# Float Switch Question



## emtnut (Mar 1, 2015)

splatz said:


> Any thoughts on this:


Flygt was the best back in my day , we called them blue balls.
They come in NO/NC as you see fit.
Never had one fail on me


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## JRaef (Mar 23, 2009)

emtnut said:


> Flygt was the best back in my day , we called them blue balls.
> They come in NO/NC as you see fit.
> Never had one fail on me


+1 on the Flygt blue balls. They are mercury tilt switches, or at least they were back in the day. That technology almost never failed. Unfortunately a lot of people freak out about using mercury on anything now because they are afraid they will leak and the toxic mercury will get into the environment. But I always consider what might be worse; an infinitesimal chance that a mercury tube will leak, or a far far greater chance that something else will fail to work and cause a huge spill of whatever it is that was being contained. I'd rather take the risk on the mercury switch.

Redundancy for most of what I did was a 5 float system;Low-Low Alarm, Stop, Start, High, High-High Alarm, all NO switches.


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## emtnut (Mar 1, 2015)

JRaef said:


> +1 on the Flygt blue balls. They are mercury tilt switches, or at least they were back in the day. That technology almost never failed. Unfortunately a lot of people freak out about using mercury on anything now because they are afraid they will leak and the toxic mercury will get into the environment. But I always consider what might be worse; an infinitesimal chance that a mercury tube will leak, or a far far greater chance that something else will fail to work and cause a huge spill of whatever it is that was being contained. I'd rather take the risk on the mercury switch.
> 
> Redundancy for most of what I did was a 5 float system;Low-Low Alarm, Stop, Start, High, High-High Alarm, all NO switches.


I used them recently for a flashing beacon to indicate a bridge was flooded (happens every spring.... small town road)
The floats aren't mercury anymore, but still a positive action switch. They're sill bullet proof imo.
Yep ... standard high- high/high .. and the one you don't want .. Overflow alarm !


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## ELECTRICK2 (Feb 21, 2015)

splatz said:


> Any thoughts on this:
> 
> This site I service has float switches to monitor tank levels for pump controls and alarms. Overfilling at this site would be a catastrophe, so it has to be as reliable as possible. The floats that they have been using sometimes stick and fail to close.
> 
> ...


Interesting idea to use 2 floats that if they contradict, you get an alarm. 
Might work, depends on the application. Like others have stated, you need high, high high, and maybe an "oh oh" float. One thing you could suggest is an SOP for testing whatever system is put in. If it isn't regularly tested you can put as many floats in as you want and it still may fail. They should schedule tests that imitate a failure of the floats under controlled situations. Let the fluid activate the alarm floats. Don't use the lift the float method. That bit me once. Float didn't float.


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## Sdavey1 (Oct 29, 2011)

what is being monitored in these tanks? Just curious if a pressure transmitter and controller would work, or ultrasonic. You can build a robust syatem that will far outlast the float system, and for comfort reasons, add 1 "high level" float to backup in case of any other failure then hope for the best. Depends on the medium being measured though.


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## splatz (May 23, 2015)

There is a 4-20ma pressure transducer in one spot, actually an open pond. Not a fan. It has been a lot of trouble. Getting the scaling right is a PITA. The cleaning maintenance is a PITA. Rescaling it, because it never winds up in the same spot after cleaning it, is a PITA. They haven't lasted long, either, probably on the third or fourth one in five or six years.


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## emtnut (Mar 1, 2015)

splatz said:


> There is a 4-20ma pressure transducer in one spot, actually an open pond. Not a fan. It has been a lot of trouble. Getting the scaling right is a PITA. The cleaning maintenance is a PITA. Rescaling it, because it never winds up in the same spot after cleaning it, is a PITA. They haven't lasted long, either, probably on the third or fourth one in five or six years.


