Measureing liquid levels
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Posts: 46,084
Greetings! Im trying to come up with a way to measure the level of a
liquid in a container and use the basic stamp. Has anybody seen a
good way to do this?
Thanks in advance.
Jeff
liquid in a container and use the basic stamp. Has anybody seen a
good way to do this?
Thanks in advance.
Jeff
Comments
of the liquid and as the liquid above it rises or falls, the pressure
on it at the bottom will also rise/fall. I'm still looking for a good
water proof one myself to use on a submersible. The ones I've found
are >$300 so far.
--- In basicstamps@yahoogroups.com, "jemarcks" <jemarcks@y...> wrote:
> Greetings! Im trying to come up with a way to measure the level of
a
> liquid in a container and use the basic stamp. Has anybody seen a
> good way to do this?
> Thanks in advance.
>
> Jeff
read that a thermistor is good to sense liquid level (at least water) (I'v
figured out the thermistor [noparse][[/noparse]well, the damn data sheet], but I'm figuring out
op-amps now). From what I've learned, you put enough current through the
thermistor to raise its tempurature above the ambient air tempurature, and
since a liquid (like water) will dissipate heat better than free air, the
resistance will either rise or fall depending on whether you use a PTC or
NTC thermistor. When the liquid level reached the thermistor, the risistance
should change by an amount, indicating that the liquid has either reached or
fallen below the level that you set. You should also check the trigger level
in the worst case scenario, with the free air temp at its lowest and the
liquid temperature at its highest.
For details, though, you'll need to go elsewhere. I don't know the math well
enough to determine error.
Steve
Original Message
From: "jemarcks" <jemarcks@y...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, June 19, 2003 2:21 AM
Subject: [noparse][[/noparse]basicstamps] Measureing liquid levels
> Greetings! Im trying to come up with a way to measure the level of a
> liquid in a container and use the basic stamp. Has anybody seen a
> good way to do this?
> Thanks in advance.
>
> Jeff
>
>
>
> To UNSUBSCRIBE, just send mail to:
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>
I've used cheap transducers, such as a Data Instruments XCX01DNC designed
for air- $15. I've also used really expensive, sensitive transducers
designed for water - 0 -5 in /h20 full scale - $900. The difference is in
longetivity. Although they say it is compatible with air, not water, if you
use desiccant the XCX will do pretty well, in excess of a year. You could
replace it quite a few times before you'd spend what you would for one
designed for water.
What I would do (and am about to do for the water tank in my van) is run a
length of 1/4" tubing up from the bottom of the container, into a canister
containing desiccant, and then another length from the desiccant container
to the transducer. The output from the transducer (0-5V) goes into the stamp
via an ADC. This is the setup they use in a bubble gage, a $4000 instrument
designed to measure water level in wells, only they have a small compressor
which continually pushes air through the tube to keep it dry.
Another option would be to use a float attached to a potentiometer and an
ADC. I guess it depends on the desired range and resolution.
cheers,
Jeff
Original Message
From: "jemarcks" <jemarcks@y...>
> Greetings! Im trying to come up with a way to measure the level of a
> liquid in a container and use the basic stamp. Has anybody seen a
> good way to do this?
> Thanks in advance.
>
> Jeff
using the liquid as the dielectric. This can be accomplished with two
strips of adhesive foil tape on the outside of the container. This
"Capacitor" can be used in an RC oscillator, where the Stamp can
determine the fluid level by count the frequency returned. An additional
capacitor plate located on the bottom of the container might be required.
This plate should be connected to ground.
>I've been attempting to use a thermistor to measure temperature, and I've
>read that a thermistor is good to sense liquid level (at least water) (I'v
>figured out the thermistor [noparse][[/noparse]well, the damn data sheet], but I'm figuring out
>op-amps now). From what I've learned, you put enough current through the
>thermistor to raise its tempurature above the ambient air tempurature, and
>since a liquid (like water) will dissipate heat better than free air, the
>resistance will either rise or fall depending on whether you use a PTC or
>NTC thermistor. When the liquid level reached the thermistor, the risistance
>should change by an amount, indicating that the liquid has either reached or
>fallen below the level that you set. You should also check the trigger level
>in the worst case scenario, with the free air temp at its lowest and the
>liquid temperature at its highest.
