Industrial Pressure Measurement – measure reliably, integrate cleanly

FAQ on Pressure Measurement

Answers to key questions on selection, installation, accuracy, overload protection, cleaning, calibration, and digitalization of your pressure points.

What’s the difference between gauges, digital pressure meters, sensors, and transmitters?

Absolute, gauge, or differential pressure — which do I need?

Gauge (g) references ambient (e.g., 0 bar g at open systems). Absolute (a) references vacuum (e.g., 1.013 bar a ambient). Differential (Δp) measures the difference between two points (filters, flow, level). Choose based on process and required insight.

How do I choose the correct measuring range?

Maximum working pressure × safety factor (1.3–2.0) for dynamic loads. For switches: setpoint roughly mid-span. For filter Δp allow margin for clogging.

What accuracy classes are typical?

Which process connections are common?

When do I need a diaphragm seal (chemical seal)?

For highly viscous, crystallizing, abrasive, hot/corrosive media and for CIP/SIP. The seal protects the sensing element; match fill fluid and diaphragm material to the medium.

Which fill fluids are suitable for hygienic applications?

FDA/EU-compliant fluids (e.g., food-grade oils). Consider temperature range and viscosity; archive release documents.

How do I protect instruments from pressure spikes and pulsations?

Use restrictors/capillaries, pulsation dampers/snubbers, or glycerin-filled gauges. Consider a larger span and adjust switching delays.

Does mounting orientation matter?

Yes. Gauge indication and filled systems can be position-dependent. Same for transmitters with capillaries. Follow manufacturer notes and re-zero for installed position if needed.

How does temperature affect the measurement?

Electronics/diaphragm drift and medium temperature shift zero/span. For high T: use capillary extensions, cooling elements, siphons, or remote seals.

How do I size differential pressure for filters?

Select Δp span based on expected fouling (e.g., 0…500 mbar). Install with a 3- or 5-valve manifold for isolation/zero. Keep impulse lines equal length and add condensate traps where required.

Which materials are media-resistant?

How often should I calibrate?

Usage/risk dependent: typically annually; for quality/safety loops consider semi-annual/quarterly. After mechanical events (shock/overpressure) check immediately.

What does traceable calibration include?

Reference with DKD/DAkkS/ISO certificate, documented setup, up/down points, environmental conditions, measurement uncertainty. Store the certificate in a revision-safe way.

What are common error sources?

Air in impulse lines, clogged restrictors, poor venting, vibration, temperature drift, wrong units/scaling, and EMC issues on electrical sensors.

Can existing 4–20 mA/HART devices be integrated into DCS/IIoT?

Yes. Via HART-enabled inputs/multiplexers or edge gateways. Diagnostics, zero/span, and tagging can be parameterized remotely and published via MQTT/HTTPS.

When is IO-Link or Modbus RTU the better choice?

IO-Link: short runs, fast parameterization/events, machinery. Modbus RTU (RS-485): longer cables, many nodes, process plants. Both can be bridged to IT/cloud via an edge.

Which enclosure ratings/housings should I select?

At least IP65 for outdoor/humid areas; IP67/IP69K for wash-down. In hazardous areas follow ATEX/IECEx (e.g., Ex ia) and use proper cable glands/barriers.

How do I detect leaks or energy losses in compressed air?

Trend network pressure/compressor starts, Δp across filters, compare night base load. Set alarms for rapid drops/rate-of-change; optionally add ultrasonic leak surveys.

Which units are common — and how do I convert?

How do I set pressure switch setpoints correctly?

Place the setpoint in a stable operating zone (not near spikes), define hysteresis (fallback), add damping for pulsation. For safety loops follow standards/SIL.

What matters in hygienic processes?

Avoid dead legs, use polished surfaces, EHEDG/3-A designs, CIP/SIP resistance. Manage temperature/pressure swings with suitable diaphragms and fill fluids.

How important is the installation location?

Close to the process, low vibration, easy to vent/drain, shielded from heat/radiation. For vibration: use remote seals with capillaries or proper mounts.

Can a transmitter “measure” flow?

Yes, via differential pressure across an orifice/nozzle/Venturi. The transmitter measures Δp; the calculation converts this to flow (assuming density/geometry).

How do I plan a replacement/retrofit with minimal downtime?

Pre-match type/connection/span, prepare adapters/reducers, parameterize zero/span, document switchpoints, replace seals, and perform a leak test.

Why use glycerin-filled gauges?

They damp pointer oscillation under vibration/pulsation, improve readability, and protect mechanics. Check the fluid’s temperature range.

How do I integrate pressure points into energy management?

Correlate network and compressor pressure, Δp across filters/dryers, cycles/starts, alarms, and consumption. Feed data to historian/BI to quantify savings potential.

What are typical cost packages for pressure points?

Do you support selection and documentation?

Yes. We provide media/material checks, span calculation, drawings/datasheets, calibration certificates, Ex/hygiene approvals and — if desired — the matching dashboard/alarm concept.