What are you using for the analog ?
We used to use Bristol and Rosemount Tx, that were quite robust. Only ever recalibrated on regular PM's, and they were always bang on !
Depending on how corrosive your media is, the submersible pressure Tx's last quite a long time too.


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## hardworkingstiff (Jan 22, 2007)

What is the product in the tank?

How is the tank being filled? (nozzle like a home heating oil delivery or tight connection using a camlock adapter or ....)

The reason I ask, there are overfill valves (used in fueling systems) that are mechanical in nature that are designed to deal with this.


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## hardworkingstiff (Jan 22, 2007)

Took me a while to find it, but these are what we used to use in tanks.

http://www.pneumercator.com/docs/sales/brochures/LS600.pdf


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## splatz (May 23, 2015)

hardworkingstiff said:


> What is the product in the tank?
> 
> How is the tank being filled? (nozzle like a home heating oil delivery or tight connection using a camlock adapter or ....)
> 
> The reason I ask, there are overfill valves (used in fueling systems) that are mechanical in nature that are designed to deal with this.


It's just runoff that collects into the tanks, then as they fill they are pumped into the pond. It's nasty dirty stuff.


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## triden (Jun 13, 2012)

splatz said:


> It's just runoff that collects into the tanks, then as they fill they are pumped into the pond. It's nasty dirty stuff.


Put an ultrasonic on the top. For sewage lift stations we always stick an ultrasonic on top to run the control system with a backup high level float that will bypass the controls and run pumps if it ever triggers. It's a very reliable system, and if you spec a good ultrasonic it shouldn't ever give you problems. I'd never put a submersible in that nasty stuff.


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## oliquir (Jan 13, 2011)

Ultrasonic is the way to go for tanks levels unless there is some vapor, gunk buildup that could occur at the top of tank


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## Sdavey1 (Oct 29, 2011)

I have replaced many ultrasonic units with submersible transmitters, ABS(Sulzer now) makes an excellent transmitter, completely stainless, installed within a hanging 2" pipe that extends down within a few inches on the bottom to eliminate any grease buildup on the unit. We currently have an Endress & Hauser transmitter that has been laying on the concrete bottom of one of our dirtiest lift stations and has been there since 2006, no issues. You must remember that you get what you pay for, spend the money up front to avoid problems later. Install the backup float as an alarm notification and pump run signal. Really, the options are endless. Enjoy it.


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## emtnut (Mar 1, 2015)

Sdavey1 said:


> I have replaced many ultrasonic units with submersible transmitters, ABS(Sulzer now) makes an excellent transmitter, completely stainless, installed within a hanging 2" pipe that extends down within a few inches on the bottom to eliminate any grease buildup on the unit. We currently have an Endress & Hauser transmitter that has been laying on the concrete bottom of one of our dirtiest lift stations and has been there since 2006, no issues. You must remember that you get what you pay for, spend the money up front to avoid problems later. Install the backup float as an alarm notification and pump run signal. Really, the options are endless. Enjoy it.


agreed...I've worked with many ultrasonics, and when they worked they were great... But I found the pulse susceptible to standing waves at certain levels. Also the transducer didn't like to be flange mounted.
We always had the Flygt as backup when we used them.
Also agree with you on a good quality pressure transmitter piped to the bottom of the tank.


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## hardworkingstiff (Jan 22, 2007)

emtnut said:


> Also agree with you on a good quality pressure transmitter piped to the bottom of the tank.


Since the OP stated that this was pretty dirty stuff, do you have any concerns with the contaminants causing problems with the pressure transmitter? Aren't those calibrated to the specific gravity of the product being monitored (I guess the monitor would do the calculation, right?)? Would the contaminants mess with that calibration by causing a different pressure to be sent for the same level as the contaminants build on the transmitter?


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## emtnut (Mar 1, 2015)

hardworkingstiff said:


> Since the OP stated that this was pretty dirty stuff, do you have any concerns with the contaminants causing problems with the pressure transmitter? Aren't those calibrated to the specific gravity of the product being monitored (I guess the monitor would do the calculation, right?)? Would the contaminants mess with that calibration by causing a different pressure to be sent for the same level as the contaminants build on the transmitter?


