Calibration and ordering code

The 3051L is a liquid pressure transmitter.

TiO₂ is normally a solid, a powder even, at ambient temperatures and pressures. In order to use a pressure transmitter reliably on a solid, one has to be able to ensure the absence of 'bridging' and 'rat-holing' within the drum as the solid is withdrawn.

Placing the drum on a load cell and measuring its weight at any time might be a better solution, perhaps?

Provided the TiO₂ remains in suspension then a pressure transmitter would do, after a fashion, though the next concern relates to be method and intensity of agitation of the suspension and whether there are any baffles within the vessel to prevent vortexing. It may be that ultrasonic level measurement from above the liquid surface would be a better solution.

Or is the suspension gelatinous? If so then it may be better to go back to a load cell.

Is there a digital photograph of the proposed installation available?

hi thanks for your reply but the tio2 is mixed with "etilen glycol"

It's going to be a little difficult to answer your question.

In order to obtain the pressures at low and high levels (for calibration purposes), you need to know the density of the fluids that your tank will contain. Without it, it's going to be difficult.

If you can, you can do it this way:

• Empty the tank.
• Zero the transmitter - you won't need to know the pressure, just zero it.
• Fill the tank to the highest level you want it to go.
• Adjust the transmitter output to give the high level signal (20mA if your instrument is a 4-20mA unit). Again, it doesn't matter what the pressure is. All you're concerned about is to get a high level reading when the tank is really at high level.

Now, it may be expensive to fill the tank with product just to calibrate it. The nature of your process will determine if you can be allowed to do this.

I don't know about TiO₂ but if it's a solid that is mixed with the ethylin glycol, you may have problems with the stuff sticking to or clogging the diaphragms. If you encounter this problem, I'd go with PWSlack's suggestion of converting to load cells. That's what I did.

<In order to obtain the pressures at low and high levels (for calibration purposes), you need to know the density of the fluids that your tank will contain. Without it, it's going to be difficult.>

Provided the original poster's fluid density remains constant it is possible to work around this issue in the case of a pressure transmitter. One simply zeroes the transmitter span when the liquid level is at or just above the centre of the transmitter and sets it to 100% full range at 'full' level.

The original poster needs to be aware that using a simple pressure transmitter does rely on the assumption that local atmospheric pressure remains constant at the point of use, particularly in the case of a small drum. A change in level could be significant in comparison with possible changes in local atmospheric pressure. This is why the pressure measuring technique for level is not the best for this particular application.

A differential pressure transmitter would solve the problem of allowing for local atmospheric pressure changing, which steers the solution away from the original poster's selection of the 3051L as it is not a differential instrument.

In the end it depends on what levels of accuracy and repeatability the original poster wants to achieve.

It's pleasing that there are now two votes for load cells for this particular problem!