Installing level sensor in a plastic tank

[kalabdel]

Hello everyone,


I need to install a level sensor in an existing plastic tank. It will go on top and there will not be pressure on it except if it overfilled which may happen occasionally.


The issue is that what ever fitting I will use has to be installed from outside only, no access to the inside of the tank. What options are out there aside from spin fitting.

 

[mendonsy]

What sensor are you planning to use? That will probably dictate what the options are.

 

[kalabdel]

What sensor are you planning to use? That will probably dictate what the options are.

I am stumped at how to install it and can be flexible on type of sensor but something like this; continuous level sensing.

The fitting in the picture is more like where I want to go with, but would rather no screws. So may be have that horseshoe thingie machined with a thread so that an outside fitting would just thread in it and that would be the fitting the sensor would screw into. But I will need some holder of some sort to insert the horseshoe and hold on to it while threading the fitting.

For sure someone has come up with a solution already.

 

[5618]

Not quite the right size, but maybe you could make an expanding grommet bulkhead with a similar idea. Ideally, you would be able to somehow get a nut to the back for a more traditional bulkhead by fishing a wire or something.

https://usi-rv.com/product.sc?productId=9&categoryId=4

 

[danw]

Siemens LR series FEA radars have a flat bottom that can “sit on top and shoot through plastic for a continuous level dignal. However, echoes from nearby metallic objects might give false level readings.

Siemens capacitance point level units will read through plastic or glass.

Mounting is Rube Goldberg.

 

[cardosocea]

What kind of plastic? I seem to remember that Vega has ones that can read level inside IBC containers or even through sight glasses. Perhaps one of those?

 

[ArcReactorKC]

When you say no access from inside the tank, are you saying there cannot be a penetration for the sensor?

I have been using IFM ultrasonic, and Flowline ultrasonic with great success. The IFM's are extremely flexible and small but sometimes harder to get.

 

[Saffa]

What is the process media? Are there any existing ports on the tank, either at the top or at bottom level?

For plain old PE water tanks we either use a 0.4 bar hydrostatic pressure sensor inserted through a compression gland in the top, mounted close enough to the entry hatch that you can reach under and tighten the gland nut... or, my preference... a dedicated port at minimum water level, with a 1/2" ball valve connection and a 0.4 bar 1/2" pressure sensor.

If it's a certified tank or something other than water, your options reduce.. certified tank may need re-certification if modified.

 

[James Mcquade]

is this a flat top tank, rounded, how thick?
is it possible to get a piece of plastic material, shape it to the slope of the top of the tank, then place the sensor on the plastic, then cut the hole, and use jb weld or other glue to fix it to the tank?
james

 

[kalabdel]

Thank you very much gentlemen for all those ideas and for your questions as well because they made it clear I didn't do my home work.

It is a water tank and the water can get as warm as 112F. Not sure what type of plastic but will find out ; no special certification.
No access meaning they can not reach in to install a fitting part from inside, like a flange. There are other fittings installed on the tank but the holes are too small to use as access point. Those fitting were installed using spin weld fittings but the tank is in place now, functional and no room to get the spinner thing on top. It would be nice to do it without that. I was also told that they had issues in the past with spin welded fittings leaking due to the tank getting slightly deformed by the warm water.

I also like the sensors mentioned here that do not involve drilling holes and will look into them.
@5618 that looks promising and whether I use it or not I would certainly like to test one.


Thanks

 

[Levi G]

I have used these before https://www.automationdirect.com/ad...ories/18mm_mounting_wells_-a-_brackets/mwk-01

 

[OkiePC]

The Vega rep demonstrated a radar sensor for us that will measure the level of a plastic tank or drum without having to penetrate it. That will be handy for chemical drums so the operator can park the drum under the sensor and stick the suction tube in it and be done with it.

The setup was not too complicated either and can be done with a bluetooth app from a cell phone or laptop. That feature has been great too when the sensor is mounted in a spot that is not easy to reach. I have only installed one on a wastewater flume but having that bluetooth to my laptop kept me in the truck with the windows up instead of outside in the rain while I configured the flume table.

I haven't tried the through the drum level application myself yet.

He sent us a picture of a site where they did this in a food plant using this sensor:
https://www.vega.com/en-us/products/product-catalog/level/radar/vegapuls-c-21

 

[Oceansoul]

Another vote for Vega radar sensor mounted above the tank and calibrated to read "through" the top of the tank.

https://www.vega.com/en-ca/company/...r signal can penetrate,a quick and easy setup.

 

[JTCat]

I would imagine the 'no access to tank' is because of confined space entry. Technically you've entered the space as soon as any part of your body enters the tank. I've dealt with this issue before with plastic penetrating ultrasonic sensors.

 

[mylespetro]

The setup was not too complicated either and can be done with a bluetooth app from a cell phone or laptop. That feature has been great too when the sensor is mounted in a spot that is not easy to reach. I have only installed one on a wastewater flume but having that bluetooth to my laptop kept me in the truck with the windows up instead of outside in the rain while I configured the flume table.

Another vote for Vega, the Bluetooth configuration works pretty well in my experience. Haven't used one on a project but have tried it in a lab setting. They often seem to have new/innovative measurement solutions as well, as evidenced by the example you mentioned.