Choosing Between Calibrated and Uncalibrated Pressure Sensors

Posted by Seta Davidian on Aug 3, 2017 4:54:41 PM

When selecting a pressure sensor for a specific application, designers must first determine the total system accuracy required, as well as the performance requirements for the lifetime of the product.

Like a bathroom scale that is used day after day, a pressure sensor's output may vary over time. The amount of drift depends on the specification given by the manufacturer. Other factors, such as humidity and operating temperature range, can also affect the accuracy of a pressure sensor, regardless of which type of sensor you purchase.

In critical applications requiring optimal accuracy and minimal drift, designers will have to either calibrate or tweak the performance of the pressure sensor to meet the system accuracy requirements. Furthermore, some systems often require recalibration or resetting to zero to ensure optimal reliability after extended use. Back to our example, a good analogy is a mechanical scale, in which the zero point will drift over time and the user must adjust the zero point to maintain accurate weight measurements.

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Precision Vs. Resolution

The overall reliability and accuracy of sensors depend on two main factors: precision and resolution. Optimal precision allows sensors to produce the same output for the same input, while optimal resolution allows sensors to reliably detect small changes within a measured parameter.

Noise can greatly affect precision, as measurement systems with a low signal-to-noise ratio will inevitably struggle to make repeatable measurements. Hysteresis, meanwhile, will cause sensors to read low with increasing signals and high with decreasing signals.

Like precision, optimal linearity is also critical for successful sensor operation, allowing output to be directly proportional to input. Similarly, speed plays a role as well, since sensors that produce precise readings at faster rates allow for smoother, quicker processes.

Ways to Calibrate Your Sensor

Sensor calibration can be done following a two-step process or a one-step process, in which one of the following actions is carried out:

  1. Calibration of the front-end analog circuit errors – This accounts for input offset, gain, and nonlinearity issues that are introduced in the signal from the sensing element before digitization. This step can be done by either the sensor manufacturer or by the customer. To decide who does this step depends on target performance and cost. This is the classic make or buy decision.
  2. Calibration of the back-end analog circuit errors — This accounts for errors in the signal that occur after being conditioned by the digital circuits and converted back to analog form. For example, a customer purchases a fully calibrated sensor with a 1.5% accuracy, then further refines the output with additional components to achieve 1% accuracy. Often this step is done by customers.

Sensor Choices

Three options are available when deciding what kind of pressure sensor to purchase.

  1. FPM-header.jpgCalibrated, compensated, and amplified – These sensors come with a fully signal-conditioned output (voltage or digital) and are compensated for a wide temperature range and calibrated over a broad pressure range. These sensors provide the fastest time to market for the end design. Some can be used with a high-resolution A/D to allow further tweaking in the final product. A good product example is the AP4/AG4 pressure sensor with digital output.
  2. Calibrated, compensated, and unamplified – These sensors have an output signal that is not amplified (millivolt) but feature built-in temperature compensation. Users can employ the unamplified signal to customize an output around system requirements, allowing the user to ignore portions of the calibration range that are not used in the end design or allow for wider tolerance. Here, an example of this model is the MS4425 or SM5652.
  3. Uncalibrated, uncompensated, and unamplified – This option is ideal for users focusing on trend over precision. Users can establish their own calibration process and can create their own auto-zero and single-point control functions (such as on/off). Product examples in this category are the FPN/FGN Series.

When selecting a sensor, some key considerations should be kept in mind, including:

  • What capabilities are available in regard to electronics design?
  • Are environmental chambers or other specialty equipment needed?
  • How is my bill of materials and product cost-affected by my choice?
  • Can the sensor manufacturer offer a modified solution to help me reach my goal?

Learn More

To learn more about pressure sensors and the various options available for your application, download Servoflo's comprehensive Pressure Sensor Selection Guide.

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Topics: Pressure Sensors, calibrated, uncalibrated

Reduce Your Overall Bill of Materials with a Sensor Solution Tailored for Your Application

Posted by Seta Davidian on Jun 1, 2017 3:03:17 PM

A bill of materials, though intended to estimate project costs for production volumes, can actually distract from one of the most expensive aspects of a project — the labor required to inspect, install, and test different components. By focusing on the price tag of individual components themselves, manufacturers often overlook the additional costs of board space, sourcing from multiple distributors, calibration labor, stocking locations, and multiple purchase orders.

