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A wide variety of pressure gauges are used for measurement purposes across industries today. Liquid-filled brass gauges are popular for their durability and precision. Brass gauge applications have significantly expanded with the rise in use of portable equipment such as compressors, pumps, and hydraulic tools.

Inner working of a Bourdon tube pressure gauge

One hundred and seventy years ago, French engineer Eugene Bourdon invented the C-shaped hollow tube that is sealed at one end. The sealed end shifts with rise in pressure inside the tube, and this displacement is used to measure pressure. Despite a wide range of pressure instruments that exists today, the mechanical Bourdon tube gauge remains the most common method of pressure measurement. 

WIKA’s model 213.40 Bourdon tube brass gauge utilizes this age-old technology in combination with a solid piece of forged brass that constitutes the socket, and a liquid-filled case. The use of solid brass increases durability and minimizes leakage and damages due to misapplications.

The 213.40 was the first liquid gauge introduced to the U.S. market, in the 1960s, and WIKA continues to be the sole U.S. manufacturer of this type of solid brass gauge. Over the years, overseas importers have copied numerous models of brass gauges and introduced them to the market, but WIKA’s model 213.40 remains unparalleled in its quality, robustness, accuracy, and long service life. 

The Advantages of Liquid Gauges over Dry Gauges

Liquid-filled gauges are more economical in the long run since they are designed to withstand harsh conditions. In traditional dry gauges,severe operating and environmental conditions such as vibration, pulsation, humidity, and temperature fluctuations pose serious problems. The fluid in liquid-filled gauges effectively solves these issues by protecting the internals from the elements and from mechanical impacts, thus preventing internal condensation and increased wear of all moving components. 

Case filling is by far the best solution to protect sensitive components from mechanical impacts such as vibrations and frequent pressure cycles. In the case of frequent pressure cycles (pulsations), WIKA recommends accessorizing the gauge with a restrictor or snubber in combination with the case filling, unless clogging of the pressure port becomes an issue.   

The type of liquid constituting the filling varies depending on the type of application and operating conditions. Glycerin is suitable for most applications with non-oxidizing fluids, while silicone is typically used in low ambient temperatures down to 40°FFor oxidizing fluids, inert liquids such as Halocarbon oil or Fluorolube® might be considered. Model 213.40 comes standard with glycerin case filling. 

WIKA’s Model 213.40 Bourdon Tube Brass Gauge

Model 213.40 brass gauge

WIKA’S Bourdon tube brass gauge has a “one-piece” solid forged-brass case and socket, and its liquid filling enables it to withstand most adverse conditions, including high vibration, shock, and pulsation. Known as “The Hydraulic Gauge” in the industry, the 213.40 is regularly used in mobile and stationary machinery, and many other heavy duty hydraulic applications. Mechanical brass gauges are also extensively used in upstream oil applications with pressure ranges of up to 15,000 psi. WIKA’S glycerine-filled, crimped bezel brass gauges are virtually indestructible and are the standard in the Texas oil patch.

Since the appearance of the first liquid-filled gauge in the 1960s, various models have been introduced to the U.S. market in an attempt to emulate WIKA’s reliable hydraulic gauge. However, there exists no comparable alternative to this particular model to date.

WIKA USA’s comprehensive portfolio of pressure instruments consist of a number of customizable process gauges, including models built to meet the demanding conditions of the oil and gas industry. To see whether the model 213.40 Bourdon tube brass gauge would be right for your particular application, contact our pressure specialists.



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