WIKA 131.11 Stainless Steel Bourdon Tube Pressure Gauge

WIKA 131.11 compact stainless steel Bourdon tube pressure gauge, NS 40, 50 and 63

The WIKA 131.11 is a small-format pressure gauge in which both the case and the wetted parts are made of stainless steel. It comes in three nominal sizes, 40 mm (1 1/2 in), 50 mm (2 in) and 63 mm (2 1/2 in), and the manufacturer positions it for aggressive gaseous and liquid media that are not highly viscous or crystallising. Because the dial is small and the price point moderate, the 131.11 is a common choice on skids, compressor packages, gas cylinder regulators and general machine building. Seven Star LLC supplies the 131.11 in Oman and the GCC as an independent supplier in Muscat, and this page explains how the model is built so that an RFQ can name the exact version.

How the 131.11 is configured

The 131.11 is a modular instrument, so one model number covers many physical designs. The data sheet lets you combine a nominal size, a connection location, a window type, a case safety level, a ring, a mounting accessory and a scale range. The main choices are:

• Nominal size: 40 mm, 50 mm or 63 mm.
• Connection location: lower mount (radial) or centre back mount.
• Window: snap-fitted polycarbonate as standard; laminated safety glass or instrument glass are offered only together with a slip-on bezel.
• Ring: none, a slip-on bezel in stainless steel, or the same bezel polished.
• Mounting: none, a panel mounting flange or a triangular profile ring with bracket (both only with centre back mount), or a surface mounting flange for NS 63 only.
• Special designs: oil- and grease-free, oil- and grease-free for oxygen (not available for NS 63), silicone-free, and an ammonia version with an R 717 temperature scale.

Technical specifications of the 131.11

How a Bourdon tube gauge such as the 131.11 works

Inside the case a curved or coiled stainless steel tube is closed at one end and open at the process connection. Pressure tries to straighten the tube, and the small tip movement is multiplied by a gear movement into pointer rotation. The data sheet specifies a C-shaped tube for lower pressure ranges and a helical tube for higher ones. The 131.11 has no case filling, so the pointer is undamped; on pulsating duty the pressure should be smoothed upstream, for example with a snubber such as the WIKA 910.12, or a liquid-filled gauge such as the 213.53 should be chosen instead.

The data sheet also states a working-pressure rule that is easy to overlook in practice: the pointer range should be selected so that steady load does not exceed three quarters of the scale end value, fluctuating load stays within two thirds, and only short peaks reach full scale. A gauge selected too close to the operating pressure ages faster and loses accuracy.

Where the 131.11 fits and related WIKA gauges

The 131.11 sits at the compact end of the WIKA Bourdon tube range. When a larger dial is needed the manufacturer points to the 232.50 and 233.50 stainless steel gauges in 63, 100 and 160 mm, and to the 232.30 and 233.30 safety versions where a solid baffle wall is required. The 131.11 itself reaches S1 safety level only, so it is not the right choice if the plant specification demands S3. Typical accessories on the same instrument connection are the 910.10 stopcock, the 910.11 shut-off valve and the 910.17 sealing rings.

Selection and ordering checklist for the 131.11

• Nominal size and the space on the panel or skid.
• Scale range and unit (bar, psi, kPa, MPa or kg/cm²), with the working pressure kept inside the three-quarter rule.
• Connection location, thread type (EN 837, NPT, ISO 7) and size.
• Window material, ring and any panel, triangular or surface mounting hardware.
• Special cleanliness: oil- and grease-free, oxygen service (not for NS 63), silicone-free.
• Accuracy class and whether an ASME grade is wanted.
• Medium: it must not clog the pressure path and must be compatible with 316L.

Installation and maintenance of the 131.11

Fit the gauge with a suitable flat sealing ring or WIKA sealing at the male connection and tighten on the wrench flats, never by turning the case. Check the zero position before the first pressurisation. The medium temperature limit is 100 °C and the ambient range is -40 to +60 °C, with an extra reading error of 0.4 % per 10 °C outside 20 °C. If the line is hot, a syphon or cooling element between the line and the gauge keeps the Bourdon tube within limits. For blow-out devices keep the 6 o’clock side clear so escaping pressure cannot hit a person. A gauge that has seen overpressure or a hard shock should be compared against a reference before it is trusted again.

Typical applications in Oman and the GCC

In Oman and the wider Gulf the 131.11 is used on compressed air and nitrogen skids, instrument air headers, gas cylinder stations, test benches, chilled water balancing points and small packaged plant. The all-stainless build helps where coastal humidity, salt air and dust attack painted or plated cases, and the CDA (clean dry air) duty named by the manufacturer matches the many instrument air systems in oil and gas, power and desalination plants. For safety-critical process lines Seven Star LLC would normally discuss the larger 232.30 or 233.30 safety versions instead.

Variants of the 131.11 at a glance

Information to send with an RFQ

• Model 131.11 with nominal size and scale range
• Connection location, thread and size
• Window, ring and mounting hardware
• Special design (oxygen, silicone-free, ammonia scale)
• Accuracy class or ASME grade
• Quantity, delivery site and certificate requirements

Documents and quotation

The WIKA data sheet for the 131.11 is attached on this page. It contains the full scale tables, dimension drawings and ordering options.

Send the nominal size, scale range, connection and quantity and Seven Star LLC will confirm availability and a quotation.