle count - Particle size Range No. of particles per 100 ml of oil 5 to 15 µm 195,200 15 to 25 µm 3,880 25 to 50 µm 1,280 50 to 100 µm 232 Above 100 µm 76 Total No. of Particles above 5 µm 200,668 In this case the total number of particles above 5 µm is 200,668 and hence could have range number 18, similarly. The number of particles above 15 µm is 5468 and hence would have a range of 13. By considering the two numbers with solid line we get an 18/13 (Range Table 2).PowerPoint Presentation: Typical Fluid Cleanliness Levels for Different Types of Hydraulic Systems, Defined According to ISO, NAS and SAE Standards Measuring & Managing ContaminationPowerPoint Presentation: NAS GRADE (Nos. in 100ml) 1 2 3 4 5 6 7 8 9 10 11 12 5-15 500 1000 2000 4000 8000 16000 32000 64000 128000 256000 512000 1024000 15-25 89 178 356 712 1425 2850 5700 11400 22800 45600 91000 182000 25-50 16 32 63 126 253 506 1012 2025 4050 8100 16200 32400 50-100 3 6 11 22 45 90 180 360 720 1440 2880 5760 >100 1 1 2 4 8 16 32 64 128 256 512 1024 | < KLEENOIL > | < NEW > |PowerPoint Presentation: NAS GRADE National Aerospace Standard (1618)PowerPoint Presentation: New NAS coding AS4059 Cleanliness Coding System You do not have the permission to view this presentation. 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