The pressure transmitter should have a diaphragm seal. An off-line seal has a cleanout valve. The flush face are self cleaning.
Good point on the weight/contaminant of the material. I worked in water so 2.3' was always 1 psi. For most wastewater applications I thought it would be the same. Maybe someone in wastewater here could chime in.


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## splatz (May 23, 2015)

The pressure transducer was something I inherited, this one 

http://www.meas-spec.com/product/t_product.aspx?id=8998#

I thought it was pretty freaking expensive, I think in the $500 range, but I don't have any frame of reference. Is that considered a low budget pressure transducer? 

The surface is of course pretty nasty, most of the year - algae, pond scum, etc., I'd think that would make ultrasonic a bad idea. Is that correct?


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## emtnut (Mar 1, 2015)

splatz said:


> The pressure transducer was something I inherited, this one
> 
> http://www.meas-spec.com/product/t_product.aspx?id=8998#
> 
> ...


Haven't heard of this one, but it looks fine. I think any submersible will gunk up on you, giving you problems for your application.

"If" you have access to plumbing on the tank, my personal preference would be a diaphragm and pressure sensor for you analog level.
Flygt blue balls, or as someone mentioned magnetic level probe for your pump failsafe start.

I think we're at 1 for and 2 against ultrasonic :whistling2: ( I did just read that they've come a long way with standing wave issues ) :blink:


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## triden (Jun 13, 2012)

emtnut said:


> The pressure transmitter should have a diaphragm seal. An off-line seal has a cleanout valve. The flush face are self cleaning.
> Good point on the weight/contaminant of the material. I worked in water so 2.3' was always 1 psi. For most wastewater applications I thought it would be the same. Maybe someone in wastewater here could chime in.


We use submersibles in waste water all the time except for primary sludge tanks. WAS is thin enough not to bother the transmitter. For this reason we always use ultrasonic on tanks with grit and grime which I believe is exactly what the OP is running.


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## triden (Jun 13, 2012)

splatz said:


> The pressure transducer was something I inherited, this one
> 
> http://www.meas-spec.com/product/t_product.aspx?id=8998#
> 
> ...


That's a cheap sensor and I wouldn't trust it at all. Get yourself and E&H or a Druck. You'll pay around $1500, but you'll have equipment built to last. Now with that said, I think ultrasonic would be your best bet for this application.

http://www.ca.endress.com/en/Tailor...n/level-measurement/Ultrasonic-Prosonic-FMU40


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## Sdavey1 (Oct 29, 2011)

Like stated earlier, spend the money up front. A $500 transmitter is like a $500 car, probably last you a month or two, and if any longer you'll always be wondering when its gonna calve. As far as any variation due to specific gravity, I wouldn't get too hung up on it, water is just that, water, debris won't effect the SG, and if you are pumping water from a tank to a pond, I don't think that accuracy is of that great of importance. You are talking 1-2% error likely at the most, and the better quality transducers aren't going to wander at all. They can handle the brutal environment, I have many sites that are a testament to that. A good quality controller and transducer will run you around the same as a good quality ultrasonic unit, without the worries of surface conditions interrupting your process. I service ultrasonic units in these locations often while the submersibles are working away.


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## Sdavey1 (Oct 29, 2011)

No replies? I do like emtnut's idea of the transmitter with a nice diagphram setup. have you found a supplier that offers a package? Or is this something that you have developed? I'm quite curious.


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## emtnut (Mar 1, 2015)

Not my design, here is a pdf of what's I was looking at.

http://www.barksdale.com/en/products/datasheet/262/diaphragm-seals/
I would think that E&H and Bristol would have a line as well.

