Help me design a weight detector for a water filling system

[gg]

Weight Detector

I am working on a water filling system. When i set 500ml of water, the water will be filled into the bottle, once it fill till 500ml, it will stop. I want to create something like a weight detector that can detect the water level reach 500ml and then stop the water from filling the bottle. Can anyone provide information on these?

 

[glenjoy]

Weight Detector

Better use a flowmeter for the design.

 

[sinatra]

Re: Weight Detector

Hello gg.
I would propose 2 different techniques.

1- If your system can get in contact with the liquid I think a capacitive sensor could do the job. You just take 2 wires (can be straight or twisted) and deep them into the bottle (deep to the botom of the bottle). The wires can be covered with a plastic insulating material. The dielectric constant of the water is very high (arroung 70 or more). You should be able to measure a big change in capacitance when those wires are imerged into water. This method should give a linear relation between the capacitance and the depth.

2- If it is an non-invasive problem (no contact with the water is allowed) you can try to use ultrasound. For long distances you can measure time difference between a sent pulse and the reflected received pulse. The transmiter and the receiver can be the same device. If the distance is small I sugest you to transmit busts of a sinusoidal waveform (in the resonant frequency of the tranmiter/receiver to get maximum efficiency) and beat the received waveform with the transmited one. This way will allow you to measure phase differences and then the depth.

Hope it helps.
S.

 

[glenjoy]

Weight Detector

I think he will use it in bottled water.

 

[gg]

Re: Weight Detector

Thanks for your information. But, isn't the used of flowmeter is to measure the water rate and then by this can detect how much is filled into the bottle? The type i want is the type that can measure the weight of the water filled into the bottle. Please help me with this.

 

[dpsman]

Re: Weight Detector

How about a strain gauge ?.

 

[sinatra]

Re: Weight Detector

dspman: I think it is a good idea to use strain gages to measure the weight or simply a balance.

The empty bottle is weigthed before filling (calibration=zero liquid).
Then during the time it is filled up the weght is continuously monitored. When you reach the right weight of 500ml of liquid you stop the filling process.


S.

 

[IanP]

Re: Weight Detector

A small "load cell" based on strain gauges will do the job.
https://www.omega.com/literature/transactions/volume3/load3.html
Strain gauges are inexpensive, linear and reliable.
Regards,
IanP

 

[chupos]

Re: Weight Detector

I would also suggest using a load cell, as they are pretty easy to use and calibrate, and are really accurate.
If you need more info on load cells, I can provide some, as I work with them pretty often
The suggestion of using a flow meter, is, in my opinion, not very good, as it is much more complicated, and actually not as accurate if you are interested in stopping at 500ml water.
With water its accurate enough in most cases to assume 1 ml = 1 gramm, so a load cell will perform great for your application

 

[freewilly30]

Re: Weight Detector

simply u could use any piezo material the voltage generated is directly proportional to the force applied( weight) ,but the voltage generated would be so small
use an amplifier( non inverting )
then an ADC to a controller which output could be used to close the water system by giving a signal to the valve

 

[grabik]

Re: Weight Detector

RS flow sensor

1330 pulses/L
stock No 256-225

 

[scdoro]

Re: Weight Detector

Hi,

To Chupos : I am very keen to know abt the load sensor which u mention can detect that weight of the water.. Is there any way that i can write to u ? below is the msg i have post at the forum. I need help on that. thanks

Hi All,
I need to build a device that are build on the drip and can detect and alert me when the weight of water drops from ( let say 500ml to 10ml ) . Meaning when the water in a full fill drip bag drops to a level of 10 ml, i will be able to detect that.( there is no need to give me the exact reading when the weight is dropping.).all i need is to alert me when the water goes below the weight of 10 ml. I was thinking of getting that to trigger an alarm. i have no idea where i should start from.. and was wondering how to build that weight detector circuit using ??
oh, btw, the specification of my sensor is between the range from 1000ml to 10 ml
that will be great.
Thanks for ur help..