Pressure gauges: which range to buy
The most common mistake with a pressure gauge is buying one whose scale ends just above your working pressure. The needle then sits at the end of the dial all day, and the gauge wears out and loses accuracy.
The rule
Choose a scale about twice your normal working pressure. Your normal reading then sits near the middle of the dial, where it is easiest to read.
- Steady pressure: keep the working pressure under three quarters of the scale.
- Pressure that jumps (pumps, compressors): keep it under two thirds.
Example: a line that runs at 6 bar needs a 0–10 bar or 0–16 bar gauge, not 0–6.
What to tell the seller
- Dial size: 63 mm for machines, 100 mm when you read it from a distance.
- Connection: thread size (usually 1/4 or 1/2 inch) and whether it is at the bottom or the back.
- Vibration: on pumps and compressors, ask for a glycerine-filled gauge. The needle stays still and lasts longer.
- What is inside the pipe: for water and air brass is fine; for chemicals, steam or food ask for stainless steel.
