Sensor Recalibration

How often do I need to recalibrate my sensors?

It would be wonderful if we could take a sensor out of the box, get measurements, and see those measurements perfectly track reality forever.  Unfortunately, that's not currently possible.  Sensors, whether mechanical or digital, do drift over time.  Eventually, the device that you are using to measure the environment will diverge from what's actually happening.  

Drift is usually documented in the spec sheet for a sensor.  For measurements like temperature or relative humidity, this is usually expressed in terms of a number or percentage drift per year.  For example, the RH sensor in the Conserv SCS-1 sensor has a manufacturer documented drift of 0.25% RH per year.  That means after 3 years, the sensor measurement could be off by 0.75%.  The longer the sensor is in the field, the more drift you can expect to see.  This is true of every digital sensor on the market.

Companies approach recalibration different ways.  Some make devices that are inexpensive enough to be thrown away when they reach the end of their useful life.  Others specify a recalibration interval and provide a recalibration service.  Others provide some procedures that the end user can undertake to understand drift and compensate for it.  If you want to know what recalibration interval is right for you, you should look at two things:


1.  What is the drift specified by my sensor or logger vendor?

2.  How much drift am I willing to live with in my readings?  How accurate is accurate enough?


If you know these two things, you can figure out how often to replace or recalibrate your devices.

Conserv has taken a different approach.  We understand that accuracy is important, and recalibration is a pain.  With a Conserv subscription, we simply replace your devices when they reach a drift threshold.  We take the devices we get back and replace their sensor parts as a part of our refurbishment process.  Our customers get new, accurate sensor hardware and we avoid the electronic waste problems that come with disposable devices.  Win-win!