Non Invasive Pressure Indicators

Acoustic Pressure Monitoring

Acoustic pressure monitoring is exactly what it sounds like. The use of acoustic pressure monitoring enables quick and easy detection of even small changes in pressure, which can indicate a potential leak or other issue. It is an effective tool for ensuring the safety and stability of container contents without the need for invasive pressure testing or other time-consuming procedures. Whether you are dealing with sensitive materials or simply require precise pressure monitoring for industrial applications, acoustic pressure monitoring can provide a reliable and efficient solution.

How Does Acoustic Pressure Monitoring Work?

Acoustic pressure monitoring is a non-invasive technique that monitors the internal pressure of a sealed container by detecting changes in resonant frequency response. Every object has an intrinsic resonant frequency, which is the frequency at which it “vibrates” or “rings” when excited.

The intrinsic properties of an object, such as its shape, size, thickness, and material, can affect its resonant frequency. In the case of a sealed and pressurised container, such as those used for industrial compressed gases, the tension in the material is also a significant factor. The physical principles that explain how tension affects resonance in a string or wire can also be applied to more complex systems, including those used for gas pressure monitoring and pressure testing.

In the case of a pressurised container, such as a fire cylinder, the tension within the walls plays a vital role in determining the resonant frequency. The tension is generated primarily by the internal pressure of the cylinder, resulting in a quantifiable relationship between pressure and resonant frequency. By accurately adjusting for changes in temperature, the pressure can be used to predict the exact amount of gas present within the cylinder. This highlights the significance of pressure monitoring and testing, particularly for industrial compressed gases, to ensure safe operation and efficient management of contents.

Therefore, Acoustic pressure monitoring detects even minor changes in the internal pressure of a cylinder by safely exciting resonant vibrations, analysing them, and carefully calibrating the system. Temperature measurements can be combined with pressure testing, to utilise the most accurate mathematical models available, to distinguish changes in contents (i.e., a leak) from fluctuations in pressure caused by temperature.

Continuous Monitoring of Pressure using Mass

Contents monitoring of fire cylinders, pressure testing and monitoring can be an effective solution. However, an alternative option is to monitor the mass of the contents. This method is particularly useful for industrial compressed gases, as it provides a simple and effective way to detect any leaks or changes in the quantity of gas, and eliminates factors such as temperature.

For instance, the mass monitoring method can be used to monitor liquefied gaseous systems, which contain both a propellant gas and a liquefied extinguishing agent. While this method cannot differentiate between a loss of agent or a loss of propellant gas, any type of leak can still be rapidly detected and addressed.

For non-gaseous systems, pressure loss is often used as a reference point, but it is equally important to report mass loss as an equivalent loss in temperature-adjusted pressure. To address this, a digital fixed weight monitoring system such as PermaMass® FEATHERWEIGHT can be used. This system utilises the intrinsic link between mass and pressure in pressurised gases. When connected to inert gas cylinders, PermaMass® FEATHERWEIGHT can automatically convert any measured mass loss into an equivalent loss of pressure, which is adjusted to the original fill temperature and compared to the fill pressure. This helps to ensure compliance with regulations and provides a comprehensive understanding of how systems are performing.

Why is Monitoring Pressure Important?

Inert gas fire suppression systems, like Inergen™, are commonly used to protect high-value assets and critical infrastructure in occupied spaces, where CO2 systems are not appropriate due to the risk to human life. In the event of a fire, if this concentration is not met, or is met for an insufficient length of time, there is no guarantee that the fire will be successfully extinguished, potentially leading to catastrophic damage. It is vital, therefore, to accurately monitor the contents of fire extinguishing cylinders, to ensure that there is no leakage of agents that could lead to an area being unsafe without you even knowing about it.

Therefore, proper content monitoring of fire extinguishing cylinders, therefore, becomes essential to avoid any leakage of agents that could potentially lead to a hazardous situation. Pressure monitoring is vital for inert gas fire systems, as per the standards such as ISO 14520 and NFPA 2001, where temperature-adjusted pressure is a direct indication of cylinder contents. If the true loss of pressure is more than 5%, the cylinder needs to be refilled or replaced.

For this reason, accurate pressure monitoring, coupled with precise temperature adjustments, is critical for effective and reliable monitoring of an inert gas fire system. Regular and reliable gas pressure monitoring can detect any leaks long before the 5% threshold, ensuring a higher level of safety and security for the assets that the fire system is designed to protect. Trusting in our gas pressure monitoring solutions will give you peace of mind that your industrial compressed gases are being monitored accurately and reliably.

List of applications:

• Healthcare – Respiratory therapy, anaesthesia, and other medical applications.
• Pharmaceutical – Production of medicine.
• Food and Beverage – Carbonation and preservation of food and beverages.
• Power Generation – Fuel sources for power generation and heating.
• Oil and Gas – Maintain pressure and prevent corrosion in oil and gas pipelines.
• Manufacturing – Used in welding, cutting, and other industrial processes.
• Environmental – Monitor and reduce greenhouse gas emissions.
• Mining – Mine ventilation and safety.
• Chemicals – Production of chemicals and fertilisers.
• Transportation – Alternative fuels for vehicles.
• Agriculture – Enrich the air in greenhouses to enhance plant growth.
• Construction / Metal – For welding, cutting and heating.
• Textile – Spinning and weaving of textile fibres.
• Aerospace – Pressurization and propulsion.
• Refrigeration – Refrigerants in commercial and industrial refrigeration systems.