Cleaning and maintenance methods for screw air compressors
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6. Cleaning of return oil check valve
A one-way valve consists of valve body, steel ball, steel ball seat, spring and other components. The oil and gas mixture compressed by the main engine of the air compressor is first separated by centrifugal force in the oil and gas tank. As the weight of oil is greater than that of air, most of the oil in the solid oil and gas mixture falls into the oil tank through centrifugal force. The screw air compressor then returns to the main engine for a lubrication cycle under internal pressure, while the compressed air containing a small amount of oil is separated again by the oil and gas separator. At this time, the lubricating oil separated by the oil and gas separator will fall to the bottom of the oil and gas separator. In order to prevent this part of the oil from being carried away with the compressed air, the unit uses an oil pipe inserted into the bottom of the oil and gas separator during design. Through internal pressure, this part of the oil is directly introduced into the main engine for lubrication. There is a one-way valve on the oil pipe, and the screw air compressor is called back. Oil single valve.
Its function is to smoothly recover the oil from the oil and gas separator to the main engine without allowing the oil from the main engine to flow back to the oil and gas separator. The return oil single valve has a connection on the valve body. Unscrew it from there and remove the spring, steel ball, and steel ball seat.
Cleaning the oil return check valve: Clean the valve body, spring, steel ball, and steel ball seat with cleaning agent. Some check valves also have internal filters. If there are any, clean them together.
7. Cleaning temperature control valve of screw air compressor
A temperature control valve consists of a valve body, valve core, temperature sensing element, spring, etc. The temperature control valve plays a role in constant temperature control. When the oil temperature measured by the temperature sensing element of the temperature control valve is lower than the operating value (the operating value of the temperature sensing element is generally 71 degrees), the lubricating oil returns directly from the oil and gas tank to the main engine. When the oil temperature measured by the temperature sensing element of the temperature control valve is higher than the operating value, the top pin of the temperature sensing element of the temperature control valve moves to push the valve core to open its own bypass valve, allowing the lubricating oil to enter the cooler for cooling (if the temperature measured by the temperature sensing element is higher, the bypass valve opens larger). The cooled lubricating oil returns to the main engine.
The temperature control valve of the screw air compressor has a cover with screw holes on it. Find a suitable nut and screw it into the cover. Then use a clamp pliers to remove the clamp spring that fixes the cover, and use pliers to pull the nut that has just been screwed in to remove the cover and all internal components. Clean all components of the temperature control valve using the same method as cleaning the load reducing valve.
After cleaning and drying all the above components, they should be installed onto the air compressor. After installing all the components onto the air compressor, they should be checked again for any omissions and any tools or items used during installation should be cleaned.
8. Correct all parameters
After the machine is cleaned and installed, the operating parameters of the air compressor should be adjusted to ensure normal and safe operation
(1) Preparation before starting the screw air compressor:
Belt (coupling) calibration: If the air compressor is driven by a belt, the tightness of the belt should be between 10-20 millimeters. If the air compressor is driven by a coupling, after installation, the motor and main engine should be manually turned and the balance of the coupling rotation should be checked. Screw air compressor couplings generally use elastic couplings, which can be ignored when the deviation in solid balance is not significant.
Rotation correction of screw air compressor host: If the main power supply has been removed during maintenance, attention should be paid to the forward and reverse rotation of the motor after the power supply is connected back. The rotation of the motor should be based on the rotation of the host. For the correct rotation of the host, please refer to the rotation icon marked on the host.
Correction method: Swap any two power lines in the three-phase power supply.
(2) Loading, unloading, and proportional value correction:
When setting these three parameters, the unloading value should be determined first. The unloading value should be determined based on the rated pressure of the air compressor and the required pressure at the gas end. After determining the unloading value, the loading value should be set. The pressure difference between the two should be between 0.1 and 0.2 MPa. After setting the unloading and loading values, the proportional value should be set. The proportional value should be set between the unloading and loading values. For example, for a screw air compressor, if a factory needs an air supply pressure of 0.8 MPa and the air supply requirement is relatively stable, the following three parameters should be set: unloading pressure set at 0.8 MPa, loading pressure set at 0.65 MPa, and proportional control pressure set between 0.73 and 0.75 MPa.
Calibration method for screw air compressor: Set this parameter in the microcomputer controller (if the control of the air compressor adopts button control, the loading and unloading parameters should be adjusted from the pressure switch, and the proportional value should be adjusted at the adjusting nut of the proportional valve on the load reducing valve).
(3) Positive internal pressure effect of the unit: The internal pressure of the unit should be between 0.2 and 0.45 MPa.
Correction method: The pressure value should be adjusted during the unloading operation of the unit, and the magnitude of the value should be adjusted on the adjusting nut of the minimum pressure valve. In order to facilitate reading the set value, a pressure detection point should be taken before the minimum pressure valve and a pressure gauge should be installed (some microcomputer controllers have internal pressure parameter display function, if this function is not available, a pressure gauge should be installed before the minimum pressure valve).
(4) High temperature protection value is effective:
When the screw air compressor is working normally, its temperature should be between 65 and 98 ℃. The automatic shutdown temperature for high temperature protection shall not exceed 105 ℃.
Correction method: Adjust the temperature value of high-temperature automatic shutdown in the controller to 1.2 (that is, amplify 20% margin).
Summary: Proper maintenance and upkeep play a crucial role in the service life and operational reliability of screw air compressors, and air compressor cleaning is a skill that after-sales maintenance service personnel and even equipment operators must master.
JOY MACHINERY always adheres to the corporate vision of "building a leading brand of oil-free air compressors in the world", and hopes to provide high-quality, clean and safe air for food, beverage and other production enterprises on the road of oil-free air compressor research and development, production and sales. Source protection, and also contribute a little bit to people's health and safety.
JOY MACHINERY oil-free air compressor series is widely used in the food and beverage processing industry due to its clean air source and continuous and stable gas transmission. If you have any needs, please contact us! JOY Machinery (Shanghai) Co., Ltd. has a professional design team with rich experience and welcomes customization. Diversified products can meet most applications and meet your one-stop shopping needs. The air compressor series includes power frequency screw air compressors, variable frequency screw air compressors, permanent magnet variable frequency screw air compressors, two-stage compression screw air compressors, integrated screw air compressors, laser cutting air compressors, medium and high pressure air compressors. Air compressors, oil-free water-lubricated screw air compressors (special oil-free screw air compressors for the medical industry), diesel-moving screw air compressors, electric-moving screw air compressors and other products.
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