The Right Way to Record Filter Dimensions for Multi-Site Reordering

When you manage filters across multiple buildings, plant rooms or tenancies, the hard part is often not the reorder itself, but knowing exactly which filter belongs where. A clear naming and measurement system makes it easier to find the right size quickly, avoid mix-ups and keep records usable when staff, contractors or tenants change.

The good news is that you do not need a complicated system. A consistent way to record dimensions, construction details and location tags is usually enough to keep multi-site reordering organised.

Start with a naming system that tells you where the filter lives

The fastest way to reduce confusion is to give each filter a site-specific name before you worry about part numbers or supplier codes.

A practical naming structure might include:

• •Building name or site code
• •Plant room, AHU, FCU or cassette reference
• •Level, tenancy or zone
• •Filter stage, if there is more than one filter in the unit
• •Size or product code, once confirmed

For example, a record might read in a simple internal style such as “Site B / Plant 2 / Level 4 / Pre-filter / 595 x 595 x 25”. The exact format matters less than using the same format everywhere.

If your portfolio already uses asset registers, align filter names with those records. The goal is for anyone in the organisation to be able to identify the filter by location without needing to guess.

Measure the filter the same way every time

A lot of ordering mistakes happen because people measure different parts of the filter frame, or record dimensions in a different order. Before you save a size, confirm the method and keep it consistent across every site.

If you are unsure how to measure a filter, use how to measure an air filter as a starting point.

When recording dimensions, note:

• •Length, width and depth, in that order
• •Whether the measurement is the nominal size or the actual frame size
• •The unit of measurement, usually millimetres
• •Any special frame features such as a lip, gasket, handle or header
• •The direction of airflow, if the design depends on it

A useful habit is to measure the filter itself and also photograph it in place. Photos can help later when comparing replacement options or checking whether a size refers to the outer frame, media pack or housing opening.

If you manage several similar sites, record whether the size is the exact measured size or the size shown on the old label. Older labels may use nominal sizing that does not match the visible frame perfectly.

Include the details that affect fit, not just the dimensions

Two filters can look similar and still be wrong for a unit if one has a different frame depth, seal type or media construction. A good record should capture the practical details that influence fit and function.

Useful fields to store in your register include:

• •Filter type, such as panel, pleated, bag, box, carbon or HEPA
• •Frame material, such as cardboard, galvanised steel, aluminium or plastic
• •Seal or gasket style
• •Number of pockets or pleats, where relevant
• •Brand or supplier reference, if known
• •Any special notes, such as terminal use, high dust loading or limited access

If you are dealing with higher-efficiency filters, keep the rating information exactly as marked on the product. MERV, EN 779 and ISO 16890 ratings do not convert directly, so avoid trying to “translate” one system into another. If the product is a HEPA filter, record the class as marked; H13 is at least 99.95% and H14 is at least 99.995% efficiency at the most penetrating particle size under EN 1822.

Build one shared register for all sites

A spreadsheet, asset register or maintenance platform can work well if it is used consistently. The main thing is to avoid scattered notes in emails, hand-written labels and different versions of the same file.

A simple register should let you search by:

• •Site
• •Plant room or tenancy
• •Equipment tag
• •Filter name
• •Size
• •Supplier reference
• •Last replacement date or inspection note
• •Current stock status

For multi-site teams, one of the most useful habits is to give each item a unique internal code. That code can sit beside the measured dimensions and supplier description, so you can find the same filter later even if the old label is faded or missing.

If you manage a larger portfolio, it can also help to separate “as fitted” records from “as ordered” records. The fitted size tells you what was in the unit at the time of inspection. The ordered size tells you what the supplier should supply next time. Keeping both avoids confusion when a unit has been modified or replaced.

Add inspection notes so reordering stays accurate

Filter records should be updated when there is a change in the system, not just when a filter is replaced. That keeps the register aligned with the actual equipment on site.

Record notes such as:

• •Access restrictions
• •Housing condition
• •Missing clips, damaged frames or bypass issues
• •Visible dust loading or moisture exposure
• •Whether pressure drop is monitored where gauges are fitted
• •Any change to the fan, housing or ductwork that could affect filter fit

Inspection frequency depends on the system, site conditions and dust load. Follow the filter and equipment manufacturer instructions and monitor pressure drop where gauges are fitted. If your building falls under mechanical ventilation requirements, check site needs against AS 1668.2:2024 with the mechanical services engineer or building owner.

If the application involves washable products, remember that some filters are designed to be washable - check the product instructions. Do not rely on the label alone if the filter has been in service for some time.

Make reordering easy for contractors and internal teams

The best record is one that another person can use without asking follow-up questions. When you send a reorder request, include enough detail for the supplier to match the filter without ambiguity.

A good reorder note might contain:

• •Site and room name
• •Equipment tag
• •Full measured dimensions
• •Filter type and rating, if known
• •Frame and seal details
• •Quantity required
• •Any photo or sketch reference

This is also the point where custom filters can save time if a unit has an unusual size or construction. If standard items do not match what is installed, consider custom air filters rather than forcing a near fit.

Where a site uses common stock items, storing the filter against the product code from our products can make future ordering straightforward. Where the site has multiple buildings, it can help to tag each item by tenancy or AHU so the right filter is sent to the right address.

Keep the system simple enough to be used every time

The right process is the one your team will actually maintain. A short, consistent naming format and a reliable measurement method will usually do more for accuracy than a complex database with too many fields.

Aim for a record that answers these questions at a glance:

• •Which site is it for?
• •Which unit or room does it fit?
• •What are the dimensions?
• •What type of filter is it?
• •What extra features matter for fit?
• •Is the record current?

If you already have a maintenance contractor, ask them to use the same naming convention when they inspect or replace filters. That way, your records stay aligned across internal teams, tenant requests and service visits.

Need help matching a filter size?

Total Air Filtration is a family-owned air filter manufacturer and supplier based in Hillcrest, Brisbane QLD, and we can help you identify, supply or make the right filter for your site records. Call 07 3800 3448 or request a quote.

If you are updating a portfolio register, you may also want to review filter servicing, commercial filter servicing or contact us for help with a specific site or tenancy.