What's measured
Static pressure is one of the most useful numbers on an LEV system because it is quick to read and it moves the moment something changes. Taken at the right points, it exposes a blocked hood, a loading filter or a tiring fan - often before airflow visibly suffers. It is the system's vital sign.
The short answer
Static pressure is one of the most useful numbers on an LEV system because it is quick to read and it moves the instant something changes. Taken at the right points, it exposes a blocked hood, a loading filter or a tiring fan - often before airflow visibly suffers. It is the system's vital sign.
The detail
Static pressure is the pressure inside the ductwork compared with the air outside it, and it is directly related to the airflow rate and the characteristics of the system. Examiners read it at several points: the static pressure behind the hood, along the duct, across the air cleaner or filter, across the fan, and at discharge. Each point tells a different part of the story - together they map where the energy in the system is going and where it is being lost.
Hood static pressure is the most useful single reading. Because it tracks the airflow through that hood, a change from the commissioned figure is an early flag that flow has changed - a partial blockage, a leak upstream, a damper knocked out of position or a filter starting to load. Many simple airflow indicators work on exactly this principle, sampling the negative static pressure in the duct and showing a clear signal when it falls out of the safe range.
What it means for you
Static pressure across the filter is the classic loading indicator: as dust builds up, the resistance rises and the pressure drop across the cleaner climbs. Read against the commissioned value, it tells you when the filter needs attention rather than guessing. A shift across the fan, by contrast, can point to fan wear, belt slip or a problem on the clean side of the system. Reading these points together, rather than one in isolation, is what lets an examiner say not just that flow has dropped but where in the system it is being lost.
The real value of static pressure is that it is re-checkable. A thorough examination and test sets the picture every fourteen months, but a simple gauge or indicator lets the people using the system watch the same vital sign daily or weekly and catch a change early - which is exactly the ongoing check that COSHH expects between statutory examinations.
The service behind the guide
We measure static pressure at every meaningful point against your commissioning figures, pinpointing where flow is being lost, with a clear report.
Questions
It is the pressure inside the ductwork compared with the air outside it. It relates directly to the airflow rate, so a change in static pressure signals a change in how much air the system is moving.
At several points - behind the hood, along the duct, across the filter or air cleaner, across the fan, and at discharge. Each location reveals a different part of the system's condition.
Because it tracks the airflow through that hood. A drop from the commissioned figure is an early sign of a blockage, leak, misplaced damper or loading filter, often before the loss of capture is visible.
The filter is loading with dust. As it fills, resistance rises and the pressure drop across it climbs, which tells you when it needs cleaning or replacing rather than guessing.
Yes. A simple gauge or airflow indicator lets operators watch the same reading daily or weekly and spot a change early. That ongoing check is what COSHH expects between the fourteen-month examinations.
Phoenix Duct Clean · by the numbers
We measure static pressure across your system against its commissioning figures, pinpointing where flow is being lost, with a clear report and remedial actions.