Pressure sensors: The top 10 things not to do

Elden Tolman, design engineer of the Automation Products Group and his team have heard and seen just about everything when it comes to level sensors and pressure transducers. They’ve detailed the top 10 things not to do with a pressure sensor. The order of this list was determined based on two factors: frequency of the mistake, and the seriousness of the offense.

08/13/2012


10: Calibration without reference

If you must recalibrate a sensor yourself, then be certain you have an accurate reference with which to calibrate. Otherwise, you will end up with an inaccurate sensor.

9: Ignoring enclosure protection ratings

If the application is one that experiences high moisture or humidity, then use a sensor that is rated for such environments. Using an indoor rated sensor in an outdoor environment is a poor choice, and will most likely result in moisture damage.

8: Under-ranging

If you are measuring ranges that are well below your sensor’s specified range, you are under-ranging. If the application range is below 50% of the sensor’s range, you are sacrificing resolution and accuracy. Accuracy is rated based on the full scale, so 0.25% of full scale is a larger error band for high pressure rated sensors.

7: Incorrect wiring

Always verify that a sensor has been wired properly, according to specification, before applying power. 24 Vdc is not the same as 120 Vac!

6: Improper handling of the diaphragm

The diaphragm is the sensing element of the pressure transducer. It needs to be protected from damage. Rough handling of the sensor often results in non-conforming sensors. This is more frequent with flush mount sensors when the diaphragm is more exposed.

5: Using as a tool

It is important to remember that you are working with instrumentation, not tools. They are not designed to be used as anchor points, hitches, or levers, and you must be careful about how you tighten them.

4: Over-ranging

If you are measuring ranges well above the specified range of your sensor, then you are over-ranging. While it is true that over-pressure specs are intentionally conservative, it is a poor practice to rely upon them long term. Over-pressure ratings are defined with the understanding that it will be a rare occurrence. These ratings are not intended for standard operating ranges and will degrade the life of the sensor.

3: Improper ground

Multiple ground locations should be avoided. They can cause ground loops that will affect sensor performance, and can even compromise both wire shielding and surge protection. Electrolysis damage is a common result, particularly with submersible sensors.

2: Chemical incompatibility

If the wetted surface is not chemically compatible with the media being measured, it is only a matter of time before the sensor will fail. Even seemingly benign fluids and gasses can cause problems. For example, water is not compatible with all materials.

1: Wrong process connection

The threads of the sensor fitting or process connection need to match up and be properly rated for the pressure that will be applied. Not doing so will likely result in either damage to the process connection or in creating an unsafe situation. This is especially true in high pressure situations.



No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
Mobile HMI; PID tuning tips; Mechatronics; Intelligent project management; Cybersecurity in Russia; Engineering education; Road to IANA
Save energy with automation; Process control system upgrades; Dispelling controll myths; Time-sensitive networking; Control system integration; Road to IANA
Additive manufacturing advancements; Machine vision enhances robotics; Fieldbus evolution; Process safety; Advice from System Integrators of the Year; Road to IANA
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Flexible offshore fire protection; Big Data's impact on operations; Bridging the skills gap; Identifying security risks
The digital oilfield: Utilizing Big Data can yield big savings; Virtualization a real solution; Tracking SIS performance
Getting to the bottom of subsea repairs: Older pipelines need more attention, and operators need a repair strategy; OTC preview; Offshore production difficult - and crucial
click me