Pressure Gauge -FAQ 

The pressure gauge is an instrument for measuring the condition of fluid and pressure. The reading of the gauge is known as gauge pressure, which is the difference between two pressures. Therefore, the pressure gauge does not reflect the true pressure but the pressure difference.

This guide will discuss the common FAQs about the pressure gauge, its functions, and its working. Hopefully, this information will help you purchase a pressure gauge if you are looking for a pressure gauge for your business.

Q1-What is a pressure gauge?   

Pressure gauges are used for measuring the constant pressure of air, water, and oil, etc.

It is important to the safe and proper functioning of various industrial systems, such as water-based systems, oil-based systems, gas-based systems, and corresponding industrial products, such as water heaters, fire extinguishers, medical gas cylinders, etc.

Measuring pressure is important to maintain mechanisms that directly run on proper pressure control. It is also critical to properly operate mechanisms that depend on values tied to pressure control, for example, the flowmeters where pressure levels affect flow rates. In fact, the pressure value is so important to the modern industrial process, and a pressure gauge is an idea and economy select to measure pressure value.

The device which measures the pressure is called a pressure gauge, where pressure is the force applied per unit area of a surface. There are many techniques for measuring pressure. While measuring pressure, it is important to consider with which reference point it is measured against. The reading on the gauge is the difference between the two pressures.

The pressure gauge is relative to the atmospheric pressure and equals the difference between absolute and atmospheric pressure. Therefore, the pressure gauge is zero referenced against the air pressure.

Q2 – What is a pressure gauge used for?

The pressure gauge measures the pressure difference between the system and the surrounding atmosphere. It is the most effective tool for pressure measurement, used in many applications. As atmospheric pressure is part of many calculations, it is also added to gauge pressure. The gauge pressure affects by the changing atmospheric pressure due to weather conditions.

The gauge pressure measures the working fluid that exists in a closed system. You can calculate gauge pressure by the following equation:

Pg = PS – patm

Where:

Pg = Gauge pressure

PS = System pressure

Paytm = Atmospheric pressure

Gauge pressure is equal to the gauge pressure minus atmospheric pressure. Thus, the pressure gauge has zero references against ambient air pressure.

Q3 – When pressure gauge was first introduced?

The pressure gauge is an easy and direct way of measuring the pressure relative to atmospheric pressure. It is very commonly used equipment in industrial plants, refineries, health care, and energy production. Pressure gauges were first introduced 150 years ago. At that time, the usage of steam processes was common during the industrial revolution.

With technological evolution over the years, the basic mechanics of the pressure gauge remain unchanged until the 80s. Then, with the digital age, a digital pressure gauge was introduced. The digital pressure gauge offers more advantages than the traditional one.

Q4 – How does pressure gauge work?

A pressure gauge is the measurement device for fluid intensity and for tuning fluid power machines. Without a pressure gauge, the fluid power system would be inaccurate and unreliable. Therefore, it is an important tool to make sure there are no pressure changes in the system that could affect the operating condition of the system.

When the pressure exceeds, the pressure gauge raises the alarm. Keeping the workers and organization safe is also important because if the pressure level exceeds, the machine may explore. There are three ways to measure pressure in the pressure gauge – absolute, gauge, and vacuum.

Q5 – What is the working principle of the pressure gauge?

The working principle of the pressure gauge follows Hooke’s law. Hooke’s law states that the force required expanding a spring scale regarding the distance of extension or compression. Thus, the pressure applied on the surface of the object is more on the inner side. This technique is used widely in many industries.

The recent advances in technology have resulted in the popularity of digital pressure gauges. In a digital pressure gauge, the AC and DC power supplies are used. First, the AC is converted into DC. Next, the measured pressure is transmitted to the sensing diaphragm, and then the electrical signal reaches the computer or smartphone. With smartphones, the pressure gauge comes with a small LCD.

Q6 – What are the techniques of measuring pressure in pressure gauge? 