Alternatively, sourcing one complete sensor solution from one provider can alleviate all of these pain points while incurring lower service costs down the road. In particular, customers without explicit sensor design/calibration expertise can greatly benefit from an all-in-one solution, as it allows them to reduce both labor and overall bill of materials costs.

gauge.jpgPartnering with the factories we represent,  Servoflo supports customers anywhere along the price/performance continuum from the most basic components to modified output sensors to completely customizable turnkey sensor solutions across a wide range of industries. Depending on the factory/partner, it could be possible to add a display unit, Wi-Fi, or Bluetooth capabilities.  Or,  adding a flex to a sensor, creating packaging enclosures and custom flow paths, or integrating multiple parameters into a single sensor.  It is worth the time and effort to ask:  Who can best provide the required features:  factory or customer?

Throughout our nearly 30 years of experience providing efficient, reliable sensor related services, we’ve handled a diverse range of projects. Below are some examples of our past work and tailored solutions.

  • flex.jpgCreating a pressure gauge with display and enclosure
  • Integrating a pressure sensor and electronics in a hybrid circuit design for better protection in high-temperature and high-humidity environments
  • Eliminating installation assembly and testing by adding a flex cable to a standard board level sensor
  • Customizing sensor calibration and output to meet exact customer specifications
  • Designing a custom flow path in a mass flow sensor for medical equipment
  • Designing custom electronics to create pressure switches, mass flow switches, and other environmental sensors

As with all of our application specific work, these solutions helped customers simplify their bill of materials and reduce downstream maintenance costs for maximum lifetime cost efficiency.

Optimize Your Sensor Solution with Servoflo

Servoflo is proud to be a one-stop shop for reliable, industry-leading solutions tailored to your unique system requirements. By dealing with one vendor, one point of contact, and one invoice, you can greatly simplify your bill of materials and reduce overall costs.

To discuss a custom sensor solution based on your specific needs, contact Servoflo today.

 

Topics: Pressure Sensors, Sensor Solution

Visit Us at Sensors Expo June 27-29!

Posted by Seta Davidian on May 18, 2017 1:12:49 PM

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Come visit Servoflo at Booth 648 during Sensors Expo June 27-29 in San Jose, California! Here is a great from Sensors Expo:

"The Sensors Conference is where you'll find the best in the sensors industry, along with new and innovative ways to jump start your sensor solutions. It's North America's largest and most comprehensive educational program that brings together thousands of engineering professionals all under one roof.

With updated and expanded tracksexciting and visionary Keynote Presentations, and new Pre-Conference Symposia, the Sensors 2017 Conference Program brings you the leading sensors content that you need to succeed from over 100 industry experts. Expanding the program to include interactive content, applications, demos, and hands-on components, the 2017 Conference will have you walking away with the sensors solutions you need."

Visitors to our booth who share their pressure sensor or mass flow sensor application is elible to enter our drawing for a $100 Amazon gift card!

 

Topics: Sensors Expo, Pressure Sensors

Medical Sensor Design Conference May 8-9, 2017

Posted by Seta Davidian on Apr 11, 2017 12:40:38 PM

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Servoflo will be participating in the first ever Medical Sensors Design Conference taking place May 8-9, 2017 in Newton, MA. This event focuses on driving sensor development and innovation in medical applications. 

The conference is filled with various industry speakers from cutting-edge medical design companies and technologies. 

Key themes covered in the conference include:

  • Artificial Intelligence
  • Battery-powered Wearable Fitness
  • Biometric assessment
  • Biosensors
  • Blood & Oxygen Meters
  • Concussion assessment
  • Critical Care Sensor Devices
  • Data & Analytics
  • Drug Delivery
  • ECG & EEG
  • Fluid Management
  • Healthcare and Security
  • Low-Power Sensors
  • Medical Grade Wearables
  • Metabolic Measurement
  • Non-Contact Measurement
  • Non-Vascular Therapies
  • Patient Friendly Medical Products
  • Patient Monitoring and Diagnostics
  • Respirators
  • Security
  • Sensing and the Future of Healthcare
  • Sensors in Clinical Trials
  • Wearable Sensors

Sensors Magazine is offering a special code for $100 off your all-inclusive Attendee Pass. The code is SENSORSMAG.

Join us at this new, informative conference!

Topics: Sensors Expo

Pressure Sensor Clearance Sale!!

Posted by Seta Davidian on Jan 19, 2017 12:07:16 PM

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We have some specific pressure sensors on sale! Take a look at our clearance inventory for heavily discounted opportunities. These parts have never been used by customers. Check back frequently for updates.

