advertisement
from the Automation department...
Flow measurement in an open channel
Continuous process industries, DCS questions. topic
Posted by Imran on 21 February, 2007 - 10:58 pm
Could any body suggest or have experience how to measure flow in an open channel. Fluid is waste water, biological water and chemical water in a pharmaceutical plant. I was thinking about using ultrasonic level transmitter.

Also I need flow totalizer (one with auto reset and other with reset in same device).

If anybody has experience of using any product for the same or similar application please share experience.

Regards,
Imran


Posted by Issac Issachar on 23 February, 2007 - 12:17 am
Buy a commercial channel flume like one of these:
http://www.tracomfrp.com/parshall.htm

Put an open channel ultrasonic flow meter like this:
https://pia.khe.siemens.com/index.asp?Nr=10848

Issac Issachar


Posted by Michael Batchelor on 25 February, 2007 - 10:15 am
I have used exactly this type of arrangement on a number of jobs, and it works fine. Meets all the local municipal discharge monitoring regulations, etc.

If the plant has particular "favorite" suppliers, they're probably going to work fine. The flume technology has been around and understood for decades - if not centuries, and how you measure the level in it can be most anything you like. The ultrasonics work great, and seem to be the industry favorite, but I have seen bubblers on occasion.

The most unusual one I have ever seen was an ancient thing made by BIF that used a float which moved an arm on cam that controlled the on/off duty cycle of a telephone circuit back to the control room. In the control room was a
receiver that accumulated the total and derived the flow. We replaced the receiver with an input to a Modicon doing the conversion in the PLC, but the 50 year old float and cam was left in place at the flume.

MB
--
Michael R. Batchelor
www.ind-info.com
GUERRILLA MAINTENANCE [TM] PLC Training
5 Day Hands on PLC Boot Camp for Allen Bradley
PLC-5, SLC-500, and ControlLogix
www.ind-info.com/schedule.html
training@ind-info.com

Industrial Informatics, Inc.
1013 Bankton Cir., Suite C
Hanahan, SC 29406

843-329-0342 x111 Voice
843-412-2692 Cell
843-329-0343 FAX


Posted by denn on 24 February, 2007 - 2:30 pm
Imran,

Look at Miltronics model OCM devices.

Dennis


Posted by Rahul P Sharma on 24 February, 2007 - 2:30 pm
Use Ultra Sonic Level (and hence flow) transmitter-cum-monitor-cum-integrator by Nivelco (http://www.nivelco.com) for an open channel application... all you may have to do is to make a Parshall Flume of one of the standard types that the instrument supports... There is even a general parshall flume structure which the unit can be programmed for... Just feed in the basic raw data of the parshall flume and you should get a fairly good reading of flow... For exact model number etc you can write back...

au revoir
Rahul


Posted by G. Annala on 24 February, 2007 - 2:31 pm
This is typically done with a specifically shaped narrowing of the channel called a Parshall Flume. Yes, an ultrasonic level transmitter is typically used as the feedback device and the level in the flume is proportional to the flow rate. Companies such as Siemens/Milltronics have ultrasonic devices with built-in algorithms for such applications.

Hope this helps.


Posted by John Ilse on 25 February, 2007 - 12:35 pm
Imran, Grab any basic civil engineering book and look up flow wiers. They show how to calculate the flow (of standard water, you may have to calibrate for anything else which is true for any measurement device) based on the shape of the V (or flat bottomed V obstruction placed in the flow. It's kind of like an orfice plate used for closed pipe measurements where you measure the flow based on pressure difference across the orfice. With the weir,the "pressure difference" is the height of the fluid flow as it passes over the weir. Ultrasonic seems to be the way to go, or even possibly a simple arm float with analog output. I'm not familiar with the Parshall Flume. I'm sure someone would be glad to sell you one for bucho bucks but you can simply construct your own based on the shapes shown in the civil engineerng books. You have to calibrate anyway since you have fluid other than clear water, so why spend the big bucks. very simple.

good luck
John


Posted by L Kolbert on 25 February, 2007 - 1:09 pm
There are many suppliers of this type of device

Siemens, Pulsar, Ohmart-Vega, Ametek Drexelbrook, Fisher Scientific/ThermoElectron, Endress Hauser, to name a few.

L Kolbert


Posted by G. Annala on 25 February, 2007 - 6:44 pm
This is typically done with a specifically shaped narrowing of the channel called a Parshall Flume. Yes, an ultrasonic level transmitter is typically used as the feedback device and the level in the flume is proportional to the flow rate. Companies such as Siemens/Milltronics have ultrasonic devices with built-in algorithms for such applications.

Hope this helps.


Posted by M A Muqtadir on 3 March, 2007 - 2:46 pm
The ultrasonic level sensor is mounted above the flow stream and transmits a sound pulse that is reflected from the liquid surface. The elapsed time between sending a pulse and receiving an echo determines the level in the channel. Because the sensor does not contact the liquid, the 3010 provides long-term dependability with no scheduled maintenance. It is ideal for measuring flows containing harsh chemicals, grease, suspended solids or silt.
Try with Teledyne Isco Products.

Hope this will help you.

Best of Luck & Regards,
M A Muqtadir
Saudi Arabia

Your use of this site is subject to the terms and conditions set forth under Legal Notices and the Privacy Policy. Please read those terms and conditions carefully. Subject to the rights expressly reserved to others under Legal Notices, the content of this site and the compilation thereof is © 1999-2014 Nerds in Control, LLC. All rights reserved.

Users of this site are benefiting from open source technologies, including PHP, MySQL and Apache. Be happy.


Fortune
Any excuse will serve a tyrant.
-- Aesop
Advertise here
Advertisement
our advertisers
Help keep our servers running...
Patronize our advertisers!
Visit our Post Archive