In simpler terms, the pressure gauge is the tool to measure pressure. Pressure is the amount of perpendicular force applied per unit area. There are various techniques to measure pressure. These techniques are:

• Absolute pressure gauges

Absolute pressure measures the pressure that exists in the full vacuum. It is absolute pressure when the pressure at full vacuum is zero. It consists of a measuring cell and a diaphragm. The gauge has a reference chamber and a vacuum. A barometer measures the absolute pressure.

This technique is popular for measuring the vapor pressure of liquids and vacuum reactors. Absolute pressure gauges also measure leakages in tanks and circuits and perform distillation operations in oil refining industries.

• Gauge pressure measuring devices 

The Gauge pressure technique measures the atmospheric pressure at sea level. It is positive when atmospheric pressure is more, and gauge pressure is negative when it is lesser than atmospheric pressure. The device which measures the gauge pressure is the Bourdon tube pressure gauge which consists of a tube formed at C shaped and sealed from the other end.

The other device that measures the gauge pressure is bellows, diaphragm, and U-tube manometer. Gauge pressure measuring devices are suitable for many industrial applications, including power, chemical, petrochemical, food, and sanitation.

• Differential pressure gauges

A differential pressure gauge measures the difference between two pressure readings. These instruments are mechanical. The device that measures the differential pressure gauge includes piston-type, diaphragm type, and bellows differential pressure gauges.

The differential pressure gauge is used in many industries for monitoring the liquid level and filtration. For example, they have a usage in refineries like petrochemical and chemical plants.

Q7 – What are the types of pressure gauges based on usage?

Each application has usage of different pressure gauges. The commercial and industrial pressure gauge is a measuring instrument used in Heating Ventilation, Air Conditioning (HVAC), and refrigeration. In addition, it is applicable in production processes, manufacturing industries, hydraulic and water treatment.

The process pressure gauge is suitable for industries with intense conditions, such as high pressure and corrosive environment. The low-pressure gauge is for the measurement of liquid and gas pressure in industries. A sealed gauge prevents potential leakage and has wide applications in industries, preventing corrosive chemicals and pharmaceutical requirements.

The high-precision test pressure gauge is well suited for industries with high precision requirements. The duplex pressure gauge is a differential pressure gauge that measures the difference between two applied pressures.

Q8 – How to choose a Pressure Gauge fit for your application?

Choosing the right pressure gauge for your application is very important. You have to consider many factors in mind, like the level of accuracy, durability, size of the dial, and other environmental conditions. You also need to consider the mounting options and how much the pressure gauge can measure the pressure.

These factors determine what kind of gauge is suitable for you. There are many designs of pressure gauges, and each serves different industries or applications. So first, familiarize yourself with the factors that can affect your application, and then choose the one.

Q9 – What is the role of Bourdon tubes in pressure gauges?

The function of Bourdon tubes and bellow pressure ranges is different depending on the application. The function of the Bourdon tube is to take the pressure and convert it into mechanical energy. This mechanical energy causes the movement of the dial and shows the current amount of pressure in the system. The Bourdon tube pressure gauge has various configurations, such as curved, helical, and spiral.

The pressure range determines the size of the tube, its material, and other factors. When the pressure rises, the cross-section of the tube also changes. The operation of the Bourdon tube in a pressure gauge is simple. It consists of a flat tube of metal. One end of the tube is fixed, and the other is attached to the lever mechanism.

Q10 – How do below pressure gauges measure pressure?

The function of the bellow pressure gauge is similar to the Bourdon tube. The only difference is that the bellow gauges use a spring to judge the amount of energy used to push the dial. The spring compresses and expands the pressure in the tube. This creates the energy that can move the pressure dial.

The bellow type pressure gauge measures the absolute pressure, which is more sensitive than the Bourdon gauges. They have the capacity of measuring pressure up to 40mm Hg. They have high strength and ductility.

Q11 – How does choose the right pressure gauges to help Hydraulic applications?

