Overview
First-stage pleated pre-filter, 1" × 18" × 18". Phoenix part number 4031877.
It is the first filter the air meets in a Guardian R air scrubber, and its job is to protect the HEPA filter behind it.
What it fits
- Phoenix Guardian R air scrubber — named as item 1 in the Guardian R Pro 50 Hz service parts list, Air Filter, Pleated, 1" × 18" × 18"
- Climate Rental Solutions AAS800 air scrubber — its owner's manual specifies a first stage of 1" pleated media, 18" × 18". See the note below.
The filter stack, and why the order matters
The Guardian R runs a staged filter arrangement:
- Stage 1 — pre-filter 4031877, 1" × 18" × 18" pleated. This part.
- Stage 2 (optional) — carbon / potassium permanganate filter 4031878, for odour and gas-phase work.
- Stage 3 — HEPA filter 4031864, 2.5" × 18" × 18", 99.97% efficient, held by clip 4031863.
The economics of this are the whole point. The pre-filter is a fraction of the price of the HEPA. Every gram of bulk material the pre-filter catches is a gram that never reaches the HEPA, and a HEPA filter that is changed on schedule instead of prematurely pays for a great many pre-filters.
Running a Guardian R without a pre-filter, or with one that is long past its useful life, is a false economy that shows up as an expensive HEPA change.
When to change it
Change the pre-filter often. On fire, soot or demolition work that can mean daily. On general water damage work, between jobs is a reasonable baseline.
The signs are straightforward: visible loading, a drop in airflow at the discharge, or the machine sounding like it is working harder at the same speed setting.
Do not wash it. Pleated media does not recover.
Other machines that take a 1" × 18" × 18" pleated filter
The 500 CFM two-stage HEPA air scrubber is a widely rebadged platform, and several machines sold in Australia use the same first-stage filter size.
The Climate Rental Solutions AAS800 is one. Its owner's manual lists the first stage as 1" pleated media, 18" × 18", the optional media as 1" carbon and potassium permanganate, and the second stage as a 2.5" pleated HEPA, 18" × 18" — the same three sizes as the Guardian R. The AAS800 manual also still carries "Guardian R" references in its own body text, which is a fair indication of where the design came from.
Filters are sized to the machine, not to the badge on it. If your air scrubber takes a 1" × 18" × 18" pleated pre-filter, this is the part. If you are not certain, measure the old filter or send us a photo of it and we will confirm before you order.
Related parts
- HEPA Filter (4031864)
- Carbon / Potassium Permanganate Filter (4031878)
- Round Filter Cover for Guardian R (4032968)
Frequently asked questions
Does it replace the HEPA filter?
No. It protects it. Both are fitted.
How often should I change it?
As often as the work demands — daily on soot and demolition, between jobs on general water damage.
Can I run two pre-filters for extra protection?
No. Doubling up restricts airflow, and airflow is what an air scrubber does.
Can I wash it?
No.
Running Guardian R units? Tell us how many and what work they do and we will help you set a sensible filter stock level.
