Industral Engineer, Iran University of science and technology
The techniques and methods of developing cost models for respirators are discussed. Models are developed and implemented in this study for nineteen types of respirators in two major classes (air-purifying and supplied-air) and one LEV system. One respirator model is selected for detailed discussion from among the twenty models. The technical cost method is used in constructing the cost models for each of the respirators and the LEV system. In this methodology, the costs of purchasing and using a typical respirator or LEV system are divided into two categories, variable costs and fixed cost s. Variable costs consist of the cost of replaceable components and probabilistic mortality cost. Fixed cost is the annualized capital requirement plus interest cost. The criteria for estimating some of the cost elements are based on existing equations in the literature, engineering judgement and manufacturer-provided information. A technical cost model results from the integration of this information into a computerized framework. The cost models for discussion are presented in the order of increasing computational complexity. Through the economic analysis, the lowest cost type in each class of respirator is determined. The determination criteria are based on the minimum total annual cost and highest benefit cost ratio. The selected lowest cost respirators are compored with the LEV system from the economic standpoint to reveal the cost optimal alternative.