A pressure transmitter is the core instrument that converts pressure into a standardized, remotely transmittable signal in process and machine systems. This guide is written for procurement and design engineers: six chapters cover measurement types, sensing principles, key parameter interpretation, a cited comparison of five real models, and selection decisions, with six selection FAQs. Every parameter in the comparison table is cited to the manufacturer's official datasheet; values were taken from official WIKA and Endress+Hauser documentation (2026-05) — verify against the manufacturer's current PDF before procurement.
Chapter 1 / 06
What is a pressure transmitter
A pressure transmitter integrates signal-conditioning electronics, temperature compensation and a standardized output on top of a pressure-sensing element. It converts media pressure into a signal linear with pressure (4–20mA, voltage, HART digital overlay or IO-Link) that connects directly to a PLC, DCS or recorder for long-distance, noise-immune transmission.
Compared with a bare "pressure sensor / pressure cell", a transmitter adds signal standardization and field configurability: zero/span turndown, damping, unit switching and self-diagnostics. The terms overlap in practice; the real procurement boundary is whether you need a standardized, remote, configurable output. Choose a transmitter whenever the device must connect to a control system.
Chapter 2 / 06
Pressure measurement types
The first selection step is the measurement type, which fixes the reference and the construction:
Type
Reference
Typical use
Gauge
vs. atmosphere
line pressure, hydraulics, pneumatics, pump outlet
Absolute
vs. absolute vacuum
vacuum process, gas partial pressure, baro compensation
Differential
between two taps
flow restriction, level, filter ΔP
Sealed gauge
sealed reference
high pressure, deep water, offshore
One transmitter usually serves a single measurement type and is not interchangeable across types. Level measurement is hydrostatic and must account for media density and mounting height.
Chapter 3 / 06
Sensing principles
The sensing principle drives accuracy, overload capability, media compatibility and price:
Principle
Characteristics
Representative models
Piezoresistive / thin-film silicon
wide range, cost-efficient, good dynamics
WIKA A‑10 / S‑20 / IS‑3
Piezoresistive metal welded diaphragm
high pressure/temperature, strong overload, process grade
E+H Cerabar PMP51
Ceramic capacitive (oil-free)
corrosion- and abrasion-resistant, hygienic
E+H Cerabar PMC51
Metal diaphragms suit high-pressure, high-temperature demanding process; oil-free ceramic capacitive cells resist corrosion and abrasion and suit aggressive or hygienic media; thin-film silicon is most cost-effective across general industrial ranges.
Chapter 4 / 06
Key specifications explained
Accuracy reference: %span/%FS is referenced to the selected range full scale; %URL is referenced to the model's maximum settable range — normalize the reference before comparing vendors, otherwise the numbers are not directly comparable.
Output: 4–20mA two-wire is noise-immune, low-wiring and broken-wire diagnosable, the industrial mainstream; HART overlays digital data on 4–20mA for configuration and diagnostics; IO-Link suits the smart-sensor layer. Process connection must match site thread/flange/hygienic clamp. Ingress protection IP65/67 is general; choose IP68 or IP6K9K for washdown/outdoor. Functional safety: pick a SIL2 model for safety instrumented loops per IEC 61508/61511. Ex: use an intrinsically safe Ex ia model with a barrier in hazardous areas.
Chapter 5 / 06
Real model comparison (every parameter cited to the official source)
Data taken from manufacturers' official product pages and datasheets (WIKA PE 81.58/81.60/81.61 · 02/2026; Endress+Hauser Cerabar official product pages). SpecForge only structures and compares; technical values are not rewritten. Verify against the manufacturer's current PDF before final selection.
Chapter 6 / 06
Selection by service
Service
Recommended direction
Model
General machinery / hydraulics / pumps
cost-efficient, wide range coverage
WIKA A‑10
Demanding industrial / high-accuracy process
multi-class accuracy, strong ingress
WIKA S‑20 / E+H PMP51
Hygienic / corrosive media
oil-free ceramic, hygienic connection
E+H Cerabar PMC51
Hazardous (Ex) areas
intrinsically safe Ex ia + barrier
WIKA IS‑3
Safety instrumented loop (SIS)
SIL2 certified
E+H PMP51 / PMC51
Recommended decision order: measurement type → media & temperature → range & overpressure margin (working pressure at 50–75% of range, 1.5–2× overpressure reserve) → normalize the accuracy reference → output & protocol → approvals (Ex/SIL/hygienic) → process connection & ingress protection.
FAQ
What is the difference between a pressure transmitter and a pressure sensor?
The sensor is the element that converts pressure to an electrical signal; the transmitter adds signal conditioning, temperature compensation and a standardized, remotely transmittable output (4–20mA / HART / IO‑Link) for direct PLC/DCS connection. Choose a transmitter when connecting to a control system.
%FS, %span vs. %URL — what is the difference?
%span/%FS references the selected-range full scale; %URL references the model's maximum settable range. %URL yields a larger real error on small turned-down ranges; normalize the reference before cross-vendor comparison.
How is a 4–20mA two-wire transmitter wired?
Power and signal share two wires; a 24V DC supply and load resistor are in series in the loop. 4mA = zero, 20mA = full scale; noise-immune and broken-wire diagnosable (current drops to 0).
Which model for hazardous (Ex) areas?
An intrinsically safe Ex ia model with a barrier, e.g., WIKA IS‑3, with ATEX/IECEx (NEPSI in China) approval matched to the zone EPL.
How do I pick the measuring range?
Keep working pressure at 50–75% of range with a 1.5–2× overpressure reserve; add damping or a higher overpressure-limit model for pulsation/water hammer.
What is SIL2 and when is it required?
The IEC 61508/61511 functional-safety integrity level. Safety instrumented loops are rated by risk assessment; SIL2 is common for process safety — pick a SIL2-marked model (e.g., Cerabar PMP51/PMC51) and proof-test per the manual.
The pressure transmitter is a core category within the pressure-measurement family of Test & Measurement, widely used across petrochemical, power, water treatment, machinery, building services and pharmaceutical industries. SpecForge catalogs models from WIKA, Endress+Hauser, Siemens, Emerson, ABB, Yokogawa and ifm, providing range, accuracy (%span / %URL), output (4–20mA / HART / PROFIBUS / IO‑Link), process connection, ingress protection, Ex and functional safety (SIL) selection parameters, with every spec cited to the manufacturer's official datasheet so procurement engineers can verify parameters before a selection decision. All data comes from manufacturer sites and public technical documents with attribution; technical values are not rewritten; updated regularly.