Bourdon tube pressure gauges – find manufacturers and suppliers

Bourdon tube pressure gauges are used to measure the pressure of gaseous or liquid media and display it directly on site.

They are among the most commonly used mechanical pressure gauges and are employed, among other things, in mechanical and plant engineering, in hydraulic and pneumatic systems, and in energy and process engineering.
The measuring element that gives the device its name is a curved metal tube known as a Bourdon tube. It deforms under the influence of the applied pressure. This movement is mechanically transmitted to a pointer and displayed on a scale. Since Bourdon tube pressure gauges operate without an external power source, they enable simple, robust, and cost-effective pressure monitoring.

Below is an overview of the operating principles, designs, applications, and advantages of Bourdon tube pressure gauges, as well as the most important criteria for selecting them.

How Bourdon tube pressure gauges work

The Bourdon tube consists of a bent metal tube, usually with an oval cross-section. One end is firmly connected to the process connection, while the other end can move freely.
When the medium to be measured enters the Bourdon tube under pressure, its cross-section changes slightly. At the same time, the bent tube attempts to straighten itself. As a result, the free end of the Bourdon tube moves in response to the applied pressure.
A mechanical transmission mechanism amplifies this movement and transmits it to the pointer. The pointer indicates the measured pressure on an appropriately graduated scale. If the pressure drops, the Bourdon tube returns to its original shape within its elastic operating range.
Bourdon tube pressure gauges typically measure pressure relative to ambient atmospheric pressure. Depending on the model, they can display overpressure, vacuum, or a combined vacuum and overpressure range.
For very low pressures or particularly sensitive measurement tasks, diaphragm or capsule pressure gauges are often more suitable. Electronic pressure sensors and pressure transmitters, on the other hand, are used especially when measured values need to be continuously transmitted, stored, or digitally processed.

Types of Bourdon tube pressure gauges

Bourdon tube pressure gauges are available in various designs. They differ primarily in the shape of the Bourdon tube, the materials used, the housing design, and any additional functions.

Bourdon tube pressure gauges with a C-shaped Bourdon tube

The C-shaped Bourdon tube is the most widely used design.
It is suitable for numerous standard industrial applications and allows for a compact and cost-effective design.
For higher pressures or special measurement ranges, helical or spiral Bourdon tubes can be used.
Due to their shape, these designs produce greater movement of the free end of the Bourdon tube. 

Bourdon tube pressure gauges with copper-alloy wetted parts

Models with wetted parts made of copper alloys are frequently used for neutral, non-corrosive liquids and gases.
Typical applications include water technology, pneumatics, heating technology, and general mechanical engineering.
Before use, it must be verified that the materials are sufficiently resistant to the medium being measured as well as to the prevailing temperatures.

Stainless steel Bourdon tube pressure gauges

Stainless steel versions are suitable for more demanding industrial applications and for media that are incompatible with copper alloys.
They are used, among other places, in the chemical and petrochemical industries, in plant engineering, and in energy and process engineering.
For particularly aggressive media, special materials or a diaphragm seal may be required.

Liquid-filled Bourdon tube pressure gauges

In these versions, the case is filled with glycerin or silicone oil, for example.
The liquid dampens pointer movements caused by vibrations or pulsating pressures.
This improves readability. At the same time, it reduces the stress on the pointer mechanism and mechanical transmission components.
Liquid-filled pressure gauges are therefore frequently used on pumps, compressors, hydraulic units, and mobile machinery.

Bourdon tube pressure gauges with additional functions

Mechanical Bourdon tube pressure gauges can be equipped with electrical switching contacts or an electrical output signal. 
When predetermined limit values are reached, the switching contacts trigger, for example, warning messages or switching operations.
Models with an electrical output signal combine the highly visible mechanical on-site display with the ability to transmit measured values to a control system or a higher-level system.

Applications of Bourdon tube pressure gauges

Bourdon tube pressure gauges are used wherever pressures need to be reliably monitored and read directly on a machine, system, or pipeline.

Mechanical and plant engineering

In machine and plant engineering, Bourdon tube pressure gauges are used to monitor operating pressures in supply lines, cooling circuits, lubrication systems, and various auxiliary units.

Hydraulics

In hydraulic systems, they display, among other things, pump, working, accumulator, or return pressures.
Since pressure spikes and pulsations can occur in such systems, the measurement range and damping must be carefully selected.

Pneumatics

In pneumatic systems, Bourdon tube pressure gauges are used to monitor compressed air and other suitable gases. 
Typical installation locations include compressors, compressed air treatment units, manifolds, and pneumatic control systems.

Pumps and compressors

On pumps and compressors, these instruments monitor suction, discharge, or compression pressures. 
In cases of severe vibration or fluctuating pressures, liquid-filled versions or additional damping elements are advantageous.

Chemical and process plants

In process plants, Bourdon tube pressure gauges measure pressures in vessels, piping, and production processes.
For hot, aggressive, highly viscous, contaminated, or crystallizing media, a diaphragm seal can be used. This isolates the measuring instrument from the process medium and hydraulically transmits the pressure to the measuring element. Standard Bourdon tube designs, on the other hand, are particularly suitable for media that are not highly viscous or crystallizing and do not corrode the materials used.

Energy and utility systems

Additional applications can be found in heating systems, water distribution systems, power generation plants, and other utility systems. For hot media or steam, the measuring instrument and any necessary protective devices must be adapted to the process temperature.

Mobile machinery

Robust Bourdon tube pressure gauges are used in construction, agricultural, and industrial machinery to monitor hydraulic and pneumatic systems. Here, resistance to vibrations, shocks, moisture, and fluctuating temperatures is particularly important.

