Sensing level in a sight tube

Brijm

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Brijm
Join Date
May 2006
Location
St. Marys, PA
Posts
645
We have an oil impregnator, that fills a tank with oil using a vacuum (and gravity).

We wanted to sense the level using proximity switches through the sight tube. The problem I'm having, is that I get a bubbling effect in the sight tube, which gives me an incorrect level.

I wanted to see if anyone has experience with a similar situation, and a rememdy, or should I be looking at a different method of level sensing.

Thanks,
 
What brand/model of sensor are you currently using? There are some capacitive (I think?) type sensors that can be taught the On/Off conditions and work from there.
 
Yes, the one I am thinking of is an IFM Efector product. I've only used it once, and in a non-foamy liquid, but it worked well and was easy to teach On/Off.
 
We tried a P&F capacitive prox made for a sight tube application, but it was non-adjustable. We now have an 18mm cap. prox mounted facing the tube. The problem is that it is seeing the oil bubble in the sight tube (it might make the HL Switch, when there is only half a tank) Also, from a control standpoint, my HL switch is very close to my port for vaccum, and can't go much above my shutoff point to add a timer.

Just curious if I was spinning my wheels trying to make this work, or if I should add ports for a float type switch.
 
Brian,

Can you use a simple de-bounce timer.

If you see the level for longer for 5 seconds you will know that is the actual level, so if it is bouncing about the de-bounce will take care of it.

Mark
 
We used to use the IFM KN5124, however I believe this is no longer available. If I'm not mistaken the IFM KI5086 and IFM KI5087 should suit your purpose.
 
Brian, how tall is your tank? If its a deep tank then you might want to think about IFM Efector's tank level pressure transducer. It is calibrated to 0 to 100 inches of water column. It would be easy to correct the scaling to the specific gravity of oil. Its available in models with 4-20mA output and models with switch outputs. You may be able to tap it into the bottom sight gage port or even any port near the bottom of your tank. There is also a submersible model that you drop in the tank and let it lay on the bottom.
 
We are submersing parts in the tank, so anything added has to be outside the tank. Tank is probably about 40" tall. I don't think that pressure would work, as the vacuum can vary, while we are filling. I've thought about the denounce timer, I'd have to set the level low, and rely on time to fill the tank.
 
Use a magnetic float inside the sight glass, and a simple reed switch on the outside of the sight glass. Many manufacturers have this, capacity, light etc not working proper as the liquid is boiling. radar etc also no good.
 
shooter said:
Use a magnetic float inside the sight glass, and a simple reed switch on the outside of the sight glass. Many manufacturers have this, capacity, light etc not working proper as the liquid is boiling. radar etc also no good.
Click to expand...

That sounds like it would work....Now to find a magnetic float, that will fit my 3/8" tube. Need something light enough to float in oil, but not get sucked up by the vacuum.

We where trying to put a float in the tube, that would displace the sensor better, but I think a magnet is best.
Thanks,

-Brian
 
Last edited:

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