The Rosemount 2051 is Emerson's general-purpose pressure transmitter: the same coplanar and in-line platform shapes as the flagship 3051, at a lower accuracy class and a lower price. The model code is an ordering matrix, read left to right, where each position narrows the build. This guide explains how to read a 2051 code with the Rosemount 2051 Decoder and the decisions that ride on each position.
Everything here is anchored to Emerson PDS 00813-0100-4101 Rev RG (March 2026). The decoder cites each position to its PDS page so a decode can be checked against the source.
Three Families Under One Number
The 2051 prefix forks into three families, distinguished by the fifth character:
- 2051C (coplanar) measures differential (D) or gage (G) pressure. The coplanar flange bolts directly to a Rosemount 305 manifold, to diaphragm seals, or to primary flow elements, which is what makes it the workhorse for DP flow and DP level. It carries the flange-material and O-ring positions that the in-line bodies do not.
- 2051T (in-line) measures gage (G) or absolute (A) pressure through a single in-line process connection, with ranges up to 10,000 psi. No coplanar flange, no O-ring position; a process-connection-style position takes their place.
- 2051G (in-line, HART-only) measures gage (P) or absolute (A) pressure, HART output only, with a reduced housing set. It is the lowest-cost member and uses a different ATEX flameproof code (E1) than the C and T families (E8). Do not assume approval codes carry across families.
Rosemount 2051 Pressure Transmitter Decoder
Decode a Rosemount 2051 model code (2051C coplanar, 2051T or 2051G in-line) against Emerson PDS 00813-0100-4101 Rev RG. Reads measurement type, pressure range in context, output protocol, flange and diaphragm materials, housing, and the full option string. Constraint-violation warnings and source-cited every position. Shares the engine with the 3051 decoder.
Pressure Range Depends on Measurement Type
The single biggest source of confusion in a 2051 code is that the pressure-range character means different things depending on the measurement type chosen earlier in the code. On a 2051C, range 1 is -25 to +25 inH2O whether differential or gage, but range 3 is symmetric (-1000 to +1000 inH2O) on differential and shifted (-393 to +1000 inH2O) on gage. On a 2051T, the same range numbers map to entirely different spans, and the absolute variant starts every range at 0 psia rather than at a vacuum-referenced lower limit.
The decoder resolves this for you: it reads the measurement type first, then interprets the range character in that context and shows you which context it applied. Reading the range character in isolation, off a table, is how people order the wrong span.
Output Protocol Pulls In Constraints
The output character (HART A, FOUNDATION Fieldbus F, PROFIBUS PA W, WirelessHART X) is not just a protocol choice; it gates other positions.
PROFIBUS PA (W) cannot do local addressing or configuration without the M4 LOI option, and it is not available with several EAC and combination approval codes. Wireless (X) is the most constrained build: it requires the engineered polymer housing (P), the wireless transmit-rate and antenna options (WA3/WP5), and an intrinsically safe approval, and it drops the LOI, transient protection, conduit plug, ground screw, shipboard approvals, and alarm-level options. On the 2051T specifically, wireless only works in one of two narrow lanes (absolute with 1/2-14 NPT, or G1/2 DIN with range 1-4, 316 SST diaphragm, and silicone fill).
The decoder fires a constraint warning only when a code actually violates one of these rules, so the warning list stays meaningful.
The 2051-vs-3051 Accuracy Decision
Because the 2051 and 3051 share the coplanar coding shape, it is tempting to treat them as interchangeable. They are not the same accuracy class. The 2051C reference accuracy is up to 0.065 percent of span; the 3051C is 0.025 percent. The 2051 high-performance option (P8) reaches 0.05 percent, but only on ranges 2-5, with SST or alloy C-276 diaphragms and silicone fill fluid.
For general-purpose monitoring and most control loops, the 2051 is the right, cost-effective choice. For custody transfer, precision DP flow, or any loop whose accuracy budget was built around the 3051 number, the substitution quietly blows the budget. Decide on accuracy class before you decide on price, and decode the 3051 codes in the dedicated Rosemount 3051 Decoder.