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State of the art key control systems are important for many reasons; safety, security, and of course, loss prevention, to name a few. Once installed these systems pretty much run themselves and all staff quickly adjust to the new technologies and steps involved.youtube.com Knowing who is in possession of all keys at all times ensures a safe and secure environment, where staff and occupants feel safer and potential thieves or vandals are less likely to target your facility. A key control system like this is capable of following and identifying thousands of keys with thousands of users, so it can really be utilized by groups of all sizes and demographics. Key control systems have a variety of useful options to choose from (such as the types of security they want to be required to gain access to locking cabinets).yokogawa.co.jp Each customer is encouraged to decide which options best fit their facility's needs. This ensures absolute customer satisfaction and prevents clients from having to pay for features that they will not utilize. With so much customization available, it is a guarantee that there is a package ready and waiting that perfectly suits just about every situation.
The importance of understanding your flow metering application and undertaking careful monitoring and maintenance of your flow meter system will ensure your flow readings continue to give repeatable and accurate readings. Having received thousands of flow meters for routine re-calibration, it is often the end users' lack of knowledge of their application, which creates the largest measurement errors, rather than the errors observed within a flowmeter calibration. Maintenance Engineer has just moved to a new company and has inherited a mirage of old, new and modified instrumentation across the plant. For years gone by, the flowmeters have been removed from the pipe work and sent for re-calibration during the summer shutdown.
The calibration company undertakes its routine calibration and sends the meter back, ready for installation back into the plant. Great, all systems back underway and everyone's happy! Well, all was great until "Mr Plant" comes along and starts to look into the processes involved. Being more of a temperature and pressure instrumentation specialist, he wasn't quite sure of the flow metering issues, and so contacted a specialist calibration laboratory, dealing with flow meter calibrations. It turns out the meters being used were correctly specified for their application and have been giving excellent low measurement drift year on year. But amazingly they had been sent for calibration for seven years, and calibrated on water, but have been installed in an oil process line running at 30 cSt viscosity.
The outcome was a 3 - 5% error on all his flow measurements. This is an all too occurrent story seen within flow laboratories, which can be easily rectified with a basic understanding of flow metering systems. There are many parameters which can effect a flow meters' calibration, but remembering a few of the larger contributors will help you achieve a more reliable and accurate performance from your flow system. The key contributors which can affect a flow meters performance are; fluid type, fluid viscosity, fluid temperature and meter installation. There are now many laboratories offering flow meter calibrations for different types and sizes of flowmeters, but ensuring you have your meter calibrated on the correct operating fluid will play a large part in the accuracy of your flowmeter. Once you have identified a suitable laboratory for your flow meter calibration, ensure the laboratory has a complete line of traceability for the "Calibration Rig", not just for a master meter installed within the line.
Procure your test instruments from reliable suppliers that deal in varied equipment like multifunctional tribometer, high temperature indenter, scratch test, profilometer, etc. Such suppliers won't just deal in quality instruments but also offer paid consultation services as well. If you're in industries like lubricant, semiconductor, automobile, bio medical, bio technology or nano technology, you'll invariably require reliable test instrumentation. You may require equipment like Multi-Functional Tribometer, Atomic Force Microscope, Raman Spectrometer, Indentation and Scratch Tester, High Temperature Indentation, Polishers, 3D Profilometer and Stress Tester. A multifunctional tribometer can run several standard tribological and mechanical tests on same platform. Tribometers are of several types like Universal, Heavy Duty and Micro.
A sturdy instrument will be equipped with various in-situ characterization techniques, easy-to-use software and high end electronics. High temperature indenter can calculate hardness at various temperatures under vacuum or inert gas atmosphere. It can measure high temperature hardness of metal, alloys, powder metallurgy, ceramics, glass, thin films, etc. The indenter is a potent tool which is suitable for both research and manufacturing environment. Atomic force microscope offers metrological and high resolution measurements for the advanced materials research at the nano scale in all AFM and STM modes. You need to procure equipment that is equipped with cutting edge technology and ultra-fast processing. A basic package would include various modes like Kelvin Probe Microscopy, Piezoresponse Force Microscopy, Nanolithography and Nanomanipulation. A high end Raman Microscope can meet all your research needs.