Advantages of Bourdon tube pressure gauges

• No external power supply: Measurement and display are purely mechanical. The pressure can therefore be read directly even without an electrical power supply.
• Direct on-site display: The operating status of a machine or system can be quickly checked at the installation site.
• Robust construction: The proven mechanical design ensures reliable pressure monitoring when the correct model is selected and used properly.
• Versatile designs: A variety of measurement ranges, materials, case sizes, connection types, and additional functions allow for adaptation to numerous applications.
• Cost-effective use: Bourdon tube pressure gauges offer a cost-effective solution for many standard measurement tasks.
• Good readability: An appropriate scale and a sufficiently large dial allow for a quick visual assessment of the pressure.
• Combination with accessories: Diaphragm seals, damping elements, shut-off valves, siphons, or overpressure protection devices can expand the range of applications.

Limitations of Bourdon tube pressure gauges

• Bourdon tube pressure gauges are not suitable for every pressure measurement task. Highly viscous, contaminated, or crystallizing media can obstruct the narrow cross-section of the Bourdon tube. Corrosive media can attack unsuitable materials.
• Severe vibrations, rapid pressure changes, pressure spikes, and prolonged overloading can also impair readability, measurement accuracy, and service life. Such operating conditions must be taken into account during selection and, if necessary, controlled by appropriate protective or damping measures.
• For very low pressures, particularly high accuracy requirements, or the digital transmission and storage of measured values, other mechanical or electronic measuring systems may be more suitable.

Key purchasing criteria for Bourdon tube pressure gauges

Bourdon tube pressure gauges perform important monitoring tasks in many systems. Careful selection helps prevent measurement errors, premature wear, and unplanned failures.

Measurement task and pressure range

First, it must be determined whether gauge pressure, vacuum, or a compound pressure range is to be measured. Not only the normal operating pressure but also possible pressure fluctuations and pressure spikes must be taken into account.
The operating pressure should be sufficiently below the full-scale value. A measurement range that is too small increases the risk of overload. Conversely, an unnecessarily large measurement range reduces readability within the normal operating range.

Accuracy class and scaling

The required accuracy depends on the intended use. Different requirements apply to general operational monitoring than to testing or quality-related measurements.
The size of the dial and the scale division must also be appropriate for the application. The measured value should be clearly readable from the intended viewing distance. Required pressure units or dual scales must be specified at the time of ordering.

Process medium and materials

All parts in contact with the process medium must be resistant to that medium. In addition to the type of medium, concentration, temperature, impurities, and possible chemical reactions must also be taken into account.
Copper alloys may be suitable for neutral media. For corrosive or more demanding media, stainless steel or special materials are often used. If direct contact between the medium and the Bourdon tube is not possible, a diaphragm seal may be required.

Process connection and installation

The thread type, connection size, sealing system, and position of the connection must be suitable for the installation location. For example, versions with a bottom connection or a rear connection are available.
The installation orientation, available space, and desired reading direction must also be taken into account. Mechanical stresses in piping must not be transmitted to the pressure gauge.

Vibrations and pulsating pressures

Vibrations and pressure pulsations can occur in pumps, compressors, or hydraulic systems. Significant pointer fluctuations make the reading difficult and place additional stress on the measuring mechanism.
Liquid-filled instruments, throttles, pulsation dampers, or installation separate from the machine can reduce this stress. The appropriate measure depends on the specific operating conditions.

Temperature and environmental conditions

The temperature of the medium and the environment must remain within the permissible limits of the pressure gauge. For hot media, siphons, cooling sections, or diaphragm seals may be necessary.
Dust, moisture, splashing water, corrosive atmospheres, and outdoor exposure determine the required housing design and protection class. In corrosive environments, stainless steel housings and highly resistant seals may be necessary.

Safety and standards

In cases of high pressures, hazardous media, or installation near operating personnel, it should be determined whether a safety pressure gauge is required. Safety versions may feature, among other things, a shatterproof sight glass, a solid partition wall, and a blow-out back wall. This ensures that, in the event of damage, escaping media or components are diverted away from the operator as much as possible.
DIN EN 837-1 covers, among other things, dimensions, metrological requirements, design, and testing of Bourdon tube pressure gauges. DIN EN 837-2 contains recommendations for the selection and installation of pressure gauges. Depending on the industry and application, additional approvals, test certificates, or calibration certificates may be required.

Manufacturer, service, and lifecycle costs

A suitable manufacturer or supplier should be able to advise on the selection of the measurement range, materials, connections, case design, and accessories.
The availability of standard and custom designs, delivery capability and spare parts supply, calibration and repair services, technical documentation and certificates, as well as the long-term availability of comparable devices, should also be taken into account.
In addition to the purchase price, installation, maintenance, calibration, replacement frequency, and potential downtime costs should also be considered. A technically suitable and robust pressure gauge can be more cost-effective in the long term than a model selected solely based on the lowest purchase price.

Summary

Bourdon tube pressure gauges are proven mechanical measuring instruments for the direct display of the pressure of gaseous and liquid media. They operate without an external power supply and are used in numerous machines, plants, and supply systems. Different measurement ranges, materials, case designs, and additional functions allow them to be adapted to a wide variety of industrial requirements. However, reliable measurement results require that the pressure gauge be carefully matched to the process medium, pressure range, accuracy, connection type, and environmental conditions. Pulsating pressures, vibrations, high temperatures, corrosive media, and potential pressure spikes require special attention. In such applications, liquid-filled gauges, diaphragm seals, damping elements, or special safety designs may be necessary.

Bourdon tube pressure gauges can be purchased from various manufacturers and suppliers. Comprehensive information about manufacturers and suppliers of Bourdon tube pressure gauges from around the world can be found on Exportpages.