Pressure · Measurement
Pressure Gauge
A dial gauge, usually with a Bourdon tube inside, that shows pressure on site without power.
What it does
Gives the operator a direct local reading at the wellhead, flowline and vessels. Liquid filled cases damp needle flutter from vibration and pulsation.
Basics
| Element | Bourdon tube, diaphragm or capsule for low pressure |
| Dial sizes | Commonly 2.5, 4, 4.5 and 6 in |
| Range rule | Normal pressure near the middle of the scale |
| Accuracy grades | Defined in ASME B40.100 |
Common failures
- Range too low, the Bourdon tube takes a permanent set
- Dry gauge on a pulsating line, the movement wears out
- Wrong wetted material for sour or corrosive service
Troubleshooting
- Symptom
- Needle does not return to zero
- Likely cause
- Overpressure or worn movement
- What to check
- Replace and size the range so normal pressure sits mid scale
- Symptom
- Needle shakes
- Likely cause
- Pulsation or vibration
- What to check
- Add a snubber or use a liquid filled gauge