Near real-time BTEX monitoring
The Optical Tent sees inside the fence, not just along it.
Fenceline monitoring tells you a release already left the property. The Optical Tent covers the interior of the facility as well, so operators learn where a release started while there is still time to stop it.
<1 ppb
average BTEX detection limit across all paths
>99%
data completeness over 20 months of operation
10
absorption paths, 373–891 m in length
6×
more likely to catch a release than fenceline paths alone
Ultraviolet light, read as a fingerprint.
The Optical Tent uses open-path differential optical absorption spectroscopy. Each measurement is a physical one: no gas standards, no routine recalibration.
A beam across the facility
A transmitter sends UV light to a retroreflector hundreds of meters away and collects what comes back. Each system aims at five reflectors in turn.
Absorption identifies the gas
Each BTEX compound absorbs ultraviolet wavelengths in a pattern unique to that molecule. Those cross-sections are physical constants, so identification cannot drift out of calibration.
A concentration with its own error bar
We fit each measured spectrum against reference spectra, which gives a path-averaged concentration and the uncertainty on that measurement. The detection limit comes from the observation itself, not a spec sheet.
Results in near real time
Spectra upload as the systems record them, and we analyze them on arrival. Fenceline results feed the refinery’s public display and its regulatory alert thresholds; the full dataset goes to refinery staff and the air district.
What it caught
Twenty months at a working refinery
The system has run continuously at a refinery in the South Coast air basin since August 2020.
December 18, 2020
Leak found and fixed within the hour
An emission event appeared on an interior path and at the fenceline, triggering a public notification. The interior data pointed the operator at the source, and they stopped the release within an hour.
March 9, 2021
Tank roof failure, tracked to resolution
A floating roof tank failed overnight. BTEX rose first on an interior path, then at the fenceline, and both kept registering through the two weeks the repair took.
February 14, 2021
Maintenance work, told apart from a leak
Coating work beneath two paths raised BTEX for three weeks, staying under the acute reference level throughout. Because staff knew which paths saw it, they could tell planned work from a malfunction.
A fenceline-only system would have missed most of it.
Over the same period, hourly benzene passed the 8 ppb acute reference level for 149 hours on interior paths and 20 hours at the fenceline.