01-09-2014, 03:22 PM
ABSTRACT This present document is the sum of my experience obtained at instrument lab. In this document a detail analyses has carried out on how the instruments . Safety management systems have been set up in industry to reduce the number of adverse events. Safety management systems use a combination of activities, such as identifying and assessing safety risks in the organizational processes through retrospective and prospective risk assessments. Devices measures risk factors in five organizational domains: (1) Procedures, (2) Training, (3) Communication, (4) Incompatible Goals and (5) Organization.
SIX MONTH INDUSTRIAL TRAINING REPOT ON INSTRUMENTATION COMPLETED AT C-TECH Bathinda Submitted in partial fulfillment of the requirement for the award of the degree of B.tech in E.CE ¬¬ UNDER GUIDANCE : Mr. Amrinder singh Submitted By : Submitted To : lovepreet singh bhullar Er. P.S. bhullar Roll No: 1184111 H.O.D ( E.C.E) DEC./MAY 2014
DECELARATION I hereby declare that the six months training report submitted in the partial fulfill of the requirement for the award of the degree of bachelor of technology in Electronics & Communication Engineering to the Punjab Technical University , Jalandhar , is an authentic record of my own work carried out at C-TECH BATHINDA. LOVEPREET SINGH BHULLAR ACKNOWLEDGMENT I am highly grateful to the ER. P.S. BHULLAR ,HOD of Electronics and Communication engineering department, GTBKIET CHHAPIANWALI MALOUT, , for providing this opportunity to carry out six months industrial training at C-TECH BATHINDA. I would like to express my gratitude to the other faculty member of E.C.E deptt. Of Gtbkiet faculty of engineering for providing academic inputs, guidance &encouragement throughout the training period. The author would like to express a deep sense of gratitude and thank to Mr. Amrinder singh . Without whose permission, wise counsel and able guidance, it would have not been possible to pursue my training in this manner. Name: Lovepreet singh bhullar Roll No. 1184111 E.C.E/8th ABSTRACT This present document is the sum of my experience obtained at instrument lab. In this document a detail analyses has carried out on how the instruments . Safety management systems have been set up in industry to reduce the number of adverse events. Safety management systems use a combination of activities, such as identifying and assessing safety risks in the organizational processes through retrospective and prospective risk assessments. Devices measures risk factors in five organizational domains: (1) Procedures, (2) Training, (3) Communication, (4) Incompatible Goals and (5) Organization. . 1) INTRODUCTION C-TECH BATHINDA located at near bus stand bathinda . c-tech has reached the dizzying heights of success through sheer determination, dedication and hard work leading a team of , development coaches, frontline entrepreneurs and associates. Mr. AMRINDER SINGH is the managing Director of the C-TECH. There are two labs : • Instrumentation • Electrical 2. List of Instruments Used • Bourdon tube pressure gauge • Temperature gauge (liquid filled type) • Vacuum gauge (bourdon tube type) • Glass thermometer • RTD (three wires) • Thermocouple ( J and K type) • Differential pressure transmitter(DPT) • McLeod gauge • Manometer • Multimeter • Orifice • Pressure regulators and control valve • I/P converter • Dead weight tester • Temperature calibrator • mA, mV source • Resistance source • Weighing scale • Single Loop Programmable Controller (SLPC) • Solenoid Valve To control the process at fast rate and make it accurate Digital Control System (DCS project) is now introduced. It has the features that are not available in SLPCs. 3. DEAD WEIGHT PRESSURE GAUGE TESTER 3.1 Construction:The main components of the tester are fixed on a rigid steel base plate. The base plate is provided with four legs for taking leveling screws with their lock nuts and base pads. A sheet metal cover is provided for protecting the interconnecting piping against damaging. Screw pump: this is basically a plunger which moves into a cylinder when the screw pump handle is turned clockwise, and pushes oil into the circuit to generate pressure. Anticlockwise turning of the handle saves to reduce pressure and also to draw in oil into the circuit at the start of the test. Piston block this is a solid steel block with srilled interconnection at the rear of the tester. The screw pump is fitted to it on the front side and the free piston assembly is fitted on its top. A tube leads out from the piston block to the gauge block. Gauge block: this is mounted on the front side of the base plate and is connected by piping to the piston block and to reservoir block. A gauge valve is provided to isolate the gauge. Reservoir block: this is provided with 3/8" BSP threads on the top side for mounting the oil reservoir. Oil from the reservoir flows into block through the release valve into the piping connecting to the gauge block. Free piston assembly: this is fitted directly to the top face of the piston block and is in communication with the oil in the system. A weight carrier is screwed on to the free piston which serves table fro loading more weights. The pressure equivalent of the weight of the carrier and the piston is marked on the carrier. This is min pressure which can be tested by the instrument. floats freely in its cylinder and the pressure in the circuit will be determined by the weights loaded divided by the affected area of the piston with connections for gravity, air buoyancy, surface tension and datum level. The effect of friction is minimized by rotating the rotating the piston along with the weights loaded on it. True floating action is also required for that the piston be truly vertical. This is accomplished by leveling the top face of the weight carrier by means of a sprit level and the leveling screws provided on the tester. The free piston is provided with a circle lock to prevent it from accidentally ejecting out of its cylinder. The lock is not intended to withstand the full force of the high pressure acting on the piston. This force must invariably be balanced by loading the appropriate weights on the carrier. A stepped region 1/2" long is machined on the top end of the piston after which the polished portion is seen. The piston will be free from constraint if the piston is lifted anywhere within this 1/2" region. If the piston is lifted more than this step mark the circle lock will come into play (with another 1/4" safety margin) and the piston is no longer free. Set of weights: the top face of each weight including carrier is marked with pressure equivalent of its weight and the serial number tester for which it is calibrated. Every weight is projection on the top face and a recess on the bottom face to facilitate stacking of the weights on the carrier or elsewhere. The top projection has a top recess for taking incremental weight which may be ordered at any time by quoting the serial no. of the tester. 