Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel
Member Login
Arrow Left Previous Page
Page / 3
Posted: 2/23/2006 3:01:38 PM EDT
[Last Edit: 3/29/2006 5:10:30 PM EDT by scottryan]
Does anyone know of a method to detect boiling water inside a tank? Somehow detecting the turbulance of the water? Or just a way to detect if the tank is full or empty.

Conductivity detection cannot be used and floats cannot be used.

I was thinking of using halleffect detectors through the tank but I don't want to penitrate the tank if possible.
Link Posted: 2/23/2006 3:03:30 PM EDT
Open the valve for a second.
Link Posted: 2/23/2006 3:04:43 PM EDT
Touch it and see if it's Hot
Link Posted: 2/23/2006 3:07:18 PM EDT

Originally Posted By Carhlr:
Touch it and see if it's Hot



That won't work. The presence of water must be detected, not heat. The water just happens to be boiling.
Link Posted: 2/23/2006 3:07:48 PM EDT
audio?

Link Posted: 2/23/2006 3:07:55 PM EDT
Sound or thermometer
Link Posted: 2/23/2006 3:08:11 PM EDT
[Last Edit: 2/23/2006 3:09:00 PM EDT by xinflt]
Ask the crew when they climb out.

What's boiling water doing in a tank anyway?

Edit to add: open a hatch and look inside.
Link Posted: 2/23/2006 3:10:47 PM EDT

Originally Posted By xinflt:
Ask the crew when they climb out.

What's boiling water doing in a tank anyway?

Edit to add: open a hatch and look inside.



The device has to be left alone. There is not someone there to look at it.
Link Posted: 2/23/2006 3:11:44 PM EDT
Is this an open top tank or a pressure tank?
Link Posted: 2/23/2006 3:12:28 PM EDT
[Last Edit: 2/23/2006 3:12:56 PM EDT by scottryan]

Originally Posted By AMZ:
Sound or thermometer



A thermometer will not work. The level of the water must be detected. When the water boils off (no more turbulence) the device must shut off.
Link Posted: 2/23/2006 3:12:55 PM EDT
[Last Edit: 2/23/2006 3:13:52 PM EDT by xinflt]

Originally Posted By scottryan:

Originally Posted By xinflt:
Ask the crew when they climb out.

What's boiling water doing in a tank anyway?

Edit to add: open a hatch and look inside.



The device has to be left alone. There is not someone there to look at it.



Is it in the motor pool? How did it get filled with water?

what kinda tank is this?
Link Posted: 2/23/2006 3:13:39 PM EDT
What class is this homework problem for?
Link Posted: 2/23/2006 3:13:43 PM EDT

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.
Link Posted: 2/23/2006 3:16:11 PM EDT

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



Not if you are expecting it to boil.
Link Posted: 2/23/2006 3:17:13 PM EDT

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



If the tank is enclosed then the pressure inside will be higher than outside unless there is a way for pressure to release. If there is a way for pressure to release then there is a way to check the temp/level. If the tank is fully enclosed but with a pressure release valve you could catch the steam being released and cool it back down to water and then use that as a mesure on how much water is left in the tank.
Link Posted: 2/23/2006 3:18:04 PM EDT

Originally Posted By The_Reaper:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



Not if you are expecting it to boil.




It is not completely inclosed. Steam escapes out of the top of it.

It is not pressurized like a tea kettle.
Link Posted: 2/23/2006 3:19:15 PM EDT

Originally Posted By scottryan:

Originally Posted By The_Reaper:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



Not if you are expecting it to boil.




It is not completely inclosed. Steam escapes out of the top of it.

It is not pressurized like a tea kettle.



steam escapes out of the top?

So watch the steam. When it stops your tank is dry.

Link Posted: 2/23/2006 3:19:28 PM EDT

Originally Posted By none:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



If the tank is enclosed then the pressure inside will be higher than outside unless there is a way for pressure to release. If there is a way for pressure to release then there is a way to check the temp/level. If the tank is fully enclosed but with a pressure release valve you could catch the steam being released and cool it back down to water and then use that as a mesure on how much water is left in the tank.



