Quick answer: Most pressure measurement problems are caused by an unsuitable tapping point, trapped gas or liquid, excessive temperature, pulsation, vibration, leaking connections, poor manifold operation, incorrect mounting, wiring issues or incomplete commissioning. Good installation protects both measurement accuracy and equipment life.
Why installation quality matters
A high-performance pressure transmitter cannot compensate for a poor process connection. Installation errors can create zero shift, slow response, unstable output, false alarms, plugged impulse lines and premature sensor failure. The following ten mistakes are common in industrial piping systems and should be reviewed during design, construction and commissioning.
1. Choosing the wrong pressure tapping location
Tappings placed directly beside control valves, elbows, reducers, pump discharge turbulence or dead legs may see unstable or unrepresentative pressure. Select a location with stable process conditions, adequate access and low risk of sediment buildup. For dirty liquid service, avoid positions where solids naturally collect.
2. Allowing gas pockets in liquid service
Trapped gas compresses and can cause delayed or unstable response. In liquid service, mount the transmitter below the tapping point when practical and slope impulse piping continuously downward toward the transmitter. Provide venting at high points where gas may accumulate.
3. Allowing liquid pockets in gas service
Condensate in a gas impulse line creates an additional hydrostatic head and may block the pressure path. Mount the transmitter above the tapping point and slope lines so liquid drains back to the process or to a controlled drain point. Where condensation is expected, design the arrangement deliberately rather than relying on field adjustment.
4. Exposing the transmitter to excessive process temperature
Direct mounting on high-temperature steam or thermal-oil lines may exceed sensor, electronics or seal limits. Use a siphon, condensate leg, cooling element, impulse line or suitable remote seal. Confirm that the fill fluid and seal design remain suitable across startup, shutdown and ambient temperature extremes.
5. Ignoring pulsation and water hammer
Reciprocating pumps, compressors, fast-closing valves and long liquid lines can create pressure spikes that exceed the calibrated range or overpressure limit. A snubber, pulsation dampener, diaphragm seal or piping modification may be required. Software damping can stabilize the displayed signal but does not protect the sensing element from mechanical overload.
6. Mounting in severe vibration without support
Pipe vibration can fatigue fittings, loosen terminals and shorten transmitter life. Use a stable bracket or remote mounting arrangement and flexible impulse tubing where allowed by the plant standard. Keep tubing supported and avoid creating a lever arm on small process connections.
7. Using incompatible seals, tubing or wetted materials
The transmitter diaphragm may be compatible while a gasket, manifold, valve seat or impulse tube is not. Review the complete wetted path for corrosion, pressure class, temperature and cleaning chemicals. Do not mix connection standards or sealing methods without an approved adapter design.
8. Incorrect manifold operation
Opening or closing differential-pressure manifolds in the wrong sequence can apply one-sided overpressure or disturb the zero. Use an approved operating procedure for isolation, equalization, venting and return to service. Clearly identify high-pressure, low-pressure, equalizing, vent and drain valves.
9. Poor cable entry, grounding or shielding
Loose glands, downward-facing unsealed entries and incorrect shielding allow moisture ingress or electrical noise. Use certified cable glands appropriate to the area classification and enclosure rating. Maintain drip loops, close unused entries with approved plugs, verify polarity and follow the control-system grounding philosophy.
10. Skipping zero verification and loop commissioning
A transmitter may be correctly calibrated but show an offset after mounting because of position, impulse-line head or remote-seal elevation. Verify zero under the proper process condition, check the configured lower and upper range values, simulate or apply known inputs, and confirm the value at the DCS or PLC. Record the as-left configuration for maintenance.
Installation summary table
| Service | Preferred arrangement | Main risk to control |
|---|---|---|
| Clean liquid | Transmitter below tapping, lines sloping downward | Trapped gas |
| Clean gas | Transmitter above tapping, lines draining to process | Condensate pockets |
| Steam | Condensate seal or siphon with temperature protection | Heat damage and unequal head |
| Dirty or viscous fluid | Flush connection or remote diaphragm seal | Plugging and slow response |
| Pulsating service | Snubber or pulsation dampener | Pressure spikes and unstable signal |
| Corrosive service | Compatible alloy or isolated seal system | Wetted-part failure |
Pre-startup inspection checklist
- Tag number and measuring range match the approved datasheet.
- Pressure rating and wetted materials match the line specification.
- Instrument and manifold are securely supported and accessible.
- Impulse lines have the correct slope, supports, vents and drains.
- All process joints have passed the required leak test.
- Unused electrical entries are sealed and enclosure covers are secure.
- Hazardous-area certificates and installation details match the location.
- Zero, span, damping and output protocol are correctly configured.
- Local indication agrees with the control-system value.
- Commissioning and as-left records are complete.
Review your pressure measurement installation
SANTAN supports transmitter, manifold, remote seal and installation accessory selection for new projects and replacement applications. Send your process conditions or instrument datasheet to sales@santanfluid.com or contact WhatsApp +86 136 9022 318.