The Model 400-SVS1 Sentry Visibility Sensor measures atmospheric visibility, also known as meteorological optical range (MOR), by determining the amount of light scattered by particles (smoke, dust, haze, fog, rain, and snow) in the air that passes through the optical sample volume. A 42-degree forward scatter angle is used to ensure performance over a wide range of particle sizes.

Performance in all weather conditions was a design prerequisite for the Sentry. An integrated, one-piece housing design keeps all cabling internal to the sensor for the ultimate protection against the elements. The sensor housing is made from anodized aluminum and the enclosures are rugged, UV-resistant fiberglass rated to IP66. Based on the proven experience of the NWS and FAA, the sensor uses a “look down” geometry to reduce window contamination and clogging from blowing snow. The windows use continuous duty anti-dew heaters and thermostatically controlled external hood heaters are offered for protection in extreme environments. All power and signal lines to the Sentry are protected with surge and EMI filtering to help guarantee uninterrupted service for the life of the sensor.

Installation and maintenance effort is minimal for the Sentry. A flange located on the bottom of the sensor signal processing box mates with a user supplied 1-1/2 inch IPS pipe. Power and signal connections are made through waterproof cable glands to terminal boards in the signal processing box. Cables are not included.

Calibration of the Sentry in the field is as simple as connecting a factory supplied calibration fixture and following a simple procedure that takes less than 30 minutes. Semiannual calibration is recommended.

• Standard environments
• Compact lightweight package
• 10 mile (16km) visibility range
• Forward scatter measurement technique
• Ice-resistant “look down” geometry
• Flexible output options
• Simple installation and maintenance