Acid tank level indication

[Admanderson]

Any suggestions for a good simple way to measure liquid level in an acid circulating tank.
Conditions:
Acid strength up to 37% HCL
Tank size- 6 ft inside diameter, 8 feet tall.
Some solids entrained occasionally.

Have already tried magnetic strip and various clearish tubing but they all foul up shortly. Glass is frowned upon due to safety reasons.

Cost limit of 1000 USD.
Thanks

 

[TD2K]

Radar? Can you install a bubbler tube?

 

[itdepends]

If you can see the top of thank you could use a floating ball and stick arrangement (I can't remember the technical name for them). Otherwise you could stick a pressure gauge on the bottom of the tank.

As a chem eng/metallurgist the first part of any answer I give starts with "It Depends"

 

[siretb]

Floater (ball) + nylon cable + pulley + level indicator outside

 

[moltenmetal]

Ultrasonic, from the top.

Nylon is not compatible with acids, though other thermoplastics are.

 

[kkala49]

A floating ball in a vertical stainless steel pipe fastened to tank ceiling can be a way out. You can clean the pipe internally by pulling the ball out, standing on the ceiling. This was successfully applied in phosphoric acid tanks (containing gypsum, ~1979), even agitated.

 

[cloa]

No stainless steel will last in or near hydrochloric acid of any normal concentration. Phosphoric acid is totally different.

 

[MJCronin]

I agree with "molten".....Ultrasonic is the way to go.

But, the parts inside the tank ( I believe that it is called the dome ?) must be C276/Hasteloy C

Why not call your local acid supplier and ask what he uses in his storage tanks ?

Be respectful and let us know about your final decision and the reasons for it.....

Regards

 

[kkala49]

Indeed, cloa, alloys resistant to hydrochloric acid cannot be characterized as stainless steels. Perry (Chemical Engineers' HB, 4th ed - 1963, Materials of Construction) indicates only Chlorimet 2 (and Zirconium) as low corrosion metals at ambient temperature, although this is a very rough guide. I wonder what material the tank is made of.
However Perry as above shows polyethylene (PE), PVC (unplasticised ?), epoxy resins, polyesters, etc, as suitable materials. Some of them could be the base for a low budget solution of floating ball system, complying with several previous suggestions. Moreover a "guiding" pipe seems to be needed, especially for a "circulating tank".
A thick pipe of hard PE, or probably PVC, could be appropriate. Avoiding bending is assumed possible for a pipe length of (say) 6 ft (2 ft clearance from bottom). At first look, this would be preferable to the option of plastic coated steel pipe.
I would address to same vendor for a proposal on a floating ball + guiding pipe, according to its experience.
Yes, MJCronin, final implementation would be useful for us to know.
(note: my actual experience concerns phosphoric acid tanks).

 

[moltenmetal]

There is no need to invent anything here. You can buy an ultrasonic level transmitter for peanuts these days. They work. Their wetted materials are plastics resistant to HCl. They're mounted from the top, so they're exposed to HCl vapours only. And no moving parts- no float to get stuck, no linkage to maintain, and no cable pass-through to seal.

 

[Admanderson]

Wow thanks everyone for all the suggestions. Short term I ended up putting a 0-5 psi gauge on the lower level port. I will be looking into an ultrasonic in the near future. Hopefully the installation doesnt run up too much...(union plant
Thanks again and I will be sure to update when the permanent system is functional

 

[danw2]

Beryllium copper bourdon tubes are more commong than stainless steel in a 5psi gauge, but either is measured in thousandths of a inch.

The acid is eating away at either. You have a potential leak at a low elevation in the tank.

 

[hahor]

Admanderson,

put the tank on load cells.

Kind Regards,
hahor

 

[TD2K]

Retrofitting a tank with load cells would seem to me to be a fairly expensive solution given the less expensive options suggested especially given his cost limit of $1,000.

 

[aahmed]

HI all

I suggest ultrasonic level transmitter is off course a good option. However, we have experienced that some times, this sensor malfuntions if there are extensive fumes generation and hence condensation on sensor. Similarly, in case your tank pressurizes,then it may again malfunction


Best Regards
aahmed