Sensor for detecting a metal sleeve in proximity?

[userx2]

Hello,

As part of a new project, I need to detect a short 1" metal sleeve on a rubber water filled hose coming past.

The OD of the sleeve will be about the same as the OD of the hose and that is around 12mm / 1/2".
The sleeve is likely going to be stainless (rust issues) and the wall thickness is thin. Possibly around 0.8mm / 30mils.
I am not 100% sure yet what the mechanical guys are going to land on for that. The OD of the sleeve.

The hose and sleeve travel past the sensor within about 6.5mm / 1/4"

So the question is how to detect this reliably.

IR proximity seems to have issues with the signal not being very different form hose to metal.
Optical? I have concerns about this when the sleeve or hose becomes dirty and the reflection changes.

Hall effect? I don't think it can detect stainless. It will also need a biasing magnet somewhere. I am not sure.

Perhaps someone here has an idea of how to best detect this?

Best regards
X

 

[userx2]

I just looked at some industrial induction sensors but they are quite expensive and seem to require 10-30V DC.
I only have 4-5V DC available and not much more than 20mA of average current . I guess I can pulse the sensor to save power.
I like the hall effect idea with the magnetic bias but so far I have not found a sensor like this yet in component form.

 

[KlausST]

Hi,

Go for an inductive sensor.
There are so many different types around that it's likely to find a 5V supplied one.
Also look for low power and/or fast power_on timing.

Klaus

 

[danadakk]

Capacitive sensing, can the SS sleeve be grounded as it passes by ?

Or use Capacitive and pass sleeve over or between split plate C apacitor.

https://www.infineon.com/dgdl/Infineon-Component_CapSense_P4_V4.0-Software%20Module%20Datasheets-v07_00-EN.pdf?fileId=8ac78c8c7d0d8da4017d0e7a62a60b82

https://www.infineon.com/dgdl/Infineon-AN75400_PSoC_3_and_PSoC_5LP_CapSense_Design_Guide-ApplicationNotes-v06_00-EN.pdf?fileId=8ac78c8c7cdc391c017d07231aa745f8

Regards, Dana.