Inconsistent readings of Bar30 Sensor

Blue Robotics Products Sensors
1

Hi there,

My team is currently using the Bar30 sensor on our ROV for measurement of depth underwater. We are facing issues with in getting reliable and consistent readings from the Bar30 Sensor.

Firstly, we are using a 3.3V Logic Device and am able to obtain readings from the Depth Sensor. Testing it first above water we notice that:

The Depth, Pressure and Altitude readings are very inconsistent. In the same environment, restarting and power off/on of the sensor gives us drastically different readings.

  1. Depth: 0.35m, Altitude: -281.0m, Pressure: 1050mbar, T: 25.2 degC
  2. Depth -9.24m, Altitude:>25000m, Pressure: -84mbar, T= 23.59dedC

Additionally, significant drifts can also be seen when leaving the sensor on. From values shown in 2), the values have drifted to:
3) Depth: -85.5m, Altitude> 30000m, Pressure: -7366mbar, T:16.09degC.

While i understand through some forum discussions that there is a need to first calibrate and offset the values at the surface before placing in water, the large inconsistencies shown does not look like they can be solved through calibration. Have tried to submerge the ROV with depth sensor in water as well, but there was no clear difference/ sensible reading obtained from the Bar30 sensor underwater.

May I know if there is an additional step that may have been missed in calibrating the sensor? Or does these errors point to a faulty unit?

Thanks!

2

It’s stated in our Bar30 and Bar02 product pages (and accompanying sensor datasheets) that

The gel-filled sensor must be completely dried once per day or the pressure and temperature readings will drift.

It’s an unfortunate property/requirement of the gel coating on the sensor element - there’s some extra info in this comment.

If you’ve been operating in continually wet environments then I’d expect that’s your issue, but if you have been completely drying the sensor on a daily basis then this could indeed indicate a faulty sensor, in which case I’d suggest you contact support@bluerobotics.com to discuss a potential refund or replacement :slight_smile: