Measuring the level of a Hydrochlorine tank


Thread Starter


I work for a county water treatment facility and want to know the best method for measuring level in a hydrochlorine tank. This is quite a vaporous application, so I'm not sure what technology would be best suited. I prefer non contact, so maybe ultrasonic or radar?(ultrasonic much cheaper) If ultrasonic would it have to have a speed of sound parameter to accommodate the vapor? Thanks in advance,
1) Siemens Milltronics has a speed-of-sound adjustment that can compensate for vapors on its medium and top-of-the-line ultrasonics and has had it for years.

2) The comparison of radar vs ultrasonic with ultrasonic much cheaper changed 2-3 years ago. All the major players have industrial grade radar at the $1,200/point pricing. The deadband (dead zone around and immediately beneath the antenna) on radar tends to be longer that of ultrasonic and radar doesn't have the accuracy that we use or open channel flow measurements, but otherwise radar has really changed over the past couple years. I'd suggest you give radar a serious look. Radar doesn't care about vapor, just that the fluid have a high enough dielectric to bounce a signal back.

Your best bet would be to stay away from Ultrasonic due to the vapouous conditions. Non-contacting radar or guided wave would be a better soultion. You could probably get away with using a 2-wire device for your application, it will be less expensive as well.

I would think Ultrasonic is not good, as fumes or vapors will affect it. I don’t think it can be dialed out. If non-contact, you would probably want something external of the tank. It is important you study the parameters of what you need - it’s more expensive to replace one the didn’t work.

Then again -it depends on the tank size. If it’s small enough, you can simply use pressure transducers that convert weight to level. Another option, again depending on the tank size - you could use - say a PVDF (or other material) external flag or magnetic type like at

Again - depending on the tank size - you should look at pressure transducers as a cost effective reliable solution.

Bob Hogg

P.S. If cost is an issue, a 4-20 level probe works just fine if the material is compatible.
I work for a company that maintains many such instalations Western Australia. We have found that by venting the system every couple of hour that Ultrasonics work fine. All we do is put a solonoid on a vent line and that solonoid is opered automatically from a plc.

I hope this helps