4 What is a Filter?A filter consists of a series of pores (channels) of a given sizeAll particles bigger than the pore size are retainedAll particles smaller than the pore can go through the membrane
5 Depth Filter Characteristics & Structure Relatively thick (fractions of an inch)Random structureHigh particle holding capacityRelatively low retention efficiencyPotential for shedding & particle releaseTypically used as pre-filterHigh material contentMaterials: Polypropylene fiber or fiberglass
6 Membrane Filter Characteristic Relatively thin (150 microns)Continuous polymeric sheetDefined pore size with high retention efficiencyHigh Porosity ( Track etched low porosity )Low particle holding capacityTypically used as final filtersMaterials - PTFE, PVDF, UPE etc.
7 Comparison of Membrane and Depth Filter Characteristics
8 Depth Filter – Graded Density FlowFilter is constructed by wrapping multi-layers of fibrous non-woven media on a coreThere is retention gradient along the depth of flow direction by using different mediaLarger particles retained at outer section and smaller particle retained at inner sectionPlanargard : CMP1,3,5,7,9,11,13,16Schematic of Depth Filter
9 Typical Filtration Devices: Pleated Cartridges Filter "pack" contains membrane, plus upstream & downstream fibrous supports.Supports can be a source of particles and can prevent efficient removal of bubbles.Pleat pack is thermoplastically potted to form a cartridge.Can be made in varied lengths from 2" to 40".PermeateFlow PathInlet Flow PathCrossSectionof Pleats
12 Retention Mechanisms: Sieving and Interception In sieving (size exclusion), particles are too large to pass though the pore structure. They are either captured on the surface or in smaller passages inside of the structure.For interception to occur, the particles move with the fluid flow but touch a surface and are held there by strong forces.
13 Retention Mechanisms: Adsorption Most particles in liquids have a negative charge and can be captured by attraction to a positively charge spots on the filter.Can be a large factor in liquids with some membranes.
14 Retention Mechanisms: Diffusion ActualpathMeanFree PathDue to molecular motion, very fine particles move in an almost random manner that follows a mean free path. Variations along this path may cause the particles to come in contact with the filter structure and be captured.Although this is a factor in liquids, it is the largest factor for high efficiency gas filters.
15 What is Pore Size Rating and Nominal Retention? Pore Size Rating Definition:the largest actual or estimated size pores or “holes” in a filterNominal Retention:Some Fractional Retention of a particular particle size (ex. 90%, 95%, 99%, 99.9%, etc.)
16 What is Pore Size Distribution? Pore Size Distribution Definition:An estimate of the range and frequency of pore sizes which make up a given filter membraneLoose Vs Tight Distribution0.20.10.050.011.0Pore Size (micrometers)# Of PoresLoose DistributionTight DistributionBoth are 0.2 um ratedfilters based on definitionof pore size rating
17 Effects of Particle Loading Increase in pressure drop or reduction in retentionSmaller membrane pores are plugged first.Larger pores remain open resulting in pathway for particles to travel throughRetention decreases with heavy loadingDecrease in retention can occur before any noticeable pressure drop increase
18 Housing Type For Cartridge Filters Chemlock Housing Simple Cartridge/Bowl InstallationTwist cartridge 1/4 turn to lockAttach bowl to headTighten locking ring
19 Micro Contamination Removal What do we use to Remove This Undesired Matter?Filters - Particle RemovalPurifiers - Molecular Impurities(e.g. H2O, O2, Hydrocarbon..)
20 Gas filters- Materials of Construction PTFE (Teflon)Chemically stable to all gasesLow pressure dropMetalStainless steel (316L Low sulfur)Chemically stable, except in corrosives & OzoneNickelChemically stable to most gasesNot for Ozone, CO, hydride gases (PH3, AsH3, B2H6)Ceramicscan release organics and light metals
23 What’s a valveA valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category. In an open valve, fluid flows in a direction from higher pressure to lower pressure.Valves may be operated manually, either by a handle, lever or pedal. Valves may also be automatic, driven by changes in pressure, temperature, or flow. These changes may act upon a diaphragm or a piston which in turn activates the valve, examples of this type of valve found commonly are safety valves fitted to hot water systems or boilers.More complex control systems using valves requiring automatic control based on an external input (i.e., regulating flow through a pipe to a changing set point) require an actuator. An actuator will stroke the valve depending on its input and set-up, allowing the valve to be positioned accurately, and allowing control over a variety of requirements.
28 逆止閥(Check Valve)A check valve, clack valve, non-return valve or one-way valve is a mechanical device, a valve, which normally allows fluid (liquid or gas) to flow through it in only one direction
29 Advantages over Ball and Gate Valves In order to operate and seal effectively, seat wear is inherent in most ball and gate valve designs. When the seats eventually wear away so does the ball or gate valve ability to seal. Emergency sealant injection to energize the seal most often enters the flow, potentially damaging downstream instrumentation and or contaminating the flow media. In fire-safe ball and gate valves when the primary elastomeric or plastic seals wear away or are destroyed, metal to metal contact between the secondary metal seal on the ball or gate creates abrasion and costly damage to the key sealing components.
