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Frequently Asked Questions
How does ULPA differ from HEPA?
By efficiency at the most penetrating particle size.
Both are tested at that size.
ULPA achieves a higher figure there.
The difference is in what penetrates.
The capture mechanisms are the same.
The grade, not the principle, changes.
What does the higher grade cost?
Pressure drop, for the life of the installation.
Finer media and denser packing raise resistance.
Fan energy rises continuously.
In a retrofit the fan may not cope.
Air change rate then falls.
Check available static before substituting.
Which rooms genuinely need it?
A narrow set.
Critical semiconductor and microelectronics areas.
Certain pharmaceutical and biotechnology suites.
Specialised research facilities.
Theatres, general cleanrooms and laboratories do not.
HEPA is the appropriate grade for those.
Where are these filters usually damaged?
In transit and installation, not in service.
The media is fragile and a pinhole destroys the rating.
They should stay packaged until the last moment.
Installation needs people who have done it before.
Handling by the frame, never the face.
Most failures happen before first use.
Why is in-place testing essential?
Because the seal fails more often than the filter.
A perfect filter badly seated leaks.
Nothing downstream reveals it.
Scan testing checks the installed assembly.
It must be repeated after every change.
Record results as the acceptance evidence.
Does airflow direction matter?
Yes, and arrows are ignored surprisingly often.
Media and separators are directional.
Reversed installation reduces efficiency and life.
It can also collapse the pack.
Check the arrow before clamping.
Verify during any inspection.
How is life judged?
By pressure drop, and by testing.
Loading raises resistance predictably.
A change point is set at commissioning.
Scan testing may reveal a fault before that.
Pre-filtration extends life considerably.
Protecting them is cheaper than replacing them.