It has thermoelectrically cooled detectors for low light detection, simple design, high end gratings, electronics and easy-to-use software. You must also look for low machine noise, advanced controllers, self-calibration system and option to choose selective working wavelength that allow the instrument to achieve high repeatability and reliability. 3D Profilometer comes in various types like Optical Profiler, White Light Interferometer and Universal Profilometer. A multi-functional 3D Universal Profilometer includes Interferometer, Raman, Laser, AFM, Film thickness, etc. It measures chemical, surface roughness and magnetic stress properties on same spot without taking the sample out of the tool. 3D White Light Interferometer produces best resolution images with least florescence.
Multi-color LED allows to generate real color images of sample. Advanced camera, fast data acquisition and high speed controllers allow the tester to create images up to 5 million pixels. 3D Optical Profiler is an economical solution for generating high resolution 3d images. Indentation and scratch tester can be used for linear, rotary, zig zag scratch as well as indentation and limited tribology. Scratch test allows to calculate scratch resistance, adhesion and hardness of coatings. Indentation test is used to calculate hardness, indentation, modulus, nano-indentation work etc. vs. Reputable suppliers of test instrumentation would offer paid consultation to test tribological, mechanical, surface morphology and other properties of your samples as per various standards (ASTM/DIN/ISO) or non-standard test procedures. They would also offer legal protection by providing both expert test and expert witness services. If you've any specific requirements, they'll be willing to work in close collaboration with you to develop test instruments.
Are you planning for job change ? We prepared an article for DCS and Field Instruments Questions and Answers which might helpful for your preparation. Share your feedback on the article. What is DCS & PLC? Distributed control system(DCS) and Programmable logic controller. These are the control systems which handles fields I/Os. DCS handles more nos of I/Os rather than PLC. PLC is faster system than DCS. DCS can handles handsome quantity of I/Os so that can be used for total plant automation. In the above mentioned case the these PLC’s can be get connected with the DCS with the help of soft link. Generally this is used to make alert to both the operator.
As I heard the PLC used to handle the DI/DO signals so it can take fast actions. Some of the time it is used to handle few nos of AI/AO. DCS & PLC’s speed depends on the scan rate of I/Os. For both the system Marshalling panels, Consoles and other faculties of Ethernet Etc can be used according to the need. According to the Cause and effects diagrams the System programmer assigns the control action block into the system, we can call them as memory assigning. While making Datasheets which things are to be considered? Basically it depends on the instrument item for which you are preparing the datasheet. As an Example. Temperature Element.
We have collect following information to prepare D/s. What is potential free contact? What is the significance and application of this contact? Contacts having not potential. E.g. Relay contacts/ field switches contacts. They are used in logic circuits. A potential free contact is usually wired into an electrical circuit. However it must be ensured that the contact ratings are suitable for the service in which it is used. In split range control, whether the signal is splitted through I/P convertor or the convertor itself? By connecting o/p of one I/P converter to two positioners adjusted suitably for split range operation of control valves.
Taking two Analog Outputs (AO) from DCS. Split range to be defined in DCS. Both I/P converters and positioners to be calibrated with input as 4to20 ma dc and 3to15 psi respectively. When do we use SOV of rating 110vac and 110vdc? Primarily depends upon the availability of reliable power supply source. How is cold junction compensation in thermocouple carried? This is typically performed in modern programmable instruments by means of measuring actual reference junction temperature using a temperature sensor mounted close to the ref. In which applications do we use 4 wire RTD? Three wire is a better alternative.
Primary objective of 3-wire and 4-wire arrangements is to eliminate effects of lead resistance on temp. What is the sensor used in coriollis mass flow meter to measure density? Density is measured here by measuring the resonant frequency of a vibrating U-tube. What if thermocouple wire is opened in the field? What signal goes to DCS? In most modern instruments the signal may be programmed to go to either maximum or minimum depending upon end user’s requirement. What signal will go to DCS? Usually there is a blocking diode to protect the transmitter against supply reversal and almost zero current signal should be transmitted. What are the possible reasons for the failure of barrier? Fuse blowing sometimes. Power circuits are most likely to fail. How can we say that the given RTD or Thermocouple is correct?