Model Description Qty  Price  Comments
XFGM-6100KPGSR Fujikura pressure sensor, 0-100 kPa, 2.5% accuracy, surface mount 6 mm port 865 $1.00 or best offer Various lots since 2007, must purchase in reels of 500 pcs.
33A-002F-3210-R Sensormate SLP Series, SMT, 0-2 psi, 0.5 to 4.5V output, tape & reel 10,754 $3.75 or best offer From 2014 & 2015. Must purchase reels of 250 pcs.
AG203-050KG-TP Fujikura pressure sensor, 0-50 kPa, 1.5% accuracy, surface mount, 3 mm port, 5V supply, tape & reel 6,000 $3.00 or best offer Brand new! From 2016 & 2017. Must purchase in reels of 500 pieces


ag2.jpgPayment terms are prepayment via check or credit card only. No performance guarantees or warranties are in effect. The pdf data sheet is in the model number link. The quantity available is subject to change without notice.

Contact us or call us at 781-862-9572 to make an offer.

Topics: Pressure Sensors

Ceramic Pressure Sensors - Application Examples

Posted by Seta Davidian on Dec 12, 2016 11:05:29 AM

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Ceramic pressure sensors from Metallux have unique features making them ideal in many applications. These features include:

  • Long-life
  • Robust and reliable
  • High temperature tolerance
  • Ability to have direct contact with liquids and harsh media
  • Washable

Servoflo has in depth experience in helping customers integrate ceramic sensors into their designs. Here are some examples:

  • Utilizing a ceramic sensor to develop an oil level sensor in an automotive application
  • Hydraulic & emissions controls for other types of transportation equipment
  • Industrial transducer development for use in the gas & oil industries as well as heavy manufacturing
  • Semiconductor applications to measure process flows
  • Level sensing applications such as reservoir water level management, wastewater controls and chemical processing
  • Food & beverage applications to monitor ingredient flow
  • HVAC pressure transducers to measure refridgerant levels

One of the most important aspects of our customers' success is the wide range of ceramic sensors offered. Our ceramic pressure sensor line includes many models with unamplified mV signals or signal-conditioned with analog or digital outputs. Customers can use sensors with the mV output if they are able to do signal conditioning and calibration. This allows the customer to modify pressure ranges, output, and accuracy to meet their specific application. The fully calibrated versions with voltage, 4-20 mA or I2C come in two levels of accuracy. Customers can do offset calibration after packaging the ceramic sensor. A customer can utilize these many options in one particular sensor model to create a family of products that can be offered to their own customers. 

housing.pngUnlike typical board mount pressure sensors, ceramic pressure sensors do need to be packaged. Our team of experts can assist you in designing the ideal package for your application. Furthermore, Servoflo offers a special evaluation mounting kit called MEKIT 0400 to help users test ceramic pressure sensors.  This kit costs $145 and is useful for the following 18 mm diameter Metallux sensors: ME501/ME505/ME662/ME651/ME75X/ME77X/ME780.

Learn more about Metallux ceramic pressure sensors

Download the information on the MEKIT 0400

Download Ceramic Pressure Sensor Product & Pricing Guide

Topics: Ceramic Pressure Sensors, Pressure Sensors

Water Level Pressure Sensor FPWS

Posted by Seta Davidian on Nov 14, 2016 1:22:05 PM

water level pressure sensorServoflo is pleased to announce the FPWS Water Level Sensor. The FPWS is a gauge pressure sensor for -49 kPa to 68.5 kpa with a linear voltage output. The sensor is oil-filled for specific use in tank level measurement applications. Typical water exposure is tap water with or without bath or cleaning agents.

Below is a sample bath system using the FPWS.

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The following cross sectional diagram illustrates the sensor in detail. Items marked in red are exposed to the water.

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No. Part Material
1 Housing PPS
2 Cover PBT
3 PC Board FR4
4 Pin Copper Alloy Sn plating
5 Pressure sensor  
6 O ring  
7 Plate SUS
8 Fluorine oil  

 

Applications where the FWCS can be used include:

  • Consumer bath systems
  • Gas & oil heaters
  • Heat pumps
  • Solar heaters
  • Fuel cells

Download the data sheet

or

 Contact Us About the FPWS

 

Topics: Pressure Sensors

Sensor Design Engineering Services

Posted by Seta Davidian on Sep 26, 2016 11:48:16 AM

gauge.jpgServoflo, a premier supplier of pressure, mass flow, environmental sensors and micropumps,  is pleased to announce expansion of its design engineering services for custom sensor development. The objective is to be a primary resource for customers who require modification or customization of sensors and how they are integrated into product designs. Services include but are not limited to:

