First, there are ways to minimize buildup of product on even a mechanical tank gauge. Gauging Sytems Inc. manufactures a mechanical gauge kit for Asphalt tanks that actually works very well (under simular product conditions).
- Inverted float clips (puts the guides within the product and prevents product buildup on the guides).
- Float with extended tape/cable connector (keeps product from building on the connector) (Note: coated floats are also available)
- Tape/cable combination tank minimizes product buildup on the cable portion within the tank.
- A Liquid Seal to use as a bath to clean product from the tape/cable combination and prevent condinsation from getting into the gauge head.
I'm sure that there would be consideration for the styrine product taken into account (Temperature, viscosity, cleaning agent).
The properly configured gauge kit would provide a local indication to inventory / process accuracy and could be used with a switch, a 4-20mA Analog Transmitter, or Digital transmitter.
Second, what type of accuracy is the customer looking for? Process - Inventory - Custody Transfer. The amount of data and communications topology is directly based upon the accuracy question.
The previous suggestion of Ultrasonics should be looked at carefully. If the tank (product) is heated, condensation will form on the antenna and build there. Also installation location is critical with Ultrasonics.