We can only measure sensor output (resistance / maillots ) accurately and look-up corresponding temperature in reference tables.youtube.com The accuracy depends upon quality / condition of the sensor. Degraded sensors may not give accurate readings and must be replaced. To test a sensor, the sensor response may be tested using a high quality temperature calibrator and compared with reference tables. In some cases we have to select the cam position in a control valve for different application? How do we select that? Refer to instruction manual for the positioner / control valve. The cams are often marked with limited amount of information, which may help an experienced person.
What is the difference between a protocol and a field bus? A protocol defines a standard method for communications. A fieldbus is a multidropping arrangement where multiple instruments communicate with special interface hardware using the same pair of wires and in most of the cases draw power from the same pair of wires. What happens if transmitter wires get shorted? The barrier if installed limits electrical energy flowing into hazardous area. If there is no barrier, typically a fuse in the power distribution system will blow. What will happen if thermocouple wires get shorted? A cold junction compensated instrument will typically indicate temperature of the location where the T/C wires are shorted. Why do we require loop-terminating resistor in any digital communication loop?
A minimum loop resistance is required so that modulated current signal produces a modulated voltage signal, which may be detected by the receiving equipment. What is adapter flange? It is a transmitter part for allowing process connection to pipe/tube. How to calculate the safe distance between cables to avoid electromagnetic interference of each other ? The design engineers / equipment manufacturers follow/publish certain guidelines w.r.t. How Control loop should be tuned in process loop? You may use Ziegler-Nichol’s method ( open loop / closed loop ) or special tuning software tools. What is the significance of single ended & differential ended input for PLC? Application wise comparison of these two types of inputs? Differential inputs provide better common mode rejection and signal-to-noise ratio.
What is Ground Loop? Preventive steps to avoid ground loop? When ground wiring is not done properly, grounding of various points is not effective and potential differences exist between them resulting in currents flowing between them. This leads to measurement errors and is not desirable. It can be eliminated by proper ground wiring. In a globe type control valve, what is the importance of flow direction (top to bottom or bottom to top)? Control valves must be installed as per direction marking provided by the manufacturers or instruction manuals. Though people tend to generalize, this is often misleading. What is ATEX directives / FM Approval / CSA approved / CE certified ?
What is the importance of individual certification? Are all these certification required for each instruments? Which certification do we prefer? ATEX/FM/CSA certifications generally refer to certification for suitability of instruments for use in hazardous area when installed in accordance with recommended guidelines. Any certification, which is locally acceptable as per statutory requirements, may be used. We typically accept American/European/Indian certifications/approvals in India. Advantages of tachometer as speed measuring device compared to inductive type proximity switches? Some tachometers provide analog output with almost instantaneous response time. They are highly suitable for speed control in some applications. Application wise advantages of Inductive type proximity switches over capacitive type switches? Inductive proximity switches are better suited for detection of conducting metal objects and are easily tested for proper operation. Capacitive switches are typically used for detecting non-conductive materials.
What is cable tray? Cable tray is nothing but the way or media through which we lay the field cables in plant. 2. Perforated Type(Solid sheath consist of Holes for ventilation). Basically discussing about tray support than we could say it depends on the site conditions. Only care has to be taken considering adequate space for laying cable, considering their bends.Etc. How to decide cable tray size? According to the no. of cable occupancy in the cable tray and available tray size we have to choose it. What is meant by instrument location & JB location? This consist of Instrument location considering the piping drawing given from Piping dept. We identifies the locations of the instrument in the equipment layouts and put the bubbles and elevation and JB nos for the location.
Same way depending upon the accessibility we decide the location of JB and marking of it into the instrument location plan is JB location. There is no need to make a different drawing for this. While locating Instrument & JB which things we have to consider? Loop power indicators : Man approach Illumination from Electrical if instrument is not going to provide. What is the use for cable entry in control room? In the process plant Control room built considering the non-hazardous area. So in case if fire/Explosion takes place in the plant than that has to be restricted from entering into the control room. So MCT (Multiple cable transient) blocks are used. They are designed to sustain the fire for a fixed time duration.
That block hold the cables which are entering into the CCR. What are Analog Input/output & Digital Input/output? 4-20 mA signals from instrument (transmitters) are analog input to control system. 4-20 mA signals to instrument (I/p & electro pneumatic positioner) are analog output from control system. Volt free (24V) contact (NO/NC) by instruments (all type of switches, ex. All powered signals (24V,48V,110V….) from system to instruments (SOV) are Digital outputs. Types of instrument cables? Which cable to use, depends upon hazards condition. Instrument JB’s depend upon hazards area classification. For analog I/p & o/p signal we can use same JB.
