HSS VPF-710 Visibility Sensor

(digital output)

The HSS VPF-710 Visibility Sensor is suitable for use in any system where a digital output to a computer or logger is required. This sensor has sophisticated levels of self test for remote monitoring and is used particularly on airports, helipads, wind turbines and offshore weather stations. As with all HSS sensors it has excellent time proven performance and is suitable for use in extreme conditions.

Features

• measures visibility AND fog density
• proven accuracy, reliability and repeatability
• self-test and monitoring system
• very low power requirements
• long and trouble-free operational life
• minimal maintenance requirements and running costs
• highly resistant to sea-water corrosion
• built to last
• optional ambient light sensor for RVR applications
• optional sensor inputs to provide completely synchronised weather parameters

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Measurement Principle

The HSS VPF-710 Visibility Sensor uses forward scatter meter technology to measure visibility in all weather conditions. The sensor measures the amount of light scattered by small suspended particulates (i.e. fog, haze and smoke aerosols) or larger particles (i.e. rain, snow, ice pellets, drizzle and mist) passing through the sample volume. The sensor calculates the atmosphere EXtinction COefficient (EXCO) from which the Meteorological Optical Range (MOR) is calculated. Using an infra-red light source and intelligent sensing technology the measurements are unaffected by other light-sources.

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Data Output

The HSS VPF-710 Visibility Sensor is configured with RS-232C signal output as standard with RS-422 communications available as an option. The data is output in various ASCII data strings, such as a small compressed data string, expanded data string and monitoring data string amongst others. The unit can be set in either automatic or polled mode and data sent to a printer or to a PC for tagging, processing and archiving.

To see an example of this please see the data example pdf in the download tab

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Construction

The HSS VPF-710 Visibility Sensor is a single lightweight unit and can easily be installed by one person. The sensor is constructed of dip brazed high grade aluminium. All components that are exposed to weather are hard-coat anodised for protection against corrosion.

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Maintenance and calibration

The HSS VPF-710 Visibility Sensor is fully calibrated at the time of manufacture. Routine maintenance, including a check on calibrations, can be performed easily by one person in a matter of a few minutes and a re-calibration (although this should never be required) takes only slightly longer.

The sensor condition and performance can be monitored remotely using the self-test and monitoring system detailed below.

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Operation in temperature extremes

The HSS VPF-710 Visibility Sensor operates in temperatures ranging from - 58º F to +140º F (-50º C to +60º C). For operation below -27º F (-32º C) the heated version is recommended (please refer to the heated option below).

NB The temperatures quoted apply when using the sensor in a non-condensing environment. If you are unsure whether or not you require heating for your own application please contact us for advice.

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The HSS VPF-710 Visibility Sensor System

The HSS VPF-710 Visibility Sensor is constructed of high quality aluminium which is hard anodised to give a superior finish that lasts for years and does not require painting.

The sensor has:

• RS-232C digital output
• window de-misters
• power line surge arrestors
• signal line surge arrestors
• self-test and monitoring system (see below)
• 19 ft (5.7 m) power and signal cable
• waterproof mini-connectors
• calibration reference certificate
• manual

The HSS VPF-710 Visibility Sensor is also supplied with a stainless steel mounting kit.

The stainless steel mounting kit includes a U-bolt and fasteners to secure the sensor to any pole with a diameter between 1.5 - 2.5 inches (38 mm - 64mm).

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Self-test and monitoring system

STANDARD self-test and monitoring software

The sensor condition and performance can be monitored remotely using the self-test diagnostic software which comes as standard with the HSS VPF-710 Visibility Sensor to monitor:

• Optical Source Power
• Transmitter Window Contamination
• Non-Volatile Memory Check Sum Test
• EPROM Check-Sum Test
• Restart Occurrence
• Sensor Sample Interrupt Verification
• RAM Read/Write Verification
• Register Read/Write Verification
• A/D Control Signal Test
• A/D Conversion Accuracy Check
• Forward-Scatter Background Illumination Level

ADVANCED self-test and monitoring software

Even greater self-test and monitoring is available with the optional advanced self-test and monitoring system in addition to the functions of the standard self-test and monitoring.

