User Key Logix Pro 500 Plc Simulator 107
Download ->>> https://urluso.com/2t7ODh
For retrofitting pneumatic devices, selecting the appropriate silencer type is critical for this control measure to succeed over time. If the source is a solenoid valve, air cylinder, air motor, or some other device that simply exhausts compressed air to the atmosphere, then a simple diffuser-type silencer will suffice. The disadvantage of these types of devices is that they can cause unacceptable back pressure. Therefore, when selecting a diffuser silencer, it is important that the pressure-loss constraints for the particular application be satisfied. Diffuser silencers can provide 15-30 dB of noise reduction.
Another source treatment involves using alternative equipment or materials that are inherently quieter yet still meet the production needs. This option is called substitution for the source. Often, equipment manufacturers have alternative devices that perform the same function at lower noise levels. These quieter devices typically cost more, however, as they require tighter tolerances and more precision as they are manufactured. Therefore, when applicable, it will be necessary for the user to determine if the noise reduction benefit justifies the additional cost. The supplier's or the manufacturer's website should be consulted to learn if quieter equipment is available and at what additional cost. Examples where alternative and quieter equipment may exist include:
There might also be opportunities to replace equipment with different devices or materials. Here, the user should investigate whether alternative and quieter ways exist to accomplish the task or intended service. Where practical, examples of source substitution include:
Keep in mind that adding sound absorption to decrease the reflected or reverberant noise in a room will do nothing to reduce the acoustical energy propagating by direct line of sight from the source. Therefore, it is helpful for the user to estimate what portion of a worker's noise exposure comes from the direct sound field and what percentage results from reverberant sound. When reverberant noise is a major contributor to a worker's daily noise exposure, then adding sound-absorbing materials may be beneficial.
A user must understand and apply the principles of room acoustics when adding sound-absorbing materials to the walls and ceiling to reduce the noise levels throughout the room. If a user installs sound absorption in a room without putting any science behind the decision, then the likelihood of success will be tenuous at best.
The acoustical enclosure is the most common path of treatment. Quite often enclosures are used to address multiple noise sources all at once or when there are no feasible control measures for the source. However, there are a number of advantages and disadvantages associated with solid enclosures (no acoustical leaks) that must be considered by the user.
The noise reduction provided by a barrier is a direct function of its relative location to the source and receiver, its effective dimensions, and the frequency spectrum of the noise source. The practical limits of barrier attenuation will range from 15 to 20 dB. For additional details on calculating barrier insertion loss or attenuation, the user should review some of the references, particularly The Noise Manual (AIHA, 2003; or latest edition). Recommendations for acoustical barrier design and location to maximize noise reduction capabilities include:
Earmuffs are another type of hearing protector (Figure 11). They come in a variety of sizes, shapes, and materials and are relatively easy to dispense, as they are one-size devices designed to fit nearly all adult users. Earmuffs are designed to cover the external ear and thus reduce the amount of sound reaching the inner ear. Care must be taken to ensure that the seal of the earmuff is not broken by safety glasses, facial hair, respirators, hard hats, or other equipment, as even a very small leak in the seal can destroy the effectiveness of the earmuff. Earmuffs should be chosen based on the frequency that needs to be reduced. Refer to the EPA label on the manufacturer's product. Earmuffs are a good choice for intermittent exposure, given how easy they are to put on and take off. Additionally, in cold environments, their warming effect is appreciated (OTM/Driscoll).
Confirm that you understand the procedures for calibrating each of the instruments you use. If in doubt, review instructions in each instrument's user's manual and consult CTC if questions arise. In general, as long as the sound level readout is within 0.2 dB of the known source (the calibrator output), it is suggested that no calibration adjustments be made. If large fluctuations (greater than 1 dB) in the level occur, then either the calibrator or the instrument may have a problem.
Additionally, confirm that you know how to change or charge the battery in both the calibrator and the instruments. If in doubt, review instructions in each instrument's user's manual. A low battery is the number-one cause of equipment failing pre- and post-use calibration. Changing the battery will often bring the equipment back into an acceptable calibration range immediately, but a little practice is needed to change the battery quickly on some equipment. Most rechargeable batteries cannot be changed in the field so it is even more important their charge status is known and changed as necessary prior to instrument usage. Rechargeable batteries that can no longer be recharged must be replaced by CTC or the manufacturer. Be prepared, so that a low battery doesn't slow you down during an early morning calibration session (Figure 15).
Whether detachable or integrated into a sound level meter, an octave band analyzer receives its daily calibration in conjunction with the sound level meter with which it will be used. This might involve activating an additional setting during the daily meter calibration. Consult the user's manual for the equipment you will be using.
Some octave band analyzers can be set to automatic function (i.e., the instrument automatically checks the sound level of each frequency band and stores the results). Other instruments require the user to manually switch between the different frequency bands, recording each reading in sequence.
Many of the newer model dosimeters feature Bluetooth connectivity with smartphone applications. These applications let the user control certain dosimeter functions (e.g., start and stop) and allow for remote viewing of the real-time measurement data.
When monitoring is complete at the end of the day, follow standard procedures for recording results from the instruments. If necessary, consult the instrument user's manual or contact CTC for assistance. Dosimeter output usually includes the TWA (normalized to 8 hours), the LAVG or LEQ representing the average dose for the period monitored, the percent dose, and the maximum or peak reading. Do not neglect to perform the post-use calibration check on each instrument.
Figure 27 shows that installing softer bends in the pipe and increasing the distance between the valves will reduce the turbulence in the line and, consequently, reduce the noise generated. This solution takes up more space and is often not possible in a process. However, it is sometimes possible in air ejection processes to reduce the required velocity of the air flowing from the nozzle by increasing the accuracy of the aim of the nozzle. Often, large pressure drops across valves, which cause noise, can be prevented with in-line diffuser silencers, which reduce the pressure upstream of the valve. Installing a muffler on the end of the nozzle is another option. All these methods can help reduce noise from compressed air sources. For additional information see Appendix J.
If you are a Siemens PLC user then you've more then likely have run into Statement List (STL) programming. STL corresponds to the Instruction List language defined in the IEC 61131-3 specification. The programming is done with very simple mnemonics that can be hard to remember if you don't use it very often. 2b1af7f3a8