Won't work because the tank is sometimes not completely full before starting the machine. There is no way to quantify how much water you start and end with.
Link Posted: 2/23/2006 3:19:49 PM EDT
[Last Edit: 2/23/2006 3:22:12 PM EDT by krpind]

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



As you raise the pressure, the temp that it takes to make the water boil also rises. You could use a thermostat that kills the heat source......that is simple. Figuring out the temp you need to set it at will be more of a challenge. (someone where will know the formula to figure out how much temp rise is needed with how much pressure)

There are switches that make conections when submurged(sp?) this will be a problem because I don't know how many heat cycles they could survive. Plus boiling water doesn't have a steady level.
Link Posted: 2/23/2006 3:20:04 PM EDT

Originally Posted By Red_Beard:

Originally Posted By scottryan:

Originally Posted By The_Reaper:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



Not if you are expecting it to boil.




It is not completely inclosed. Steam escapes out of the top of it.

It is not pressurized like a tea kettle.



steam escapes out of the top?

So watch the steam. When it stops your tank is dry.




By that time the heating element is ruined.
Link Posted: 2/23/2006 3:20:16 PM EDT
you'd need sensors of some sort pressure and temp, from those 2 plus the volume of the tank and knowning the volume of the water you could probably detect boiling. Just my guess.
Link Posted: 2/23/2006 3:21:25 PM EDT
[Last Edit: 2/23/2006 3:22:09 PM EDT by none]
n/m just got caught up.
Link Posted: 2/23/2006 3:22:03 PM EDT

Originally Posted By krpind:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



As you raise the pressure, the temp that it takes to make the water boil also rises. You could use a thermostat that kills the heat source......that is simple. Figuring out the temp you need to set it out will be more of a challenge. (someone where will know the formula to figure out how much temp rise is needed with how much pressure)

There are switches that make conections when submurged(sp?) this will be a problem because I don't know how many heat cycles they could survive. Plus boiling water doesn't have a steady level.



Thermostats will not work.

Pressure dectection will not work.
Link Posted: 2/23/2006 3:23:59 PM EDT
tell us why thermostats or pressure sensors will not work. Just saying something will not work does not give enough info for a work around.
Link Posted: 2/23/2006 3:24:45 PM EDT
Not an easy answer without a lot more info...

If the water is going to boil off then we must think that the tank is vented to the outside.. If the tank were closed then for ever 1psi increase in pressure the boiling point of the water would go uo by 3*F.

Do you want to detect if the water is at a boil or not... or just the presence of water?

If you are just looking for the presence of water then you can use a optical prisim sensor. I don't know what the temature limits of these are but they work very well.. This would be the best bet for the low water sensor.
Link Posted: 2/23/2006 3:24:53 PM EDT

Originally Posted By none:
tell us why thermostats or pressure sensors will not work. Just saying something will not work does not give enough info for a work around.



The pressure difference between the outside and inside is not great enough for cheap, pratical detection.
Link Posted: 2/23/2006 3:25:13 PM EDT

Originally Posted By scottryan:

Originally Posted By krpind:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



As you raise the pressure, the temp that it takes to make the water boil also rises. You could use a thermostat that kills the heat source......that is simple. Figuring out the temp you need to set it out will be more of a challenge. (someone where will know the formula to figure out how much temp rise is needed with how much pressure)

There are switches that make conections when submurged(sp?) this will be a problem because I don't know how many heat cycles they could survive. Plus boiling water doesn't have a steady level.



Thermostats will not work. I wonder why?

Pressure dectection will not work. I wonder about this as well



What exactly are you trying to accomplish?

Because to detect boiling water in a tank.......either a thermostat or pressure detection if properly calibrated will work.
Link Posted: 2/23/2006 3:26:04 PM EDT

Originally Posted By NwG:
Not an easy answer without a lot more info...

If the water is going to boil off then we must think that the tank is vented to the outside.. If the tank were closed then for ever 1psi increase in pressure the boiling point of the water would go uo by 3*F.

Do you want to detect if the water is at a boil or not... or just the presence of water?

If you are just looking for the presence of water then you can use a optical prisim sensor. I don't know what the temature limits of these are but they work very well.. This would be the best bet for the low water sensor.



BLUE: This is preferable

RED: I want to avoid penitrating the tank wall.

Link Posted: 2/23/2006 3:27:20 PM EDT
So basically you have a pot of water and want to turn off the heat before all the water has boiled away. Right?

Why can't floats be used?


I guess I'd rig up some kind of microphone/stethescope up the side of the tank and see if you can hear a difference when the water drops below the level of the mic.

Link Posted: 2/23/2006 3:27:54 PM EDT

Originally Posted By krpind:

Originally Posted By scottryan:

Originally Posted By krpind:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



As you raise the pressure, the temp that it takes to make the water boil also rises. You could use a thermostat that kills the heat source......that is simple. Figuring out the temp you need to set it out will be more of a challenge. (someone where will know the formula to figure out how much temp rise is needed with how much pressure)

There are switches that make conections when submurged(sp?) this will be a problem because I don't know how many heat cycles they could survive. Plus boiling water doesn't have a steady level.



