Product category:
Level and tank contents instrumentation
News Release from: Vega Controls UK | Subject: Silo levels
Edited by the Processingtalk Editorial
Team on 09 May 2005
Safety is important in silo level
measurement
Vega have increased the reliability, accuracy and safety of silo level measurement at a plastics manufacturer, reducing risks to personnel who previously needed to climb to the top of the silo
Vega have increased the reliability, accuracy and safety of silo measurement at a plastics manufacturer, reducing risks to personnel who previously needed to climb to the top of the silo to make repairs or manually dip the silos Costs have been recovered through increased reliability of measurement thus reducing overfills, charges from returned products (following aborted deliveries to already full silos) and disruption to production
This article was originally published on Processingtalk on 10 Dec 2007 at 8.00am (UK)
Related stories
Radar measures wood dust silo levels reliably
Vega radar is reliably monitoring the silo level of wood waste at a furniture plant, providing instant silo contents display and Ethernet transmission of the data for improved plant efficiency
The easy way to get tank and silo levels on the PC
Vegamet and Vegascan are the new, easy to use Vega signal conditioners with connectivity for local and global networking, powering and connecting to transmitters using 4-20mA, HART or HART multi-drop
Therefore saving time, money and most importantly increasing safety.
The customer, RPC in Hereford, manufacture a range of food containers for products such as salads and margarines for leading food producers and retailers in the UK, making around 4 million items per week.
The site uses both injection moulding and thermo forming techniques and offer full offset colour printing as well as the latest 'in mould' labelling too.
Further reading
Vibrating level switches for bulk solids
With a new temperature range of -40 to +150C, the application range for Vega vibrating level switches for bulk solids is extended even further
Guided wave radar for flammable product storage
Vega guided microwave radar technology can increase the safety and security when storing dangerous fluids, and ease the administration of COMAH or other safety regulations
Vega Controls offers slimline pressure transmitter
The Vegawell 51 is a new generation of slim design (diameter only 22mm) suspension pressure transmitters for water/waste-water applications
The sheets of material for thermo forming are also produced on site using extruders, giving RPC flexibility and control over supply of materials to suit production and their customer needs.
The polymer used to supply the production lines fall into approximately 6 different types of polyethylene.
They are stored in various quantities inside 18 silos in two blocks on the site.
Because of the high throughput, the silo inventory for this site needs to be carefully controlled.
Product levels were originally monitored using electro mechanical 'plumb bob' devices.
However the devices were unreliable, unable to measure during filling, inaccurate, and high in maintenance.
The on site engineers experienced regular cable breakages, weights being buried in product: plus failure of motors and mechanical components resulted in all too regular climbs to the top of the silos in all weathers to manually dip or carry out repair work at high level.
The inaccurate readings from these plumb bob devices caused overfills on the silos and RPC also incurred charges from returned products following aborted deliveries: plus occasionally production would run out of particular materials.
These inefficiencies, resulting in high maintenance and operational costs, drove RPC to look for a reliable solution.
The options initially looked at were.
* Load cells: accurate but expensive to 'retro-fit'.
* Ultrasonic: convenience of non-contact but not always reliable as they are affected by dust, filling and surface angles.
* Guided microwave or TDR: this was chosen, because although in contact with the product, it is easy to fit, unaffected by filling or surface angles and the plastic granules would not cause any wear on the sensor cable.
TDR has a proven reliability and repeatability in level measurement.
The integration and distribution of the level information was also considered: availability of stock can be used by many departments; production, purchasing, accounts and sales, for example.
The ability for the levels to be shared on the site via the PC network was seen as an essential part of this upgrade.
The networking idea was also extended to the sensors themselves; 'multi dropped' devices all sharing a single two core cable connecting via a simple 'T' connector.
It uses the industry standard Profibus protocol and connects to a central signal processor fitted with a PC network card.
This digital solution saves on cabling, work at high level and installation costs and allows remote communications to each device for setting up, operation and maintenance from the PC network.
There is also scope for expansion should any additional silos or other Profibus sensors be installed in the future.
The complete installation took place over a 1 month period, the signal cabling and the special 'T' junction boxes were installed.
The TDR units were mounted in the same nozzle as used by the old level systems.
However, their small size (from 1" BSP) means even making new connections could be considered.
Being able to fit a single cable, which supplies power to and data from each set of transmitters at the two silo blocks, was especially useful, because the silos were in two different places on site, a few hundred metres apart.
The cable, when used in this format, can run in excess of 1000m.
The Vega central signal processor unit was installed in the production office.
Final commissioning of all 18 measurements took 2 days including setting up the Local Area Network connection to provide data for a networked stock spreadsheet for accurate, on-line inventory data.
The equipment also has capabilities of: internet web-browser publishing, graphics and trend displays.
(Information can also be distributed by modem, internet web page, e-mail fax and SMS).
The increased reliability and accuracy of the measurement has meant the system is now an integral part of material control for this site, the information is shared by different departments.
Since the installation there have been no more overfills, no personnel have had to climb to the top of the silo to make repairs or manually dip the silos.
This is saving time, money and importantly increasing safety.
Vega Controls offer level solutions for all types of silo and tank level measurements from one vessel to many on one site or several sites using remote set up and telemetry.
Experienced engineers are happy to provide advice, support and even supply trial systems for proving on any application for level measurement.
All Vega systems underline their quality with a 3 year warranty. Request a free brochure from Vega Controls UK ...
• Vega Controls UK: contact details and other news
• Email this article to a colleague
• Register for the free Processingtalk email newsletter
• Processingtalk Home Page
Search the Pro-Talk network of sites
