Visibility Sensor

EEx Sentry™

Specifically designed for ATEX Zone 1 hazardous area applications. Measures atmospheric visibility, also known as meteorological optical range (MOR) by determining the amount of light scattered by particles (smoke, dust, haze, fog, rain, & 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. MOR is calculated by the user by converting the received signal strength (extinction coefficient, σ ) using Koschmeider's formula, where MOR (Km) = 3/ σ .

Performance in all weather conditions was a design prerequisite for the EEx Sentry™. The sensor uses ATEX rated EEx housings and offshore marine grade sheathed cables to ensure all-weather, Zone 1, IP66 certified performance. A sturdy aluminum frame painted with durable powder-coat paint is used to mount the housings and provide mounting to a customer supplied mounting pipe. Power and signal lines to the EEx Sentry™ are protected with surge and EMI filtering to help guarantee uninterrupted service for the life of the sensor.

Installation of the EEx Sentry™ is easy. A mounting flange located on the bottom of the sensor housing mates with a user-supplied 4 inch IPS pipe. Power and signal connections are made through M25 threaded holes using user supplied, ATEX approved cable glands and wiring. User wiring is made to DIN rail mounted terminal boards in the Signal Processing Box.

Calibration of the EEx Sentry™ in the field is as simple as attaching a calibration fixture to the back of the sensor and following a procedure that requires less than 20 minutes. Semiannual calibration is recommended.

Performance

Range: 10 m to 8 km (other ranges available)
Accuracy: +/- 10%
Time Constant: 60 sec
Scatter Angle: 42 deg nominal
Source: 880 nm LED

Power
DC Version: 12 or 24 VDC, 10 VA

Environmental
Temperature: -20 to 60 C
Humidity: 0-100%
Protection: IP66 (NEMA-4X)

Physical
Dimensions: 1170 mm W x 915 mm H x 560 mm D (46" x 36" x 22")
Weight: 40 kg (88 lb)
Mounting: Nominal 102 mm pipe, 122 mm OD max (4" IPS pipe, 4.8" OD max)

Construction

Frame: Aluminum with exterior grade powder-coat paint

Housings: Aluminum with exterior grade powder-coat paint

Hardware: 316 grade stainless steel

Data Outputs

Analog Voltage: 0-10 VDC standard, 0-5 VDC optional
4-20 ma Current Loop: Single ended and isolated optionally available
Relays: Control & diagnostic relays optional

ASCII Coded Serial: RS-232, RS-422, RS-485 optional