Here is the datasheet of Honeywell ABP2 Pressure Sensors series.

In Figure 7 on page 11, you can see a lot of options. Here are the absolute ones:

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I don't understand why they have to provide different output units. They are all linear and it's easy to convert from one to another. If the output is digital it's just a multiplication, if the output is analog the units are virtually meaningless - it's a matter of adjusting a voltage to the following stages.

On the other side, if they did so there must be a real need.

Can you please help me to understand why?

Do I need to mind this when I select the component or I can just pick up the one closer to my requirements that is available on the market?


To better clarify the question, I'm not interested about why people use different units. I'm asking what the implications are in selecting a component (especially for the digital output) and what the advantages are to have different products with the very same range (i.e. 1 bar = 100 kPa.)

  • \$\begingroup\$ This might not be a question specific to electrical engineering, but general engineering, or just non-engineering question. Some people are used to certain units. E.g. imperial vs metric. You might ask why people use F or C or inches vs millimeters. For temperature conversion between F and C that's not even a simple multiplication but includes offset. The analog sensors not only have different units, but different ranges, so you might want to use same 3.3V MCU with ADC to sample the full 3.3V range, whether you need to measure 10 bar or only 1 bar. \$\endgroup\$
    – Justme
    Dec 1, 2023 at 11:19
  • \$\begingroup\$ Why don't we just all stick to K? Or to SI units in general? looking at you, America migrate to history of science? \$\endgroup\$
    – tobalt
    Dec 1, 2023 at 11:52
  • \$\begingroup\$ @Justme, actually my question is related about selecting a component reading its datasheet. I'm not interested why people uses different units. But why an electronic sensor may have different units and what are the implications using it in the circuits (if any) \$\endgroup\$
    – Mark
    Dec 1, 2023 at 12:44
  • \$\begingroup\$ Strangely, while they all have a (near enough) 1 bar (rounded to 2 S.F.) the MPa set lacks a 1MPA (10 bar) and the psi set goes in different steps - and in the differential range there's even more difference in availability \$\endgroup\$
    – Chris H
    Dec 1, 2023 at 20:52
  • \$\begingroup\$ @Mark Something like this and I think a "legal beagle" had a hand. Perhaps someone calls on the phone looking to replace a product needing 4 bar and was told to buy the "60 psi" product. But on buying, the confused buyer selects the "30 psi or 100 psi" product, installs it, and half the oil refinery blows up as a result. In court, the judge and/or jury needs to figure out who was at fault. Was it the low-information buyer who can't be expected to know all this stuff? Or the high-information seller who should have known better than to sell a product labeled in units the buyer can't interpret? \$\endgroup\$ Dec 2, 2023 at 5:13

2 Answers 2


If a manufacturer is providing options, you must assume there's a market for those options.

It's 'just' a multiplication to you. It's the 'wrong number' for some technician who's got to repair an industrial control system by dropping in an exact replacement.

  • \$\begingroup\$ Good point. What I still missing is the "equivalent numbers": 1 bar = 100 kPa. There's no need even for a replacement to have two different products. \$\endgroup\$
    – Mark
    Dec 1, 2023 at 12:57
  • \$\begingroup\$ @Mark: There’s still the “My spec sheet says 100 kPa. Is there a 100 kPa sensor in the product line? Yes, add it to the cart, no, I’ll look somewhere else, and not take the chance of being liable if I got my conversion wrong” factor. \$\endgroup\$
    – RLH
    Dec 2, 2023 at 5:11

The point may be in the analog output range, not units.

If you have a 3.3V AD converter, you want to utilize the full scale of it.

So depending on what you are measuring, you want a 3.3V output range for whatever pressure range you may have to measure, 1 bar or 10 bars.

  • 3
    \$\begingroup\$ This does not answer the question. Of course the range is important, but it's the same if the range is 1 bar or 100 kPa \$\endgroup\$
    – Mark
    Dec 1, 2023 at 12:45
  • \$\begingroup\$ That may be the case for the "PSI" sensors, but the "Pa" and "bar" sensors have exactly the same output ranges -- they're probably exactly the same sensor, just with a different part number. \$\endgroup\$
    – Mark
    Dec 1, 2023 at 21:46
  • \$\begingroup\$ @Mark Except for some reason there is no 1.0 MPa sensor when there is a 10 bar sensor. \$\endgroup\$
    – Hearth
    Dec 4, 2023 at 15:57
  • \$\begingroup\$ @Hearth, under the naming pattern they're using, both sensors would be "001GA". \$\endgroup\$
    – Mark
    Dec 4, 2023 at 23:06

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