WIKA 73 Gas-Actuated Dial Thermometer, Stainless Steel

Overview

The WIKA 73 is a gas-actuated thermometer made completely from stainless steel and manufactured in accordance with EN 13190. WIKA designed it for the process industry, and it is used particularly in chemical and petrochemical plants, oil and gas facilities and power engineering, as well as machine building, tank and equipment manufacturing and the food industry. Scale ranges span from −200 to +700 °C, the response is fast, and the instrument is available in versions for direct mounting or for remote reading through a capillary of up to 60 m.

Seven Star LLC supplies the WIKA 73 family, including the back-mount A73, lower-mount R73, adjustable S73 and capillary F73 versions, to industrial customers in Oman and across the GCC, with engineering support in Muscat. When a site needs a robust dial thermometer that can be read at a panel away from a hot or inaccessible pipe, this is usually the instrument we propose.

Measuring Principle

A gas-actuated thermometer works on the pressure of an enclosed gas. As general engineering background, the bulb, capillary and Bourdon spiral form a sealed system filled with inert gas; when the bulb temperature rises, the gas pressure rises almost linearly, and the measuring element converts that pressure into pointer rotation. In the WIKA 73 the filling is an inert, physiologically safe gas, which matters in food and pharmaceutical plants.

Because the active part sits in the bulb, the WIKA 73 can display temperatures far from the measuring point. The capillary is stainless steel 316 with a 2 mm diameter; WIKA allows up to 60 m without a protective sleeve, 40 m with a spiral protective sleeve and 20 m with a PVC-coated sleeve. A contact bulb version measuring 120 x 22 x 12 mm can be strapped to pipes or tanks, so temperature can be measured without contact with the medium, even on very small pipe diameters.

Engineering Design of the WIKA 73

The case and bayonet bezel are stainless steel 304, the dial is white aluminium and the black aluminium pointer has micro adjustment. Nominal sizes are 100 and 160 mm with laminated safety glass or polycarbonate windows. Connection locations are back mount (A73), lower mount (R73), back mount with adjustable stem and dial (S73), which swivels 90° and rotates 360°, and capillary versions (F73) with surface mounting flange, panel flange, triangular ring or instrument bracket.

Wetted parts are stainless steel 316. Stem diameters are 6, 8, 10 or 12 mm, and threads include G ½ B, ½ NPT, M20 x 1.5 and female G ½, ½ NPT or M24 x 1.5, with plain, rotatable, union nut and compression fitting designs. Liquid damping with silicone oil, or a food-compatible damping fluid, allows operation under high vibration. Ingress protection is IP65 or IP66, and the dial carries a QR code linking to instrument-specific documents.

Key Features

The WIKA 73 delivers these advantages for process temperature measurement.

• Very wide scale ranges from −200…+50 °C up to 0…700 °C, with °C, °F or dual scale.
• Class 1 accuracy per EN 13190 at 23 °C ±10 °C ambient, valid within the marked measuring range.
• Fast response behaviour compared with many mechanical alternatives.
• Remote reading through stainless steel capillaries up to 60 m long.
• Contact bulb option for temperature measurement without contact with the medium.
• Ambient temperature range −40 to +60 °C, extendable to −50 °C, and to −70 °C in the POLARgauge® version.
• Liquid damping options for vibrating machinery, including a food-compatible fluid.
• Case and stem in stainless steel for corrosive outdoor and offshore environments.

Industrial Applications

Typical uses of the WIKA 73 in Oman include heater and furnace outlets, hot oil systems, steam headers and turbine bearings in power and desalination plants, reactor and column temperatures in Sohar and Duqm petrochemical units, and LNG and cryogenic nitrogen lines where the low ranges down to −200 °C are needed. The capillary version of the WIKA 73 is valuable on tank tops and elevated pipe racks, where the dial can be mounted at grade for safe reading, and the contact bulb suits retrofit monitoring without a hot tap.

For simple HVAC and utility points, a bimetal unit such as the WIKA A52 Bimetal Thermometer, Back Mount, Stainless Steel Case is more economical. When the temperature must reach a DCS, a WIKA TR10 RTD Sensor or a WIKA TC10-B Thermocouple for Additional Thermowell can share the same thermowell design. Seven Star LLC supplies the WIKA 73 with engineering support, and our team in Muscat helps customers across Oman and the GCC choose range, capillary length and thermowell.

Technical Specifications

The WIKA 73 data below is summarised from WIKA data sheet TM 73.01.

Installation Notes

WIKA recommends a thermowell for all but low-load applications, so the thermometer can be exchanged during operation. As general guidance, route the capillary of an F73 away from hot surfaces and respect the minimum bending radius of 6 mm for a bare capillary or 20 mm with a spiral sleeve, and check the minimum insertion length table in the datasheet for your scale range and stem diameter before fixing the thermowell length of the WIKA 73.

The movement can be specified as a combination of brass and stainless steel or completely in stainless steel; as a general recommendation, the all-stainless movement is the better choice for coastal and offshore sites where salt-laden air can eventually reach the inside of the case. For storage before installation, the datasheet allows −50 to +70 °C without liquid damping and −40 to +70 °C with damping, which covers warehouse conditions in the Gulf summer.

How to Order

For a quotation on the WIKA 73, send Seven Star LLC the version (A73, R73, S73 or F73), nominal size, scale range, stem diameter and insertion length, connection type, capillary length and damping requirement. Our Muscat instrumentation team will confirm availability and lead time, share the WIKA data sheet TM 73.01 and support temperature projects throughout Oman and the GCC.