Thermostats will not work. I wonder why?

Pressure dectection will not work. I wonder about this as well



What exactly are you trying to accomplish?

Because to detect boiling water in a tank.......either a thermostat or pressure detection if properly calibrated will work.



Detecting the water in a water distiller.

The tank is the incomming water that is boiled off and then purified.

The tank holds about a gallon of water.
Link Posted: 2/23/2006 3:28:21 PM EDT

Originally Posted By scottryan:

Originally Posted By NwG:
Not an easy answer without a lot more info...

If the water is going to boil off then we must think that the tank is vented to the outside.. If the tank were closed then for ever 1psi increase in pressure the boiling point of the water would go uo by 3*F.

Do you want to detect if the water is at a boil or not... or just the presence of water?

If you are just looking for the presence of water then you can use a optical prisim sensor. I don't know what the temature limits of these are but they work very well.. This would be the best bet for the low water sensor.



BLUE: This is preferable

RED: I want to avoid penitrating the tank wall.




Is this a still?

The tank is already penetrated if there's away for the steam to boil off.

Link Posted: 2/23/2006 3:29:14 PM EDT
[Last Edit: 2/23/2006 3:29:31 PM EDT by scottryan]

Originally Posted By Red_Beard:
So basically you have a pot of water and want to turn off the heat before all the water has boiled away. Right?

Why can't floats be used?


I guess I'd rig up some kind of microphone/stethescope up the side of the tank and see if you can hear a difference when the water drops below the level of the mic.




BLUE: Yes, that is exactly what I want to do.

Floats can be fouled.

Also, the tank is stainless steel. Everything in the tank should be stainless.
Link Posted: 2/23/2006 3:29:15 PM EDT

Originally Posted By scottryan:

Originally Posted By krpind:

Originally Posted By scottryan:

Originally Posted By krpind:

Originally Posted By scottryan:

Originally Posted By krpind:
Is this an open top tank or a pressure tank?



The tank is inclosed but the pressure difference between it and the outside is negligible.



As you raise the pressure, the temp that it takes to make the water boil also rises. You could use a thermostat that kills the heat source......that is simple. Figuring out the temp you need to set it out will be more of a challenge. (someone where will know the formula to figure out how much temp rise is needed with how much pressure)

There are switches that make conections when submurged(sp?) this will be a problem because I don't know how many heat cycles they could survive. Plus boiling water doesn't have a steady level.



Thermostats will not work. I wonder why?

Pressure dectection will not work. I wonder about this as well



What exactly are you trying to accomplish?

Because to detect boiling water in a tank.......either a thermostat or pressure detection if properly calibrated will work.



Detecting the water in a water distiller.

The tank is the incomming water that is boiled off and then purified.

The tank holds about a gallon of water.



OK, measure how much water you put into the thing, and then shut it down and refill when about half of that comes out the other end.

Link Posted: 2/23/2006 3:29:53 PM EDT
The boiling water carries away heat. A thermostat or thermistor placed near the heat source, presumably near the bottom of the tank, will detect the heat rise when the water drops below that level and the temperature starts to run away.
Link Posted: 2/23/2006 3:30:35 PM EDT

Originally Posted By Red_Beard:

Originally Posted By scottryan:

Originally Posted By NwG:
Not an easy answer without a lot more info...

If the water is going to boil off then we must think that the tank is vented to the outside.. If the tank were closed then for ever 1psi increase in pressure the boiling point of the water would go uo by 3*F.

Do you want to detect if the water is at a boil or not... or just the presence of water?

If you are just looking for the presence of water then you can use a optical prisim sensor. I don't know what the temature limits of these are but they work very well.. This would be the best bet for the low water sensor.



BLUE: This is preferable

RED: I want to avoid penitrating the tank wall.




Is this a still?

The tank is already penetrated if there's away for the steam to boil off.




Yes, it is a still.

I know it is penitrated. I just don't want to penitrate it with electronic equipment.
Link Posted: 2/23/2006 3:32:28 PM EDT

Originally Posted By Arlis:
The boiling water carries away heat. A thermostat or thermistor placed near the heat source, presumably near the bottom of the tank, will detect the heat rise when the water drops below that level and the temperature starts to run away.



