ML3 ThetaKit

Question

How do I cold boot (reset) the HH2 Moisture Meter Readout Unit?

Answer

To cold-boot the HH2 proceed as follows:

1. Disconnect the battery.
2. Short out the battery connection terminals with a metal object, e.g. a screwdriver blade.
3. Reconnect the battery: snap the connector in place in a single continuous action.
4. While doing so, observe the display and ensure that:
   a) the entire display blacks out
   b) no error messages are displayed
   c) the title screen ‘Delta-T Devices Moisture Meter’ is displayed.

As all volatile memory will be cleared, you’ll have to check your settings are ok (soil calibration, for example) and change if necessary. Also, if you are using a WET sensor, you’ll have to load the WET calibration file back on (see other FAQ about this).

Question

I see that the environmental protection rating for Delta-T soil moisture sensors is IP68. In practical terms what does this mean for the performance of the sensors and their cable connections, and can they be buried?

Answer

The IP68 Standard
The IP standard defines the degree of protection against the entry of water and dust that an instrument has. The first digit corresponds to performance for dust protection, the second figure for the level of water resistance. A rating of IP68 means that a device is completely sealed against dust and that it can withstand complete and continuous submersion in water. More information on the standard can be found here: https://en.wikipedia.org/wiki/IP_Code.
When Delta-T develop products for use in the field, we not only aim to meet the requirements of relevant IP standards, but, where possible, to surpass them. Our product design and testing aims to establish the highest performance we can achieve for the sensor and the cable connection.

Sensor sealing
During the design of the *SM150, SM150T, *SM300 and ML3 sensors, extensive water resistance tests were performed with reference to IP68 standards. Thermal shock tests were also carried out, which involved continuously monitoring the humidity inside the sensor as it was subjected to temperatures above 100^OC before being plunged into ice cold water. It was demonstrated that, even under these harsh ‘shock’ regimes, the sensors showed no signs of water ingress.

M12 connector sealing
During the design stage of the ML3 ThetaProbe (our most recently released sensor) we completed a comprehensive range of tests on the M12 cable connector (also fitted to several other Delta-T soil moisture sensors) to ensure satisfactory water resistance when submerged in water at depth.These tests will continue and results made available. Test results so far indicate that the M12 connection with the soil sensor can withstand burial to a depth of 2m – providing care is taken to ensure the connectors are clean and dry when assembled, and that they are hand-tightened securely.

Routine production testing
*SM300s, *SM150, SM150T and ML3 sensors are batch tested using the hot water leak test – which involves submerging a proportion of sensors from a manufacturing batch in a 60°C water bath for a fixed time whilst checking for bubbles emerging from the sensor or connector. In terms of pressure, this treatment is comparable to an immersion in 1.4m depth of water. We have determined that this an acceptable test to discover assembly errors.

5 year warranty
All Delta-T products will benefit from a 2 year warranty. However, for additional peace of mind, once you have registered your SM150T or ML3 soil moisture sensor with us, the warranty increases from 2 years to 5 years.

*SM300 and SM150 are now discontinued