Shandong Zhongjie Special Equipment (formerly Heze Boiler Factory Co., Ltd.) holds an A-grade boiler manufacturing license, A2-grade pressure vessel manufacturing license, A2-grade pressure vessel design license, B-grade boiler installation license, GB2 and GC2 pressure pipeline installation licenses, and equipment and machinery installation contracting qualifications. It is a member of the China Boiler and Water Treatment Association, the China Chemical Equipment Association, and a director unit of the Shandong Equipment Manufacturing Association. The company has also passed certifications for the ISO9001 Quality Management System, ISO14001 Environmental Management System, OHSAS18001 Occupational Health and Safety Management System, and the American ASME/U2 certification.
The primary reason for pre-cooling a liquid oxygen tank before use is to lower the tank's internal temperature to below the boiling point of liquid oxygen, facilitating the conversion of oxygen into a liquid state.
The boiling point of liquid oxygen is -183°C, and at room temperature, oxygen exists in a gaseous state. Liquid oxygen tanks require cooling the oxygen below its boiling point to convert it into a liquid for storage and supply.
The pre-cooling process typically involves the following steps:
Clean Storage Tank: First, the tank must be thoroughly cleaned to ensure there are no impurities or contaminants inside, to avoid affecting liquid oxygen.
Drainage and Exhaust: To empty the gas from the storage tank and expel it through the exhaust system to reduce the gas content within the tank.
Add Liquid Nitrogen: Injecting liquid nitrogen into the tank will rapidly cool the air and walls inside the tank with its low temperature, thereby reducing the tank's temperature.
Waiting for cooling: The liquid nitrogen inside the tank will gradually lower the temperature of the tank through the process of heat conduction until it reaches below the boiling point of liquid oxygen.
The purpose of pre-cooling is to ensure that the temperature inside the tank is low enough to meet the storage and supply requirements for liquid oxygen. Pre-cooling can reduce the evaporation and loss of liquid oxygen, while also contributing to the safety and stability of the tank.

Routine inspections and maintenance of liquid oxygen storage tanks are crucial for ensuring safe operation. The following are general steps for the daily checks and maintenance of liquid oxygen storage tanks:
Appearance Inspection: Regularly inspect the tank's exterior, including the shell, welds, valves, and fittings, etc. Pay attention to any abnormalities such as cracks, corrosion, or deformation.
Leak Detection: Utilize appropriate leak detection equipment to inspect for leaks in storage tanks and connecting areas. Leak detection can be conducted using methods such as gas detectors or liquid oxygen detection agents.
Pressure Testing: Conduct regular pressure tests to inspect the tank's sealing and pressure resistance. Perform pressure tests in accordance with relevant standards and regulations, and record the test results.
Valve and Fitting Inspection: Verify that the valves and fittings on the tank are functioning properly and there are no loose or damaged parts. Ensure the valves operate smoothly and reliably.
Insulation Layer Inspection: Check for any damage or detachment in the tank's insulation layer. Repair or replace any damaged insulation material to ensure effective insulation.
Cleaning and Drainage: Regularly clean the interior of the tank to remove accumulated impurities and dirt. Regularly drain to prevent damage to the tank from impurities and sediments in liquid oxygen.
Safety Equipment Inspection: Examine the safety equipment around the storage tanks, such as fire separation areas and alarm systems, to ensure they are functioning properly.
Record and Document Management: Document the results of each inspection and maintenance, including the inspection date, contents, issues found, and measures taken. Establish comprehensive management records and documents to facilitate tracking and managing the storage tank's operational status.
Note that inspections and maintenance of liquid oxygen tanks should be conducted by trained personnel and in accordance with relevant specifications and standards. Ensure safety during maintenance and operation, and consult with experts for accurate guidance.

The filling of a low-temperature liquid nitrogen tank refers to the process of transferring liquid nitrogen from an external supply source into the tank. Below is an explanation of the filling process for low-temperature liquid nitrogen tanks:
Preparation: Before filling the liquid nitrogen tank, preparation steps must be taken. This includes inspecting the tank's condition and safety, ensuring the interior is clean, free of impurities, and pollutants. Additionally, verify the quality of the liquid nitrogen from the supply source and the safety of the supply pipeline.
Connect supply source: Link the liquid nitrogen supply source to the liquid inlet of the storage tank. Ensure the connection is secure and reliable to prevent leaks.
Control Liquid Level: During the bottling process, it's necessary to control the liquid nitrogen level to prevent overfilling or overflow. A liquid level gauge or a liquid level control system can be used to monitor and control the level.
Slow injection: The injection of liquid nitrogen should be slow to prevent rapid vaporization and pressure increase. Appropriate valves and flow control devices can be used to regulate the injection rate.
Monitor Pressure: During the canning process, it is necessary to monitor the pressure of the storage tank to ensure it remains within a safe range. Pressure gauges or pressure sensors can be used for monitoring.
Canning Complete: Stop the injection of liquid nitrogen when the liquid nitrogen level reaches the predetermined filling quantity or the tank's capacity limit. Disconnect the connection to the supply source and ensure the tightness of the filling port.
Safe Operation: Throughout the bottling process, it is necessary to adhere to relevant safety regulations and operational guidelines. Liquid nitrogen is highly flammable and at low temperatures; operators must wear appropriate personal protective equipment and ensure the operation environment is free of ignition sources.
When bottling liquid nitrogen, be mindful of its low-temperature characteristics and safety. Ensure safe operation and control throughout the bottling process to guarantee the safe operation of the storage tank and effective storage of the liquid nitrogen.

Prior to using the liquid oxygen tank, the following preparations must be made:
Safety Inspections: Ensure that the tank and its surrounding environment are safe. Check for any damage, leaks, or other safety hazards on the tank. Make sure there are no flammable materials or other hazardous items in the vicinity of the tank.
Tank Preparation: Inspect the tank's exterior, including the shell, welds, valves, and fasteners. Ensure there are no visible damages or corrosion. Check that the insulation layer is intact and undamaged.
Liquid Oxygen Filling: Utilize the liquid oxygen supply equipment to fill the storage tank. Ensure the flow rate and pressure of the liquid oxygen are maintained within a safe range during the filling process.
Pressure Control: Storage tanks should be equipped with pressure control devices to ensure the internal pressure of the tank remains within a safe range. Inspect and adjust the pressure control devices to ensure proper operation.
Valve Operation: Check that the valves and connecting parts of the tank are functioning properly. Ensure the valves open and close smoothly and reliably. Adjust the opening and closing status of the valves as needed.
Safety Equipment: Inspect the safety equipment around the storage tank, such as fire separation zones and alarm systems, to ensure they are functioning properly.
Operator Training: Ensure operators are proficient in the safe operation of liquid oxygen storage tanks.
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