3.2 SETTING UP Place the tester on a strong rigid table in the instrument room. Direct rays of the sun should be avoided. The instrument should not be near a furnace or in a hot area. Clean the instrument with a soft cloth, especially the top stepped region of the free piston. Check the free movement of the free piston by moving it up and down by hand. The feel of the dust on the piston should not be there. If necessary clean it as per maintenance instructions given later. Also check the free rotation of the Screw Pump Handle both the valves. Install the following as shown in fig. • Leveling screws with lock nuts and base pads. • Weight carrier on free piston. • Screw pump handle rods with knobs. • Wheel of the release valve • Oil reservoir on the reservoir block Place a sprit on weight carrier and adjust by means of leveling screws by tightening lock nuts on to the legs. If the tester is not moved, leveling needs to be checked only periodically. In permanent installation, it is advisable to fix the base pads on the instrument table by screws in the screw holes provided. 3.3 OPERATING PROCEDURE Pour a clean mineral oil to approximately 2/3 rd of the capacity of the reservoir. SAE 30 (or 40) Heavy Duty engine oil is suitable and restricts seepage past the free piston to a reasonable level. A higher viscosity oil will cause the free piston to move sluggishly particularly at low pressure but seepage will reduce. The opposite effect will be noticed with low viscosity oil. If the instrument is being used under extreme ambient temperatures appropriate viscosity oil may be used. The instrument cover will normally be marked with recommended grade for normal conditions. SAE 20/40 multigrade oil is also suitable. a) • Open release valve. • Turn screw pump handle clockwise fully. This will expel some air from the system which will bubble out from the oil cup. • Turn the handle anticlockwise fully to draw in oil into the instrument. • Repeat clockwise/anticlockwise turning of handle no. of times until no bubble appear in the oil cup. Finally, draw in oil. b) • Remove blanking plug from union connector. • Open gauge valve. • Turn screw pump clockwise slowly until oil shows at the union connector. Install the gauge to be tester on the union connector using adapter if necessary. Please insure that gauge and adapter are seating properly, are tightened well and the assembly is rigid. • Draw in oil fully and close the release valve. 3.4 TESTING • Check that the tester is leveled properly by means of sprit level. • Place the necessary weight on the weight carrier so that the sum of the pressure values of the carrier and weights loaded is equal to the first reading to be taken. • Slowly turn screw pump clockwise. This will build up pressure in the circuit, which, after a few turns will show on the pressure gauge. • Rotate the weight with carrier by hand to reduce the effect of friction in the free piston. Continue to increase the pressure and also to rotate the weights until the free piston rises up. Watch the top of the piston, where the first 1/2 " portion is of smaller diameter. After which polished portion is seen. The piston can rise a 1/4 " more before the internal lock stops further movement. It will be evident that the free piston is free from constraint and is floating on the oil pressure if:- • It has risen • Is anywhere within the first 1/2 " stepped region, and • Is rotating as explained above. • Tap the by a finger to eliminate the friction in the gauge mechanism and take the reading on it. Write it down against the sum of carrier and weights loaded. • Progressively loads in the desired step on weight carrier and take reading at each point in same manner as first reading. • After the max reading have been taken, take reading for decreasing pressure at the same pressure as before. Consider mean reading at each point. Sometimes, especially while diaphragm gauges, the required pressure may not be build up even though the screw pump travel has been fully used up. In such a case, proceed as follows: • Proceed unto the maximum pressure possible • Close gauge valve. • Slowly open release valve. • Turn screw pump handle fully anticlockwise. • Close release valve. • Turn screw pump handle clockwise slowly until the free piston with previously loaded weights rises up. • Slowly open gauge valve. The pressure may fall slightly. • Continue adding weights and increasing pressure to take • further reading as before. 3.5 CLOSING UP After the work is over, please insure the tester is left in the following condition: • Release valve- open • Screw pump- fully anticlockwise • Weights- removed from the carrier, properly cleaned and stacked, properly in the storage box. • Dust cover- placed over the instrument. This will ensure that there is no accidental pressure build up and prevent damage to the free piston which is an expensive component. READJUSTMENT OF THE PRESSURE GAUGE: Study the test results of the pressure gauge and resolve the error at each point so as to find zero error and the continuous increase/decrease of error. Install the pressure gauge on tester and proceed as follows: ZERO ERROR: (constant error at each point) Install the pressure gauge on the tester and raise the pressure unto the value the first main division of the pressure gauge. Remove the pointer by means of pointer puller and place at correct position by hand. Finally fix it on position by means of the pointer punch which may be tapped by the handle of a screw driver or a very light hammer. Check readings once again. This correction may also be carried out at the specific operating pressure of the pressure gauge in which you are interested. RATIO ERROR (error continuously increases/ decreases) There is link which connects free end of the burden tube to the arm of the segment gear. The segment gear arm has a slot in which the link is connected. Moving the position of the link in slot toward the bearing pin of segment gear will cause the pointer to move faster with increasing pressure. Moving the link away from the bearing pin will make the pointer move slowly. This adjustment is a trial and error procedure, but with practice can be done quickly. For adjustment of pressure instruments of the non-burden type or electrical type, refer to instrument manufactures for the adjustment procedure. However all zero error adjustment must be done at a positive pressure. 3.6 MAINTENANCE Cleanliness and lubrication The instruments and weights should be kept scrupulously clean. A soft cloth without loose threads may be used. The top of free piston requires special attention and should be wiped and oiled every day before start of the test, as dust can easily enter the piston from their causing movement to become sluggish or even causing irreparable damage. The weights may also be given a thin coat of oil for storage purpose. Besides the free piston, the screw pump requires periodic lubrication which may be done every 3 to 6 months depending on the conditions. God lubrication oil should be applied to the acre. A few drops of oil should be poured into the hole of the sheet metal cover retaining the screw near the screw pump handle, to lubricate the main main nut of the pump. Grease should be applied to the thrust bearing and to the guide way for the torque prim. Sheet metal cover would have to remove for serving the screw pump. Care of free piston assembly: This is automatically lubricated by the slight leakage which takes place past it. Normally SAE 30 will restrict the leakage to a reasonable level. A higher viscosity oil will cause the piston to move sluggishly, particularly