30 電磁閥 Solenoid Valve, Pneumatic Control Valve A- Input side B- Diaphragm C- Pressure chamber D- Pressure relief conduit E- Solenoid F- Output side
31 Valve BodyInlet PortOutlet PortCoil / SolenoidCoil WindingsLead WiresPlungerSpringOrificeThe media controlled by the solenoid valve enters the valve through the inlet port (Part 2 in the illustration above). The media must flow through the orifice (9) before continuing into the outlet port (3). The orifice is closed and opened by the plunger (7). The valve pictured above is a normally-closed solenoid valve. Normally-closed valves use a spring (8) which presses the plunger tip against the opening of the orifice. The sealing material at the tip of the plunger keeps the media from entering the orifice, until the plunger is lifted up by an electromagnetic field created by the coil.
32 Direct acting 2-way valves Two-way valves are shut-off valves with one inlet port and one outlet port. In the de-energized condition, the core spring, assisted by the fluid pressure, holds the valve seal on the valve seat to shut off the flow. When energized, the core and seal are pulled into the solenoid coil and the valve opens. The electro-magnetic force is greater than the combined spring force and the static and dynamic pressure forces of the medium.Direct acting 3-way valvesThree-way valves have three port connections, one being the "common" port and two valve seats. One valve seal always remains open and the other closed in the de-energized mode. When the coil is energized, the mode reverses. This is the pneumatic equivalent of a single-pole single-throw electrical switch.Direct acting 4-way valvesFour-way valves have four port connections and two valve seats. When the coil is energized, one set of ports is connected straight through to the other set of ports. In the de-energized mode, the connection is reversed.
35 What’s pipingWithin industry, piping is a system of pipes used to convey fluids (liquids and gases) from one location to another. The engineering discipline of piping design studies the efficient transport of fluid. Industrial process piping (and accompanying in-line components) can be manufactured from wood, fiberglass, glass, steel, aluminum, plastic, copper, and concrete. The in-line components, known as fittings, valves, and other devices, typically sense and control the pressure, flow rate and temperature of the transmitted fluid, and usually are included in the field of Piping Design (or Piping Engineering). Piping systems are documented in piping and instrumentation diagrams (P&IDs). If necessary, pipes can be cleaned by the tube cleaning process.
40 PVC管PVC管是水電工最常用的管材,它可用於水管也可以用於電管,因厚度不同有分給水管與排水管或電管,因為耐酸鹼所以適合作各種場所,但是 PVC管怕熱 , 加熱之後會軟化,所以不適合在高溫場所,但也因此可利用加熱來彎曲PVC管及擴管,縮管等,使配管更方便,再搭配預製好的彎頭與三通等另件及專用膠水一般來說PVC管.管壁上都有標示.電管~E水管~A or B 其製造材質相同.唯有管壁厚度的差異而已.因電(E)管為配線保護使用.故其管壁厚度也較薄.水管又紛給水(需承受水壓故管壁厚度大於排水用管)/排水使用.建議按實際需求使用合適管件.較為安全.
42 What’s the PTFE (Teflon) In chemistry, polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that finds numerous applications. PTFE is most well known by the DuPont brand name Teflon.PTFE is a fluorocarbon solid, as it is a high-molecular-weight compound consisting wholly of carbon and fluorine. PTFE is hydrophobic: neither water nor water-containing substances wet PTFE, as fluorocarbons demonstrate mitigated London dispersion forces due to the high electronegativity of fluorine. PTFE has one of the lowest coefficients of friction against any solid.PTFE is used as a non-stick coating for pans and other cookware. It is very non-reactive, partly because of the strength of carbon–fluorine bonds, and so it is often used in containers and pipework for reactive and corrosive chemicals. Where used as a lubricant, PTFE reduces friction, wear, and energy consumption of machinery.
43 Material Poly Tetra Fluoro Ethylene (PTFE) Propertiesgeneral Upper service temperature 260 °CChemical resistance excellentSpecific gravity 2.15Melting point 327 °Celectrical Dielectric constant 2.1Dielectric dissipation factorDielectric strength > 1400 Volt / milMechanical Tensile strength 3500 psiElongation 300 %Compressive strength 3500 psiFlexural Modulus psiHardness D-60Enviromental Water absorption < 0.01 %Water resistance excellentOxygen index >95 %
44 Datasheet PTFE TubingPTFE is the most chemically resistant plastic known. Its mechanical properties are low compared to other engineered plastics, but it can be improved by adding fillers such as glass fiber, carbon, graphite and similar materials.PTFE has almost ideal dielectric properties. Its dielectric constant (2.1) and power-loss factor (0.0002) are low and remain so over a wide range of temperatures and frequencies. In certain applications, such as fuel hoses, some electrical conductivity is required to dissipate static charges. When exposed to flame, PTFE decomposes leaving just a little residue.PTFE is extremely inert and stable up to a temperature of 260 °C.PTFE is also virtually unaffected by oxygen, ozone and UV light.
45 Homework Please briefly describe retention mechanism of filter. What is the definition of pore size distribution?Please briefly describe valve classified and choice 3 types valve and describe its function.What is the PTFE tube and its character?