>
>For details, though, you'll need to go elsewhere. I don't know the math well
>enough to determine error.
>
>Steve
>
>
Original Message
>From: "jemarcks" <jemarcks@y...>
>To: <basicstamps@yahoogroups.com>
>Sent: Thursday, June 19, 2003 2:21 AM
>Subject: [noparse][[/noparse]basicstamps] Measureing liquid levels
>
>
> > Greetings! Im trying to come up with a way to measure the level of a
> > liquid in a container and use the basic stamp. Has anybody seen a
> > good way to do this?
> > Thanks in advance.
> >
> > Jeff
> >
> >
> >
> > To UNSUBSCRIBE, just send mail to:
> > basicstamps-unsubscribe@yahoogroups.com
> > from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
> >
> >
> > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
> >
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
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>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
zman97211@y... writes:
>
>
> I've been attempting to use a thermistor to measure temperature, and I've
> read that a thermistor is good to sense liquid level (at least water) (I'v
> figured out the thermistor [noparse][[/noparse]well, the damn data sheet], but I'm figuring out
> op-amps now). From what I've learned, you put enough current through the
> thermistor to raise its tempurature above the ambient air tempurature, and
> since a liquid (like water) will dissipate heat better than free air, the
> resistance will either rise or fall depending on whether you use a PTC or
> NTC thermistor. When the liquid level reached the thermistor, the risistance
> should change by an amount, indicating that the liquid has either reached or
> fallen below the level that you set.
This approach is likely the easiest, cheapest and very reliable. In MOST
automobiles today, the LOW FUEL WARNING LIGHT works as described above for the
water......When the fixed position thermister is immersed in fuel, the
temperature of the thermister goes down, resistance goes up and it keep the low
fuel
warning lamp OFF (thermister provided direct ground for the warning lamp).
Once the fuel level inside the fuel tank is below the thermister that is now
in free air, the thermister heats up, resistance goes down and the thermister
then provides ground for the low fuel warning lamp which now illuminates.....
Did you ever notice how when you are just getting low on fuel the light will
glow dimly, then go out (back and forth).....this is when the fuel level is
"just at" the same level as the thermister, fuel sloshing causes the thermister
to be covered with fuel, and not covered with fuel which corresponds the the
low fuel warning light off and on.......
[noparse][[/noparse]Non-text portions of this message have been removed]
method from scott edwards and as mentioned to by
others.
snip...The dielectric constant (an important factor in
determining the capacitance of
two conductors separated by an insulator) of water is
very different from that of
air. Measure the capacitance across the tank to
determine the proportion of water
to air and therefore the level of the water...snip
http://www.parallax.com/Downloads/Documentation/nv/v1/col/NV27-Measuring_Water_L\
evel.pdf
hope this helps,
ross
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I don't know a lot about the Capacitive sensing method, and Im away from the
office, but I seem to remember that National made a chip that does this type
of measurement. It used two rods in the tank.
The other thing to remember is that this type of sensing is not for flammable
liquids, Gasoline, Kerosene, and fuel type liquids.
Alan Bradford
Plasma Technologies
> here is an excellent reference using the capacitance
> method from scott edwards and as mentioned to by
> others.
>
> snip...The dielectric constant (an important factor in
> determining the capacitance of
> two conductors separated by an insulator) of water is
> very different from that of
> air. Measure the capacitance across the tank to
> determine the proportion of water
> to air and therefore the level of the water...snip
>
>
> http://www.parallax.com/Downloads/Documentation/nv/v1/col/NV27-Measuring_Wate
> r_Level.pdf
>
> hope this helps,
> ross
>
[noparse][[/noparse]Non-text portions of this message have been removed]
aircraft. It is an off the shelf unit that is used in numerous aircraft.
About $90. Small aluminum tube inside of a larger tube. Simple and quite
accurate.
Hi,
I don't know a lot about the Capacitive sensing method, and Im away from
the
office, but I seem to remember that National made a chip that does this
type
of measurement. It used two rods in the tank.
The other thing to remember is that this type of sensing is not for
flammable
liquids, Gasoline, Kerosene, and fuel type liquids.
Alan Bradford
Plasma Technologies
> here is an excellent reference using the capacitance
> method from scott edwards and as mentioned to by
> others.
