400-SVS1 Sentry™ Visibility Sensor 
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The 400-SVS1 Sentry™ Visibility Sensor measures atmospheric visibility (meteorological optical range) by determining the amount of light scattered by particles (smoke, dust, haze, fog, rain, and snow) in the air that pass through the optical sample volume. A 42-degree forward scatter angle is used to ensure performance over a wide range of particle sizes. MOR is calculated by the user by converting the received signal strength (extinction coefficient, σ) using Koschmeider's formula, MOR (Km) = 3/σ.
Performance in all weather conditions is achieved with an integrated sensor design that keeps all sensor cabling internal to the sensor for complete protection against the weather. The sensor is made from anodized aluminum and rugged, UV resistant fiberglass enclosures rated to IP66. Based on the proven field experience of the NWS and FAA, the sensor uses a "look down" geometry to reduce window contamination and clogging from blowing snow. The optical windows have continuous duty anti-dew heaters and optional thermostatically controlled external hood heaters are available 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 are simple with the Sentry™. A mounting flange located on the bottom of the main enclosure box mates with a user supplied 1-1/2 inch IPS mounting pipe. Power and signal cables are installed through waterproof cable glands on the bottom of the main enclosure box to terminal boards for simple but reliable connections.
Calibration of the Sentry™ in the field is as simple as attaching a factory supplied calibration fixture and following a procedure that takes less than 30 minutes. Semiannual calibration is recommended.
Specifications
Performance
Visibility Range: 30m - 16 km standard (10m - 10 km optional)
Extinction Range: 100 - 0.1863 km-1 standard (300 - 0.30 km-1 optional)
Accuracy: ± 10% RMSE
Time Constant: 60 sec
Scatter Angle: 42 deg nominal
Source: 880 nm LED
Power
AC Version: 100-240 Vac, 24 VA Nominal; 75 VA with hood heaters
DC Version: 10-36 Vdc, 6 VA Nominal; 18 VA with hood heaters
Environmental
Operating Temperature: -40 to 60 °C
Operating Humidity: 0-100%
Protection: IP66 (NEMA-4X)
Physical
Dimensions: 889 mm W x 292 mm H x 305 mm D (35" x 11.5" x 12")
Weight: 8 kg (18 lbs)
Mounting: Nominal 40 mm ISO pipe, 48 mm o.d. max (1-1/2" IPS pipe, 1.9" o.d. max) or Nominal 25 mm ISO pipe, 33 mm o.d. max (1" IPS pipe, 1.3" o.d. max
Data Outputs
Standard: 0-10 Vdc analog
Optional:
0-5 Vdc analog
4-20 mA single ended or isolated
Relays: Control (up to 2), diagnostic, or latching
Serial RS232, RS422, RS485
Wireless RF modem
Ordering Information
400-SVS1-xx-y-H-P Sentry Visibility Sensor
Specify:
xx = mains voltage = (AC) 100-240 Vac 50/60 Hz or (DC) 10-36 Vdc
y = analog output = (1) 0-10 Vdc, (2) 0-5 Vdc, or (A) 4-20 mA single-ended, (B) 4-20 mA isolated
y = serial output = (MA) RS232 serial data, (MB) RS422 serial data, (MF) RS485 serial data
H = hood heaters = (H) yes or (blank) no
P = pipe mount flange = (P) 1" pipe flange or (blank) standard 1-1/2" size
400-SVS1-20004 Calibration Fixture
400-SVS1-20007 Day/Night Photometer (for MA, MB, MF options only)
400-SVS1-70009 AC Power Cable 3C 18AWG 3M
400-SVS1-70010-xx Signal Cable 1 Twisted Pair 22AWG Shielded
Specify xx length of cable in meters
400-SVS1-70011-xx DC Power Cable 2C 20AWG Shielded
Specify xx length of cable in meters
400-SVS1-20014 Mounting Bracket
400-SVS1-70015 RF Modem, RS232 (for MA, MB, MF options only)
400-SVS1-70016 RF Modem, USB (for MA, MB, MF options only)
400-SVS1-30023 Serial RS232 Test Cable (for MA, MB, MF options only)
400-SVS1-30025 SentryView GUI Software (for MA, MB, MF options only)
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