Question

Question 5: (a) For a compressor the probability of failure occurring during a given week is given in Table Q5(a) (i) Calculate the Annual Breakdown Maintenance Costs (where no Preventive Maintenance is carried out). The costs are 300 OMR to repair the compressor, every time it fails. (ii) Preventive maintenance costs 60 OMR for each service. Calculate if Preventive Maintenance is cheaper than Breakdown Maintenance, and if so how often Preventive Maintenance should b carried out. There are 48 working weeks in a year. [2 Table Q5(a) Probability of failure Week of Operation during the given week 1 2 3 4 0.00 0.08 0.17 0.35 0.40 un

Answer 1

(i) Calculation of Annual Breakdown Maintenance Costs Probability Breakdown OMR Week (A) Costs (B) (A) * (B) 0.00 300 0 2 0.08 300 24 3 0.17 300 51 4 0.35 300 105 5 0.40 300 120 Annual Breakdown Maintenance Costs OMR 300 1

OMR (ii) Comparison of Annual Breakdown Maintenance Costs & preventive costs Breakdown Costs Preventive Week (A) cost (B) (A) - (B) 0 60 -60 2 24 60 -36 3 51 60 -9 4 105 60 45 5 120 60 60 Benefit due to preventive costs OMRO 1

(ii) continued..

Preventive cost should be carried out in week 4 & week 5 because breakdown cost in week 4 & week 5 is more than preventive cost.

(ii) Benefit if preventive costs is carried out in only week 4 & week 5 Breakdown Costs Preventive OMR Week (A) cost (B) (A) - (B) 1 0 0 0 2 24 0 24 3 51 0 51 4 105 60 45 5 120 60 Benefit due to preventive costs OMR 180 60

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