Operational correctness

Analytical chemists make a distinction between calibration and standardization. Calibration ensures that the equipment or instrument used to measure the signal is operating correctly by using a standard known to produce an exact signal. Balances, for example, are calibrated using a standard weight whose mass can be traced to the internationally accepted platinum-iridium prototype kilogram. 

Operation When operated correctly, thickeners require a minimum of attention and, if the feed characteristics do not change radically, can be expected to maintain design performance consistently. In this regard, it is usually desirable to monitor feed and underflow rates and sonds concentrations, flocculant dosage rate, and pulp interface level, preferably with dependable instrumentation systems. Process variations are then easily handled by changing the principal operating controls—underflow rate and floccirlant dose—to maintain stability. 

Observe the pump operation for a short time after starting to make sure it is operating correctly. 

As long as pressure, level, and temperature control devices are operating correctly, the safety system is not needed. If the control system malfunctions, then pressure, level, and temperature safety switches sense the problem so the inflow can be shut off. If the control system fails and the safety switches don t work, then relief valves are needed to protect against overpressure. Relief valves are essential because safety switches do fail or can be bypassed for operational reasons. Also, even when safety switches operate correctly, shutdown valves take time to operate, and there may be pressure stored in upstream vessels that can overpressure downstream equipment while the system is shutting down. Relief valves are an essential element in the facility safety system. 

Section 5.4.1 discussed the need for nitrogen blanketing. However, if it is to be effective, it must be designed and operated correctly. 

The impact of the system design on human performance should be examined during this phase. The designer should consider whether or not the operator will be able to keep the system operating correctly under normal conditions and is he or she able to effectively handle unusual conditions, returning them to normal operating conditions. Observation of persormel and discussions with them are effective ways that should be employed in this phase. Where necessary, appropriate modifications should be made to the system to ensure proper performance. 

Reliability is generally understood to measure the degree of certainty that a piece of equipment will perform as intended. Relays, in contrast with most other equipment, have two alternative ways in which they can be unreliable. They may tail to operate when they are expected to, or they may operate when they are not expected to. This leads to the two-pronged definition of dependability, the measure of certainty that the relays will operate correctly for all faults for which they are designed to operate and security, the measure of certainty that the relays will not operate incorrectly for any fault. 

Tests carried out on protection systems comprise factory tests, on-site commissioning tests and maintenance checks. Those made on individual relays will demonstrate the compliance of the equipment with specification and the verification of its operation under simulated conditions, while tests carried out on-site prior to the equipment being put into service ensure that the full protection scheme and associated equipment operate correctly. These on-site tests must be comprehensive and should include ... 

Electrical supply systems and equipment are grounded in order to maintain the voltage at any part of the system at a known potential relative to true earth and to provide a path for current flow under earth fault conditions so that protective devices operate correctly. The connection to earth should be such that the flow of fault current to earth does not cause voltages or voltage gradients to be of sufficient magnitude or duration likely to cause danger. 

The resistance of the system to earth must be low enough to ensure that earth fault protection equipment operates correctly. 

After any maintenance work involving replacement or adjustment of components it is essential that the plant be re-commissioned in a safe way, including dry mns with the gas turned off to ensure that flame failure devices operate correctly and pilot turndown tests to ensure that if the pilot can energize the flame detector then it can also smoothly ignite the main burner. 

When initially commissioned all safety devices should be proved to be operating correctly. At intervals, these should be checked to ensure that no undetected failure has taken place. Checks that are necessary include ... 

Make no excuse for checking whether the sun shines on the thermostats or someone has washed the floor. Another common occurrence is that while the room is not being controlled as specified, the plant appears to be operating correctly. Here a series of simultaneous readings of air flows and wet and dry bulb temperatures should be taken around the whole of the air circuit - on and off coil, condition after fan, condition at inlet grilles, etc. Referring these to a psychrometric chart will usually indicate where the fault or leak lies. 

Energy management systems can vary in cost from low to high ( 100,000- 200,000) for the system itself. In addition, energy controls may have to be provided either to replace existing controls which are not compatible or which are not operating correctly or have never been provided in the past. 

The shaking and continuous filters are regenerative, but there is a third group usually associated with ventilation work rather than dust and fume. These are throwaway filters, which, as the name implies, means that when they become too caked with dust to operate correctly the filters are removed and replaced with new ones. They will only handle low incoming dust burdens, but their efficiencies are the highest of any filter. Typical applications are fresh air input plants, clean-room filtration and nuclear processes. 

