Ashwin Salgaocar
Training Content and DevOps @ BoltIoT

Accuracy of Blake readings as compared with other local devices

Wait… What is this Blake?

Blake is a temperature and humidity monitoring solution. It is a data logger that collects temperature and humidity data and stores it in the Bolt IoT cloud. The prime components of the Blake device are:

  • The sensor.
  • An LCD display for viewing the sensor readings.

Okay… what is the sensor used?

The sensor used in the Blake Temperature & Humidity Monitor is a Evelta SHT21 I2C Temp and Humidity Sensor Probe MRS Type. This sensor is very popular and is used in a wide variety of applications. Each SHT21 is pre-calibrated and provides linearized sensor signals in digital, I2C format.

And, why do we use this sensor?

The sensor is fully digital and multi-point calibrated, with high accuracy, good consistency, long-term stability, low drift, and full temperature compensation for humidity. The surface of the sensor is covered with a waterproof and breathable membrane to protect it. The shell is waterproof and will keep water from seeping into the body of the sensor and damaging it, but allows air to pass through so that it can measure the humidity (moisture) of the environment. It has been widely used in HVAC, consumer goods, weather stations, test & measurement, automation, medical, and humidifiers, especially performing well in extreme environments like acid, alkali, corrosion, high temperature, and pressure.


Key Features

  1. Breathable shell
  2. Corrosion resistance
  3. High-temperature resistance
  4. Large air permeability, fast gas humidity flow and exchange rate, uniform divergence.
  5. Excellent ability of anti-dust, anti-corrosion, and waterproof (IP65)
  6. Protecting PCB modules from dust, particulate pollution, and oxidation of most chemicals to ensure sensors a long-term stable operation, higher reliability, and long service life
  7. Remarkable performance in harsh environments such as small space, pipe, trench, wall pass mounting, high-pressure space, vacuum chamber, test chamber, large flow mediums, high humidity area, high temperature and heat environment, hot drying process, dangerous zones, explosive environment containing explosive gas or dust, etc
  8. 150 bar anti-pressure capability
  9. Seamless integrated, shedding-free
  10. The stainless steel porous housing for the sensor probe has accurate pore size, and uniform and even-distributed apertures.
  11. Pore size range: 5 to 120 microns; it has good filtration, dustproof and interception effect, and high filtration efficiency.
  12. Fully calibrated
  13. Digital output, I2C interface
  14. Low power consumption
  15. Excellent long-term stability

But once interfaced with Blake how do we trust the readings?

Upon interfacing the sensor with the Blake device, each device goes through a Calibration and Validation process. We send the device to a Third Party Calibration lab, where the Blake interfaced with the sensor is calibrated against a master device to check for accuracy. All Blake devices shipped to the customers are calibrated to have the following level of accuracy:





± 0.5 °C

± 2.5 %RH

You may also check the NABL Traceability for reference:

Okay great! But what if the Blake device readings are way off as compared to the local device we have?

Given that the Blake device is thoroughly calibrated and validated to the above levels of accuracy, its readings have been tried and tested with a master device from the third part calibration labs.

Non calibrated devices

Some wall clocks come with a temperature and humidity sensor. Unless there is a calibration certificate from the manufacturer stating the levels of accuracy to any master device, these readings cannot be compared with a calibrated device such as the Blake.

Air Conditioners(ACs)

You may also notice that the Blake devices readings are different as compared to the ACs in the room. Do note that the temperature set on the AC will not be the same throughout the room. This depends on the placement of the sensor, and the airflow in the room.

Say for example; if you set the AC at 22 °C, then the sensor(connected to the Blake), if placed closer to the vent of the AC will accurately match the AC. But if the sensor is far away, then it will show the temperature in the vicinity of where it has been placed.

IoT temperature Humidity monitoring BTHM Blake server room

Ashwin Salgaocar
Training Content and DevOps @ BoltIoT