HSS VPF-710 - Alliance

Visibility Sensor
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
The VPF-710 digital visibility sensor is designed for accurate
measurement of visibility and has been in operation for over 20 years.
It is a compact, robust instrument with excellent time proven
performance and is suitable for use in extreme conditions.
Measurement Principle
The VPF-710 sensor uses forward scatter meter technology to measure
visibility in all weather conditions. The sensor calculates EXCO (the
atmospheric EXtinction COefficient) by measuring the amount of light
scattered by small suspended particulates (ie fog, haze and smoke aerosols)
and larger particles (ie rain, snow, ice pellets, drizzle and mist) passing
through the sample volume. From this EXCO value the MOR (Meteorological
Optical Range) and thus visibility is determined.
Data Output
The 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.
Maintenance, calibration, self test and monitoring
The 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 overleaf.
Operation in temperature extremes
The sensor operates in temperatures ranging from -500C to +600C. For
operation below - 30C the heated version is recommended (please refer to
the variants overleaf).
The sensor is a single lightweight unit and
can easily be installed by one person.
The sensor includes as standard:
- Sensor head of high quality aluminium
construction which is hard anodised
to give a superior finish that does not
require painting.
- RS-232C digital output
- Window de-misters
- Power line surge arrestors
- Signal line surge arrestors
- Self-test and monitoring system
- 6 metre power and signal cable
- Waterproof mini-connectors
- Calibration reference certificate
- Manual
Available VARIANTS see overleaf
- Heating
- Advanced self test and monitoring
- Alternative RS-422 Output
- Ambient Light Sensor
- Weather Station Module
Available ACCESSORIES see overleaf
- Stainless Steel Mounting Kit
- Calibration Kit
- Transit Case
For sensor specifications please refer to HSS brochure
The VPF-710 Visibility Sensor comes with 2 years warranty as standard.
visibly better
RS-422 communications - where there is 12 metres or more between
the sensor and control computer RS-422 configuration is required.
Heated version - the sensor is fitted with window de-misters allowing
operation of the sensor in temperatures down to -30C. However, where
the temperature drops below -30C 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 -500C.
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 - provides 3 analogue inputs (0-10 V)
allowing the VPF-710 to be used as a weather station. Output is a single
time correlated data string.
VPF-710 sensor as part of a weather station
Self-test and monitoring system
The sensor condition and performance can be
monitored remotely using the self-test
diagnostic software which comes as standard to
Optical Source Power
Transmitter Window Contamination
Advanced self-test and monitoring see right panel
Non-Volatile Memory Check Sum Test
EPROM Check-Sum Test
Restart Occurrence
Sensor Sample Interrupt Verification
RAM Read/Write Verification
Register Read/Write Verification
Calibration reference kit - recommended for
end-user confidence checks and re-calibration.
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.
Stainless steel mounting kit - includes a U-bolt
and fasteners to secure the sensor to any pole
with a diameter between 40 - 64 mm.
Transit case - scientific case lined with 3 inch
foam to hold the sensor securely in place in
extreme handling conditions.
A/D Control Signal Test
A/D Conversion Accuracy Check
Forward-Scatter Background Illumination Level
Increased levels of diagnostic testing are
available as an option see below.
Advanced self-test and monitoring system
In addition to the above functions this option
will also allow you to monitor:
Forward-Scatter Receiver Sensitivity
Forward-Scatter Receiver Window Contamination
Power Supply Voltages
Input Voltage Check (Battery Check- DC Powered
Sensors Only)
The HSS range is in continuous development therefore
specifications may change without prior notice.
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Biral, P O Box 2, Portishead, Bristol BS20 7JB, UK
Tel: +44 (0)1275 847787
Fax: +44 (0)1275 847303
Email: [email protected]
HSS Sensors are manufactured by Biral to
rigorous IS0 9001:2000 quality standards
Ref: HSSD.710.0505.03