Tolerance limits

How Many Samples. A first step in deciding how many samples to collect is to divide what constitutes an overexposure by how much or how often an exposure can go over the exposure criteria limit before it is considered important. Given this quantification of importance it is then possible to calculate, using an assumed variabihty, how many samples are required to demonstrate just the significance of an important difference if one exists (5). This is the minimum number of samples required for each hypothesis test, but more samples are usually collected. In the usual tolerance limit type of testing where the criteria is not more than some fraction of predicted exceedances at some confidence level, increasing the number of samples does not increase confidence as much as in tests of means. Thus it works out that the incremental benefit above about seven samples is small. 

The trend for increasing viscosity with increased dose is shown in Eigure 18 for several petroleum oils (72). Eor many lubricant appHcations, a dose that gives a 25% increase in 40°C viscosity can be taken as a tolerance limit. Lower radiation absorption seldom changes the lubricant sufficiently to... 

Table 17. Radiation Tolerance Limits of Several Oil Types...

Cost. The color matcher should know any cost limitations. An important element affecting cost is the tolerance limits permitted in production. 

The tolerance limits of metal ions and foreign anions at the optimal conditions were investigated. 

Application of IP and NCS in conjunction with specification tolerance limits enables to substantiate acceptance criteria for linear regression metrological characteristics (residual standard deviation, correlation coefficient, y-intercept), accuracy and repeatability. Acceptance criteria for impurity influence (in spectrophotometric assay), solution stability and intermediate precision are substantiated as well. 

Table A13.. s also indicates the test results of the samples of the final discharge when the effluents are treated along similar lines as discussed later. The test results are well within the tolerable limits. The recommended tolerance levels are provided in Table A 13.6, Any constituent exceeding the prescribed limits must be properly treated before final discharge.

Effects of current passing through a human body and the body s tolerable limits 21/679... 

We discussed in Section 21.1.1 the maximum tolerable currents through a human body and their duration. The potential difference in a ground conductor at any point where a human body may come into contact with it during the course of a ground fault should be such that the resultant current through the human body will remain within these tolerable limits. 

This is Ihe maximum totich voltage of a grounding station that may occur under the worst sittiation (position 3. Figure 22.9). The design of the grounding station must ensure thtit in actual service this voltage does not exceed the permissible tolerable limits noted in Section 22.9.6. 

After the final designs are complete it is recommended that the actual touch (actual) and step voltage (actual) are rechecked for both power plant and switchyard areas separately, to ensure that they are within the tolerable limits as determined above. After the ground stations have been finally installed the actual step and touch voltages must be measured to verify the designs. 

Quality c ontrol for an existing installation where a proven quality must be maintained within given tolerance limits see section 5.1. 

The critical characteristic on each component was analysed, calculated from the analysis and the value obtained was plotted against the process capability indices, Cpk and Cp, for the characteristic in question. See Appendix V for descriptions of the 21 components analysed, including the values of Cp and Cp from the SPC data supplied. Note that some components studied have a zero process capability index. This is a default value given if the process capability index calculated from the SPC data had a mean outside either one of the tolerance limits, which was the case for some of the components submitted. Although it is recognized that negative process capability indices are used for the aim of process improvement, they have little use in the analyses here. A correlation between positive values (or values which are at least within the tolerance limits) will yield a more deterministic relationship between design capability and estimated process capability. 

The variability or spread of the data does not always take the form of the true Normal distribution of course. There can be skewness in the shape of the distribution curve, this means the distribution is not symmetrical, leading to the distribution appearing lopsided . However, the approach is adequate for distributions which are fairly symmetrical about the tolerance limits. But what about when the distribution mean is not symmetrical about the tolerance limits A second index, Cp, is used to accommodate this shift or drift in the process. It has been estimated that over a very large number of lots produced, the mean could expect to drift about 1.5cr (standard deviations) from the target value or the centre of the tolerance limits and is caused by some problem in the process, for example tooling settings have been altered or a new supplier for the material being processed. 

By using the nearest tolerance limit, which is the tolerance limit physically closest to the distribution mean, the worst case scenario is being used ensuring that overopti-mistic values of process capability are not employed. In Figure 3, a — 1.5cr shift is shown from the target value for a Cp =1.5. Cp is a much more valuable tool than Cp because it can be applied accurately to shifted distributions. As a large percentage of distributions are shifted, Cp is limited in its usefulness. If is applied to a non-shifted Normal distribution, by the nature of its formula it reverts to Cp. 

The principal function of a thrust bearing is to resist the thrust unbalance developed within the working elements of a turbomachine and to maintain the rotor position within tolerable limits. 

FINAL RESULTS SATISFYING TOLERANCE LIMIT IN THE C F.S.T.R. TRAINS ARE ... 

TABLE 12.12.1 Emergency Tolerance Limits for UDMH VaporVersus Exposure Time... 

In general, a reflected shock wave of 55 psi on a human for 400 milliseconds would be just about the tolerance limit [41] (see Table 7-25B). For a more detailed discussion of blast scaling and overpressure, see Ref [40]. 

Diameter of Ropes and Tolerance Limits. The diameter of a wire rope shall be tbe diameter of a circumscribing circle and shall be measured at least 5 ft (1.52 m) from properly seized end with a suitable caliper (see Figure 4-65). The diameter tolerance of wire rope shall be... 

Diameter of Wire and Tolerance Limits. In separating the wire rope for gaging of wire, care must be taken to separate the various sizes of wire composing the different layers of bright (uncoated), drawn-galvanized, or galvanized wires in the strand. In like-positioned wires total variations of wire diameters shall not exceed the values of Table 4-24. 

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