at low pressures, but leakage will reduce. The opposite effect will be noticed for the oil with low viscosity. If instrument is used under extreme ambient temperature conditions then all the oil used will change accordingly. If the piston is moved up and down by hand and it is found that it is giving a feel of rough and sluggish movement as distinguished from the normal smooth movement, this will be dust or dirty oil. It is now necessary that the piston be cleaned as follows: Unscrew the weight carrier. Unscrew the free piston assembly from the instrument. Extract the retaining lock. Take out the piston from the cylinder. Wash the piston and cylinder bore with a solvent and wipe carefully with a cloth. Dip the piston in oil and reassemble. The piston assembly must be tightened and hard on the main block with necessary nylon washer inserted in its seating. Valves: If leakage is noticed from any valve stem, tighten the gland nut slightly. If leakage is not stopped, the 'O' rings packing needs replacement. Use one small size 'O' ring removes the hand wheel and gland nut. A packing bus presses the 'O' ring in position. Remove these and clean the 'O' ring recess. Smear a new 'O' ring with oil and insert in the recess, followed by the packing bus and finally tighten the gland nut. Excessive force is not required. Install the hand wheel and check rotation of the valve. Adjust the gland nut so that the valve movement is smooth and no leakage takes place on pressurization. If the valve is not closing properly, unscrew out the entire valve from the block and check the nylon seating washer in the block. Clean or replace the seating as necessary. A new will have to force into its seating and then pressed carefully by valve rod itself before pressure is build-up. The hole in the centre of seating must be open. Drill if necessary. Insure copper washer is seating properly. Screw pump: • Handle body is loose on its bearing: loosen Allen screw on the handle body and pull the handle out. Wipe the inside and projecting bearing piece dry. Push in handle, tighten Allen Screw and push handle snugly against the bearing plate. Tighten Allen Screw well. Check for smooth movement of screw pump handle. • Handle is tight but screw inside is free: Remove sheet metal cover and inspect stopper torque pin assy. ensure that the Allen Screw of stopper ring is tight in the recess provided in the long screw. Also ensure that the the torque pin on the side of stopper ring in tight and moves freely in the guide slot. • Oil leakage requiring replacement of ' O ' ring: Use 2 nos. big size of ' O ' rings from the tool box. Remove sheet metal cover. Turn screw pump handle anticlockwise to nearly max position. Loosen the Allen screw on the stopper torque pin unit and slide the stopper to the cylinder end. Fully unscrew knurled cover nut on the cylinder. Tighten the Allen screw on the position marked and turn handle anticlockwise slowly so that floating piston head of the screw pump comes out. The head is separate from pump screw and carries the two ' O ' rings. Install new ' o' rings and reassemble in the reverse manner ensuring that stopper unit is finally fixed at the original operating position. New rings should be smeared with oil before assembly and be free from twist after installation. In case the piston head is not freed by above procedure, the screw pump handle may be removed and pump screw pulled out manually from the outer end. If cylinder appears dirty, it may be removed, cleaned and tightened hard. 4. Calibration 4.1 Bourdon Tube Pressure Gauge: This gauge is used for gauge pressure measurement. It is installed in various distillation columnsand pressure lines. It gives the indication of process pressure. Bourdon tube pressure gauge used is of C type. Calibration: • Close the isolation valve of pressure gauge. • Remove the pressure gauge from point with the help of proper tools. • Bring pressure gauge in the instrumentation workshop. • Calibrate pressure gauge with the help of dead weight tester with the following procedure: • First remove the front glass cover of pressure gauge. • Check zero of pressure gauge, if any deviation is found adjust it with zero setting screw. • Now fix pressure gauge on dead weight tester. • Apply pressure as per range of pressure gauge. • Check pressure gauge at 3-4 different pressure condition. • If any deviation found, adjust it with the help of pointer puller. • If error other than zero error occurs then adjust the angularity screw and positional screw inside the gauge. • Now fix pressure gauge on its place and open the isolation valve. Note: during calibration of pressure gauge try to avoid pressure leakage, otherwise it will cause error. Release valve should be closed and gauge valve should be open while performing calibration. Release the pressure valve when calibration is over. 4.2 Vacuum Gauge: vacuum gauges are used for measurement of pressure below atmosphere pressure i.e. vacuum. Vacuum gauge used is used is of bourdon tube type and similar in construction to bourdon tube pressure gauge only different in gearing arrangement. The installation of vacuum gauge is similar to the pressure gauge. Calibration: • Close the isolation valve for vacuum gauge. • Remove the vacuum gauge from point with the help of proper tools. • Bring vacuum gauge in instrumentation workshop. The following procedure: • First remove the front glass cover of the vacuum gauge. • Check zero of the vacuum gauge, if any deviation found adjust it with the help of ZERO setting screw. • Now fix vacuum gauge on dead weight tester. • Apply vacuum as per range of vacuum gauge. • Check vacuum gauge 3-4 different vacuum readings. • If any deviation found, adjust it with the help pointer puller. • If error than zero error occurs then adjust the angularity and positional screw inside the gauge. • Now fix vacuum gauge on its place and open the isolation valve. 4.3 Temperature Gauge: Temperature gauge used is of liquid filled bourdon tube type. It based on the principle that liquid expands when temperature increases. With the expansion of liquid force exerted on the tip of bourdon tube and it get deflected. The scale is calibrated in terms of temperature. Calibration: • Remove temperature gauge from point with the help proper tools. • Bring temperature gauge in the instrumentation workshop. • Calibrate temperature gauge with the help of temperature calibrator as follows: • First remove the front glass cover of temperature gauge. • Fix temperature gauge on the temperature calibrator. • Give the set point to the calibrator. • Switch on the heater. • When the temperature reaches the set point note the calibrator reading and gauge reading. Take 3-4 reading for different set points. If any error found, adjust the pointer. • Now fix gauge on its place. 