Sizing and Configuration

Sizing

How to correctly measure filters and understand the difference between exact and nominal sizing

Custom Filters

How to order a custom filter correctly

MERV Ratings

How the MERV rating system is used to measure the efficiency of a filter

Header Configuration

How to identify whether your box filter has a header, and the configuration of the header

Pocket-Bag Filter Configuration

What information is required to correctly order a Pocket-Bag Filter

Cartridge filter Sizing and Configuration

What information is required to correctly order a Cartridge Filter

Sizing

In order to receive the correct filters, it is important to provide us with the exact size.

We need to know the exact length, width and thickness of your filter, in order to provide an accurate quote and provide a filter that will fit your housing.

Exact Sizing vs Nominal Sizing

Exact sizing can be found by measuring your filters length, width and depth dimensions.

  • However, the standard convention is that filters are listed by the size of the housing they fit into, not the size of the filter.

  • The filters themselves are usually slightly smaller than the size written on them. For standard filters sizes, the Nominal Size is often labelled on the side or outer frame of the filter.

For most standard filters, it is sufficient to know the Nominal Size. For 5” filters and custom filters, please see the “Custom Filters” section, below.

 
 

Custom Filters

One of our specialties at Taff-Guard Filtration is providing custom-sized filters to customers without an excessive waiting period.

  • Before inquiring about a custom filter, it is important to measure the exact length, width and thickness dimensions, as shown on the right.

  • The filter might have dimensions written on it (nominal sizing), but it is common for these numbers to be slightly different from the exact measurements.

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Pleated and Throwaway Filters

Our production facility is equipped to resize frames from pleated and throwaway filters to any length and width required.

  • For pleated and throwaway filters larger that 30” on any one side, it will be necessary to make two filters and bond them together using special adhesives.

  • This is necessary to ensure the filter will not be too weak to support itself.

  • This is called a “two-piece filter.” The filter to the right is an example of this..

High Efficiency Filters

We are able to provide high efficiency filters, such as pocket filters, rigid cells, mini-pleats and many others, in custom sizes.

  • For quotes or orders on High Efficiency filters we will need to know the efficiency of your filter and whether it has one, two or no headers.

  • These types of custom filters often have longer lead times than other filters, so please inquire well in advance.

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two piece FILTER

Filter frames bonded together to achieve large custom sizes

MERV Ratings

MERV stands for Minimum Efficiency Reporting Value. It is a rating system created by the American Society of Heating Refrigeration and Air conditioning Engineers (ASHRAE). The current standard for MERV rating comes from the ANSI/ASHRAE 52.2 standard.

  • Some filters are not MERV-rated. To be MERV-rated, a filter must go through a particular test of performance.

  • Most media, throwaway filters, washable filters and other low-efficiency filters perform approximately at the level of MERV 3-4, but have not be tested for a MERV rating.

  • By clicking the button below, you can download an explanation of each MERV rating, examples what sort of particles a filter of each rating can collect, and examples of filters commonly available in each MERV rating.

 
 

Header Configuration

Rigid cell type filters can be made with or without a header around the outside.

  • Here, we can see the three most common header configurations: Box Style, with no header; Double Header, with a header on both the air leaving and air entering sides; and Single Header, with one header, usually around the air entering side.

  • Single and Double Header filters can both be used in side-access systems, where the filter is installed with the side of the frame first and the header can slide into a track, which holds the filter in place.

  • Box Style and Double Header filters can be used with face-loading systems, where the filter is installed air leaving or air entering side first.

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Pocket Filter Configuration

Pocket filters are installed in a similar fashion to single-header rigid cell filters.

  • When measuring a pocket filter, measure the length and width of the metal frame, and the depth of the pouches.

  • You should also count the number of pouches, and note if they have any special attachments, such as loops, to hold the pouches in place.

  • Standard lengths and widths for pocket filters are 24x24, 12x24, 20x24 and 20x20.

  • For any other sizes, you must specify which side the pouches are attached to.

  • For example, if you were to measure the filter in the picture, left, suppose you found the D was 18”, the L was 20” and the W was 14”. You would inform us that the pouches are attached to the 20” side.

  • In the example picture, the filter has eight pouches.

Pocket filters are available with synthetic and fiberglass media. If you are unsure which is better for your application, please ask.

Cartridge Filter Sizing and Configuration

Cartridge filters are installed in a number of different ways. This means it is very important to ensure replacement filters are of the same size and configuration, so they will be compatible with your filter housing.

  • Sizing: There are three important dimensions to measure on any cartridge filter.

    • Outer Diameter, shown at OD in the picture, is the distance across the round side of the cartridge, measured from the very outside of the cartridge, directly across the filter.

    • Inner Diameter, shown at ID in the picture, is the distance across the opening in round end of the filter, taken from the inside edge and directly across the filter.

    • Length, shown at L in the picture, is the length of the cartridge, from top to bottom.

  • End Caps: There are three common configurations for the end caps of cartridge filters and one less common one. In all three of the common configurations, at least one side will be Open.

    • Open/Open: Both end caps are Open, leaving the center of the filter unobstructed.

    • Open/Closed: One end cap is open, the other closes off the opposite end.

    • Open/Closed with Bolt Hole: As Open/Closed, but with a bolt hole in the Closed end, to allow the cartridge to be bolted into position. Measure the size of this hole.

    • Flange: The less common configuration, features one conventional Closed end and has a rectangular metal flange around the opposite end, used to hold the cartridge in place. It is important to measure the size of this flange.

  • Media: Cartridge filters can be made with different media, such as nanofiber, polyester-paper blend or spunbond. It is important to know which type of media you need, or what your application requires, so we can recommend the correct media.

  • Outside: There will either be outer bands or an outer metal mesh on the outside of the media. Certain media are not able to be used with some outside configurations.

Once you have all the required sizing and configuration information, please feel free to CONTACT us for a quote