NAFA Guide To Air Filtration Fifth Edition Chapter 13 Owning and Operating Costs presented by the National Air Filtration Association

Owning and Operating Costs An owning and operating cost study should be conducted when comparing…. Two systems that provide equal performance (apples to apples)

Owning and Operating Costs Annual operating costs include: Materials (including freight in) Warehouse, Storage and Shrinkage Labor to remove/install Electric power Disposal and other miscellaneous charges

Owning and Operating Costs As outlined by NAFA, an owning and operating cost for new or retrofit systems comparison should include… First cost of equipment Installation cost Electrical and/or plumbing Initial filter cost and filter installation costs Misc. such as gasketing, etc.

Owning and Operating Costs The major operating cost of a filter system is… Energy required to overcome filter resistance? First Cost? 81% 18.5% 0.5% Carlsson, Thomas; “Indoor Air Filtration: Why Use Polymer Based Filter Media”, Filtration+Separation, Volume 38 #2, March 2001, pp 30-32.

Owning and Operating Costs Electrical usage in a system is measured in watts and charged per 1000 watts – one kilowatt hour (kwh) The actual power is the theoretical power adjusted for the efficiency of the fan, drive and motor. kWa = kWt (fan x drive x motor efficiency)

Factors Affecting Filter Life Particle size distribution Negative effect on panel filters – surface loading Positive effect on extended surface filters – increased bed depth

Factors Affecting Filter Life 2. Underrating/Overrating Underrating increases filter life more than directly proportional to the percent of underrating Double effect with extended surface filters: A. Reduces pressure drop B. Reduces the rate of pressure drop increase

Factors Affecting Filter Life Underrating/Overrating (continued) Underrating may reduce the efficiency of a panel filter because the reduced velocity decreases the impingement process

Optimum Final Pressure Drop The point where the sum of power costs and filter costs is at a minimum Total Cost Power Cost per Hour Filter Life Time Final Pressure Drop

Total Cost Total annual cost equals: the sum of all first costs that can be depreciated plus the sum of the annual operating costs

Sample Questions What percent of the total cost of a filter is energy costs? 81% Fan efficiency, Drive efficiency and Motor efficiency calculate into what cost? Energy cost Underrating a filter may have the unintended consequence of? Changing the efficiency curve Running filters to their maximum pressure drop may? Cost more in energy than the cost to change it sooner

Thank you. Other Questions?