Filter condition
Air handling units, extract systems and spray booths, with filters changed on evidence. The trend shows how fast each filter loads, which sites load fastest, and when a change is due.
Differential air pressure monitoring tag
The ZARC differential air pressure tag reports the difference in air pressure between two points: either side of a filter, across a fan, or between a room and the corridor outside it. It shows that a filter is blocking, that a fan has stopped moving air, or that a room has lost the pressure it is meant to hold. It runs on its own battery and needs no wiring and no connection to the building controls.
01
What it reports
The tag has two pressure ports, each connected by a short tube to one of the two points. It reads the difference between them continuously and reports in pascals at the interval set for the site, down to every minute.
Across a filter, the difference rises as the filter loads. The dashboard shows that climb over weeks, so filters are changed when they need it and not by the calendar, and a filter that has torn or been left out shows as a difference that is too low.
Across a fan or in a duct, the difference shows that air is moving. A fan can be powered and turning while a belt has gone or a damper has shut; the pressure shows the truth.
Between a room and its neighbour, the difference shows whether the room is holding positive or negative pressure. An alert is raised when it leaves the band you set for longer than a door opening would explain.
02
Applications
A pressure difference is often the first sign that an air system has stopped doing its job. The uses below are the common ones; the tag works wherever air is filtered, moved or held at pressure.
Proof of airflow
A fan or extract that is running but not moving air is invisible to a power or run signal. The pressure across it is the direct measure.
Kitchen extract
Grease filters and canopy extract load quickly and fail quietly. The differential shows a filter that needs cleaning and an extract that has stopped pulling.
Cleanrooms and clean stores
A room held above its surroundings keeps dust out. The tag reports the pressure it holds and the time it spends outside its band.
Isolation rooms
A room held above or below the corridor, to protect a patient or to contain an infection. The tag supports the monitoring; where a standard requires validated room pressure monitoring, it does not replace it.
Laboratories
Containment rooms are held below the corridor so that air flows inward. A lost pressure is reported with its time and duration.
Data hall containment
The pressure between cold and hot aisles shows whether cooling air is reaching the equipment or leaking past it.
Stair and lobby pressurisation
A complementary view between tests of a pressurisation system; it does not replace the commissioning and testing of a smoke control system.
Dust and fume extraction
Collector filters and ductwork in workshops and production areas, where a blocked filter means dust in the air people breathe.
Plant and switch rooms
Rooms kept at slight positive pressure to keep dust and moisture off equipment.
03
Where it can go
The tag sits within a tube's reach of both points. Typical fittings:
On an air handling unit
Ports either side of the filter bank, using the unit's existing tappings where it has them.
On ductwork
Either side of a fan, coil or damper.
Beside a door
One port in the room, one in the corridor, through the wall or above the ceiling.
Above a ceiling
Out of sight, with a tube dropped to each space.
On an extract canopy
Either side of the grease filters.
On a collector
Across the filter of a dust or fume unit.
04
In the dashboard
The dashboard shows the live difference for each tag and its history, so a filter's slow climb and a room's sudden loss of pressure are both plain to see. It works out the minimum, maximum and average over any period and the time a room has spent in and out of its band. Records export for maintenance files, audits and validation packs.
Limits are set per tag: high, low or a band to stay within, with a delay so that a door opening does not alarm. When one is crossed the alert is raised in real time and goes by email or SMS, and through an app where required, to the people you name, with escalation to further contacts.
- Live differential in Pa for every tag
- High and low limits, or a band to stay within
- Delay before alert, so a door opening is ignored
- Filter loading trend over weeks and months
- Time a room spent in and out of its band
- Minimum, maximum and average over any period
- Units, rooms and sites compared side by side
- Every alert logged with the reading that raised it
- Records exported for audits and maintenance
- A tag that misses its reporting interval is flagged
05
Industries
Differential tags are fitted wherever air is filtered, moved or held at pressure, including:
Healthcare
Isolation rooms, theatre plant and pharmacy stores.
Data centres and critical infrastructure
Aisle containment and air handling filters.
Facilities management
Filter changes across a portfolio of plant.
Industrial and manufacturing
Extraction, spray booths and clean areas.
Buildings and estates
Air handling and stair pressurisation.
Logistics and supply chain
Clean and controlled stores.
