If you want the right pressure type, you need to understand what they are, how they measure, and why they're used. There are five pressure types:
Gauge pressure measures everything above atmospheric pressure. It considers the pressure of the atmosphere as zero pressure - just like you do. This is widely used, and definitely the most popular type amongst the pressure sensors we sell.
Compound measures above atmospheric and below atmospheric - all the way to vacuum. This pressure type is useful when you need to see positive and negative pressure. However, there are usually good reasons to use the Absolute pressure type instead (see below).
Vacuum pressure measures from atmospheric pressure to vacuum. It's only measuring the vacuum. This is useful when you want to compare a negative pressure to atmosphere.
Sealed pressure uses the atmospheric pressure at the time it was sealed as it's zero point. This comes with it's own set of difficulties at lower pressure ranges. But it's great for higher pressure where the minute differences in atmospheric pressure don't matter.
Absolute pressure is also sealed, but under a full vacuum. It's zero point is true, or absolute, zero. Even vacuum pressures are seen as positive pressure to the absolute pressure sensor. This is often a better choice than compound because your reference point is fixed. It's also the basis of many calculations, such as head and resistance calculations in pump systems. Using an absolute pressure gauge on your pumps reduces the conversions needed to make use of your measurements.
To know which type you should use, you need to understand your goals. You should also understand what types of conversions you would have to do once you have a measurement. It's also hepful to know that sealed pressure sensors are better for dusty or moist environments. In many cases, you would do yourself some good to use an Absolute pressure sensor as long as you know how to interpret it properly.
If the explanations above aren't helping you, please contact us so we can discuss your application and get the right sensor.