Hydrostatic Tank Gauging FAQ
- How many 3201 HIU or 3202 SAM modules are needed for an HTG system?
- How many pressure transmitters are needed per tank in an HTG system?
- What are the differences between the 3201 HIU and the 3202 SAM?
- What does the 3402 Applications Interface Module (AIM) do?
- How many 3402 AIM units are required in an HTG system?
1. How many 3201 HIU or 3202 SAM modules are needed for an HTG
system?
One 3201 HIU or one 3202 SAM is needed for each tank in an HTG system.
2. How many pressure transmitters are needed per tank in an HTG
system?
All HTG applications require at lease one pressure transmitter per tank. A second
transmitter is needed if an on-line density measurement is desired. A third transmitter,
located at the top of the tank, is needed if a vapor pressure is present in the tank and a
measurement is desired. An alternative to measuring the vapor pressure is to install a
heat-traced dry leg.
3. What are the differences between the 3201 HIU and the 3202 SAM?
Where the 3201 is geared towards the petrochemical industry, inventory management, and
bulk storage tank applications, the 3202 is geared towards the specialty chemical, food
and beverage, pharmaceutical industry and process tanks. Some functionality differences
between the HIU and SAM include: the SAM cannot measure water bottom, has no floating roof
or transfer capabilities, and is not approved per NMI for custody transfer. In addition,
the SAM has only 20 strapping points compared to the HIU which has 100.
4. What does the 3402 Applications Interface Module (AIM) do?
The 3402 AIM serves as the interface and power supply for the 3201 Hydrostatic
Interface Unit (HIU) or the 3202 Smart Application Module (SAM). The 3402 AIM converts the
MCAP digital signal from the HIU and SAM to standard RS-232 and RS-485 MODBUS for use by a
host system (PC, PLC, DCS, etc.) It also provides dc voltage across the same two wires.
The 3402 AIM also supplies the power for the HIU or SAM to function. The HIU or SAM then
supplies the power for the transmitter(s) to function.
5. How many 3402 AIM units are required in an HTG system?
One 3402 AIM can power and communicate with up to 14 Model 3201 HIUs or 3202 SAMs on a
2 wire MODBUS Communications and Power (MCAP) network . The 3402 AIM itself requires 115
Vac or 230 Vac power.
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