What is delta T?

Delta T (ΔT) is the difference between two temperatures.  We use this term to refer to the difference between:

• The temperature of the oil in a vessel’s jacket (also called internal temperature) and
• The temperature of the vessel contents (also known as process temperature or reaction temperature).

We usually consider the delta T when a jacketed vessel is being heated or cooled.  The temperature of the vessel contents will lag behind the temperature of the oil in the jacket.  If the delta T is too large, it could stress the glass and lead to breakage.

We therefore recommend that the delta T limit is set to 50°C (50K).  With current Huber thermoregulators with Pilot ONE controllers, you can adjust this by Menu → Protection Options → Delta T Limiter → type 50 in ‘New value’ field → tap ‘Ok’ to confirm. In the previous Nuevo controllers the delta T limiter can be found in the ‘Limits’ menu, and in older Unistat controllers it is program 18.

Please note, this control can only be achieved if the contents temperature is being monitored. If it is not being monitored (if the vessel is empty, for instance) then great care should be taken to heat or cool the vessel in a controlled, gradual way to prevent thermal shock (e.g. by use of a ramp function).  When using a temperature probe in the vessel (external Pt100), please ensure the end of the Pt100 is always immersed in the vessel contents.

Please also be aware that even if a delta T limit is set, it is possible for this limit to be exceeded slightly in practice.  If this poses a problem for you, we recommend you reduce the delta T limit setting to below your desired limit.