4.4 RTD: RTDs are used for medium temperature measurement up to 400 °c. it based on the principle of change in resistance with temperature. The resistance of RTD increases with increase in temperature. Three wire Pt100 RTD are used in IOL. The output of RTD is given to temperature indicator which is calibrated in terms of temperature. Calibration of Temperature Indicator: • Remove the temperature indicator from site and bring it to the instrumentation workshop. • Calibrate it with the help of resistance source as follows: • Apply resistance equal to the low range of the indicator. Note the reading. If deviation is found adjust with ZERO pot. • Apply resistance equal to full range of indicator. Note the reading. If deviation is found adjust with the help of SPAN pot. Check the indicator for 3-4 different resistance values. • Install the indicator at its site. 4.5 Thermocouple: Thermocouples are used for high temperature measurement more than 500°c. Thermocouple is based on the Seeback Effect. It provides output in terms of mV. The output of thermocouple is given to the electronic indicator which is calibrated in terms of temperature. J and K type thermocouples are used in IOL. The temperature indicator for thermocouple is calibrated with the help mV source. Calibration of indicator: • Remove the temperature indicator from site and bring it to the instrumentation workshop. • Calibrate it with the help of mV source as follows: • Apply voltage equal to the low range of the indicator. Note the reading. If deviation is found adjust with ZERO pot. • Apply voltage equal to full range of indicator. Note the reading. If deviation is found adjust with the help of SPAN pot. • Check the indicator for 3-4 different resistance values. • Install the indicator at its site. Glass Thermometer: Glass thermometers are used to check the other temperature measuring instruments like RTD, thermocouples and temperature gauges. Level Gauge: Glass tube level gauge is used for tank level measurement. Two outlets are taken from the tank and are connected to two sides of level gauge. The scale on the level gauge is calibrated in terms of percentage of maximum tank level. It is used fro on line indication. Generally DPT is used to transmit level reading to the control room. If the DPT get defected then level gauge used foe level indication. 4.6 Weighing Scale: Electronic type weighing is used for measurement of weight in stores. Calibration: Calibrate weighing scale with the help of standard weight as follows: • Switch ON the power supply. • Check reading on scale. It should be zero. If not then press TARE. • Press function key for 5 seconds. Display will show c50. Put the 50 Kg weight on the platform. Press TARE display will show 50 Kg. Remove the weight from platform. 5. DIFFERENTIAL PRESSURE TRANMITTER ( DPT) : 5.1 Principle of operation: During operation, the isolating diaphragm detects and transmits the process pressure to the oil filled fluid. The fluid in turn transmits the process pressure to the sensing diaphragm in the centre of the cell as shown. The sensing diaphragm deflects in response to differential pressure across it. The displacement of the sensing diaphragm, a maximum deflection of 0.004 inch is proportional to the applied pressure. Capacitor plates on both sides of the sensing diaphragm detect the position of the diaphragm. The transmitter electronics converts the differential capacitance between the sensing diaphragm and the capacitor plats into a two-wire, 4- 20 mA DC signal and a digital output signal 5.2 Front view of DPT: 5.3 Selecting the installation location for pressure transmitter: The transmitters are designed to withstand severe environmental conditions. However, to ensure stable and accurate operation for many years, the following precautions must be observed while selecting an installation location: 1. Ambient temperature: avoid locations subjected to wide temperature variations or significant temperature gradient. If the location is exposed to radiant heat from equipment, provide accurate thermal insulation and/or ventilation. 2. Ambient atmosphere: avoid installing the transmitter in corrosive atmosphere. If transmitter must be installed in corrosive atmosphere, there must adequate ventilation as well as measures to prevent incursion or stagnation of rain water in conduits. 3. Shock and vibration: select an installation location suffering minimum shock and vibration. (Although the transmitters are designed to be relatively resistant to shock and vibration). 4. Installation of explosion protected transmitters: explosion protected transmitters can be installed in hazardous areas according to type of gasses for which they are certified. The following precautions must be observed in order to safely operate the transmitter under pressure. • Make sure that the two process connector bolts tightened firmly. • Make sure that there is no leakage in the impulse piping. • Never apply a pressure higher than the specified maximum working pressure. • Instrument installed in process is under pressure. Never loosen or tighten the process connector bolts as it may cause dangerous spouting of process fluid. • During draining condensate or venting gas in transmitter pressure detecting section, take appropriate care to avoid contact with skin, eyes or body, or inhalation of vapors, if the accumulated fluid may be toxic or otherwise harmful. • Although the transmitters are designed to resist high frequency electrical noise, if a radio transceiver is used near the transmitter or its external wiring, the transmitter may be affected by high frequency noise pickup. To test for such effects, bring transceiver in use slowly from a distance of several meters from the transmitter and observe the measurement loop for noise effects. Therefore always use transmitter outside the area affected by noise. 5.4 Installing the impulse piping: The impulse piping that connects the process outputs to the transmitter must convey the process pressure accurately. If, for example, a gas collects in a liquid filled impulse piping, or the drain of gas filled impulse piping becomes plugged, the impulse piping will not convey the pressure accurately. Since this will cause error in the measurement output, select the proper piping method for process fluid. Pay careful attention to the following points when routing the piping to the transmitter: • Symbols 'H' and 'L' are shown on capsule assembly to indicate high and low pressure sides. Connect impulse piping to 'H' side. • After connoting the impulse piping, tighten the process connector mounting bolts uniformly. • The impulse piping connecting port of the transmitter is covered with a plastic cap to exclude dust. This cap must be removed before connecting the piping. 5.5 Routing the impulse piping: • If condensate, gas, sediment or other extraneous in the process piping gets into the impulse piping, pressure measurement error my cause. To prevent such problems, the process pressure taps must be angled as shown in figure. According to kind of fluid being measured: • If process fluid is gas, the tape must be vertical or with in 45° of either side of vertical. • If process fluid is liquid, the tapes must be horizontal or below horizontal, but not more than 45 degree below horizontal. • If the process fluid is steam or other condensing vapor, the tape must be horizontal or above horizontal, but not more than 45° above horizontal. • If the process fluid is gas then as a rule the transmitter must be located higher than the process pressure tapes. If the process fluid is a liquid then as a rule, the transmitter must be located lower than the process pressure tapes. • If there is any risk that the fluid in the impulse piping or transmitter could freeze, use a steam jacket or heater to maintain the temperature of the fluid. 