Pressure Gauges

More Information about Pressure Gauges

Differential pressure gauges measure the difference in pressure between two points. This measurement can be critical in certain applications such as monitoring filtration systems or flow rates in pipes. They often use diaphragm or capsule elements, which deform under pressure differences, providing a measure of the differential pressure.

Absolute pressure gauges measure pressure relative to a perfect vacuum. This type of gauge is often used when dealing with vacuum systems or low pressure applications where atmospheric pressure can significantly affect measurements.

Liquid-filled pressure gauges contain a damping liquid, often glycerin or silicone oil, which provides shock absorption to protect the delicate internal parts of the gauge from vibration and pressure fluctuations. They also prevent potential leaks and enhance the gauge's lifespan and reliability.

Each type of pressure gauge comes in multiple dial sizes and pressure ranges, allowing for their use in a wide array of applications. For instance, low-pressure gauges are ideal for applications dealing with pressures near atmospheric pressure, while high-pressure gauges are designed to withstand and measure high pressures, such as in hydraulic systems or compressed air systems.

In terms of construction, many pressure gauges feature a stainless steel case for durability, especially in challenging industrial environments. The process connection, or the part of the gauge that connects to the system where pressure is being measured, is also typically made of robust materials to withstand the pressure sensed.

When selecting a pressure gauge, several factors need to be considered, including the pressure range, the maximum working pressure, the accuracy class, and the type of pressure (gauge, differential, or absolute) to be measured. The choice depends on the specific needs of the industrial application.

FAQs

What are diaphragm pressure gauges?

Diaphragm pressure gauges are a type of pressure measuring instrument that uses a diaphragm, a flexible membrane, for measuring pressure. These gauges are particularly well-suited for low-pressure measurements, including differential pressure measurements, where the difference between two pressures is being monitored.

Instrumentation: Elements & Transmitters

2 pieces of hardware used in modern day instrumentation: measuring elements and transmitters.

Measuring Elements

Measuring elements are the part of the device that performs the measurement. For example, the measuring element of a pressure transducer is the part that is actually lowered into a tank that will take a pressure measurement. The measuring element of a flow meter is the part that actually measures the flow and an RTD or thermocouple takes the temperature measurement.

Transmitters

Transmitters collect information from measuring elements and sends the information to where it is needed. The transmitter interfaces with the measuring element and interprets the information. It then sends that information to a PLC, RTU or some other type of control unit. In many cases, the transmitter has the ability to communicate the information via multiple communication protocols. This may be necessary when the measuring element does not send the same type of signal that is needed by the controller. For example, it may be necessary to convert a temperature reading from a thermocouple to a 420 milliamp signal that can be received by a local PLC.