The pressure gauge help reduces costly downtime whether you are using it for testing equipment or machinery. However, in most hydraulic systems, the issues with gauge reliability are pressure spikes and vibration, so it is best to look for the pressure gauge designed for hydraulic applications.

The features that you should consider while purchasing the pressure gauge include a forged brass case to prevent any damage to internal components and a liquid-filled case to prevent the gauge from extreme pressure and vibration. The restrictor in the pressure gauge also prevents the system from extreme pressure spikes. Consider the temperature range, pressure range, and the amount of vibration from each application.

Q12 – What are the safety concerns while choosing the pressure gauge?

For the safety purposes of the organization, you should select the pressure gauge with the maximum steady pressure range that does not exceed 75% of the scale value. The maximum limit of the cyclic pressure is 65% of the maximum scale value. If you are using hazardous pressure media, such as oxygen and other toxic substances, choosing the pressure gauge with additional safety measures is necessary.

For all organizations, it is essential to follow these safety measures to avoid any accidents or leaks of the pressurized components or injury of anyone at the front of the scale. First, with high-pressure gauges, fill the gauges with oil or glycerin.

Q13 – What are the capsule element pressure gauges?

The capsule element pressure gauge measures the air and gases at low pressures. It consists of two circular membranes joined at the outer edge. The opening at the middle of the diaphragm lets media enter. The expansion or contraction of the chamber between the inner and outer media measures the pressure.

The capsule pressure gauge is most popularly used in the precise measurement of gaseous media. It is suitable for applications with low-pressure pneumatic systems, vacuum pumps, and the monitoring of filters. The accuracy class of this pressure gauge is between 0.1 and 2.5. These gauges require little or no maintenance.

Q14 – What are the accessories used in pressure gauges?

Some of the common accessories used in the pressure gauges are:

Seal/gaskets: These ensure that there is proper sealing. It could be flat or profile. The flat seal does not allow extra rotation of the pressure gauge’s readout. The profile allows a full turn of the pressure gauge readout to ensure proper installation. The profile can be external or internal.

Safety caps: The safety caps are attached to the pressure gauge to ensure shock absorption and durability.

Reducers: When there is a variation between the input of the pressure gauge and output, reducers are used.

Heat Necks: Heat necks can protect the hot process applications and protect the pressure units.

Push-On Connectors: These are part of the pressure gauge for easy installation and uninstallation. Snubbers: A pressure snubber dampens the high-pressure spike environment and ensures the durability of the pressure gauge.

 

Q15 – Advantages of the Pressure Gauge?

Pressure gauges offer many advantages to various applications.

Durability

Pressure gauges can perform in extreme temperatures and conditions. They have a design that can withstand cracking because of the aluminum and stainless steel material. In addition, they have crack-resistant plastic covers that prevent shocks, debris, and other hazardous chemicals. It makes them durable and reliable.

Customization options

You can get the customize pressure gauge according to your requirement. In addition, you can add or remove features and create custom units when the custom application requires it.

Readability

Pressure gauge with digital technology has a feature of clear readout on display. In addition, some of the pressure gauges have a backlight as well. As a result, the readings are fast and precise.

Q16 – What are the double-sided pressure gauges?

The double-sided pressure gauge is the type of pressure gauge. It is applicable in various industries. The double-sided pressure gauge is made up of a plastic body with a heavy, rugged design. It offers high resistance to chemicals, corrosion, and abrasion. You don’t need any proper filling for these gauges, as they are already filled with glycerin.

The double-sided pressure gauge has a polycarbonate lens which has the feature of high resistance. You can use it in mechanical systems where visibility is an issue by installing them on chemical pumps. Before purchasing the pressure gauge, make sure to read all the gauge features and the autonomy of its operation before purchasing it.

Q17 – How accurate is the pressure gauge?

The pressure gauge accuracy is the difference between the true value and indicated reading on the pressure gauge. It is defined as the percentage of full-scale range for mechanical pressure range. The accuracy range of test gauges is 0.25% through 0.10% full-scale accuracies. Therefore, it is 1.0% accuracy for industrial processes and 1.6 or 2% for less critical commercial uses.

