Read Beta with its two defining temperatures
Nominal resistance describes an NTC at a reference condition. Beta addresses a different property: the shape of its resistance-versus-temperature relationship. TDK's general technical information connects the B value with the ceramic material and defines its rated value using two temperatures. A comparison that retains resistance but detaches those defining temperatures has therefore discarded part of the meaning of the Beta specification.
Consider two candidates presented with matching nominal resistance. That match says something about their resistance at the stated reference point, but it does not determine how their resistance descriptions relate elsewhere. The Beta field supplies additional curve information. It should remain a separate selection condition, rather than being inferred from resistance or treated as another name for the same property.
The defining interval also belongs to the field itself. A Beta description based on one temperature pair and a description based on another are not automatically interchangeable entries in a comparison. First establish which interval each manufacturer means. This is a question about the parameter's definition, before any judgement about whether the available curve information addresses the application's temperature span.
Separate an interval approximation from a full curve
TDK describes a simplified exponential relationship as an approximation suited to a restricted range around the rated temperature or resistance. That qualification matters because a convenient curve parameter and a complete resistance-versus-temperature description serve different purposes. A compact Beta entry can help characterize the relationship without supplying the full detail needed throughout every possible application range.
The technical information points to more detailed models or tabulated characteristics when a more precise curve description is needed. The practical distinction is between choosing a parameter representation and establishing that the representation covers the required span. A proposed NTC can have a clearly stated Beta while the application's necessary curve information still needs a different form of manufacturer evidence.
For example, a requirement concerned with a narrow region around the reference condition is a different model-coverage question from one spanning substantially different temperatures. Neither should inherit an accuracy conclusion merely because the same Beta heading appears. Identify the range the representation is intended to describe, then distinguish that scope from the availability of fuller characteristic information. No conversion formula is needed to preserve this distinction.
Keep local sensitivity and tolerance distinct
Local sensitivity asks how resistance changes with temperature at the particular temperature of interest. TDK calls the temperature coefficient an indication of sensitivity at a given temperature. Beta, by contrast, is defined across an interval. The two descriptions are related to the same characteristic, but their definitions address different questions: local response and an interval-based description of curve shape.
Manufacturing tolerance introduces a further distinction. TDK treats rated-resistance tolerance and B-value tolerance separately. Matching the nominal resistance and its tolerance does not establish that the second candidate has the same allowed variation in curve shape. The note explains that B variation affects resistance spread away from the reference temperature, so a reference-point comparison leaves part of that question unanswered.
A useful technical requirement therefore keeps the local sensitivity question separate from both tolerance descriptions. It can ask what response matters at the intended temperature while retaining the manufacturer's independent resistance and Beta tolerances. This avoids turning a tightly specified reference resistance into a claim about temperature sensitivity or complete conversion uncertainty. Those are different interpretations of the characteristic, not additional names for nominal resistance.
Keep the zero-power basis visible
The resistance characteristic also has an electrical-loading context. TDK distinguishes an unloaded thermistor's zero-power characteristics from behaviour under electrical load. Current through a thermistor can produce enough heating to raise its temperature above the surroundings. The electrical quantity being observed can therefore be associated with a thermistor temperature different from the surrounding temperature the application intends to sense.
This is a different issue from the mathematical range of a Beta approximation. A more detailed unloaded curve describes that unloaded relationship more fully; it does not, by itself, remove self-heating caused by the application. Similarly, a well-defined Beta interval does not say how much the sensing arrangement influences the thermistor's temperature. Model coverage and electrical loading need their own interpretations.
When selecting the sensor description, establish whether the required characteristic is the manufacturer's zero-power basis or behaviour in an electrically loaded application. Keep that distinction attached to the intended temperature interpretation. It explains why a curve description alone cannot promise the temperature result of a complete sensing arrangement, without prescribing a measurement current, heating procedure or new calibration exercise.
Sources and further reading
TDK/EPCOS general technical information, January 2018, physical pages 3–5: qualitative Beta, sensitivity, tolerance and zero-power prose. Numeric temperature pairs, equations, curves and measurement procedures are not used.