What Are the Differences Between Pressure Transmitter and Pressure Gauge

When it comes to monitoring and measuring pressure in industrial settings, two essential devices come to the forefront: pressure transmitters and pressure gauges. While both serve the fundamental purpose of providing insights into fluid and gas pressures within systems, they do so in markedly different ways. Pressure transmitters are the modern, electronic marvels of precision, capable of offering highly accurate measurements and the convenience of remote data transmission and integration with control systems. In contrast, pressure gauges are the reliable mechanical workhorses that have been trusted for generations, delivering instant visual feedback on pressure levels. In this article, we’ll delve into the distinctions between these two stalwarts of pressure measurement, exploring their unique features, applications, and the advantages each brings to the table. Whether you’re navigating the complexities of industrial automation or seeking to understand the basics of pressure measurement, this comparison will illuminate the key differences between pressure transmitters and pressure gauges.

What Is A Pressure Transmitter?

A pressure transmitter is a pressure sensor that outputs a standard signal. It is a device that contacts a pressure variable and converts it in proportion to a standard output signal. Pressure transmitters are made up of three parts: a pressure detecting element (also known as a pressure sensor), a measurement circuit, and a process connection. Its function, like that of a translator, is to convert the sensed pressure of a gas or liquid into a standard electrical signal (such as 4-20mADC, for example). This enables the use of instruments such as signaling alarms, recorders, regulators, and so on for measurement, indication, and process regulation.

Pressure Transmitter Working Principle

When direct pressure is applied on the measuring diaphragm, it bends slightly out of form. The high-accuracy circuit on the measuring diaphragm transforms this small deformation into voltage output which is highly near proportional to pressure and the excitation voltage. A specific circuit processing chip in the pressure transmitter converts this voltage signal into an industrial standard 4-20mA current signal or 1-5V voltage signal, for example. The measuring diaphragm can achieve excellent precision and stability because it uses a standard integrated circuit with linearity and temperature compensation circuits. The transmission circuit adopts a dedicated chip, guaranteeing the output of two-wire 4-20mA current signal, three-wire 0.5V-4.5VDC, 1-5VDC, 0-5VDC, and other voltage output signals.

Pressure Transmitter	Advantages	Disadvantages
	High accuracy	Higher initial cost
	Remote monitoring capabilities	Vulnerable to electronic failures
	Digital output for data integration	Complexity in setup and calibration
	Wide measurement range	Limited suitability for certain harsh environments
	Long-term stability	Dependency on power sources
	Minimal maintenance	Limited compatibility with legacy systems
	Resistance to environmental factors	Possible signal interference
	Enhanced diagnostics and alarms	Risk of inaccurate readings due to sensor drift
	Compatibility with automation systems	Calibration requirements.
	Continuous measurement updates

Pressure Transmitter Applications

• Industrial process control
• HVAC (Heating, Ventilation, and Air Conditioning) systems
• Oil and gas production and refining
• Water treatment and distribution
• Aerospace and aviation
• Automotive manufacturing
• Pharmaceutical and chemical processing
• Food and beverage production
• Pneumatic systems
• Environmental monitoring and compliance
• Medical equipment
• Research and laboratory experiments
• Marine and shipbuilding
• Power generation
• Mining and mineral processing.

What Is A Pressure Gauge?

A pressure gauge is very common in our everyday life. It measures and displays the pressure in excess of the ambient pressure. Pressure gauges can be found in various areas, whether in power plants, piping systems, medical devices, automotive repair shops, and food and pharmaceuticals. Mechanical pressure gauges are becoming increasingly used in industrial process control and technical measures due to advantages such as durability and ease of fabrication.

Pressure Gauge Working Principle

A bourdon tube pressure gauge, or a spring tube pressure gauge, is a common pressure measurement instrument. As a sensitive component, it employs a spring tube. It deforms when pressure is applied to the spring tube, and one end is displaced. With the pointer and dial attached, we can easily read the value of the pressure measurement. When atmospheric pressure is present inside the gauge body, the pressure measured by the gauge can be either positive or negative. However, when the gauge case is sealed and evacuated, the pressure measured by the gauge is absolute. When fitted with an isolation device, a bourdon tube pressure gauge can also measure pressure in high-temperature, corrosive, viscous, crystallizing, and particle-containing media. In high-accuracy elastic pressure measuring instruments, such as those with a precision level of 0.25 or better, the elastic elements are often made of constant elastic alloy and sometimes even quartz glass. The transmission mechanism’s shaft bore is inlaid with gem bearings or rolling bearings. Pressure gauges typically have long dials with digital displays.

Pressure Gauge	Advantages	Disadvantages
	Simplicity of operation	Limited accuracy
	Immediate visual feedback	Lack of remote monitoring capabilities
	No external power source required	Inability to provide digital output data
	Durability in harsh environments	Prone to mechanical wear and tear
	Wide temperature tolerance	Subject to parallax errors in reading
	Long lifespan	Limited measurement range
	Low initial cost	Susceptible to vibration and shock damage
	Minimal maintenance	Gradual loss of calibration over time
	Ease of installation	Limited diagnostic features
	Compatibility with legacy systems	Unsuitability for critical automated systems

Pressure Gauge Applications

• Automotive tire pressure monitoring
• Hydraulic system pressure monitoring
• Pressure monitoring in water treatment plants
• Refrigeration and air conditioning systems
• Pressure measurement in food processing
• Monitoring boiler and steam system pressure
• Aerospace and aviation applications
• Pressure gauges in pharmaceutical manufacturing
• Marine vessel pressure monitoring
• Pressure measurement in laboratory equipment
• Pressure gauges in HVAC systems
• Process control in petrochemical plants
• Monitoring pressure in pneumatic systems
• Pressure measurement in construction equipment
• Pressure gauges in agricultural machinery.

Differences Between Pressure Transmitter and Pressure Gauge

• Calibration of pressure transmitters requires more accurate instruments, much more accurate than pressure gauges.
• The pressure gauge only needs to be checked for the relationship between inputs and outputs, whereas the pressure transmitter may need to be checked for the relationship between input and communication data.
• Specific measurement qualifications are required when calibrating pressure gauges, which are normally reserved for manufacturers and new installations. Pressure transmitters, on the other hand, are rarely calibrated.
• The pressure gauge’s accuracy could be improved. It has no output and cannot be manipulated by hand. To distinguish between pressurization and depressurization, 5 points are often examined. Smart pressure transmitters, on the other hand, normally just need to be calibrated for zero and full scale.
• The pressure gauge’s output is a simple scale indication. The pressure transmitter produces an analog output, which must be connected to an ammeter with sufficient accuracy to display the pressure measurements.