Huber Pilot ONE Unistat T3*0, Operation Manual

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Introduction
OPERATION MANUAL Chapter 1
Unistat® T300 Series
V2.4.0en/22.07.20//17.12
18
1.4.2 Safety devices to DIN 12876
The rating of your temperature control unit is stated on the data sheet in the appendix.
Classification
Temperature
control medium
Technical requirements Identification d)
I Non-combustible a) Overheat protection c) NFL
II Combustible b) Adjustable overheat protection FL
III Combustible b)
Adjustable overtemperature protection
and additional low-level protection
FL
a)
Usually water; other fluids only if non-combustible even within the temperature range of an individual fault.
b) The temperature control media must have a fire point of ≥ 65 °C.
c)
The overheat protection can, for instance, can be realized using a suitable fill level sensor or a suitable temper-
ature limiter.
d) Optional at the choice of the manufacturer.
Combined electronic low level and overtemperature protection
This temperature control unit has been equipped with an electronic overtemperature protection
and low-level protection. Instead of a mechanical float switch, temperature sensors are employed
on the surface of the heating coils. These sensors monitor overtemperature at this potential ignition
source, thus ensuring the controller regulates the heating coil temperatures below the critical tem-
perature (fire point of the thermal fluid). An appropriate message is output via the >Touchscreen<
[88].
There is no longer a need for mechanical tools to set the trigger values of the overtemperature
protection. It is replaced by a software engineering tool. The threshold value for the overtempera-
ture protection can be set only if a code, randomly generated by “Pilot ONE”, is entered correctly. As
with the mechanical tool, accidental settings are thus prevented.
Low level protection
Low level protection is achieved via a pressure sensor in the fluid circuit. The pump ensures, togeth-
er with the thermal fluid, the requisite pressure at the pressure sensor. Air in the system (fill level
too low, inadequately vented) prevents the pressure from reaching value specified at the pressure
sensor. Temperature control and circulation are interrupted.
Process safety
This type of overtemperature protection is driven by a desire for further protection of operator and
system. Protective devices typically disconnect all poles when reaching the overtemperature protec-
tion trigger value. This may result in more heat being fed into the process (e.g. exothermic reaction)
than the existing cooling machine is able to cool as the overtemperature protection trigger value is
usually set above the controller setpoint. Turning off the temperature control unit eliminates the
possibility to extract heat from the process. The temperature could therefore rise further and sys-
Rating of laboratory
thermostats and
laboratory baths
Overview of the tem-
perature thresholds