Well, many methods were discussed here and will to permite the determaination of the flow of liquids in a pipe. Interesting is to observe that in some applications, were corrosive or dangerous liquids are been transfered, the measurement of the mass variation during the time is largelly used. This mass measurement can be done locating the storage tank or container over a balance with a necessary precision. The PLC of the balance can give your information continuously in "mass flow" or "volume flow", in the second case you need to introduce the specific mass of the liquid in the software of the PLC.

Best regards

Depending on your actual system there are a couple of options. The first would be optical detection. If you can add view ports to your piping and the liquid is not clear it should work. You could use aligned LEDs and photocells for a rough level measurement. The next option would be ultrasonic level sensors. I don't know how having multiple on the same line would effect them. If you are just looking for an emergency shut off in case the level drops a single sensor would do.

Regards,

Jake

Thanks jecob

using IR sensor

Prashant,

There are many solutions - but also I need to know what you mean by a 'flowmeter'

If we take that to mean a prohibition against spinning paddle wheels then we have;

1) Calibrated pitot tubes

No description needed.

2) Ultrasonics

Using Doppler effect - a TX/RX pair straddling the pipe

3) Thermal methods

If the liquid has well known c and k then a hot-wire 'anenometer' would suffice

4) Piezoelectric vortex/swirl meters

Flow creates a stable pattern that exerts pressure against piezo elements

5) Electrodynamic

If the liquid is conductive, then passing a current through it in the presence of a magnetic field will yield a detectable voltage.

If you can describe the liquid, and the reason why flowmeters are forbidden, I'll come up with even more methods.

;)

In response to the first reply by Jacob Bertrand "If you are just looking for an emergency shut off in case the level drops a single sensor would do."

Any emergency system would in itself have a backup so at least two source and sensor systems should be used for safe operation. One if the flow fails and one if one of the detectors fails. However, a single sensor is in most cases better than no sensor at all. Aircraft crashes due to failing pitot tubes have been reported.

A simple technique is to use a known volume and a watch to measure the time.

Well, many methods were discussed here and will to permite the determaination of the flow of liquids in a pipe. Interesting is to observe that in some applications, were corrosive or dangerous liquids are been transfered, the measurement of the mass variation during the time is largelly used. This mass measurement can be done locating the storage tank or container over a balance with a necessary precision. The PLC of the balance can give your information continuously in "mass flow" or "volume flow", in the second case you need to introduce the specific mass of the liquid in the software of the PLC.

Best regards

Maxim, thank you for pointing out the discrepancy in my wording. I was thinking of a simple system and should have worded it as "a quick shut-off" or "low level-alert". I completely agree that systems that handle hazardous materials need redundant safeties.

Magnetohidronamic

Hi Dear Prashant

Flow Meter Directory is a very good site on flowmeter technology. It is dedicated to flow and contains useful flow information. There is in easy loading html for your convenience. Examples are :Orifice Plate Calculator,Unit Converter , Flow Rate Calculator (For Windows 7 and Windows XP) and Pipe Properties Calculator (For Windows 7 and Windows XP) small but handy flow programs which enables you to make very fast flow related calculations offline you can download them free.the html address is as below:

http://www.flowmeterdirectory.com/flowmeter_flow_calc.html

I hope this is useful and solve your problem.

I think that you should change the flow, for other variable of control, could be volume, level of volume in the tank discharge, or level of feed tank.

To keep the balance of the process; is necessary that the level, the volume or other variables must be constants in the time. Using indirect control, establishing some values of mass balance or flow balance it is possible to measure the other control parameters.

Also, one specific flow could be measure (Only in the case of one pump discharge pipe). Install first a pipe returning to feed box (with valve). Checking first the difference in the volume in the feed box, time and flow when the pump is started, the flow could be modify using the valves at the pump discharge or at the circuling pipe installed to this control.

After of establish the flow; you could keep constant it and could be modified it using the valves.

Regards

You can use pressure tabs in an elbow (centrifual force) and with a differential pressure device. If you dont want to modify the pipe an external ultrasonic device (Panametrics) is very useful, and accurate

You may use Magneto-fluid-dynamic Flow meters : It is assumed here that the fluid under consideration has significant electrical conductivity that when it flows in the presence of a magnetic field potential differences are induced in it. By placing two electrodes in opposite sides of the pipe wall on a radial line transverse to an imposed magnetic field, you might measure the induced potential difference which can be correlated to measure the flow rate. If the flow is fully-developed and is radially symmetric, then the ratio of the induced potential difference to the flow rate is not influenced by the shape of the velocity profile. For further details you may refer to a good book on MFD like Cramer and Pai. It is a well-known technique.

You cthe use a weighing device with time measurment and calculate the flow of liquid like water by m/t

You can use a weighing device with time measurment and calculate the area of flow and dtermine the flow of liquid like water by m3/m2/t

Any instrument used to measure flow is, by definition, a flow meter. You should rephrase the question.

I do agree with Alexander Dvorkin