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Hi to all,

i am looking forward to buy one sensor with the precision to read volumes in the range of millilitres (ml).

I found this one selling over atlas-scientific, but it is quite expensive:
https://www.atlas-scientific.com/product_pages/sensors/small-flow-meter.html

I would like to find a more economical solution.

Best regards,
Sousa.
« Last Edit: March 27, 2013, 03:45:15 pm by Sousa » Logged

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Would this fit my needs?

http://www.ebay.com/itm/High-precision-water-flow-meter-Water-flow-sensor-counter-G1-4-RoHS-/140942551599?pt=LH_DefaultDomain_0&hash=item20d0d4aa2f

I am not familiarized with the functioning of this sensor, but if this one measures about 100ml per minute, means that i could get a rate of 50mL per 30 seconds, and even though i need to insert on my system liquids in very low quantities, i could dissolve these liquids into wanter.

So, dissolving 6ml of my compound at my 100ml reservoir and injecting 50mL into my system, i could get my 3ml inside my system.

Would this be possible?
« Last Edit: March 27, 2013, 04:14:55 pm by Sousa » Logged

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I think they both have a small turbine inside and count the rotations.

The cheap one is for water. I read 0.1-3L/min, so 100ml/min is the minimum. Don't expect any accuraty at the minimum. Don't be surprised if the inaccuracy at 100ml/min is 100%.
You could use 100ml/min for 30 seconds to get 50ml.

Is your compound aggressive ? The atlas-scientific is made from a special material to be able to handle all kind of liquids.

There are other ways to measure liquid flow.
http://en.wikipedia.org/wiki/Flow_measurement
http://en.wikipedia.org/wiki/Mass_flow_meter
Some liquid flow meters are for in cars, they are not very expensive.
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Dee Why NSW
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Would this fit my needs?

Would this be possible?

Probably no, and probably not.

Both devices are hall effect flow meters. The first uses a turbine and the second a paddlewheel. I understand that turbines usually run faster and are inherently more accurate in smaller devices but I submit neither is suitable and neither company knows what it is doing anyway.

The most fundamental issue is that these devices are for measuring rate and you want to measure volumes, and small ones at that. For that, you would be better off with a batch volume dispenser. 

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Hey guys,

thank you both for your replies, in fact, in the meanwhile i found that solenoid valves can be very precise:

http://www.ebay.com/itm/Aquarium-Peristaltic-Dosing-Pump-head-/271174784528?pt=LH_DefaultDomain_0&hash=item3f2346d610

This one measures in mL and seems very precise. What do you say?

cheers,
Sousa
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Hey guys,

thank you both for your replies, in fact, in the meanwhile i found that solenoid valves can be very precise:

http://www.ebay.com/itm/Aquarium-Peristaltic-Dosing-Pump-head-/271174784528?pt=LH_DefaultDomain_0&hash=item3f2346d610

This one measures in mL and seems very precise. What do you say?

cheers,
Sousa

That appears to me to be a pump rather then a flow measurement sensor. Says it runs at 3500 RPM. Solenoids don't rotate at any RPM they are on or off?

Lefty
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Dee Why NSW
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Hey guys,

thank you both for your replies, in fact, in the meanwhile i found that solenoid valves can be very precise:

 What do you say?


Yes, that is the sort of thing I was thinking about. Probably much simpler to programme too!
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I have never worked with peristaltic pumps, so I don't know anything about it.
But I wonder how much they leak, and I doubt if they are accurate.

Max flow rate - 0.8 to 1 ml per second.
Min Flow rate - 0.1-0.15 ml per second.
How can this be set ? The pump is 12V. Is that dependent on the the pressure or the flexibility of the tube ?
The motor life time is only 300 hours ? That is 4 month if it is for 10% of the time on.

http://en.wikipedia.org/wiki/Peristaltic_pump

Why not use the obvious ?
You want a certain amount of a fluid, use a seringe.
You want it automatically, use an Arduino with a motor or servo to control the seringe.
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http://www.ebay.com/itm/Aquarium-Peristaltic-Dosing-Pump-head-
That appears to me to be a pump rather then a flow measurement sensor. Says it runs at 3500 RPM. Solenoids don't rotate at any RPM they are on or off?


While I have no details on this particular item, the operative words are "peristaltic" and "dosing". It says it can run at 3500 rpm but it should be be able to be indexed so that it can make a set number of revolutions or even a partial revolution. It is a positive displacement pump with a compressible pipe worked by a roller cam and a stepper motor, or the like.  

Another way of doing this is by gravity feed into a fixed volume with a solenoid-operated valve above and below
« Last Edit: March 27, 2013, 08:26:16 pm by Nick_Pyner » Logged

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http://www.ebay.com/itm/Aquarium-Peristaltic-Dosing-Pump-head-
That appears to me to be a pump rather then a flow measurement sensor. Says it runs at 3500 RPM. Solenoids don't rotate at any RPM they are on or off?


While I have no details on this particular item, the operative words are "peristaltic" and "dosing". It says it can run at 3500 rpm but it should be be able to be indexed so that it can make a set number of revolutions or even a partial revolution. It is a positive displacement pump with a compressible pipe worked by as roller cam and a stepper motor, or the like.  

It is a positive displacement type pump but doesn't seem to have more then two wires and those have to power the motor, so where is the feedback signal going to come from to determine actual flow? Running the motor at reduced voltage assuming you will get reduced flow at some specific accurate amount is very unrealistic. This pump head requires an independent flow measurement sensor to be useful for precision flow control.

Lefty
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...It is a positive displacement pump with a compressible pipe worked by as roller cam and a stepper motor, or the like.  
This one has only a black and red wire (second picture). So it is a normal brushed 12V DC motor and it must have a gear.

(retrolefty wrote the same, while I was typing this)
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This one has only a black and red wire (second picture). So it is a normal brushed 12V DC motor and it must have a gear.


Ah, well, I guess not that particular peristaltic pump then.........
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