Sharing my experience - Using the PMS5003T for temperature and humidity

Hardware extensions
#1

Hi,

in my first airgradient setup I am using a PMS5003T sensor.

This sensor has a build-in temperature and humidity sensor.
After integrating this in the software, I can now share the results.
In Grafana I can display both values and are monitoring the average delta of the measurements.

The temperature reading of PMS5003T sensor is 2.9 degrees celcius lower than the SHT31 sensor. The PMS5003T value seems to be close to the actual room temperature.

The humidity reading of PMS5003T sensor is 2.7 percent lower than the SHT31 sensors. I have no value for comparison.

My personal conclusion: using the PMS5003T is more accurate than the SHT31 sensor. The SHT31 sensor is picking up the ambiant heat inside the enclosure.

#2

Thank you for sharing this.

This can be good mitigation for people that do not want to use the dongle extension on the DIY enclosure.

It would be interesting to have a comparison with another ambient temperature sensor to see how exactly it hits the real ambient temperature.

#3

I will try to do some measurements with a reference temperature meter. There must be one in my hobby workshop somewhere :thinking: . Will share ofcourse.

#4

Great. Looking forward to it!

#5

I have been doing some measurements. Since I do not have a reference calibrated thermometer, I have used the most accurate one I could find. The deviation between the reference thermometer and the PMS5003T is 0.4 degrees Celcius (reference is 0.4 degrees higher). The SHT31 measures 1.8 degrees higher than the reference or 2.2 higher than the PMS5003T.

If the airgradient is put outside (it is about current +6 degrees Celcius) in the netherlands, the PMS5003T and the PMS31 will measure exactly the same value after about 20 minutes.

The PMS5003T seems to deliver a more accurate value in house.

1 Like
#6

Thank you. This looks promising. I will get some PMS5003T soon and then will run them against our reference devices.

#7

When you put them outside was it wind protected or could there have been more ventilation bringing down the SHT value on the DIY sensor?

#8

I think it was the low ambient temperature of 6 degrees Celsius that played a role. The sensor was placed on the floor of our balcony, out of the wind. Also is my case very open.

#9

Well, I think the main reason is, that the measurement occurs with the air that is freshly sucked in by the fan.

What I wonder is, why not put SHT31 in the “way” for PMS5003, so fresh air flow over the SHT31 and then into PMS, the outlet is then separated by a “wall” in the housing. This way SHT31 should get the most current temperature from outside the housing using the PMS fan?

#10

We tried that but no success. The problem is that the PMS being out of metal and having quite some internal heat (laser, fans etc) radiates quite some heat.