The nitrogen sealing valve device is a type of self-acting control valve designed to maintain a stable pressure at the top of storage tanks, particularly for storing hazardous or volatile substances. These Valves are commonly used with various media such as air, nitrogen, steam, and liquids, depending on the application. A breathing valve is typically installed at the top of the tank to allow for controlled gas exchange. When the liquid level in a toxic medium storage tank stabilizes, the pressure at the top matches the vapor pressure of the substance at that temperature. If the breathing valve opens, it can lead to the release of harmful vapors, posing risks to personnel and causing environmental pollution. To prevent this, a constant pressure must be maintained on the liquid surface, usually by using nitrogen, which creates a protective gas blanket over the liquid—this process is known as nitrogen sealing.
The nitrogen sealing valve and system developed by Sanjing Valve Co., Ltd. is an independently designed self-operated micro-pressure control system. It ensures a steady supply of protective gas (typically nitrogen) at the top of the vessel, preventing direct contact between the stored material and the atmosphere. This helps avoid evaporation, oxidation, and potential safety hazards. The system is especially suitable for large-scale storage tanks and offers benefits such as energy efficiency, quick response, reliable performance, and ease of maintenance. It is widely applied in industries like petroleum, chemical processing, and more.
Key features of the nitrogen sealing valve and device include:
1. **Energy-efficient operation**: No external power or gas source is required, making it cost-effective and environmentally friendly.
2. **Easy pressure adjustment**: The nitrogen pressure can be set and adjusted during continuous production without interruption.
3. **High sensitivity**: The pressure detection diaphragm has a large effective area, and the spring stiffness is low, ensuring rapid and accurate responses.
4. **Low friction design**: The absence of packing reduces friction on the valve stem, resulting in faster action and higher control accuracy.
5. **Effective pressure reduction**: The pilot-operated nitrogen supply device achieves a pressure reduction ratio of up to 100:1, providing excellent control and stability.
The system consists of two main components: a nitrogen supply unit and a nitrogen release unit. The supply unit includes a pilot valve and a main valve, while the release unit is a micro-pressure regulating valve with internal feedback. Nitrogen pressure is typically set to around 100 mm water column and precisely controlled by the system.
When the tank inlet valve is opened, the liquid level rises, reducing the gas space and increasing the pressure. If the pressure exceeds the set point of the release valve, it opens to vent excess nitrogen. Once the pressure drops back to the set value, the valve closes automatically. Conversely, when the outlet valve is opened, the liquid level decreases, increasing the gas volume and lowering the pressure. At this point, the nitrogen supply valve opens to replenish the tank with nitrogen until the desired pressure is restored.
The nitrogen sealing valve is primarily used to maintain a constant nitrogen pressure at the top of the tank, protecting both the stored material and the tank itself. It consists of a fast relief valve and a micro-pressure regulating valve. The fast relief valve includes a pressure controller and a single-seat shut-off valve. When the tank pressure reaches the set point, the relief valve quickly releases the excess pressure. When the pressure drops, the micro-pressure valve opens to inject nitrogen into the tank.
To ensure optimal performance, the nitrogen supply pressure must be adjusted to a safe level (usually below 0.1 MPa). The pressure regulating valve is installed to reduce the incoming pressure accordingly. The system allows for a wide range of pressure settings, from as low as 0.5 kPa (50 mm wc) to as high as 66 kPa, offering a 132:1 adjustment ratio. The pressure detection diaphragm is highly sensitive, and the spring stiffness is minimal, enabling precise and responsive control.
For setting the nitrogen pressure, the micropressure regulator valve can be adjusted by turning the adjustment screw to change the spring pre-compression. Similarly, the pressure controller in the fast relief valve allows for adjustments by modifying the spring compression. To prevent frequent opening and closing, the set points should be spaced apart—typically, the nitrogen supply pressure is set lower than the relief valve’s set point, and the breathing valve’s setting should be higher than the relief valve’s to avoid unnecessary operations.
Sanjing Valve Co., Ltd. specializes in manufacturing electrical control valves, self-acting pressure regulators, and nitrogen sealing systems. These products are widely used across multiple industries, including oil and gas, chemicals, power generation, metallurgy, military, shipbuilding, light industry, papermaking, pharmaceuticals, and environmental protection. We welcome you to explore our solutions and experience the reliability and performance of our products.
Stop valves are closed by screwing a rubber gasket down onto a seat in the middle of the valve. Pros only use small versions that act as shutoff valves for fixtures such as sinks and toilets and outdoor sillcocks. Flow is inefficient because of the circuitous route the fluid (water, in most cases) has to follow. It's important to orient the valve in the right direction with the arrow (cast into the side of the valve) aligned with flow direction. That way, water flows against the bottom of the rubber gasket. If the valve is put in backward, the flow will force the gasket away from the top of the valve.
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