Which temperature sensor with diameter smaller than four millimeters and for measuring water temperature in thin tubes?

[CL-Beuth-Berlin]

Hello to the NI-Community,

We are looking for temperature sensors in order to measure water temperature (from 5 to 50°C) in thin tubes. We are thinking about using a T-piece in order to bring the sensor perpendicular in the tube. The sensor should have a diameter smaller as 4millimeters in order to get into the tube opening.

Can you please help us to find the right one? Somehow I could not find the informations I was needing on NI products website so I am trying it this way.

Thank you in advance.

Clement

Beuth Hochschule für Technik Berlin

[altenbach]

Most thermocouples are smaller that 4mm and some are even the thichkness of a hair.

What kind of measurment hardware are you using? What kind of software?

You could use them with e.g. this device. It comes with a standard mini plug jack, so thermocouples form any vendor will work (Omega has a huge selection, but even the optionally included bare probes seems <4mm)). All you need is define the type.

[johnsold]

You can also get thermistors in small packages.

Lynn

[CL-Beuth-Berlin]

Hi,

thanks for your help.

We already have some NI 9211 modules, because we need to measure the air temperature at other places in the experiment. We will use labVIEW. However we are doubting that we can use some normal thermocouples because of the water so I was thinking about something like this from NI or that from Omega, but for the NI one I can not find the size of the diameter, althought it seems to be smaler than 4mm. Do you think the one form Omega could work as well with the NI 9211 module?

Cheers

[johnsold]

With thermocouples the manufacturer does not matter, only the type. For any given thermocouple type the output voltage versus tempearture curve will be the same within specified tolerances.

Lynn

[Henrik_Volkers]

Well the fist questions would be:

How accurate do you need the measurements? 

How fast is the temperature changing?

Since water has a very high thermal capacity, the usual way is to clamp a senor on the tube and add a little thermal shielding.

My guess: If you use a PT1000 clamp on on a  copper (metal) pipe,  you end with the same (or less) uncertaincy than with a TC inside the pipe. (TC without dedicated calibration will end with +-1K for the sensor and +-1K for the device.....coarsly +- 1.5K )

Next question is water pressure?

So do you get the plumbing done with standard parts ?

You can get PT100 or PT1000 or TCs in 2mm (and less)  housings that you can solder into the pipe. (but need than a sensor that survive the solder process)

Pick up the phone and ask OMEGA?

Temperature sensors will report the temperature they feel. That migth or migth not be the temperature of interest 😉