Down time

The pulses of radiation are said to ring backwards and forwards between the mirrors and the time for the signal to decrease to 1/e of its original value is called the ring-down time of the cavity hence the name cavity ring-down spectroscopy. 

Figure 9.38 Cavity ring-down absorption spectrum of the 0-0 band of the a Ag-X Z system of O2, where k is the reciprocal of the ring-down time. (Reproduced, with permission, from Newman, S. M., Lane, I. C., Orr-Ewing, A. J., Newnham, D. A. and Ballard, J., J. Chem. Phys., 110, 10749, 1999)...

For chemical faciUties in the United States, hazard analysis is not an option if inventories of hazardous chemicals are maintained in amounts greater than the threshold quantities specified by the Occupational Safety and Health Administration (OSHA) regulation 1910.119. Many faciUties are finding that hazard analysis has many benefits. The process or procedure often works better, the quaUty of the product is improved, the process experiences less down time, and the employees feel more comfortable in the work environment after a hazard analysis has been completed. 

The pump-down time 0 for evacuating a vessel in the absence of air in-leakage is given approximately by... 

Costs of operations sueh as fuel eosts, labor eosts, down time eosts, overhaul hours, interest rates are neeessary in eomputing parameters sueh as time of major inspeetions, off-line eleaning, and overhauls. 

Figure 21-6. Contributions of various major components to gas turbine down time.

Quality and reliability are not free, but poor quality and reliability cost more than good quality (2]. Costs include excessive down time and asso-... 

Thus, by taking a series of readings during a trial heat-up, K can be determined. The heat-up and cool-down times for varying jacket temperatures can then be predicted. 

As a batch filtration proceeds, so the rate of filtrate collection decreases due to the increased cake thickness. While operation with thin filter cake results in a higher instantaneous filtration rate, however, it also requires more frequent dismantling of the filter and discharge of the filter cake. There is thus an optimum balance between filtration time and down time. 

Let the down time be t and assume that it is substantially independent of eake thiekness. The total time, T, of a eyele in whieh a volume V is eolleeted is then... 

Thus for the optimal operation of a bateh filter, the filtration time and the down time are equal. In praetiee t > t due to eloth resistanee, whieh is negleeted in this simple analysis. 

The major benefits that arise from the application of human factors principles to process operations are improved safety and reduced down time. In addition, the elimination of error has substantial potential benefits for both quality and productivity. There is now a considerable interest in applying quality management approaches in the CPI. Many of the major quality experts em-... 

The failure rates and times-to-restore developed used a variety of data sources and data construction methodologies and are presented in Section 2. The principal methodology used is a kind of failure mode analysis for each component several principle modes of failure are analyed by characteristics including frequency of occurence, repair time, start-up time, and shut-down time. From these an average failure rate is developed and expressed as failures per million hours and mean time between failure(MTBF). 

Maintenance cost and length of down time are higher than for centrifugal units. 

Always select the best bearing design for the application and not the cheapest. The cost of the original bearing is usually small by comparison to the costs of replacement components and the down-time in production when premature bearing failure occurs because an inappropriate bearing was used. 

The down time of the bioreactor is a significant portion of the total fermentation time. 

True. Batch cultures give lower overall outputs than continuous cultures, as they suffer from non-productive down-time (the time taken to empty, clean, re-sterilise and re-fill the fermentor). After inoculation, considerable time can be taken for biomass to build up to a level where substrates are effectively utilised. Continuous cultures do not suffer such drawbacks once they are in operation. 

A reasonable size of bioreactor, based on transport and handling considerations, is 200 m3, with a working volume of 150 m3. If file fermentation time is 48 hours and down time for reuse about 24 hours, then the total batch time is 72 hours. 

After some months of successful operation, the system began rejecting large amounts of incoming materials. Upon investigation, it was determined that the rejected materials were perfectly suitable for their intended use. It was also noticed that all of the rejected materials were provided by one particular supplier. Needless to say, that supplier wasn t too happy about the situation nor were the plant people particularly pleased at the excessive process down time due to lack of accepted feedstock. 

Installation arrangements, 351 Pump-down time, 380 Selection procedure, 374 Specification form, 377 Specifications, 373 Steam jet comparison, 356 Types of loads, 359 Ejectors, 346 Applications, 353 Barometric condenser, 249, 376 Booster, 370 Calculations Actual air capacity, 362 Air equivalent, 360... 

Pressure/vacuum, 435, 466 Vacuum systems, 343 Absolute pressure conversions, 363 Air inleakage, 366 Calculations, 366-375 Dissolved gases release, 368 Estimated air inleakage, table, 366 Evacuation time, 371 Maximum air leakage, chart, 367 Specific air inleakage rates, 368 Temperature approach, 375 Classifications, 343 Diagrams, 380 Pressure drop, 353 Pressure levels, 343, 352 Pressure terminology, 348 Pump down example, 381 Pump down time, 380 Thermal efficiency, 384 Valve codes, 26... 

Improve Catalyst Life and Steadiness. Regeneration or replacement of a catalyst is expensive both in direct cost and in lost production represented by the down time. Lowering the rate of deactivation of the catalyst whether by fouling, by sintering, or any other irreversible process will improve the economics of a process. 

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