Maintain the breather valve

Thread Content

A breathing valve is an important accessory for ensuring the safety of oil tanks; it is installed on the top of the tank and consists of a pressure valve and a vacuum valve. Its function is, under normal circumstances, to maintain the integrity of the oil tank and to reduce oil evaporation losses to a certain extent. And when necessary, it can automatically ventilate to regulate the pressure inside and outside the oil tank, thereby ensuring its safety. When the pressure of oil and gas inside the tank exceeds the allowable pressure, the oil vapor escapes through the pressure valve; at this time, the vacuum valve is in a closed state ； When the pressure of the oil and gas inside the tank is lower than the allowable vacuum level for the tank, fresh air enters the tank through the vacuum valve; at this time the pressure valve is closed, and the allowable pressure (or vacuum pressure) is controlled by the weight of the adjustment disc. Common faults in maintaining mechanical breathing valves include: air leakage, jamming, sticking, blockage, freezing, as well as the valves remaining open under pressure or vacuum conditions. 1. Air leakage: This is usually caused by rust, hard objects scratching the contact surface between the valve and the valve disc, deformation of the valve disc or seat, and an inclined valve disc guide rod. 2. Jamming: This usually occurs when the breathing valve is not installed correctly, or when the oil tank deforms, causing the valve disc’s guide rod to become misaligned or the rod to rust. As a result, the valve seat cannot move up and down along the guide rod properly, and the valve disc gets jammed at some point along the rod. 3. Adhesion: This occurs as oil vapors, moisture, and dust and other impurities deposited on the valve disc, valve seat, and guide rods undergo chemical and physical changes; over time, this leads to the adhesion of the valve disc to the valve seat or to the guide rods. 4. Blockage: This is mainly caused by the long-term lack of maintenance of mechanical breathing valves, which leads to the accumulation of dust, rust, and other debris inside the valve or the breathing tube. Additionally, bees or birds building nests at the opening of the breathing valve can also cause blockages. 5. Freezing of the breather valve: This occurs due to changes in temperature, causing moisture in the air to condense on parts such as the valve body, valve disc, valve seat, and guide rod of the breather valve, eventually leading to freezing and making it difficult to open the valve. Some of these faults prevent the breathing valve from operating when it reaches the control pressure, resulting in overpressure in the oil tank and posing a risk to its safety ； Some of them render the breather valve ineffective, leading to uncontrolled breathing processes on both large and small scales; this increases evaporation losses during feeding, reduces the quality of the oil, exacerbates air pollution in the area, affects the health of operators, and increases the risks in that region. During routine inventory checks and after each operation, it is necessary to conduct thorough inspection and analysis based on appearance and observable signs, in order to identify problems promptly and address them right away. Check for any abnormal changes in the oil tank body and the breather valve body ； When oil is being loaded or unloaded from the tank, is the breathing valve functioning properly? ； Is the gauge of the U-tube manometer functioning properly? ； Is the sealing net damaged, and is it unobstructed? ； Check for leaks in the body of the pipeline-type breather valve of the underground tank. In addition, the breathing valve should be regularly inspected and maintained in a thorough manner. For mechanical vent valves installed on above-ground and semi-underground tanks, inspections are conducted twice a month in the first and fourth quarters (to prevent freezing), and once a month in the second and third quarters ； Mechanical breathing valves installed in underground vaults should be inspected every six months