Beta factor method

This method as superseded by the beta factor method which also lacks a physical basis. 

Example of the Beta-Factor Method Emergency Electric Power... 

The fault tree for the undesired event filling level too high is shown in Fig. 9.50. High levels can be initiated by the faUure of the activation of control valve RV by LICAl and LICA2, the failure of the control valve RV itself or the failure of instrument air. Further potential causes are that LICAl and L1CA2 remain in their positions for functional tests after inspection or a CCF of both level measurements. The latter is treated using the Beta Factor Method with 6 = 0.1. 

Common-cause failures can be safe, dangerous, detected, or undetected. Those common-cause failures that exhibit random behavior are typically modeled using the beta factor method. (Refer to ISA-... 

Hence both the SIL and Beta factor methods have underlying philosophical concerns. The SIL approach uses unveriflable judgments about the relationship between system reliability and quality control techniques and measures, whereas the Beta factor approach draws unveriflable correlations between single-channel failure rates and common-mode failure rates. 

Bochkarev AV, Trefilova AN, Tsurkov NA, Klinskii GD (2003) Calculations of beta-factors by ab initio quantum-chemical methods. Russian J Phys Chem 77 622-626 Bode BM, Gordon MS (1998) MacMolPlt a graphical user interface for GAMESS. J Mol Graphics and Modeling 16 133-138... 

CCF probability can be estimated which include the use of operating experience data and theoretical models such as the beta factor and multiple Greek letter methods. 

The main purpose of the literature review was to investigate the state of the art for methods for determining model parameters of CCF models. Very comprehensive approaches like what is used in the nuclear power industry to support multiple-Greek letter CCF models, see e.g., NUREG/CR-5485 (1998) and NUREG/CR-6268 (2007), have not been studied in detail in this paper. Instead, the focus has been on identifying methods available for determining the P in the beta factor model, and on the definitions of CCF that may be useful as assistance in the analysis and classification of failures reported for safety-critical components. Literature referenced in a study by Rausand and Hokstad (2008) has been key for the review. 

The risk classification method in accordance with lEC 62061 is of general validity, and not only restricted to electrical control systems. Therefore, it can also be apphed to mechatronic control chains as ISO 13849-1 regards them. The requirement for a SF made of mechatronic components can thus be defined either with the informative decision tree, (wrongly called risk graph ) of ISO 13849-1, or with a risk classification in accordance with lEC 62061. Other parts of lEC 62061 however, for example the beta factors estimation for common cause failures, are not useable, when hydrauhc and pneumatic systems are used. 

Plant specific data for common cause phenomena are scarce therefore, industry wide data and compilations of generic data must be used to quantify common cause failure probabilities. One method of common cause probability estimation involves the use of so-called beta factors that are estimated from such industry wide data. A beta factor is the conditional probability of a component failure given that a similar component has failed. Typical values for beta factors range between 0.01 and 0.1, depending upon the type of component involved. 

The higher reactivity of 1-butanol gamma site [87] is in line with the results of Wallington and Kurylo [90] who have proven that in ketones there is a significant enhancement of the group reactivity toward OH for both CH3 and CH2 when moved from the alpha to beta positions. This has been taking into account in the Structure-Activity Relationship (SAR) method [91,92] by factors of F[-CH2C(0)] = f [>CHC(0)] = f [>CC(0)] = 3.9 [22]. In this improved version of... 

The method of zeolite synthesis, the Si/Al ratio in the synthesis gel, and the crystallite size of Beta zeolite are factors to be considered for optimum alkylation performance [123,128,129[. For both USY and Beta zeolites, the amount and type of extraframework Al species (EFAL) remaining in the zeolite after calcination and/or post-synthesis treatments also affected the catalyst performance [130,131], For both zeolites, elimination of highly dispersed cationic-type EFAL formed under mild (hydro)thermal treatments decreased the alkylation... 

In addition to the effect on the product selectivity, it is seen in Table 3 that, for a given synthetic method, the activity (1-hexene and H202 conversion) as well as the selectivity of H202 increases as the A1 content of the zeolite decreases. These results show that the A1 content of zeolite Ti-Beta is one of the most important factors in determining its activity and selectivity in oxidation reactions, and the benefits that the new methods of synthesizing Ti-Beta with low A1 content can provide. 

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