Just my preference, cause the u-sonic I used in the past has standing wave issues ... these were in reservoirs, elevated tanks, and in 12" pvc tubes( which may have been part of the issues)
We had a couple in 'open' applications, and had to remove the mounting flange, and have the transducer hang by it's cable to get them to work:blink:
But I have heard that supposedly 'modern microprocessors' have solved this.

Either way, if the u-sonic or pressure Tx is only used for analog level (and first line control) but having the blue balls (inexpensive) as back up, should make this process pretty much failsafe.


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## splatz (May 23, 2015)

That KPSI level sensor is offered in a 705 model, with a diaphragm. It didn't occur to me it was a cheapo. 

I would bet they went with a submersible because there's nothing over the pond to hang floats or an ultrasonic from. I'll recommend we make the upgrade and consider building some means to attach gear over the pond. 

BTW, having an attachment over this pond would be useful here, even aside from the level sensors. I didn't have any idea better than planting two poles / posts and stringing a wire across. Any better ideas?


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## emtnut (Mar 1, 2015)

splatz said:


> That KPSI level sensor is offered in a 705 model, with a diaphragm. It didn't occur to me it was a cheapo.
> 
> I would bet they went with a submersible because there's nothing over the pond to hang floats or an ultrasonic from. I'll recommend we make the upgrade and consider building some means to attach gear over the pond.
> 
> BTW, having an attachment over this pond would be useful here, even aside from the level sensors. I didn't have any idea better than planting two poles / posts and stringing a wire across. Any better ideas?


Sorry, I may have misunderstood here, I thought that the problem was overfilling a tank. That you needed a signal to pump out to a pond (used as an overflow)
If that's the case, would be hard to install a pressure Tx under the pond:laughing:

If there are no environmental issues, I'd build out a concrete wall or a concrete pad beside the pond, and extend out from there.


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## splatz (May 23, 2015)

emtnut said:


> Sorry, I may have misunderstood here, I thought that the problem was overfilling a tank. That you needed a signal to pump out to a pond (used as an overflow)
> If that's the case, would be hard to install a pressure Tx under the pond:laughing:


It's probably a confusing description because it is a bit of an goofy setup. (I am leaving out a lot!) 

The tanks are pumped into the pond, then the pond is pumped to another area. 

The pressure transducer is at the end of a ~25' PVC conduit stub. The cable with the vent tube goes into a junction box at the edge of the pond. The xducer has to be swung / drug ashore to service and swung back in place. 

There's no way to test a lot of things on demand, like for example I can't fill the pond on demand to scale the transducer, I have to take readings at various times and extrapolate. 



> If there are no environmental issues, I'd build out a concrete wall or a concrete pad beside the pond, and extend out from there.


That would actually work great, as long as you could swing the arm over to shore for service. I'm not climbing out there


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## emtnut (Mar 1, 2015)

Pretty much any general contractor would build a pad for you, but you need an Engineering dwg.
Something like this, any welding shop would fabricate with a rough sketch . If it's longer, use I-beam construction.


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## hardworkingstiff (Jan 22, 2007)

emtnut said:


> Sorry, I may have misunderstood here, I thought that the problem was overfilling a tank.


You were not alone, based on the OP, I was sure he was monitoring the tank levels.



splatz said:


> Any thoughts on this:
> 
> This site I service has float switches to monitor tank levels for pump controls and alarms.


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## splatz (May 23, 2015)

Sorry! Made it way more complicated than it is. 

The runoff collects in tanks. 
The tanks have floats. 
The tanks pump into a pond. 

The pond has a transducer. 
The pond pumps away to where, 
I don't care. 

That is almost haiku


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## emtnut (Mar 1, 2015)

splatz said:


> Sorry! Made it way more complicated than it is.
> 
> The runoff collects in tanks.
> The tanks have floats.
> ...


