Ideas For Level Sensor

[Blue Chips]

The flux eats plastic, and probably rubber.

Oops, I guess I missed that in @Brad93's original post.

What kinds of plastics would it dissolve? For example,k I've seen some tethered floats with polypropylene bulbs. Would it eat those as well?

 

[Onoff]

Have a word with Turk Banner in Wickford, at least for the sensor head and go from there.

I've always found them super helpful.

 

[timgunn1962]

Can you use a bubbler?

Basically, it's a tube that goes down to the bottom of the tank. A very small airflow is fed down the tube and bubbles out of the bottom. The air pressure is dependeng on the depth of the end of the pipe below the liquid level and the density of ghe liquid. A pressure switch arrangement remote from the end of the pipe switches the pump on and off without any corrosion concerns as it's only in contact with air.

The tube can be made from anything chemically compatible in the fluid it's immersed in.

If you use pneumatic control in the process, you'll have an available air supply. If not, a little pump can be used.

 

[Brad93]

I think non contact ultrasonic is the way to go.

Right then, small plc needed then

 

[daleyd]

I think non contact ultrasonic is the way to go.

Right then, small plc needed then

Not necessarily, you can get a small controller if your only doing simple on off control (you can even do more complex stuff if you want) , without needing to go to the lengths of a plc. Plus they have display built in.

 

[Bravheart]

You might get away with One sensor at the bottom triggering the pump on a timer if the liquid is consistent.

 

[8ob]

How about a small glass bottle as a float with a stainless rod bonded into the top of it and a proximity sensor up top.

Bob

 

[Jan-DIY]

Pepperl Fuchs stainless/ptfe uss.
IFM O1D Laser
Endress Liquiphant

It depends on the liquid and environment.

 

[daleyd]

I may be biased because I work for the company but these are ideal for those sorts of applications (other brands are available of course!)

3216/CC/VH/RRXX/R | Eurotherm 3216 PID Temperature Controller, 48 x 48 (1/16 DIN)mm, 3 Output Changeover Relay, Relay, 85 → 264 V ac | RS

uk.rs-online.com

You can view the level and have control to open close valves or raise alarms at certain points. A plc is great, but without an associated hmi you wouldn’t have much visibility of what’s going on, or to change things.

 

[Brad93]

I want it as simple as possible, the guys using this love an excuse to call it a day. It's currently to taxing for them to turn the pump on and off manually. Honestly they love calling me as they sit in the break room for the rest of the day doing nothing

 

[Dave-sparks]

I think non contact ultrasonic is the way to go.

Right then, small plc needed then

A logic module/smart relay such as Siemens Logo would be simpler, and cheaper, than a full blown PLC.

 

[Onoff]

A lot of basement macerator "toilet" tanks are sealed and have a tube coming off them to a piezo(?) switch on a PCB. The fuller the tank the higher the pressure and when "full" it makes the piezo switch and triggers the pump.

 

[gaz1]

first off i understand what your after

plumbers flux only cleans copper pipe so the old type ball valve is what your wanting

so go back to old school

copper ball valve no plastic and no rubber to deal with

1/2″ Part 2 High Pressure Brass Ball Cock & 4 1/2″ Copper Float, CENPA25L-COPFL

Part 2 High Pressure Brass Ball Valve & Arm With 4 1/2″

heatingpartswarehouse.co.uk

now you get to play with a micro switch or even one of those push in switches

there is 2 sorts of ball valve the one above is end close whilst the one below is a sliding shaft close

Made4Trade Float Valve Part 1

• WRAS Approved

www.toolstation.com

 

[Robotstar5]

A lot of basement macerator "toilet" tanks are sealed and have a tube coming off them to a piezo(?) switch on a PCB. The fuller the tank the higher the pressure and when "full" it makes the piezo switch and triggers the pump.

Some industrial parts washing machines use a similar system to detect water level, it threw me the first time I worked on one when a leaking tube stopped the cycle.

 

[Onoff]

Some industrial parts washing machines use a similar system to detect water level, it threw me the first time I worked on one when a leaking tube stopped the cycle.

Wait until the pipe connection to the pressure transducer on the pcb snaps off and starts backing up and overflowing!

 

[knighty]

or one of these. my only concern is the float getting bunged up with solidifying flux and then it not working. https://uk.rs-online.com/web/p/float-switches/4928946?gb=s

I think you've moved on from that idea anyway....

but those are pretty pants, I've had 2 die on me for no reason at all - used a s afloat in a fresh water tank, and only switching a relay so hardly any electrical load on it

 

[sako243]

What's the (rough) specs on the container @Brad93? Capacitive sensors can work through metals. One at the point you want it to start filling and one near the top as a safety cut-out.

It's not off the shelf but I've also developed a novel prototype capacitive sensor that's considerably more sensitive and can "see through' conductive surfaces.

 

[m_c]

I think you've moved on from that idea anyway....

but those are pretty pants, I've had 2 die on me for no reason at all - used a s afloat in a fresh water tank, and only switching a relay so hardly any electrical load on it

Having had a quick look at the datasheet for that, the 600mA is the rating for a resistive load.
A relay is an inductive load, which could cause the contacts to burn out faster.
There is also the possibility that the load was too low, which can result in not enough arcing on the contacts to keep them clean.

 

[gaz1]

if you do go back down the ball valve way use the piston type

now the piston type allows you to insert a long pin into the end of them where the washer would normally go and a cap end over the feed side of it with a drill would allow the rod to come out of the end



dont use the plastic plunger there no good for your application

one other thing there is both copper and steel balls instead of the plastic type

 

[bricol]

I've used capacitance ones through tank side walls for controlling pumped caustic. Worked well.

This is a quick shot of a level switch assembly used by a US company I started work for in '99 - a rummage in my drawers produced a drawing:

Stainless steel ball float, rod, collar etc. Exactly the same idea as the UK company had (except they used three switches - in descending order - operating level, fill level (ie call for fill) and low level (stop machine, sound alarm to protect pump, heaters etc). The only time they didn't work reliable was aireated water, or extreme foam - they would then just sit on low level as the float didn't . . .

One of the floats we used was made from chipati tins - lid and base tigged up - cheap, worked, and available just up the road from our factory in Bradford).

Conductance probes worked pretty well (could even use the tank as one of the electrodes) - but if they get covered in crap, as I suspect the flux might do, you get false readings.

Only used a few ultrasonic level sensors - they were sod ding expensve over 20 yrs ago and customers didn't like paying for them.

Gaz's ball float valve - might not be as daft, although I suspect "gloopy flux" might not allow it to work as well as hoped - any seals in there won't be happy either. But certainly still used in industry as a cheap, quick, pretty reliable method of tank level control (one of our competitors does - our equivalent has been attacked by someone with shares in IFM . . . )

I'm a little surprised the original was using a 230V tilt switch - I'm mechanical, but that doesn't seem a "safe" voltage to be using for control- 24V being more usual?