Thermistor Beta values

[spannerz]

I'm looking at replacing a thermistor, but I'm no electronics expert, and don't know enough about the specifications of such items.

The part I'm replacing is a fuel level sensor in a vehicle petrol tank.

The original part is no longer made or stocked, but I've discovered that a 1K thermistor, part # RL2004-582-97-K can be used in place of the original. The Beta value is 3972

I've found other 1K thermistors with different Beta values, such as 3800, which are more readily available in a small quantity.

How important is the Beta value when used in this context?

Thanks for any info.

 

[LvW]

Hi spannerz,

the beta value determines the slope of the R=f(T) characteristics. (T=temperature of the element).
As the difference between both values (3800 vs. 3972) is small I expect no problems with beta=3800.
Note: typically, beta values are in the range 2900...5000.

 

[spannerz]

Thanks LvW,

That's the sort of answer I was expecting/hoping for. After all, the thermistor isn't actually being used to measure the temperatue as such... It just lights a bulb.

These are the actual specs for the RL2004-582-97-K...
https://farm9.staticflickr.com/8452/7985069826_3d34a3bafa_z.jpg

...and a possible alternative, TTC-102..
https://farm9.staticflickr.com/8462/8018927775_d66594baaa_z.jpg

Do you think that's likely to be OK?

 

[spannerz]

I just found some info for the original [Panasonic] part. https://www.electro-tech-online.com/custompdfs/2011/01/AUD0000CE2-1.pdf

3.4w lamp "on" current should be 135mA minimum, and lamp "off" current 60mA maximum.

Operating Temperature Range –10 to +60 °C

Detection time 180 seconds... but not that important, I'd have thought.

 

[spannerz]

In the end, I went for ND03J00102K [NTC, 1K, 3.5MM Body diameter, 3480K Beta Value] from RS online. Stock # 697-4455


Just over a year on, and it's still working OK. The low fuel level warning light on the dashboard isn't quite as bright as it was originally, but it does the job.

I hope this info is of use to others with a similar problem.