Since cathodic protection, if operated correctly, can prevent the corrosion of a metal entirely, it is unique amongst all the methods of corrosion control. 

Post-column on-line derivatisation is carried out in a special reactor situated between the column and detector. A feature of this technique is that the derivatisation reaction need not go to completion provided it can be made reproducible. The reaction, however, needs to be fairly rapid at moderate temperatures and there should be no detector response to any excess reagent present. Clearly an advantage of post-column derivatisation is that ideally the separation and detection processes can be optimised separately. A problem which may arise, however, is that the most suitable eluant for the chromatographic separation rarely provides an ideal reaction medium for derivatisation this is particularly true for electrochemical detectors which operate correctly only within a limited range of pH, ionic strength and aqueous solvent composition. 

Corrosion anywhere within the steam-water circuits results in metal wastage and possible equipment failure. And if the boiler plant is not operated correctly or if the water chemistry is not maintained within certain control parameters, the generated steam may contain contaminants in a cause-and-effect process that ultimately affects the utilization of the steam, reducing quality in a number of areas, and increasing fuel, manufacturing, or maintenance costs. 

Hamiltonian operators, correction for parametric model for actinide... 

The impact operator corrected in such a way still remains semiclassical though the requirements of detailed balance are satisfied. It is reasonable provided that the change of rotational energy is small on average, relative to translational energy ey — ej < ikT, where the overbar means averaging performed over the distribution of products after collision. 

SRM 2391 is designed to provide quality assurance to laboratories that perform DNA profiling using PCR methods. This SRM can be used to verify that each step of the analysis system is operating correctly and within the proper limits. 

Equation (96) shows that the effective KS potential may be simply obtained by adding to the standard KS potential of the isolated solute, an electrostatic correction which turns out to be the RE potential Or, and the exchange- correlation correction 8vxc. It is worth mentioning here, that Eq (96) is formally equivalent to the effective Fock operator correction bfteffi defined in the context of the self consistent reaction field (SCRF) theory [2,3,14] within the HF theory, the exchange contribution is exactly self-contained in Or, whereas correlation effects are completely neglected. As a result, within the HF theory 8v = Or, as expected. 

After recovery of the EDC, the vent gas contains both oxygen and fuels (ethane and uncondensed EDC) that would be a flammable mixture and a serious safety hazard if the plant were not designed and operated correctly. 

The capability of dragging results from one cell to others is a very useful property of Excel and becomes even more powerful in combination with the dollar operator ( ) correctly applied within the cell reference. Referring to the previous Matlab example, if the scalar element foi,2 (cell F3) is to be subtracted from matrix A (A3 C4) in Excel, putting the dollar operator ( ) in front of the column and row reference of the source cell containing the scalar foi,2 ( F 3), prevents "dragging-over" of the source cell F3 in both column and row direction. 

An earlier Fortran version of SIMCA is available for use in the ARTHUR package available from Chemical Information Systems, Box 2227, Falls Church, VA. Recently, the operating system was changed on the CDC Cyber computer system at the University of Illinois. The new operating system does not allow the earlier SIMCA-2T version used to perform the environmental analyses to operate correctly. The authors expect that a new version of SIMCA will be installed that will function with the current operating system in use on the CDC Cyber computer. 

Robustness does the detection system continue to operate correctly in adverse conditions ... 

It is crncial that all mass-rednction equipment is operated correctly. There are a number of very practical rules to be followed when nsing any of the acceptable devices. Neglecting one or more of these will canse the entire mass redaction to be biased, and result in unnecessarily large variation. Although Petersen and colleagues [6] on the snrface primarily deal with stand-alone, laboratory bench type equipment, the principles derived must apply equally well for any type of on-/at- or in-line mass reduction that can be contemplated in the PAT context. 

The system must be provided with the environment it needs to operate correctly. This requirement applies to all environmental factors that might impact data loss, such as proper... 

Calculation of the nonlogarithmic polarization operator contributions of order a Za) Ep goes exactly like calculation of the respective corrections of order a Za) Ep and is connected with the same diagrams. In fact both logarithmic and nonlogarithmic polarization operator corrections of orders a Za) Ep and a Za) Ep were obtained in one and the same calculation in [55]. Nonlogarithmic corrections of order a Za) Ep have the form... 

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