06
Technical specification
| Parameter | Specification |
|---|---|
| Measurement | Difference in air pressure between two points, read continuously and reported in real time |
| Pressure type | Differential, positive or negative |
| Units | Pa as standard; mbar where required |
| Range | Specified to the application, from filter loading to room pressure |
| Accuracy | Specified to the requirement |
| Media | Air |
| Connection | Two pressure ports for tubing |
| Fitting | Tubes run to a tapping point on each side of the filter, fan, duct or wall |
| Values reported | Current differential, maximum, minimum and average for each reporting interval |
| Reporting interval | Configurable, down to every minute |
| Limit alerts | High, low or a band to stay within, set per tag |
| Duration alerts | A delay before alert, so a door opening does not alarm |
| Trend alerts | Differential slowly rising as a filter loads, at a rate you set |
| Alert delivery | Dashboard, email or SMS; app where required |
| Recipients | Named people and groups, with escalation to further contacts |
| Missed reports | A tag that misses its reporting interval is flagged in the dashboard |
| Gateway power loss | Raises its own platform alert |
| Dashboard | Live differential, trends, min/max/average, time in and out of band, filter loading; configured to your requirement |
| Records | Every reading and alert time-stamped and exportable for audits |
| Data | Full reading history; UK-hosted or on servers on your own site |
| Power | Internal battery, up to five years depending on reporting interval |
| Radio | 433 MHz, one-way (transmit only) |
| Radio range | Site-dependent; confirmed by site survey |
| Mounting | On the unit, duct or wall, within tube reach of both points |
| Environment | Indoor or outdoor, enclosure specified to the location |
| Charges | No per-alert, per-user or licence charges |
| Manufacture | Made to order in the UK |
| Certification | CE marked |
07
From requirement to live alerts
Requirement
Tell us what the air system must do: the filter, the fan, or the room and the pressure it should hold.
Configuration
The tag is built to order with the range for the application and the limits, band and delay agreed.
Fitting
The tag is fixed in place and its two tubes run to the tapping points. No cable, and no connection to the controls.
Commissioning
Readings are checked with the system running and stopped, and with doors open and shut, then the alert routes are tested.
Ready to get started? Every deployment begins with a site survey.
Book a site survey08
How it reports
Each reading leaves the tag on 433 MHz radio, reaches a ZARC gateway and appears on the dashboard, where the band and delay are checked. The tag is transmit-only, with no receiver, and sits apart from the building management system, so it gives an independent view of plant that the controls may be reporting as healthy.
Related tags
Air pressure
Barometric pressure at a site.
Pressure
Pressure in a pipe, cylinder, vessel or line.
Air quality
What is in the air being moved.
Temperature
Supply, extract and room temperatures.
Questions we answer most.
What does a differential air pressure tag do?
It reports the difference in air pressure between two points, such as either side of a filter or between a room and a corridor.
How does it show a filter needs changing?
The difference across a filter rises as it loads. An alert is raised at the level you set.
Can it show a fan is not moving air?
Yes. A fan that is running with no pressure across it has lost its belt, its airway or its damper.
Can it show a room has lost pressure?
Yes. It alerts when the difference leaves the band you set for longer than the delay you choose.
Will opening a door cause an alert?
Not if a delay is set. Brief changes are ignored.
How does it connect?
By two small tubes from its ports to the two points. There is no wiring.
Does it replace validated room pressure monitoring?
No. Where a standard requires validated monitoring, the tag supports it and does not replace it.
Does it connect to the building management system?
No. It is independent, which is why it catches faults the controls miss.
What pressure range does it cover?
The range is specified to the application when the tag is ordered.
Which tag do I need for water or gas pipework?
The pressure tag. This one is for air.
How is it powered?
By an internal battery lasting up to five years, depending on reporting interval.
Looking for something else?
We work with any sensor for any application.
Most sensing needs are met by a tag we already build, configured for your equipment. If yours needs a sensor or interface we don't list, we have the engineering to build it. Tell us what you need to measure, and we will tell you how we would do it.
Discuss your requirementDiscuss a monitoring
or alerting solution
Tell us what is happening on site, what you need to see, and the event you need to hear about. We will come back with the system that answers it.
Direct contact
Location
Venator House, Unit 9, 15-17 St Stephen's Road, Bournemouth
Dorset, BH2 6LA · VAT GB 409644484
Products contact
Contact the engineering team
Direct to the team that designs and builds the range. Tell us the equipment and the event that matters.