A differential pressure transmitter is specified by a single Total Error Band figure — Pondus's PT600 series, for example, limits total temperature drift to 0.1% of maximum range over −10…+70 °C, and the same vendor's PT60 type T remote-seal level transmitter adds a quantified extra error for capillary temperature gradients plus a static-pressure term, with both added to the basic accuracy to form the TEB envelope [S2].
A mechanical pressure gauge is a fundamentally different product: it gives a local dial indication, has no electronic output, and its performance is captured by an accuracy class (commonly 1.0 / 1.6 / 2.5 % of full scale), separate friction and hysteresis terms, and elastic-element creep. There is no industry TEB figure for a Bourdon or diaphragm gauge, and the head-to-head comparison should be made on what each device actually guarantees, not on whether both have a TEB line in a datasheet.
What "Total Error Band" Means in a DP Transmitter Datasheet
TEB is defined as "the difference between the most positive and most negative deviation from the true pressure," obtained by combining every possible error within the unit's pressure and operating-temperature range, and it is the figure that defines worst-case performance over the compensated range [S3].
Gems Sensors lists the components folded into its 1100-series TEB: accuracy (which itself includes non-linearity), plus hysteresis, repeatability, thermal zero shift, thermal span shift, and long-term stability [S5]. Kulite's TD-1012 technical document makes the same point — the TEB line on a transducer datasheet is a budget of error sources, not a single repeatability or non-linearity number [S9].
Why a Mechanical Gauge Does Not Publish a TEB
Mechanical gauges do not fold all error sources into a single band because the dominant errors — pointer friction, gear backlash, Bourdon-tube hysteresis, and elastic creep — are evaluated separately under accuracy-class rules, and the resulting performance is dominated by full-scale deflection, not by the process pressure value [S4].
A 100 bar gauge with 1.0% class accuracy carries ±1.0 bar of allowed indication error across the entire scale, so near 10 bar (10% of span) the relative error is 10% of reading. A DP transmitter specified at, for example, ±0.1% of calibrated span carries ±0.1% of span across the same range, and its TEB adds thermal and static-pressure contributions on top of that base [S3][S9].
The DP-Only Error That a Gauge Cannot Have
Static-pressure effect — the shift in zero and span of a DP cell when line pressure is applied to both sides — is unique to differential pressure transmitters and is one of the largest terms inside any DP TEB [S2].
For a low-range DP used in flow measurement with an orifice or Venturi, the static-pressure effect on the high and low side can exceed the basic accuracy by a large factor if the cell is not specified for the actual static line pressure — a failure mode a single-port gauge, which only sees one pressure, simply does not expose [S2][S3].
Drift and TEB: Two Different Time Horizons
TEB describes the as-new worst case at any temperature inside the compensated range; long-term drift is a separate specification and is one of the items some vendors add into the TEB budget while others list as a stand-alone stability figure [S8].
Stability of the zero point is the main drift component for many pressure technologies, and a manufacturer will either pick a sensing principle that is inherently stable or widen the published accuracy to absorb the expected drift over the calibration interval [S8]. A mechanical gauge, by contrast, drifts mainly through elastic-element set and wear, and is normally re-calibrated or replaced on a fixed interval rather than specified by a ppm/year number.
Comparison: Gauge vs DP Transmitter on Four Decision Criteria
Side-by-side on the criteria that actually drive specification, a mechanical gauge offers no single worst-case TEB number, a constant % of full-scale error band, no static-pressure term, and modest overpressure margin, while a DP transmitter offers a single TEB number over a compensated range, a % of calibrated span with thermal and static-pressure terms added, and high static overpressure tolerance [S2][S3][S5][S10]:
1. Single worst-case number — gauge: no, accuracy class only; DP transmitter: yes, TEB over compensated pressure and temperature [S3][S5].
2. Error vs reading position — gauge: class % of full scale, error grows near zero; DP transmitter: % of calibrated span, plus thermal and static-pressure terms folded into TEB [S2][S4].
3. Static / line-pressure error — gauge: N/A (one port); DP transmitter: explicit static-pressure dependence is part of TEB, and is the dominant term on low-range cells [S2][S3].
4. Overpressure survival — gauge: typically 1.25–4× range; DP transmitter: many datasheets require 2000 psig static overpressure with complete recovery on cells used for level and flow service [S10].
Selection: When a Gauge Is Right, When a DP Transmitter Is Required
Use a mechanical pressure gauge for local indication on a pump skid, a separator, or an industrial valve manifold where a human needs to read pressure on site, no signal is needed for the control system, and 1–2.5% of full-scale accuracy is acceptable [S4].
Use a DP transmitter when the measurement feeds a control loop, when a SCADA or DCS needs a 4–20 mA / HART / wireless signal, when the application is flow (orifice, Venturi, averaging Pitot) or sealed-tank level by DP, or when the TEB — including static-pressure and thermal terms — must be proved against a documented budget [S2][S3][S10]. For low-range DP cells, where many datasheets begin at 0–250 inH₂O, the static-pressure term in the TEB is often the deciding factor between a working and a non-working installation [S2][S10].
Trackable signals to watch on this topic: vendor TEB vs accuracy disclosures in the next generation of low-range DP cells for hydrogen and CO₂ service, and any move by major gauge vendors to publish a unified TEB-style number alongside the existing EN 837-1 / ASME B40.100 accuracy class for mechanical gauges.