5.6 Calibration procedure for Differential Pressure Transmitter (DPT): • Close the isolation valve of DPT. • Remove the DPT with help proper tools. • Bring it to the instrumentation workshop. • Calibrate the DPT with water column, multimeter and 24V DC power supply as follows: • Make the connection of multimeter and 24 V DC power supply. • Leave the LOW pressure side of DPT open to atmosphere. • Without applying any pressure check the zero transmitter. If deviation is found adjust with the help of ZERO screw. • Apply pressure equal to full range with the help of water column to the HIGH pressure side. The multimeter should read 20 mA. If deviation is found adjust with the help of span screw. • Take reading at 25%, 50% and 75% of full range. • Record the readings. • Install the DPT on its place and open the isolation valve. 5.7 Storage of DPT: The following precautions must be observed while storing the instrument, especially for a long period: • Select a storage area which meets the following conditions: • It should not expose to rain or water. • It suffers minimum vibration and shocks. • It has an ambient temperature and relative humidity in the following ranges: Ambient temperature: - 40 to 85 degree c for transmitters without integral indicators - 30 to 80 degree c for transmitters with integral indicators Relative humidity: 5% to 100% R.H. (at 40 degree c) However it is preferable at normal temperature and R.H. (approx. 25 degree c and 65% R.H.). • When storing the transmitter, repack it as nearly as possible to the way it was packed when delivered from the factory. • If storing a transmitter that has been used, thoroughly clean the chamber inside the cover flanges, so that no measured fluids remain in them 6. I/P CONVERTER: 6.1 Principal of operation: The input current flows through the coil (1), thereby magnetizing the soft iron yoke (2). The flux lines of the system being exposed at the gap (3), apply a force proportional to the input signal on the permanent magnet (4) which is made from a highly coercive metal. The small magnet (4) together with the flapper (5) forms the moving parts controlling the air pressure at the nozzle (6), which is proportional to magnetic force. The air flowing from the nozzle forms restoring force balanced by the force applied to magnet. The nozzle is supplied with air through a throttle (7) by the output of power amplifier (8). The described units are properly matched. Hence, a linear correspondence of electric input and pneumatic output signal is achieved. The direction of action of the converter is determined by the coil polarization. Zero adjustment is made by twisting the tensioning band (9), on which the flapper (5) is mounted. Application: The elctropneumatic (I/P) signal converter is used as linking component between electric or electronic and pneumatic systems. It converts standard electrical signals 0 – 20 mA or 4- 20 mA, respectively, into the standard pneumatic signal 0.2 – 1 bar or 3 – 15 psi or 0.2 – 1 Kg/cm sq. Due to its innovative construction principal based on the fixed coil and low mass (100 mg) moving permanent magnet, the I/P signal converter is highly resistant to shocks and vibration. 6.2 Calibration of I/P converter: • Remove the I/P converter from its site. • Calibrate the I/P converter with the help of mA source and master gauge as follows: • Make the connections of mA source and master gauge with the I/P converter. • Apply 1.4 Kg/cm sq. pressure to the I/P converter. • Give 4 mA signal to I/P converter. Master gauge should show 0.2 Kg/cm sq. if required adjust with the help of ZERO screw on the I/P converter. • Give 20 mA signal to the I/P converter. Master gauge should show 1 Kg/cm sq. if required adjust with the help of SPAN screw on I/P converter. • Take readings at 8 mA . 12 mA and 16 mA signals. • Record the readings. • Install the I/P converter on its site. 7. Orifice Installation The restriction to flow in the pipe line most often takes the form of a thin plate square edge orifice. The concentric orifice is by for the most widely used. The segmental and eccentric orifices are used for measuring flow of fluids containing solids. In both the orifice plates is located so that the bottom of the hole is nearly flush with bottom inside of the pipe. The segmental and eccentric orifice requires special calibration since the standard flow coefficient are usable only for standard thin plate, concentric orifice. The concentric orifice plate is made of flat metal sheet with a circular hole, and it is installed in the pipe line with the hole or orifice concentric to the pipe. Orifice plates are made from steel, stainless steel, monel, phosphor bronze, or almost any metal that will withstand the corrosive effect of the fluid. Its thickness is only sufficient to withstand the buckling forces caused by the differential pressure. The circular hole or orifice made with 90 degree, square, sharp edge upstream because this type can be manufactured more uniformly than one with round edges. Wear and abrasion of this sharp edge greatly affect the accuracy of the orifice flow measurement. It is necessary to err on the side of the safety in selecting an orifice plate material that will withstand erosive effect caused by the fluid. In some cases it advisable to replace the orifice frequently to maintain accuracy. The orifice with flange tapes is constructed so that the tapes for measuring pressure differential are an integral part of the orifice assembly. The tapes are usually located one inch either side of the orifice. This arrangement has the advantage that the orifice assembly is easily replaceable, no alteration in the pipe are required, and the pressure taps are accurately located. The pipe taps are made directly in the side of the pipe; the upstream tap located 2.5 pipe diameter from the orifice, and the downstream tap located 8 pipe diameters from the orifice. With this type, only the permanent differential pressure across the orifice is utilized; this differential being smaller for a given flow than with an either flange taps or vena contracta taps. Pipe taps are commonly used in measuring the flow of gases. The orifice with vena contracta taps is arranged so that the downstream pressure tap is located a variable distance from the orifice, depending on the pipe and orifice size. The taps are made directly in the pipe with the upstream tap one pipe diameter from the orifice and the downstream tap at the vena contracta. 8. Process Control Valve and Actuator: In most pneumatic process control schemes, the final actuator controls the flow of the fluid. Typical examples are liquid flow for chemical composition control, level control, fuel flow for temperature control and pressure control. In most cases the actual control device will be pneumatically actuator flow control valve. Even with totally electronic or computer based process control schemes, most valves are pneumatically operated. Although electrically operated actuators are available, pneumatic devices tend to cheaper, easier to maintain and have an inherent, and predictable, failure mode. It is first useful to discuss the way in which fluid flow can be controlled. It is, perhaps, worth noting that these devices give proportional control of fluid flow, and are not used to give a simple flow/ no flow control. 