  • adding flex to a sensor
  • creating a custom flow path for mass flow sensors
  • adding Wi-Fi or BlueTooth™ capabilities to a sensor
  • adding a display
  • custom packaging enclosures
  • hybrid circuit design

flex.jpgThis one-stop solution provides customers with efficient and reliable design expertise without having to manage multiple vendors as well as streamlining assembly. Purchasing a complete solution saves customers money and time. Often, a bill of materials is reviewed and pressure is put on individual component costs. This strategy neglects the labor needed to inspect, integrate, and test various separate components such as a sensor element, cable, and package. A complete sensor solution can actually reduce overall bill of materials and labor costs. This sensor design strategy is also important for customers who may not have design expertise in these areas.

Specific application examples include:

  • Creation of a pressure gauge with display and enclosure
  • Hybrid circuit design to integrate a pressure sensor and electronics for better protection in a high temperature and high humidity environment
  • Adding a flex cable to a standard board level sensor to eliminate the assembly and testing steps at installation
  • Customized sensor calibration and output to meet a specific customer requirement
  • Design of a special flow path in a mass flow sensor for medical equipment
  • Design custom electronics to create a pressure or mass flow switch (or other environmental sensor)

If you have a special requirement you would like to discuss, please utilize the button below for fastest response.

 Discuss a custom solution

Topics: Ceramic Pressure Sensors, Pressure Sensors, Mass Flow Sensors

Key Factors When Selecting A Pressure Sensor

Posted by Seta Davidian on Jul 19, 2016 11:20:10 AM

presentation.jpgAt Sensors Expo, held this past June in San Jose, David Ezekiel gave a special show floor presentation titled Key Factors When Selecting a Pressure Sensor. This presentation was created for those new to pressure sensors.

Presentation highlights included a discussion about:

  • The advent of MEMs sensors and resulting new product features
  • New applications using pressure sensors
  • The huge number of manufacturers and models, each having slightly different features, accuracies and packages
  • The paradox of choice - how too many options results in selection errors and overall dissatisfaction

The presentation detailed how to narrow these choices by looking at the skill set in your organization, overall product & system requirements, and other factors such as time frame, second sources, and contact manufacturers.

By understanding the application basics, mechnical, electrical, and assembly factors, a user can then begin to narrow down the myriad of pressure sensor choices. For example, when should a user pick a lower cost unamplified, uncalibrated sensor over a calibrated and compensated sensor with more features but higher cost?

For new users of pressure sensors, it is easy to get caught in this paradox of choice and be oversold on a sensor with features that may not be needed. Take a look at the presentation, and learn about how to not fall into this trap.

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Need help deciding which pressure sensor and conrfiguration is best for your project? Our experts have put together a Pressure Sensor Selection Guide to help you find the right solution for the right price. 

 

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Topics: Pressure Sensors

How to Choose an O-Ring for TR Series Pressure Sensor

Posted by Seta Davidian on Jun 2, 2016 3:36:10 PM

harsh media pressure sensorThe following is a short synopsis of a new application note for the TR Series harsh media pressure sensor.

The TR Series Pressure Sensor is a fully calibrated, back side pressure sensor for use with any media that is also compatible with silicon, glass, ceramic and solder. The TR Series is designed to be used with an o-ring, creating a face seal to the back of the sensor.

When designing an o-ring face seal, several environmental factors much be taken into consideration:

  • Temperature - What are the minimum/maximum temperatures for both operation AND storage? Does the temperature vary during operation or is it stable?
  • Pressure range - Identify the minimum and maximum pressures. Are they positive, negative or both? Fluctuating or constant?
  • Media - Identify what is in your media. What are the exposure conditions (temperature, pressure and concentration of chemicals in media). The backside is exposed to the harsh media while the front is exposed to another environment. This front side must be protected from harsh media.

Some o-ring features for users to decide include material and geometry options.

  • Material - Different o-ring materials have different temperature handling abilities. A soft o-ring will provide a very compliant seal but many not seal well at high temperatures. A hard o-ring would seal well at high pressures but may induce high packaging stresses.
  • Geometry options - O-ring size (both OD and cross-section) must ensure that media will not leak at the minimum and maximum pressure and operating temperatures.

The bottom line is to test with static and dynamic analyses in addition to customer verification, as each application is a unique combination of temperature, pressure and media.

Access the complete application note

Learn more about the TR Series

 

Topics: Pressure Sensors