What Is an Air Respirator?
An Air Respirator is a device that removes dust from the outside of an oil tank while maintaining the tank’s internal pressure.
It is a type of hydraulic equipment mainly installed above oil-filled tanks such as reservoir tanks and hydraulic oil tanks.
It has a built-in filter to remove dust from the outside. The cap is made of alloy or resin, which has excellent durability and other properties. The cap can be removed with a thumbscrew, and many products have a simple structure for easy maintenance.
Uses of Air Respirator
Air Respirators are mainly used in industrial applications. They are used in industrial equipment, such as tanks that contain oil.
The following are examples of air respirator applications:
- Electrical equipment such as generators and oil-filled transformers
- Large reduction gears with oil circulation
- Hydraulic tanks in hydraulic units
As mentioned above, air respirators are used in tanks and equipment that incorporate large volumes of oil. Generators and oil-filled transformers that handle voltages higher than high voltage incorporate insulating oil for internal winding insulation. Insulating oil for electrical equipment may also contain silica gel for moisture absorption, since moisture contamination can cause insulation deterioration.
Large reduction gears, for example, generally incorporate a large volume of oil and use it to lubricate gears. Since the temperature of the lubricating oil gradually increases with rotational motion, it may be cooled through a heat exchanger or similar device. Thus, air respirators are used in a wide range of fields such as machine tools and power generation and substation.
Principle of Air Respirators
Air respirators are mounted on top of a hydraulic oil tank or reservoir tank. Since the oil volume in an oil filled tank expands and contracts with temperature changes and other factors, sealing the tank can lead to deformation of the tank and damage to the extraction pump. Therefore, in order to maintain a constant pressure inside the tank, it is common to attach an opening to allow suction and exhaust.
However, if outside air is introduced as it is, dust and other particles will be sucked into the oil-in-oil tank. To prevent deterioration of the oil and damage to peripheral equipment caused by dust, an air respirator is attached to the opening for filtering. This removes dust and foreign matter from the outside air when the air is sucked in.
Air respirators are mainly composed of a filter element, lid, and body. The filter element filters dust and foreign matter from the outside air. Filter paper or metal mesh is used.
The body and lid play the role of guiding the outside air to the filter element while the air respirator is attached to the tank. Screw-in installation is the most common method. The material is a robust substance such as metal or hard resin, and the filter element is secured with rubber packing inside.
How to Select an Air Respirator
Air respirator selection is based on the mounting method and diameter, air flow rate, and material.
1. Mounting Method
The most common mounting method is the screw-in type. If flange mounting is desired, a flange with a callout can be manufactured. The mounting diameter is the diameter of the screw to which the air respirator is attached, and is selected according to the size of the opening screw.
2. Air Flow Rate
The air flow rate is the amount of air that the air respirator can allow. The airflow rate is determined by the product. Select a product with a permissible value greater than the expected airflow rate.
3. Material
Material is the material of the body and filter element. The material and coarseness of the filter element determines the coarseness of the dust to be separated, so select a product with the required filtering capacity. The material of the main body and filter also directly affects the allowable temperature, so metal products are preferable when the operating temperature is high.
Other Information on Air Respirators
Cleaning Air Respirators
If the element of an air respirator is used without cleaning, it will become dirty and clogged. As a result, the tank will be sealed and the internal pressure will rise, directly leading to damage to the oil-filled tank.
In addition, if the tank’s internal pressure becomes lower than atmospheric pressure, it is likely to cause excessive air to flow into the oil and cause bubbles to form. If air bubbles in the oil flow into the inside of the extraction pump, cavitation can cause damage to the pump. If debris or other substances are mixed into the oil due to pump damage, it can cause malfunctions in various hydraulic equipment.
Therefore, maintenance such as periodic cleaning or periodic replacement of filter elements and caps of air breathers is very important.