8.1 Types of Control valve: All valves work by putting a variable restriction in the flow path. There are three basic types of flow control valve. Of these the plug or globe valve is probably most common. This controls flow by varying the vertical plug position, which alters the size of the orifice between the tapered plug and valve seat. Normally the plug is guided and constrained from side ways movement by cage. Globe Valve The valve characteristics define how the valve opening controls flow. The characteristic of the globe valve can be accurately predetermined by matching the taper of the plug. There are three common characteristics. These are specified for constant drop across the valve, a condition which rarely occurs in practical plants. In a given installation, the flow through a valve for a given opening depends not only on the valve, but also on pressure drops from all the other items and the piping in the rest of the system. The valve characteristic is therefore chosen to give an approximately linear flow/valve position relationship for this particular configuration. Butterfly Valve A butterfly valve consist of a large disk which is rotated inside the pipe, the angle determine the restriction. Butterfly valves can be made to any size and are widely used control of gas flow. They do, however, suffer from rather high leakage in the shutoff position and suffer badly from dynamic torque effects. The ball valve used a ball with a through hole which is rotated inside a machine seat. Ball valves have an excellent shutoff characteristic with leakage almost as good as an on/off isolation valve. Ball Valve When fluid flows through a valve dynamic forces act on the actuator shaft. The flow assists opening of the valve. The flow assists the closing of the valve. The latter case is particularly difficult to control at low flow as the plug tends to slam into the seat. This effect is easily observed by using the plug and chain to control of water out of a house hold bath. 8.2 Actuator The globe valve needs a linear motion of the valve stem to control flow, where as the butterfly valve and the ball valve requires a rotary motion. In practice all, however, use a linear displacement actuator with as mechanism similar to that used to convert a linear stroke to an angular rotation if required. Pneumatic valve actuator is superficially similar to linear actuator but there are important differences. Linear actuator operates at constant pressure, produce a force proportional to applied pressure and are generally fully extended or fully retracted. Valve operates with an applied pressure which can vary from say 0.2 to 1.0 bar, producing a displacement of the shaft in direct proportion to the applied pressure. Pneumatic Actuator (Direct Acting) The control signal is applied to top of the piston sealed by a flexible diaphragm. The downward force from this is opposed by the spring compression force and the piston settles where the two forces are equal with a displacement proportional to applied pressure. Actuator gain is determined by the stiffness of the spring, and the pressure at which the actuator starts to move is set by pretension adjustment. Pneumatic Actuator (Reverse Acting) Fig illustrates the action of the rubber diaphragm. This peels up and down cylinder wall so the piston area remains constant over the full range of the travel. The shaft of the actuator extends for increasing pressure, and fails in fully up position in the event of usual failures of loss of air supply, loss of signal or rupture of the diaphragm seal. For this reason such an actuator is known as fail up type. In the actuator, on the other hand, signal pressure is applied bottom of the piston and the spring action is reversed. With this design the shaft moves up for increasing pressure and moves down for common failure modes. This is known as fail down or reverse acting actuator. One disadvantage of the design is the need for a seal on the valve shaft. 8.3 Calibration procedure for control valves: • Close the isolation valve of control valve. • Calibrate control valve with mA source and recommended air supply with the following procedure: • Give air supply to control valve as recommended in the specification sheet. • Connect mA source to I/P converter. • Give 4 mA signal to I/P converter. In this case the control valve should fully close. If required adjust with the help of ZERO screw provided on the positioner. • Now give 20 mA signal. In this case the control valve should fully open. If required adjust with the help of SPAN screw provided on the positioner. • Also check the control valve opening at 8mA, 12mA and 16mA signals. • Record the readings. • Open isolation valve of the control valve. 9. Solenoid valve: A solenoid is an elementary device that converts an electrical signal into mechanical motion, usually, rectilinear, that is, in straight line. A solenoid consists of a coil and plunger. The plunger may be free handled or spring loaded. The coil has some current or voltage or current rating and may be DC or AC. Solenoid specifications include electrical rating and the plunger pull or push force when excited by the specified voltage. This force may be expressed in Newton or kilograms in the SI system or in pounds in English system. Some solenoids are specified for intermittent duty because of thermal constraints. In this case maximum duty cycle (percentage of total time) will be specified. Solenoids are used when a large sudden force must be applied to perform some job. Solenoid Valve Actuator: Solenoid valve is combination of two basic units: • Magnetic construction: which comprises of stationary magnet (stopper or plug nut), fixed in stainless steel core tube, moving magnet (plunger), coil and coil housing. When coil is energized, on connecting electrical supply, sets electromagnetic field around the moving magnet and stationary magnet. A seat attached to moving magnet gets pulled upward allowing passage to the fluid, when coil is de-energized, moving magnet is pushed downward with the help of spring, closing the passage of fluid. Thus the valve is opened or closed. • Body and bonnet: which normally consists of brass forgings, stainless steel casting or bar stock, synthetic parts, diaphragm assembly and / or piston assembly. Many a times body contains one or more orifices. Solenoid operated valves commonly work at 24V DC or 110V AC. Each has its own advantages or disadvantages. A DC power supply has to be provided for 24V DC solenoids, which, in large systems, is substantial and costly. Operating current of a 24V DC solenoid is higher than a 110V solenoid. Care must be taken with plant cabling to avoid voltage drops on return legs if a common single line return is used. Current through a DC solenoid valve is set by the winding resistance. Current in an AC solenoid on the other hand, is set by the inductance of the windings, and this designed to give a high inrush current followed by low holding current. This is achieved by using the core of solenoid to raise the coil inductance when the spool has moved. One disadvantage of this is that a jumped spool results in a permanent high current which can damage the coil or the device deriving it. Each and every solenoid should be protected by an