OK ... looks like you have good suggestions for all stages of the process :thumbsup:


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## hardworkingstiff (Jan 22, 2007)

splatz said:


> Sorry! Made it way more complicated than it is.
> 
> The runoff collects in tanks.
> The tanks have floats.
> ...


Sorry splatz, but my mind keeps coming up with other questions. You may not know (nor care), but what is the runoff, parking lot rain, roof drains, ... ?

They really couldn't get gravity to work with this site? Seems like they are pumping and pumping. 

Is the tank designed to let solids drop out? Is it an oil/water separator? Just curious cause I'm old and have nothing to do (or least that I want to do :laughing: )


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## emtnut (Mar 1, 2015)

hardworkingstiff said:


> Just curious cause I'm old and have nothing to do (or least that I want to do :laughing: )


Me too ! .... But I'm also managing to avoid all the billing piled up beside me  .. Honestly, I'd rather go out and pick up dog  :thumbup:


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## hardworkingstiff (Jan 22, 2007)

emtnut said:


> Me too ! .... But I'm also managing to avoid all the billing piled up beside me  .. Honestly, I'd rather go out and pick up dog  :thumbup:


Hey, tomorrow is Sunday, kick your feet up and enjoy the rest of Saturday. :thumbsup:




You'll hate yourself tomorrow though. :laughing:


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## splatz (May 23, 2015)

emtnut said:


> OK ... looks like you have good suggestions for all stages of the process :thumbsup:


Absolutely I started out just looking at the floats and have a lot more good info and ideas on the rest of the place. Thank you and everyone for the input :thumbsup:


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## splatz (May 23, 2015)

hardworkingstiff said:


> Sorry splatz, but my mind keeps coming up with other questions. You may not know (nor care), but what is the runoff, parking lot rain, roof drains, ... ?
> 
> They really couldn't get gravity to work with this site? Seems like they are pumping and pumping.
> 
> Is the tank designed to let solids drop out? Is it an oil/water separator? Just curious cause I'm old and have nothing to do (or least that I want to do :laughing: )


I don't know about the tanks separating solids but I guess they could be? That might get cleaned out in some separate maintenance. I don't think there's anything to separate oil and water. 

I don't know if they could have laid it out better for gravity, the pond is built up around, not dug in. The terrain is really rocky and excavating may have been too much. Even trenching for a conduit is difficult, you can't hand dig anything.


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## Wirenuting (Sep 12, 2010)

splatz said:


> I don't know about the tanks separating solids but I guess they could be? That might get cleaned out in some separate maintenance. I don't think there's anything to separate oil and water. I don't know if they could have laid it out better for gravity, the pond is built up around, not dug in. The terrain is really rocky and excavating may have been too much. Even trenching for a conduit is difficult, you can't hand dig anything.


2 years ago I cleaned, rebuilt and put back online a fuel oil water separator tank. 
It had multi level floats and pumps. It skimmer the oil from the water. Worked well once it was back running. The water was then discharged into the sanitary line while the oil waste was pumped into a holding tank..


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## DesignerMan (Jun 13, 2008)

I've used these float switches many times with no problems at all.
I typically use one unit with 4 contacts (low alarm, stop, start, high alarm) with a redundant high alarm float.
Kari float switches: http://www.kari-finn.fi/index.php/En/products/float-switches/4h-4l-4y-4a


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## qckrun (May 18, 2009)

Why wouldn't you just put your NC high floats in series and NC High-High Floats in series. 

This way you get an alarm even if one fails. Could eliminate the high-highs all together putting them in series.


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## splatz (May 23, 2015)

qckrun said:


> Why wouldn't you just put your NC high floats in series and NC High-High Floats in series.
> 
> This way you get an alarm even if one fails. Could eliminate the high-highs all together putting them in series.


I am just thinking that having one NC and one NO makes sure you get an alarm even in the event of a wiring problem. A short will prevent an NC from working, a break will prevent a NO from working. Trying to anticipate as many possible failures as possible.


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