Tank Gauging Technologies
Two types of measurement methods are used for tank gauging: volume or mass based. In a volume based system, level is measured. In a mass based system, the measurement of the hydrostatic pressure of the liquid column is used. The users choice should, therefore, be based on how product inventory is calculated and accounted via volume or weight.
Both methods provide a direct measurement of one factor in the inventory equation, level or pressure. But, bulk storage tanks tend to have large diameters, store products with varying densities that can stratify, and require consideration for high tank levels and overfill protection. A small change in level can make a big difference in accountable volumes (level x diameter), while stratification can lead to level changes that are undectable by mass based systems. Varec, therefore, recommends level (volume) based measurement systems.
- Manual (Hand Dipping)
- Float and Tape (float based, level measurement)
- Servo (displacer based, multi-variable, measurement)
- Radar (non-contact, level measurement)
- Tank Gauge Transmitters (data conversion and transmission)
- Temperature (temperature measurement)
- Hydrostatic (temperature and pressure based measurement)
- Hybrid (level, temperature and pressure based measurement)
- Wireless (data transmission)
- Data Acquisition (non-contact, level measurement)
Quick Comparision |
Float |
Servo |
Radar |
Accuracy* |
± 0.2 - 0.4 " |
± 0.03" |
± 0.04 - 0.4" |
Power Required |
None** |
Yes |
Yes |
Product Contact |
Yes |
Yes |
Non-Contact |
Installation |
Tank-side |
Tank Top |
Tank Top |
Measurement |
Level or |
Level, |
Level |
Device/Temperature Integration |
With Optional Transmitter |
Spot Temp RTD and 1 HART Device via Local HART® Bus |
With Optional Tank Side Monitor |
Tank-side Display |
Yes |
Optional |
Optional |
Communications |
With Optional Transmitter |
Integrated Digital Communications |
With Optional Tank Side Monitor |
Custody Transfer Approvals |
None |
NMI |
NMI |
* Depending on model selected
** Power required when optional transmitter is used