individual fuse. DC solenoids do not suffer from this characteristic. A burned out DC solenoid coil is almost unknown. Whatever form of solenoid is used it is very useful when fault finding to have local level indication built into the solenoid plug top. This allows a fault to quickly identified as either an electrical or hydraulic problem. A solenoid can exert a pull or push of 5 to 10 kg. this is adequate for most pneumatic spool valves, but is too low for direct operation of large capacity hydraulic valves. Types of solenoid valves: solenoid valves have 2/3/4 ports and are designed by number of main ports and number of positions. For example- 2/2, 3/2, 4/2, 4/3. The solenoid valves can be sub categorized in four different types: • direct operated • pilot operated • semi lift type • remote type Construction: Internal parts which are in contact with fluid are made out of brass or series 300 or 400 stainless steel. Shading ring is fixed as per requirement of fluid. However, standard shading ring is made of copper. No shading ring is provided for DC design. AC magnetic construction can be used for DC with certain restrictions, but not vice versa. Minimum operating pressure differential: is which requires to open the valve and keep it open. Direct acting semi lift type diaphragm and piston valves do not require minimum pressure differential. 2- Way pilot operated with piston or diaphragm, will start closing below indicated minimum pressure differential. The indicated minimum pressure must be maintained throughout the operations to insure complete changeover from one position to other. Maximum operating pressure differential: is- a differential pressure between inlet and outlet sides of valve against which solenoid valve can easily operate. For practical purpose, working pressure mentioned in the inlet is considered to be maximum operating pressure differential. Safe Working Pressure: Many times regarded as safe body pressure, to which the valve can safely subjected to, without carrying damage to the valve. Safe working pressure for any valve can be three to five times of maximum operating pressure differential. Temperature Limitations: normal limitation for minimum temperature 0 °c, where moisture is present. Many a times, where moisture is not a factor minimum tolerable ambient temperature can be – 5 °c. Maximum temperature determines safe limitations for coil insulation. The operating temperature is determined under continuous energized conditions with maximum fluid temperature existing in the valve. Under certain conditions, maximum ambient temperature limitation can extended to 100°c. 10. Distributed Control System 10.1 Introduction Single loop programmable controllers (analog controllers) now has been replaced be Distributed Control System (DCS) in IOL due to its advanced features and advantages over the analog controllers. Distributed Control System used in IOL is of ABB made. The concept of DCS system was in Europe in 1994/95. window NT and redundancy reintroduced worldwide as ‘Freelance 2000’ in 1996. More than 1100 systems are sold over and 1000 are in operation. DCS is accepted in variety of applications. In 1996, Freelance 2000 was launched worldwide. It is based on Window NT and is fully redundant. DCS is industry proven in variety of applications. • Chemical, pharmaceutical, food and beverages. • Energy, water & waste utility. • Metal, glass and minerals. • Pulp, papers and others. DCS Functionality • analog and digital • control and monitoring • batch management • full redundancy • validation DCS Features 1. Smooth switching • Easy exchange of faulty CPU module. CPU can be replaced under power. 3. New secondary CPU loads automatically: • operating system • programs • process image 4. Intelligent input- output modules are available, arbitrary mounting and self testing. 5. Metal housing for modules • I/Os are galvanic ally isolated into groups. • Proximity switches. • Communication module for RS 485 • Updated EPROM • Safety valves for outputs by channel • Onboard temperature monitoring. 10.2 System Configuration: 10.3 Control Loop: TB : Terminal Box JB : Junction Box PS : Power Supply DCS : Distributed Control System FCE : Final Control Element As shown above in the fig., transmitter measures the controlled variable and send to the controller through Jb and TB. Output of various transmitters (transducers) is given to junction box. From junction box a provides single cable contains various signal wires and sends it to the terminal box (TB). Terminal Box is installed in control room. Power supply provides appropriate voltage to transmitter and current to the final control element (FCE). Fuses are used for the safety of controller and final control elements. 10.4 Field controller, basic unit PM 802F: The basic unit, PM 802F cylindrical scans signal from the field bus sensors via the corresponding field bus module, processes these signals according the application programs installed by the user and sends appropriate signal to the field bus actuator via the field bus modules. Controller redundancy can be achieved by installing two ABB field controller 800.To insure quick and smooth take over by the secondary field controllers in case the primary field controllers fails, a dedicated redundancy communications link through the second Ethernet module makes sure that both ABB field controller 800 are always synchronized. All inputs and outputs are designs to support redundant operation. Data communication between field controller, process and operator stations runs over the Ethernet system bus on the first Ethernet module. Data exchange with the engineering station is also carried via the system bus. Engineering station communication can involve new or updated configuration filed being downloaded to the process station, or information about the connected modules being reported back. When field bus modules are installed or exchanged, the required configuration information is automatically updated. Features: • superscalar RISC microprocessor • 16 K internal CPU cache RAM • 4 MB FLASH EPROM • 4 MB SRAM with error detection and correction • battery backup including battery watchdog • EEPROM, serial, 16 K bit • monitoring of temperature inside the device • watchdog • 4 slots for field bus modules Technical data: CPU : Intel 80960HT25/75 32 bit RISC superscalar processor RAM : 4 MB static read and write memory backup I/O scan cycle time : selectable by configuration, depends on the capability of the field bus module Processing time : < 1.0 ms for binary & 16 bit arithmetic instructions 1000 instructions < 2 ms for fixed point arithmetic instructions < 1.5 ms for arithmetic instructions Power consumption : 6.0 W Power supply : SA801F 115 to 230 volt AC SD802F 24 volts DC Weight : 1.6 Kg 10.5 Power supply SA801F/SD802F: The field controller modules are supplied with 5 volt DC/ 5 A and 3.3 volt DC / 5A auxiliary power by the SA801F, SD802F power supply. The power has open circuit, overload and sustained short circuit protection. The electronically controlled output voltage provides high stability and low residual ripple. In case of power loss >= 20 ms, the field controller generates a power fail signal. The signal is used by the CPU module to shutdown operations and enter to safe state. This required fro a controlled