Pressure Gauges
How to Choose the Right Pressure Gauge Range
One of the most common buying mistakes is choosing a pressure gauge range based on the highest pressure that might ever occur. The needle then sits near zero, accuracy drops, and pressure spikes damage the movement.
Why the wrong range costs money
Accuracy is usually expressed as a percentage of the full scale. A very large range multiplies that percentage into a larger absolute error. A range that is too small lets spikes exceed the limit and shortens gauge life.
The middle-third rule
Normal working pressure should sit in the middle third of the scale, roughly 30 to 70 percent of the maximum range. If the system runs at 100 bar, a 160 or 250 bar gauge is a good fit, not a 1000 bar gauge.
Working pressure, peak pressure and spikes
- Working pressure: the normal operating pressure.
- Peak pressure: the highest value under normal conditions, for example when a valve closes.
- Spikes: short surges that can be several times the working pressure.
The range must exceed peak pressure. If spikes are present, use a glycerin-filled gauge to dampen needle movement and protect the movement.
Example
| Working pressure | Suggested range |
|---|---|
| 6 bar | 10 or 16 bar |
| 40 bar | 60 or 100 bar |
| 100 bar | 160 or 250 bar |
| 400 bar | 600 or 1000 bar |
Summary
Confirm the working pressure, account for peak pressure, and pick a range where normal operation sits in the middle third. With vibration or spikes, choose the liquid-filled version of the same range.
Related: dry pressure gauges and all-stainless pressure gauges.