Accuracy is the most important element of the pressure gauge. For just a few dollars, you can find a pressure gauge that can give accurate readings. It is crucial to match the specifications of the pressure gauge with the particular application. If you install the pressure gauge with insufficient accuracy, it will lead to flawed measurement data.

Q18 – What is pressure gauge calibration?

Calibration is the process of comparing the results of the actual pressure gauge with the standard device. If the result does not match with the reference, it needs amendments. If it matches with the reference, it means the measurement is accurate. The standard measuring instrument needs to be accurate for getting the accurate results of your calibrated pressure gauge.

While calibrating the pressure gauge, it is important to check the values throughout the measuring range, zero points, and full-scale value. This is because the pressure gauges and meters are subject to drift, making these instruments less accurate with time. So to ensure the quality of the pressure gauge and safety, calibration is essential for every device.

Q19 – Why is pressure gauge an important part of hydraulic systems?

Never ignore the importance of the pressure gauge in hydraulic systems. It is part of the well-executed measurement and maintenance program. It provides information about how the system is working and whether the operation is within the desired limits. For hydraulic systems, bourdon type pressure gauge might be perfect for your needs.

The typical pressure gauge has a needle that rests at approximately 7’o clock positions. Behind the dial, there is a proper precision mechanism of spears and springs. The pressure gauge can be dry or liquid-filled. The liquid fill option dampens the environmental vibration. Glycerin and silicon are two popular options of liquid filling of pressure gauges. Glycerin is for indoor installation, while silicon is good for colder climates.

Q20 – How to maintain a pressure gauge? 

If you want a long service life for your pressure gauge, you must follow some long life and accuracy techniques. The pressure gauge is usually installed in a system with an on/off valve, which allows the pressure gauge to rest until the reading is needed. When the reading is needed, you can open the gauge. When the system is shut down, the valve is also closed. In this way, the pressure gauge remains calibrated longer in this state.

Portable diagnostic instruments are used in liquid-filled pressure gauge, which includes on/off venting valve. This valve needs to be open for an accurate reading but allows leakage if not closed once again. Therefore, maintenance of pressure gauge is minimal unless it is calibrated periodically. When performing maintenance, ensure that the system is de-pressurized.

Q21 – How to select a pressure range in the pressure gauge?

One of the common problems with pressure gauges arises when there is an incorrect selection of pressure range. It would help if you considered operating pressure and maximum system pressure while selecting a pressure range. The operating pressure is the pressure at which the gauge is exposed occasionally, while the maximum system pressure is the maximum amount of pressure it has to face.

If the maximum pressure of the pressure gauge is 6 bar, and the operating pressure is 3 bar, then the pressure gauge would have a range anywhere between 0-6. The pressure gauge should never exceed the maximum pressure limit, resulting in leakage and inaccurate readings. You can also install the pressure relief valve to prevent contact with maximum pressure.

Q22 – How to deal with pressure spikes and pulsation of a pressure gauge?

If there are frequent pressure spikes, then check the pressure range selection thoroughly. You can detect the pressure spikes in the system by using a gauge with a maximum pressure pointer. This will display maximum pressure over time. Another method is to use a digital gauge with logging capability.

One of the popular and effective ways to reduce the pulsation in the pressure gauge is by adding damping devices. Adjustable snubbers and piston-type snubbers are examples of these damping devices. They prevent pressure spikes or pulses. Unfortunately, installation damage can also result in premature pressure gauge failure. To overcome this issue, install them by using a wrench rather than using a hand.

Conclusion

A pressure gauge is an important tool for measuring pressure levels in liquid and gas. They are used all over the world in an industrial environment at reasonable rates. Measuring the pressure level in your system is very important to ensure the safety check of any leaks and consistency of the product.

At Instruthink, we offer various types of pressure gauges to our customers at very affordable rates. We have a high reputation in the market based on positive customer ratings. If you have any questions about installing the pressure gauge, you can email us at sales@instruthink.com.