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Topic Title: Paint mixing project
Topic Summary: Level sensors
Created On: 25 November 2011 09:38 PM
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 25 November 2011 09:38 PM
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tankeyttails

Posts: 19
Joined: 12 November 2009

Hi,

I am currently in the research stage of making a paint mixing system. The system is pretty simple because I am making it on a smaller scale, which uses food colouring instead of paint.

The process is 4 hoppers (water, red, yellow and blue), on the output of the hoppers they have solonoid valves that then continue into a final hopper. The solonoid valves are connected via a PLC and the PLC gets its input of what colour to make from a computer.

My question is, on my final hopper I want to not only measure the liquid that is contained in the hopper but also have a ultimate high level probe.

The kind of measurement of liquid I will be using in the final hopper is around 250-500ml.

Cheers for any input,
Adam
 25 November 2011 09:52 PM
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Dave69

Posts: 446
Joined: 16 July 2011

it all sounds a little over the top for such a small ammount,
just buy a level control relay from foxtam for a few quid and use some wire dangling down instead of an electrode and use the volt free contact from the relay to send an inhibit signal when ar high level
 25 November 2011 10:04 PM
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tankeyttails

Posts: 19
Joined: 12 November 2009

The reason why it is over top is because its a college project, where we have to put into practice different methods and practices that are used in industrie but on a smaller scale.

Cheers for your input
 26 November 2011 10:38 PM
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phow

Posts: 69
Joined: 14 April 2002

Adam.
In industrial paint manufacturiing vessels and tanks, any sort of mechanical probe into the vessel gets covered in paint or resin and can stop working, or the probe is a source of colour contamination when the batch colour changes. High level trips should be independant of any level control probe, and work in a different way to prevent "common mode" failure. Normaliy high tevel alarms (LAH) are radar or ultrasonic non contact instruments inserted in the top of the vessel which measure distance. How far is the level from the top?. Non mechanical contact instrument types are capacitive probes or tuning forks which change "value" when the probe tip becomes covered by liquid. Alarm level is the length of the probe from the roof. Try searching the HSE web site for high level alarms & instrumentation, and you will pull up a lot of technical information on high hazard Comah site and Buncefield explosion caused by failure of a LAH..
BW Peter
 28 November 2011 03:18 PM
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tankeyttails

Posts: 19
Joined: 12 November 2009

Cheers Peter for that information, i am currently looking at these other types of high level alarms.

Does anyone know if you can get any of these probes that could be used in the small appllication i will be using it in?

Thanks Adam
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