The advanced self-test and monitoring allows you to monitor:

• Forward-Scatter Receiver Sensitivity
• Forward-Scatter Receiver Window Contamination
• Power Supply Voltages
• Input Voltage Check (Battery Check- DC Powered Sensors Only)

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Alternative Variants / Options

In addition the following variations are available:

• heating
• advanced self-test and monitoring system
• alternative RS-422 output
• ambient light sensor
• weather station module

Heating

The HSS VPF-710 Visibility Sensor is fitted with window de-misters allowing operation of the sensor in temperatures down to -27º F (-32º C). However, where the temperature drops below 27º F for more than a couple of hours a day the heated version is recommended. This version will provide error free operation in conditions down to - 58º F. The operational range of the sensor is from - 58º F to +140º F (-50º C to +60º C)

Note re heating for 12 VDC sensors

The heated version is available for all mains powered units (any voltage between 100-250 VAC) and 24 VDC battery powered units. However, please note that there is a restriction on heaters for 12 VDC units. A low power heater can be provided but it will operate at half of the standard rating (standard heater output = 15 W per hood and reduced heater output = 7 W per hood).

The reduced heating units can be controlled by three methods:

1. ON all of the time...power hungry but effective.

2. OFF all of the time...conserve power but may ice up if snow accumulates.

3. Switched on and off situation depending on the temperature settings monitored internally by the sensor (best use of power and error free measurements).

RS-422 communications

Where there is 39 ft (11.5 m) or more between the sensor and control computer RS-422 configuration is required.

Ambient light sensor

The ambient light sensor allows ambient light conditions to be measured according to ICAO (4 level and with specific angle of view). Designed for use with RVR (Runway Visual Range) systems on airfields and for use with Allard’s Law if night time visibility conditions are to be determined according to this instead of using the standard Meteorological Optical Range values (MOR).

Weather station module

The weather station module provides 3 analogue inputs (0-10 V) allowing the HSS VPF-710 Visibility Sensor to be used as a weather station. Output is a single time correlated data string.

 

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Accessories

The following acccessories are available for the HSS VPF-710 Visibility Sensor

• calibration reference kit
• transit case

Calibration reference kit

The calibration reference kit is recommended for end-user confidence checks and recalibration. The kit contains a carrying case, zero plugs and a calibration plaque to a specific EXCO value. One kit can be used on any number of sensors of the same range.

Transit case

The HSS VPF-710 Visibility Sensor is delivered in an environmentally friendly, triple ply, heavy duty carton with foam inserts. Whilst this is suitable for normal shipping, you may wish to consider ordering the scientific transit case if you intend to move the sensor frequently or the sensor will have to endure extreme handling. This transit case is even more rugged than the heavy duty carton with 3 inch (76 mm) foam to hold the sensor securely in place.

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Delivery

The HSS VPF-710 Visibility Sensor is usually dispatched within 2-4 weeks ARO (After Receipt of Order)

Warranty

The HSS VPF-710 Visibility Sensor comes with 2 years warranty as standard.

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Contact Biral for more information

To find out more about this instrument or to discuss your application requirements please do not hesitate to contact Biral.

• wwwmet@biral.com (or use the Make Request button below the product photograph)
• telephone to 01275 847787 (from the UK) or +44 1275 847787 (International)

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After Sales Support

Biral offers free advice and technical support for the lifetime of the instruments we sell. Once you have purchased the unit you can always contact us for help if required at :

• wwwmetsupport@biral.com
• telephone to 01275 847787 (from the UK) or +44 1275 847787 (International).

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This range is in continuous development therefore specifications may change without prior notice. E&OE.

Product Information

• VPF710 Product Information.pdf
• HSS Visibility Sensor Brochure.pdf
• VPF710 Datastrings.pdf
• Using the VPF710 with a laser precipitation monitor.pdf
• comparison_of_hss_and_sws_visibility_and_present_weather_sensors.pdf

Application Related Information

• Aviation - SUPERAWOS system in the USA.pdf
• Aviation - ATSIN report on use of forward scatter meters for RVR.pdf
• Aviation - visibility sensors for airports.pdf
• Aviation - sensors for CAT I and CAT II runways.pdf
• Wind energy - w-red lights adapt to visibility.pdf
• Wind energy - Intelligent Switching of Warning Light Intensities.pdf
• Marine - HSS visibility sensors for coastal use.pdf
• Marine - HSS visibility sensors for offshore use.pdf

Scientific Papers and Articles

• how to measure fog.pdf