But for Digital I/p & o/p we have to use separate JB’s. Because digital outputs are powered signal, by wrong connection there may be chances to damage the card. For DCS I/p & o/p and PLC I/p & o/p we used separate JB’s. What is open loop & close loop? OPEN LOOP : This is nothing but to sense the process signals from the field and to send it to the control room for operator observation. CLOSE LOOP : This is measuring the process signals for operator’s action. Means Transmitter sense the process and send it to the control room. Where the operators takes action i.e. control action and that given to the final control element as per the process requirement. What is a PID controller?
PID stands for Proportional-Integral-Derivative. This is a type of feedback controller whose output, a control variable (CV), is generally based on the error (e) between some user-defined set point (SP) and some measured process variable (PV). Proportional : error multiplied by a gain, Kp. This is an adjustable amplifier. In many systems Kp is responsible for process stability: too low and the PV can drift away; too high and the PV can oscillate. Integral: the integral of error multiplied by a gain, Ki. In many systems Ki is responsible for driving error to zero, but to set Ki too high is to invite oscillation or instability or integrator windup or actuator saturation. Derivative : the rate of change of error multiplied by a gain, Kd.
In many systems Kd is responsible for system response: too high and the PV will oscillate; too low and the PV will respond sluggishly. The designer should also note that derivative action amplifies any noise in the error signal. Tuning of a PID involves the adjustment of Kp, Ki, and Kd to achieve some user-defined "optimal" character of system response. On limit alarms, what is meant by "failsafe"? When a limit alarm is configured for "failsafe" operation, the contact logic is reversed. This means that the coil, which controls the contact(s), will de-energize when the unit is in alarm, and energize when the unit is not in alarm.
Thus, if the limit alarm looses power, the contacts will revert to the alarm condition. This functionality is desirable if the user wants an alarm whenever the measured process is beyond acceptable values, or whenever power is lost to the limit alarm. On limit alarms, what is meant by "deadband"? Deadband is the difference between the alarm "on" and alarm "off" setpoints. For example, if a limit alarm is calibrated to trip at a 14.7 mA input, and un-trip at 13.5 mA, the deadband, (or differential) is 1.2 mA.parker.com What input range is used for the dc input limit alarms to accept a 4/20 mA signal?
All the input ranges for the Action Instruments’ field configurable devices are zero based. One of the input ranges is 20 mA. This is the input range to use for all signals up to 20 mA. Accuracy is not affected. Having the input range begin at zero allows a limit alarm to be used for open circuit detection. What is "Intrinsically Safe"? A protection method employed in potentially explosive atmospheres. Certificate IS tools are designed to prevent the release of sufficient energy to cause ignition of flammable material. IS standards apply to all equipment that can create one or more of a range of defined potential explosion sources.
What Industries are Intrinsically Safe Products Designed for? This combination is very common in chemical, petro-chemical, and pharmaceutical industries. Examples of the amount of inflammable material necessary for ignition below show how small of an amount it takes to present a danger to workers. What are the Regulations and Guidelines for IS? European Union’s 94/9/EC Directive, commonly called ATEX ("Atmospheres Explosibles") Europe’s primary regulation for protection systems and equipment intended for use in potentially explosive atmospheres. Indended to serve as total harmonization directive, laying down essential health and safety requirements, and replace existing divergent national and European legislation. Derivatives of ATEX are being adopted across the world.
National Electrical Code (NEC), is the basis for all electrical codes in the United States. Classifications and related product markings for hazardous areas are covered in NEC 500 and 505.omron.com.au Interpretations of NEC 500, a longstanding regulation are utilized throughout the world (outside Europe). NEC 505 is similar to ATEX. What is the measurement principle of an vortex flowmeter? When a shedder bar is placed in a fluid, Karman vortices are generated on the downstream side. The vortex frequency is proportional to the flow velocity, and corresponds to a specific range of Reynolds numbers. What are the advantages of a vortex flowmeter?youtube.com Frequency output is proportional to flowrate.
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