Won't work. The device needs to be stopped before the water is boiled off. The device needs to be stopped when the water level is low but not lower than the heating element.
Link Posted: 2/23/2006 3:32:31 PM EDT
A heat element that is boiling water will cycle on and off as it gets to a certain temp. Put a volt meter on the voltage to the heater element and have it do a auto shutdown when the heater element stays on too long. Preferable do this before it burns out. Will take some experamenting to get the heat cycles down before letting it run on its own.

Example: say your heater element stays on for 5 seconds during a normal heat cycle. Have a relay trip when said voltage is present for say 10 seconds. This will allow a small leeway during water adds. If you have to add water manually then hook up a override switch so you cna leave the heater element on until the water reaches boiling point.
Link Posted: 2/23/2006 3:32:54 PM EDT

Originally Posted By Red_Beard:


OK, measure how much water you put into the thing, and then shut it down and refill when about half of that comes out the other end.




Dammit.....that is too simple......we need a complicated solution.

PS put the float in the condensate tank.
Link Posted: 2/23/2006 3:34:20 PM EDT
[Last Edit: 2/23/2006 3:39:46 PM EDT by Headlice]
check for condensation?
.
ETA: Check for a condensation line?
Link Posted: 2/23/2006 3:38:20 PM EDT
[Last Edit: 2/23/2006 3:42:35 PM EDT by ffsparky26]
Ultrasonic or capacative level detection?

You would need to put some penetrations in the tank but there would be no float.

Ultrasonic Level Detection

Capacitive Sensor
Link Posted: 2/23/2006 3:39:01 PM EDT

Originally Posted By ffsparky26:
Ultrasonic or capacative level detection?

You would need to put some penetrations in the tank but there would be no float.



Nope, I can't use electricity inside the tank.
Link Posted: 2/23/2006 3:41:15 PM EDT

Originally Posted By scottryan:

Originally Posted By ffsparky26:
Ultrasonic or capacative level detection?

You would need to put some penetrations in the tank but there would be no float.



Nope, I can't use electricity inside the tank.



Seriously, can you measure the condensate?
Link Posted: 2/23/2006 3:43:08 PM EDT
You need to come up with a device that works on the weight of the tank. The tank will get lighter as water boils off.

When it gets to a preset weight have it shut off.
Link Posted: 2/23/2006 3:43:18 PM EDT
[Last Edit: 2/23/2006 3:43:37 PM EDT by Taffy223]
.
Link Posted: 2/23/2006 3:46:00 PM EDT

Originally Posted By scottryan:

Originally Posted By ffsparky26:
Ultrasonic or capacative level detection?

You would need to put some penetrations in the tank but there would be no float.



Nope, I can't use electricity inside the tank.



The hall effect solution will require electricity too.

You need to give us all of the requiremets up front, it will help us find you a solution.
Link Posted: 2/23/2006 3:50:52 PM EDT
Use some of those evil armor piercing rounds... Duh.
Link Posted: 2/23/2006 3:51:20 PM EDT
WTF IS THIS THREAD ABOUT???!!!!
Link Posted: 2/23/2006 3:54:34 PM EDT

Originally Posted By FASTSH00TER:
WTF IS THIS THREAD ABOUT???!!!!



He is building a still and don't want to burn out his electric heater element.
Link Posted: 2/23/2006 3:54:49 PM EDT
[Last Edit: 2/23/2006 4:02:25 PM EDT by ffsparky26]
How about a machine vision solution?

You can place a camera at the top of the tank looking down and use machine vision to analyze if the water is boiling or not.

You would have trouble with condensation on the lense, thats why an ultrasonic transducer looking down from the tank to measure the level would be best.

One penetration at the top of the tank is not much. You can get the ultrasonic transducers in pharmacutical and food grades, so no need to worry there.


You could measure the flow rate of the water coming in and how long the valve letting the water in is open to calculate the volume of water in the tank, measure inlet temperature. Then knowing how large the heating element is you could calculate how long to boil the water.


Link Posted: 2/23/2006 4:04:35 PM EDT
folks have suggested a lot of solutions.

Here is a fool proof one. Buy a high quality coffee maker that has auto-shutoff (like when the pot gets empty) and see how they do it.
Link Posted: 2/23/2006 4:07:47 PM EDT

Originally Posted By Thuban:
You need to come up with a device that works on the weight of the tank. The tank will get lighter as water boils off.

When it gets to a preset weight have it shut off.



I am with this guy. You should have your incoming water supply linked to the weight of the tank.
Arrow Left Previous Page
Page / 3
Top Top