>
> snip...The dielectric constant (an important factor in
> determining the capacitance of
> two conductors separated by an insulator) of water is
> very different from that of
> air. Measure the capacitance across the tank to
> determine the proportion of water
> to air and therefore the level of the water...snip
>
>
>
http://www.parallax.com/Downloads/Documentation/nv/v1/col/NV27-Measuring_Wate
> r_Level.pdf
>
> hope this helps,
> ross
>
[noparse][[/noparse]Non-text portions of this message have been removed]
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one to stay away from when dealing with flammable liquids.
-Beau Schwabe
>Hi,
>I don't know a lot about the Capacitive sensing method, and Im away from the
>office, but I seem to remember that National made a chip that does this type
>of measurement. It used two rods in the tank.
>
>The other thing to remember is that this type of sensing is not for flammable
>liquids, Gasoline, Kerosene, and fuel type liquids.
>
>Alan Bradford
>Plasma Technologies
>
>
> > here is an excellent reference using the capacitance
> > method from scott edwards and as mentioned to by
> > others.
> >
> > snip...The dielectric constant (an important factor in
> > determining the capacitance of
> > two conductors separated by an insulator) of water is
> > very different from that of
> > air. Measure the capacitance across the tank to
> > determine the proportion of water
> > to air and therefore the level of the water...snip
> >
> >
> >
> http://www.parallax.com/Downloads/Documentation/nv/v1/col/NV27-Measuring_Wate
> > r_Level.pdf
> >
> > hope this helps,
> > ross
> >
>
>
>
>[noparse][[/noparse]Non-text portions of this message have been removed]
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
There are a lot of ways to measure liquid levels, in order to start to
say which to use much more information needs to be known like what's the
liquid, water, gasoline, sewage? What's the range of levels possible?
Do you need an analog output or just switch closures? If analog how
precise?
The compressor is there not to keep the tube dry, but to maintain the
pressure in the tube the same as the pressure at the bottom of the tank.
I had a 1929 car that used this method for a gas gauge. You needed to
work a small pump on the dash and then read the gas level as a column of
red liquid. This way the sensor can be up out of the liquid. The pump
would only need to be run just prior to making a reading and the
pressure will hold for wuite some time. If the sensor has a problem
with the liquid you can use a "U" tube with oil or some other liquid
between the sensor and the fluid it does not like.
Have Fun,
Brooke Clarke, N6GCE
http://www.PRC68.com
>Date: Thu, 19 Jun 2003 12:52:45 -0700
> From: "Jeff K" <kennedy@t...>
>Subject: Re: Measureing liquid levels
>
>Jeff,
> I've used cheap transducers, such as a Data Instruments XCX01DNC designed
>for air- $15. I've also used really expensive, sensitive transducers
>designed for water - 0 -5 in /h20 full scale - $900. The difference is in
>longetivity. Although they say it is compatible with air, not water, if you
>use desiccant the XCX will do pretty well, in excess of a year. You could
>replace it quite a few times before you'd spend what you would for one
>designed for water.
>
>What I would do (and am about to do for the water tank in my van) is run a
>length of 1/4" tubing up from the bottom of the container, into a canister
>containing desiccant, and then another length from the desiccant container
>to the transducer. The output from the transducer (0-5V) goes into the stamp
>via an ADC. This is the setup they use in a bubble gage, a $4000 instrument
>designed to measure water level in wells, only they have a small compressor
>which continually pushes air through the tube to keep it dry.
>
>Another option would be to use a float attached to a potentiometer and an
>ADC. I guess it depends on the desired range and resolution.
>
>cheers,
> Jeff
>
>
Original Message
>From: "jemarcks" <jemarcks@y...>
>
>
>
>
>
>>Greetings! Im trying to come up with a way to measure the level of a
>>liquid in a container and use the basic stamp. Has anybody seen a
>>good way to do this?
>>Thanks in advance.
>>
>>Jeff
>>
Now i need to go try some out.
Thanks again everybody!
Jeff
--- In basicstamps@yahoogroups.com, "jemarcks" <jemarcks@y...> wrote:
> Greetings! Im trying to come up with a way to measure the level of
a
> liquid in a container and use the basic stamp. Has anybody seen a
> good way to do this?
> Thanks in advance.
>
> Jeff