The range from the working pressure
For 10 bar steady, 0–16 bar: 10 bar is 63 % of the scale, within 3/4. For 10 bar fluctuating the same range is just inside 2/3, and 12 bar fluctuating needs 0–25 bar.
Reference tool — not calibration
Choose the gauge range before it goes in an RFQ.
Pressure gauge
Pressure, range, class, connection.
Enter the working pressure and how it behaves, then the size and build. The dial and the RFQ line update with every change.
Examples:
All 130 engineering tools
A pressure gauge is ordered by its case size, scale range, accuracy class, connection and build. The range is the one most often wrong: a gauge run near full scale wears out, and one run at the bottom of a large scale reads coarsely. Enter the working pressure, and the selector takes the EN 837-1 range that keeps it within the makers’ limit and writes the RFQ line.
Bourdon tube gauges of nominal size 63 and 80 are rated for steady pressure up to 3/4 of the scale and fluctuating pressure up to 2/3; check the maker’s data for other sizes. The error limit of a class is a share of the whole span, so the same class reads coarser on a larger range.
How a gauge is chosen
Range, class, connection.
The class is a share of the span
Class 1.6 allows an error of 1.6 % of the span either way: 0.256 bar on 0–16 bar and 0.4 bar on 0–25 bar. The class is marked on the dial.
Size and connection go together
NS is the case diameter in millimetres. Makers’ standard lower-mount gauges of NS 50 and 63 have G 1/4 B, NS 80 to 160 G 1/2 B; panel and wall gauges may be back mounted, with a flange.
| Range, bar | Steady up to (3/4), bar | Fluctuating up to (2/3), bar | Class 1.6 error, bar | Class 1 error, bar |
|---|---|---|---|---|
| 0–0.6 | 0.45 | 0.4 | 0.0096 | 0.006 |
| 0–1 | 0.75 | 0.67 | 0.016 | 0.01 |
| 0–1.6 | 1.2 | 1.07 | 0.0256 | 0.016 |
| 0–2.5 | 1.88 | 1.67 | 0.04 | 0.025 |
| 0–4 | 3 | 2.67 | 0.064 | 0.04 |
| 0–6 | 4.5 | 4 | 0.096 | 0.06 |
| 0–10 | 7.5 | 6.67 | 0.16 | 0.1 |
| 0–16 | 12 | 10.67 | 0.256 | 0.16 |
| 0–25 | 18.75 | 16.67 | 0.4 | 0.25 |
| 0–40 | 30 | 26.67 | 0.64 | 0.4 |
| 0–60 | 45 | 40 | 0.96 | 0.6 |
| 0–100 | 75 | 66.67 | 1.6 | 1 |
| 0–160 | 120 | 106.67 | 2.56 | 1.6 |
| 0–250 | 187.5 | 166.67 | 4 | 2.5 |
| 0–400 | 300 | 266.67 | 6.4 | 4 |
| 0–600 | 450 | 400 | 9.6 | 6 |
| 0–1000 | 750 | 666.67 | 16 | 10 |
| 0–1600 | 1200 | 1066.67 | 25.6 | 16 |
The working limits are makers’ ratings for Bourdon tube gauges of nominal size 63 and 80. The error is the class in per cent of the whole span, at 20 °C. Vacuum ranges: -0.6 to 0 and -1 to 0 bar; compound ranges: -1 to +0.6 up to -1 to +24 bar.
Sources
EN 837-1 scope (Bourdon tube gauges, nominal sizes 40 to 250, ranges up to 1600 bar) per the BSI and Standards Norway listings. Nominal sizes, accuracy classes (the error limit is the class in per cent of the span, at 20 °C) and the range series per WIKA’s technical information IN 00.02, matching distributors’ listings (ebora, Pyrosales). G 1/4 B on NS 50 and 63 and G 1/2 B on NS 80 to 160 per WIKA’s data sheet PM 01.01 and RS listings. The 3/4 and 2/3 working limits per WIKA data sheets and Brannan’s and Hisco’s guidance.
Before you send the gauge
Questions about pressure gauges in an RFQ
How do I choose the range of a pressure gauge?
Take the smallest range of the EN 837-1 series that keeps the working pressure within the makers’ limit: 3/4 of full scale for steady pressure and 2/3 for fluctuating pressure on Bourdon tube gauges of nominal size 63 and 80. For 10 bar steady that is 0–16 bar; for 12 bar fluctuating, 0–25 bar.
What does class 1.6 on the dial mean?
The error limit: 1.6 % of the span, at 20 °C. On a 0–16 bar gauge that is 0.256 bar either way, on 0–25 bar 0.4 bar, so the same class reads coarser on a larger range.
Which connection does a pressure gauge have?
Makers’ standard lower-mount gauges of nominal size 50 and 63 have a G 1/4 B male thread, NS 80, 100 and 160 G 1/2 B. Back-mounted gauges and NPT or metric connections exist too: read the thread with the thread identifier when it is not marked.
What ranges does EN 837-1 have?
Pressure ranges from 0–0.6 to 0–1600 bar in the 1, 1.6, 2.5, 4, 6 series; vacuum ranges -0.6 to 0 and -1 to 0 bar; compound ranges from -1 to +0.6 up to -1 to +24 bar, for pressure and vacuum on one scale.
Why a liquid-filled gauge?
The filling damps the pointer under vibration and pulsation, which is why gauges on engines, compressors and pumps are often filled. Say in the request whether the old gauge was filled, and give the medium and its temperature.
Gauge chosen?
Send the line with the photographs.
A chosen line is a cross-check on the data, not proof. Attach photographs of the old gauge’s dial and connection, give the medium and the temperature, and Vessel Core checks them against each other before an offer goes back.
Buyer tools
