Test interval

Soufc. No. of failures No. of demands or service time Test interval No. of maintenances No. of dependent failures Failure rate Failures/ demand Repair lime... 

LOW FAILURE RATES MEDIAN UPPER AVERAGE REPAIR TEST INTERVAL REFERENCE SOURCE... 

Evaluation of Diesel Unavailability and Risk Effective Surveillance Test Intervals Nuclear DG test and accident unavailability for 10 operating years Diesel generators 97. 

This report presents an analysis of DG unavailability, caused both by failure occurring while the DG is on standby and test-caused failures. The report presents a methodology for determining testing intervals (TIs) so that diesel unavailability is at an acceptably low level. Sensitivity analyses of test unavailability to varying TIs are presented. 

Sample size and test intervals based on statistical criteria for each attribute examined to assure valid estimates of stability ... 

Carter, H. B., Epstein, J. I., Chen, D. W., et al. Recommended prostate-specific antigen testing intervals for the detection of curable prostate cancer. JAMA 227,1456-1460 (1997). 

Hydrostatic test pressure (TP) shall be limited to the pressure calculated per para. IP-10.7.2. The maximum testing interval shall be 10 years. Inline examination is normally applied to pipelines or buried piping specifically designed for this type of assessment and should be a requirement for piping systems only when the piping is specifically designed for inline examination. 

Flood JF, Smith GE, Gherkin A. (1988). Memory enhancement in mice role of drug dose and training-testing interval. Pharmacol Biochem Behav. 29(3) 635-39. 

Dosage Form Microbial Test Testing Plan Test Intervals ... 

Time intervals suggested in the 1998 FDA stability guide [5], More annual test intervals can be added if the expiration dating exceeds 36 months. 

Test Interval for the Component or System (hours or years)... 

The observation that the first order rate "constant" is not constant for the perturbation and relaxation test intervals leads to the conclusion that a simple first- order model is not sufficient to explain the behavior in this dynamically-perturbed system and another model should be proposed and tested. Often, the new models are in themselves more complex and require more information for verification than was originally collected. Thus, the direct approach may require the iteration of new experiments with additional sampling. 

Data on stability of the drug products should be presented for all testing intervals and evaluated with physical, chemical, and microbiological, microbial preservative effectiveness, antioxidant effectiveness, and functionality tests as appropriate to the... 

A sample size and test intervals for each attribute to be tested should be specified based on statistical rationale. 

The frequency of OQ/performance verification depends not only on the type of instrument and the stability of the performance parameters, but also on the acceptance criteria specified. In general, the time intervals should be selected such that the probability is high that all parameters are still within the operational specifications. Otherwise, analytical results obtained with that particular instrument are questionable. The OQ/performance verification history of the type of instrument can be used to set reasonable test intervals. Here the importance of proper selection of the procedures and acceptance limits becomes very apparent. 

Centers usually adapt company-wide guidelines to activities within their scope. For example, the S/B (styrene/butadiene) Latex Technology Center has developed a Critical Instruments Program specifically for Dow s latex plants around the world. In identifies typical latex production equipment likely to be controlled by critical instruments. The program then draws upon Dow (and non-Dow) latex and other plant and research knowledge and experience to propose test procedures and test intervals for such instruments. 

Fig. 10. Determining test interval for critical instruments. Example of tanker off loading which is operator supervised. The tank has a local level indicator (LI) and separate level alarm (LA) and level switch (LSW). Offloading is performed 10 times per year, (x) is the number of operations per year. Probability of overfill equals l(T4(x). Proposed target is less than or equal to 3 x 10 5. Testing interval 10-4(x) < 3 xl0 5(x) 3 x 10 1 = 4 months. Note that if only one tanker is offloaded per year, it is better to check LSW prior to offloading.

Establish test methods, test intervals, sampling, and accept/reject criteria. This point is critical for the success of the validation. The team must be careful to ascertain that... 

Assume that a waterworks is able to maintain water quality without problems if the actual Zn concentration is within a tolerance Ax = 10 qg L 1 around /r0 = 190 pg L 1. Is it acceptable to continue monitoring water quality by drawing n = 10 samples at each test interval Because we further assume that incorrect decisions about Zn have no dramatic effects we... 

Increase the frequency of testing (i.e., number of test intervals) to determine whether or not the aberrant result is part of a new trend. 

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