restart of the system and the user application when power is restored. The output voltage remains with in the tolerance limits for at least another 15 ms. LED display Power Green : internal supply voltage is available Failure Red : hardware failure of the basic unit Flashing red : software failure of the system Orange : self test OFF : normal status Run/stop Green : Processing active Red : processing inactive Orange : self test OFF : software initialization Primary/ For redundancy states secondaryOrange : self test OFF : normal status Features • SA801F: input voltage 115 to 230 volt AC ( self adjusting), output is electrically isolated • SD802F : redundant input voltage 24 volt DC • power supply outputs provide : 5 volt DC/ 5A and 3.3 volt DC/ 5A • enhanced power fail prediction and shutdown procedure • LED indication for power supply status and operating status of the field controller • short circuit proof , current limited • 20 ms back energy for use in the event of primary power failure Technical data SA801F: Input voltage: alternating voltage 115-230 volt AC Permissible range: 90-260 volts AC Frequency: 50-60 Hz Input current at nominal load: 230 volt AC : 210 mA 115 volt AC : 411 mA Backup energy for the event of power failure: > 20 ms Fuse: internal Output voltage: 3.3 V DC (±3%) typical 5 V DC (± 3 %) typical Output current: 0.5 – 5 A Current limit 6 A Automatic return to normal state after short circuit Total output Power: max. 26.5 W Weight: 0.460 kg Technical data SD802F Input voltage: 2×direct current 24 V DC Permissible range: 19.2-32.5 V DC Input current at nominal load: 1.3 A at 24V DC Backupenergy for event of power failure: > 20 ms Fuse: internal Output voltage: 3.3 V DC (±3%) 5 V DC (±3%) Output current: 0.5 – 5 A Current limit: approx. 6 A Automatic return to operation after short circuit Total output Power: max. 26.5 W Weight: 0.46 kg 10.6 Ethernet module EI801F: These communication module provides Ethernet communication to the system bus complaint with IEEE802.1 standard. Communication module , complaint with 10base2 for thin coax cable installations. LED display Status Off no supply, module is isolated Green power supply on, module identified and ready ready to operate as configured Orange power supply on, Module identified and either • normal transitory states after module startup • configuration mode of Boot loader Orange flashing power supply on, module identified, module not Connected to proper bus structure Red power supply on the either: --module not yet identified ( normal for short time during module startup) --error occurred during module test Battery low LED Off sufficient buffer battery voltage. Orange Buffer battery not found or low (sufficient voltage) Technical data Rated voltage: 5 V (±3%), from CPU board Power consumption: max. 3.1 W Weight: max. 0.170 kg (with battery module) Battery: 3.6 V lithium battery, 700 mA Life time: > 1.5 years System bus: Diginet S Thin Ethernet: 10base2 Features: • IEEE802.1 Ethernet module • provides 10base2 compliant communication • 32-bit data bus, 100 MB per second • direct memory access to main memory • optional battery for redundant battery backup of main memory 10.7 Profibus module FI830F: The FI830F module interfaces to the frofibus field bus. It provides functionality according to profibus – DP V1 standard and supports baud rate up to 12 MB. The module is the master on the profibus line and allows connecting upto 126 profibus slaves. Configuration and parameterization is carried out completely with Digitool – no additional external configuration tools are required. Line redundancy can be achieved using an external device which derives to profibus line parallel. In conjunction with second ABB field controller 800 the module can also operate in redundant master mode without limiting any other feature. LED display: Status Off : no supply power, moduleisolated Green : module is active and working properly Orange : module has been identified by field controller, but yet not been activated Red : module powered up, but not yet identified or an error has been occurred Busy Off : module is in passive state on the profibus Green : module has token and thus acting as the master Technical data: Power consumption : in the active state, depends on the communication cycle time : 2.8 W max. output current: 20 mA for bus termination/ repeater supply output voltage: 5V, ±5% overload voltage protection: 7.5V/ -5V either transmission line to ground weight : approx. 0.150 kg Features • PROFIBUS-DP module • transmission rate upto 12 MB • support up to 126 slaves • physical interface RS 485 • electrical isolation • shared memory onboard, to minimize the use of basic unit memory • module can be removed or inserted during operation • redundant operation with redundant ABB field controller 800 10.8 Serial module FI820F: The FI820F module provides connectivity to variety of serial field bus and serial protocols. Standard protocol is MODBUS. By using different connection cables the physical interface can easily be selected: RS 485 , RS 422or RS 232. all interface are electrically isolated support redundant operation in conjunction with second ABB field controller 800. LED display Status Off : no supply power, module is isolated Green : module is active and working properly Orange : module has been identified by field controller, but has not yet been activated Red : module powered up, but not yet identified or an error has occurred RxD0 Green : receive data on channel 0 TxD0 Green : transmit data on channel 0 RxD1 Green : receive data on channel 0 TxD1 Technical data rated voltage : 5V, ±3% from basic unit power consumption: 2.6 W power consumption: 0.15 W when idling 0.3 W during per channel communication rated voltage : 5V , ±10% max. output current: 20 mA weight: 0.145 kg Features • provides two serial interface • transmission rate up to 38.4 KBaud configurable • physical interface RS485, RS422, RS232 selectable • electrical isolation • module can be removed or inserted during operation • redundant operation with redundant ABB field controller 800 10.9 CAN-3 module FI810F: The FI810F module provides connectivity to the Freelance 2000 rack input output. It provides functionality according to can 2.0 specification and supports baud rate up to 1 MBd. All interface are electrically isolated and support redundant operation in conjunction with 2nd ABB field controller 800. LED display Status Off : no power supply , module is isolated Green : module is active and working properly Orange : module has been identified by ABB 800 controller, but has not yet been activated RxD0 : Green: receive data on channel 0 TxD0 : Green : transmit data on channel 0 RxD1 : Green : receive data on channel 1 TxD1 : Green : transmit data on channel 2 Technical data Rated voltage : 5V, ±3% from basic unit Power consumption : 1.6W to 2.6 W Channel supply: Raged voltage: 5V, ±10% Power consumption per channel : 0.15W when idling , 0.30 W during communication Weight : 0.145 kg Features • 3- channel CAN module • transmission rate up to 1 Mbaud • module can be removed or inserted during operation • redundant operation, with redundant ABB field controller 800 10.10 Battery module AM801F: The battery module provides for retention of the ABB field controller 800 RAM data when AC800F is