New to PLC programming with Flowmeter question

teamherms

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Join Date
Jun 2017
Location
houston
Posts
6
Hello,

We are a mechanical engineering senior deign team from the University of Houston building an automated beer brewing system known as HERMS (heat exchange recirculating mash system).

We are trying to measure flow rate between tanks and most of the flow meters that I have found that are analog (4-20mA) are pretty pricey and we have little to no budget for too much. During my digging I found something called a flow Transmitter;
http://www.dwyer-inst.com/Product/Flow/FlowTransmitters/Paddlewheel-In-Line/SeriesSFI-800#ordering

From what I can tell it sends a frequency pulse ranging from 1-10VDC, I assume something like a PMW only in reverse.

So to get to the point, one am I understanding how this device works? Two can this be used to measure flow rates? and lastly we were given a Siemens S71200 PLC with an analog module so is there any way that this option can be use?

Also if you have a suggestion one a cheaper flow meter that can read between 0.1 to 10GPM we are open to any suggestions.

Thank you in advance for the help

Team HERMS 🍺
Here is link to our project page in case you are interested in more information on what we are trying to achieve.
http://cot-mect4276.tech.uh.edu/~fbock/index.html
 
If you need to read 0.1 gpm flow this won't work as the range is 2-20 gpm.
Also what is the temperature range and fluid properties, clear/clean water like? cloudy with suspended solids? The Dwyer would work either way except for the low range.
Would the device need to be CIP- Clean In Place?
The analog output may work with the S71200 depending on analog input type.
Ask some of the EE guys for help in exchange for some brew! Can't hurt!

SFI-800-1/2-A711
Polysulfone sight flow indicator with A-711 sensor, range 2-20 GPM (7.6-75.5 LPM), 1/2" female NPT.
 
If you need to read 0.1 gpm flow this won't work as the range is 2-20 gpm.
Also what is the temperature range and fluid properties, clear/clean water like? cloudy with suspended solids? The Dwyer would work either way except for the low range.
Would the device need to be CIP- Clean In Place?
The analog output may work with the S71200 depending on analog input type.
Ask some of the EE guys for help in exchange for some brew! Can't hurt!

SFI-800-1/2-A711
Polysulfone sight flow indicator with A-711 sensor, range 2-20 GPM (7.6-75.5 LPM), 1/2" female NPT.

Thank you for the post, the product that I found was just an example and I think that the 0.1gpm quote was a little stupid.

I am not sure what a clean in place is but i will look into this.

the system will have both clear and cloudy liquids up to 100C also.
 
The flow measurement will be in a closed system. The main pots are open but they are 15 gallon pots. I looked up the DI specs and it can handle up to 100kHz so I think that something like this will work for us, but it could be difficult to program.

Thank you for taking the time to post.
 
Thank you for the post, the product that I found was just an example and I think that the 0.1gpm quote was a little stupid.

I am not sure what a clean in place is but i will look into this.

the system will have both clear and cloudy liquids up to 100C also.

The low flow rate needs to be clarified. Too low and you would get expensive. I always asked our production guys to be realistic with specs or give me an unlimited budget.
If you find a device that uses optical the color/clarity could be a problem.
Mechanical position, orientation and distances to fitting need to be accounted for. You may have the correct sensor but a bad install will do you in.
If the system needs to be sanitized between batches either a CIP or quick clamp fittings are needed. I haven't done food processing for almost 35 years.
Check here for some info: http://www.omega.com/technical-learning/
 
If the solids content is low then something like this will do you.

http://www.jerman.com/dljsjmeters.html

If these don't have the accuracy you need do a search for "jet flowmeter with pulse".

I'm not a siemens guy, but does your PLC have any discrete inputs? Typically you connect these pulse meters to get pulse signal for each unit of volume the meter is set for. By measuring time between pulses you can work out litres per hour or whatever unit you want. Or just increment a counter if you only need totalled volume

Meters with adjustable pulse rates are better, or you need to at least know what volume you're expecting per batch. If you're only moving 500 litres each time then a pulse every 1000 litres is no use!
 
The low flow rate needs to be clarified. Too low and you would get expensive. I always asked our production guys to be realistic with specs or give me an unlimited budget.
If you find a device that uses optical the color/clarity could be a problem.
Mechanical position, orientation and distances to fitting need to be accounted for. You may have the correct sensor but a bad install will do you in.
If the system needs to be sanitized between batches either a CIP or quick clamp fittings are needed. I haven't done food processing for almost 35 years.
Check here for some info: http://www.omega.com/technical-learning/

Ok I see what you are saying.

So I was able to find a device that could read at around 0.2GPM but only a 10% accuracy but considering it is a undergrad project it will work for us.

I have plans on programming a cleaning program that would flush the system using a solution that is common in the brewing industry for sanitation so I dont think that a quick couple will be needed either. And again being an undergrad project with little to no budget (although that can be help with donations "wink wink") it will work for us.

The one I am looking at is a pin wheel motion sensor, so the clarity of the liquid should not effect the reading, hopefully.

Again thank you for your post. 🍺
 
If the solids content is low then something like this will do you.

http://www.jerman.com/dljsjmeters.html

If these don't have the accuracy you need do a search for "jet flowmeter with pulse".

I'm not a siemens guy, but does your PLC have any discrete inputs? Typically you connect these pulse meters to get pulse signal for each unit of volume the meter is set for. By measuring time between pulses you can work out litres per hour or whatever unit you want. Or just increment a counter if you only need totalled volume

Meters with adjustable pulse rates are better, or you need to at least know what volume you're expecting per batch. If you're only moving 500 litres each time then a pulse every 1000 litres is no use!
I looked into the specs on our PLC and the DI can handle a frequency up to 100kHz!!! which i think is pretty huge but i could be wrong. I found a flow meter that is like 10 dollars, its not very accurate and we can not use it for the higher temp fluid but we are on a tight budget and the only money that we have to work with is donations.

Thank you for taking the time to reply to our post.
 
I'm a home brewer and use a SLC for controls, but no flow meters. The HERM set ups run constantly, at a throttled rate just enough not to compact the grain bed and cause a stuck sparge. The control is done in the heating circuit not flow in most home brew set ups. I have seen people use pulse flow metered, X cubic ft per pulse, and they can be found under 100$. You will just need an input that can handle that resolution, and depending on speed can get expensive.
 
Also what digital input module do y'all have?

So in order to sell this to our professor as a project the entire system needs to be automated, hence the need for flow meters so that we can measure the initial volume of water as well as how much water is taken out of the mash kettle vs how much is added during the sparge.

The DI on our controller can read frequencies up to 100kHz and the flow meter I am looking at using is something on the order of 400-500 pulses per liter. so this is well below the capabilities of the PLC.

We were lucky and I have a good working relationship with a Siemens rep so we got a pretty high end PLC for free.

Thanks for the post.

I will keep everyone up to date on the progress, as of now I have ordered the flow meters so I will test the resolution with something like gravity feed and timing how long it takes to fill a bucket and see if I can get any kind of accuracy.
 
And again being an undergrad project with little to no budget (although that can be help with donations "wink wink") it will work for us.

We take donations too! (that being your end product :) )


Here's a cheap meter ($45) with a totalizer as well as the instantaneous flow:

http://www.flows.com/digital-low-flow-meter/

Although you might have to hack it to get outputs...

And here's a thread that might help:

http://www.plctalk.net/qanda/showthread.php?t=105904&highlight=meter
 

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