What Makes OEM Pressure Sensors Accurate and Repeatable?

OEM pressure sensors are accurate and repeatable when their sensing technology, materials, calibration and construction work together to deliver consistent pressure measurements over time and under real-world operating conditions.

For OEM operators and engineers, the challenge is not just achieving initial accuracy. It is maintaining reliable performance as equipment is exposed to temperature extremes, vibration, high cycle life and demanding environments. Small measurement drift can lead to incorrect system behavior, unplanned downtime or costly recalibration.

Ashcroft has manufactured pressure measurement instrumentation since 1852 and understands how sensor design choices affect long-term performance in demanding OEM applications.

In this article, you will learn the key elements of OEM pressure sensors (also known as pressure transducers), the difference between accuracy and repeatability and the design factors that have the greatest impact on consistent pressure measurement over the life of your equipment.

What are the key elements of a typical OEM pressure sensor?

A typical OEM pressure sensor, such as the Ashcroft® S1 Pressure Transducer and G2 Pressure Transducer, consists of several core components that work together to convert pressure into a usable electrical signal. Here’s a look at some of the key elements of this product and their purpose:

Figure 1: OEM pressure sensor elements.

What is the difference between accuracy and repeatability?

Accuracy describes how close a pressure measurement is to the true value, while repeatability describes how consistently the sensor produces the same output under identical conditions. It is typically expressed as inaccuracy, which represents the deviation between the measured output and the ideal output. This deviation is stated as a percentage of the sensor’s full-scale pressure range. The table below includes two accuracy statements that are often referenced. 

Figure 2: Accuracy statement comparison chart

Repeatability, on the other hand, is inherent to the sensor’s design, materials and manufacturing process. It cannot be corrected through calibration. High repeatability is the key factor in ensuring stable performance over time without the need for recalibration or re-zeroing.

A sensor with strong repeatability characteristics supports long-term system reliability even in demanding applications.

Why accuracy and repeatability are both critical for OEM pressure sensors

OEM equipment relies on stable pressure feedback to operate safely and efficiently over long service intervals. Their systems are often exposed to wide temperature ranges, vibration and frequent pressure cycling. Sensors must continue to deliver reliable readings without frequent adjustment.

The most important factor when selecting a pressure sensor is its ability to achieve and maintain the required accuracy across the expected operating timeframe and environmental conditions.

What is included in a pressure sensor accuracy statement?

There are multiple elements that are included in an overall accuracy or sensor performance statement. Although there are generally no industry standards, the following list includes the most commonly stated elements that account for the majority (if not all) of the potential sensor inaccuracy. They are typically expressed as % of Full Scale or Span. 

• Nonlinearity error. Deviation between the actual output curve and the ideal linear output.
  
  
• Hysteresis error. Difference in output when pressure is increasing versus decreasing.
  
  
• Non-repeatability error. Maximum variation in output at a given pressure over repeated cycles. This factor is often the most critical for long-term stability.
  
  
• Zero offset error. Deviation from ideal output at zero pressure.
  
  
• Span setting error. Deviation from ideal output at full-scale pressure.
  
  
• Zero and span temperature coefficient error. Output variation caused by changes in temperature across the specified operating range.

Understanding how these factors are defined helps OEMs compare sensor specifications more effectively.

Why does sensing technology have the greatest impact on repeatability?

Sensing technology is the primary determinant of repeatability because it defines how the sensor responds to pressure cycles, temperature changes and environmental stress.

Pressure sensors may use bonded strain gauges, piezoresistive, capacitive or piezoelectric technologies. Each technology exhibits different long-term stability characteristics depending on application conditions such as vibration, temperature variation and cycle life.

For demanding OEM applications, the choice of sensing technology often determines whether performance expectations can be met over the intended equipment lifespan.

How does Chemical Vapor Deposition (CVD) technology improve sensor performance?

Chemical Vapor Deposition sensing technology improves performance by providing high repeatability and long-term stability across mid to high pressure ranges.

This high-tech sensing element is a great example of the advanced technology used in high-accuracy pressure sensors. It is designed to maintain high reliability and performance across all mid to high-pressure applications.

Ashcroft pressure transducers, including the S1 OEM Pressure Transducer, the G2 Pressure Transducer and our high-purity ZT and ZX Pressure Transmitters, all use CVD sensing technology to achieve precise and consistent pressure measuring. Watch video to learn more.

What other factors influence pressure sensor accuracy in OEM applications?

There are six additional design and application factors influence overall sensor accuracy and long-term reliability, including: 

1. Calibration
   Review accuracy statements to confirm inclusion of zero and span offset errors. For applications where recalibration is undesirable, repeatability and stability specifications become especially important.
2. Construction
   Wetted materials must be compatible with the process media. High-pressure and high-cycle applications may benefit from welded sensor construction rather than elastomer seals.
3. Temperature performance
   Accuracy specifications should clearly define performance across the full operating temperature range required by the application.
4. Signal conditioning
   Proper amplification, filtering and linearization help minimize noise and improve measurement reliability in electrically noisy environments.
5. Environmental protection
   The sensor’s ingress protection rating must match exposure conditions. Housing and vent design are especially important for gauge pressure sensors.
6. Pressure range and resolution
   Sensors must balance sufficient resolution with the ability to withstand maximum operating pressures and high cycle counts, particularly in fluid systems subject to pressure spikes.

Ready to learn more?

When sensors are designed to maintain stable output over time, equipment performance improves, maintenance requirements decrease and system reliability increases. Understanding the factors that make OEM pressure sensors accurate and repeatable is an important step in selecting pressure sensors for demanding applications.

If you want to continue building your understanding of pressure sensor performance, explore the resources provided below, or contact us to get your specific questions answered. In the meantime, download our guide to gauge the accuracy of your accuracy statement.