AIR FILTERS TECHNICAL SECTION - Technical Issues

AIR FILTER OWNING AND OPERATING COSTS

When looking at the cost of an air filter, most people only consider the purchase price. They often think that this is either the only consideration, or at least the main consideration.  This is, however not the case.  According to Engineered System (USA) " On average, energy costs account for an astounding 81 percent of the total life-cycle costs of a filter system".   This of course means that the purchase price of the filter is often less than 15 percent of the total cost of owning that filter.  On top of this, the cheaper filter is often far more expensive in both direct costs, such as energy costs, and indirect costs such as more regular coil cleaning and machinery breakdown, not to mention the increased health risks that the air may pose to those people that are breathing it.

Costs associated with air filtration can be considered in three main parts: The initial cost, the operating costs, and the replacement costs. Unfortunately, most users in this country only consider the initial or the replacement costs when selecting an appropriate filtration system for their needs and often ignore the most significant costs, which are the operating costs.

INITIAL COSTS

The initial costs include those for the original equipment – the filter holding/housing systems, the purchase of the filters and any auxiliary equipment – and the usual direct and indirect costs that can be associated with installing a new filter system such as any labour costs used in the installation, supply, delivery costs etc. as well as any production that may be lost whilst the system is being installed.

OPERATING COSTS

Annual operating costs include the cost of any labour required to maintain the system as well as the cost to replace any of the filters. It also includes the ongoing energy costs required to get the air through the filters.

REPLACEMENT COSTS

An important part of the replacement costs of the filter system relates to its estimated life expectancy. The longer the system lasts, the costs per operating hour decreases.

AIR FILTER LIFE

An air filter's life can be estimated by considering the following:

The life in hours is directly proportional to the dust holding capacity of the air filter divided by the concentration of dust in the air stream multiplied by the air flow rate multiplied by the arrestance of the filter.

All this means, is that if you increase either the volume of air passed through the filter, or the concentration of dust in the air stream, or the arrestance of the filter then the filter life will decrease.

Conversely, as the filter’s dust holding capacity increases, so does its life.

ENERGY COSTS

Energy costs are often overlooked when selecting air filters, but they are often the most expensive part of owning and operating a system. These costs are directly proportional to the resistance to airflow that the filter has. As the resistance increases so does the energy required to overcome it.

OPTIMUM FINAL PRESSURE DROP

In life cycle costing, air filter life is important. The longer a filter is in use, the greater the resistance to airflow will be, and conversely, the lower the filter cost per unit time will be. However, running the filter to its maximum rated pressure drop may be significantly more costly than changing it out sooner due to the increase in energy costs required to overcome the pressure drop through the filter may be higher than the savings in extending the filter life.

Remember that the total costs of the air filters are a combination of both the purchase and fitting costs amortized over the time of operation, plus the energy required to put the air through the filter. This can be seen graphically below.

Figure 1 – Optimum Final Pressure Drop (Source: NAFA Guide to air filtration 2001)

Also please contact your nearest Peregrine Industries distributor who has the use of the unique “Total Filter Cost” calculator. This tool provides a useful means of comparing life cycle costs of up to four filters or the ability to look at multistage filtration systems.

For assistance in selecting an appropriate air filter type to meet your requirements please refer to Peregrine Industries “Filter Selection Chart” or contact your local Peregrine Industries distributor, or contact us through our contact page on our website.

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