How to Select a Humidity Sensor

Posted by Seta Davidian on Dec 13, 2018, 8:47:37 AM

Humidity sensors are an important piece of equipment in the medical, automotive, HVAC, and food production industries, among others. Any industrial facility that requires a controlled atmosphere requires a properly functioning humidity sensor. Whether your requirements for maintaining or reducing humidity levels are for safety, function, environmental control, or comfort, it's important that you choose the most appropriate sensor for the job.

Choosing a Humidity Sensor

head-digital-humidity-elements

By knowing what questions to ask when choosing a proper humidity sensor for your situation, you can ensure successful operation and longer life for your equipment. The first step is to know your budget and assess your needs. Some of the factors to consider here include:

  • Size, accuracy, and interchangeability
  • Long-term stability needs
  • Repeatability requirements
  • Required resistances of the sensor to any chemicals or contaminants it will be exposed to

It is also important to understand the different types of humidity sensors available to choose from.

  • Resistive humidity sensors measure an electrical change that can be caused by a conductive substance. These systems use electrodes and AC excitation voltage to produce a data value for relative humidity.
  • Thermal conductivity humidity sensors measure absolute humidity. They do this by calculating the difference in the conductivity of dry air compared to air that contains water vapor. These sensors use thermistor elements to form a bridge circuit and measure the difference in resistance.

Selecting the Right Humidity Sensor for Your Application

Choosing the most appropriate humidity sensor for your application can help ensure the cost-effectiveness and success of your project.

  • Accuracy

The first aspect you should examine is the level of accuracy you need.  The more accurate the sensor needs to be, the higher the cost will be.

  • Interchangeability

Cost can also be affected by the interchangeability of the sensor, which may cause vibration and lead to additional costs for calibration. 

  • Condensation

If condensation is present, you may also need to factor in the cost of condensation resistant filters.

  • Packaging

Package type can impact cost savings if you choose a combined humidity and temperature sensor instead of two separate sensors. 

  • Power

Power consumption will have overarching long-term effect on costs.

Different applications will have additional considerations that must be reviewed.  Industrial applications have to consider the environment of the system and whether or not the sensor is resistant to chemicals or contaminants. For example, healthcare applications often require precise conditions and accurate, repeatable measurements, as well as the ability to maintain a clean environment. Similarly, humidity sensors are critical in HVAC and transportation applications to prevent excess moisture that fosters bacteria and mold growth. 

Other Important Considerations

When considering the purchase of a humidity sensor, there are a few logistical concerns that also need to be reviewed. Ask the following questions to help you narrow down the proper solution and provider: 

  • What are the lead times of the supplier and will you get your parts in time?
  • Does the supplier have a location close enough to provide in-person consultations and to deliver your product, or will the distance increase the lead time?
  • Do you have second source requirements in the event of a supply chain issue?
  • Can the supplier make a product unique to your specs or will they try to retrofit an existing product?
  • Are they willing to share data and guarantee their accuracy with a warranty and service policy?
  • Do they stand behind their products with technical support?
  • How does the price compare to the rest of the market when you look at the component, consultations, and long-term service provided?

Humidity Monitoring Solutions from Servoflo

As you can see, there are many factors to take into consideration when selecting a humidity sensor.  Not only do you need to make sure you’ve selected the right one for your application, but you also need to make sure that you select the right company.

Servoflo has been providing sensor solutions to a broad range of industries and applications for nearly 20 years. To learn more about what it takes to select the best humidity sensor for your project, check out our eBook here.

Humidity-Sensor-Guide

Download Our Humidity Sensor Selection Guide

Topics: Humidity Sensors