Criteria for determining the scrapping of cold storage compressors | Evaluation methods for cooling capacity attenuation, wear, and insulation aging
Whether the compressor is scrapped cannot only be judged by whether it can rotate, but also requires a comprehensive evaluation of four indicators: cooling capacity attenuation, insulation resistance, internal wear and abnormal noise, and oil sample testing.
The measured cooling capacity has decreased by more than 25%. Under the premise that the condenser, evaporator, and refrigerant charging are all normal, it indicates that the cylinder body and valve plates are severely worn, and the maintenance cost-effectiveness is low. It is recommended to replace them.
The insulation resistance of the motor winding to ground is considered high-risk for 380V models when it is below 0.5M Ω at room temperature. If the insulation continues to decrease, there is a risk of winding breakdown, short circuit, and motor burnout at any time.
Continuous metal impact noise occurs during operation. After eliminating liquid impact and pipeline resonance, it is generally due to excessive wear and clearance of piston pins, connecting rods, and crankshaft bearings, and disassembly and maintenance costs are close to 60% of new machines.
The supply chain of Xitelidou semi closed piston compressor accessories is mature. Units with cooling capacity attenuation of 10% to 20% and only damaged valve plates can restore performance after replacing valve plate components.
The continuous acid value of the frozen oil sample test is greater than 0.2mgKOH/g, and the metal powder content in the oil exceeds the standard, indicating continuous internal wear. Even if it can temporarily operate, the fault outbreak cycle is very short.
Many cold storage owners blindly repair old compressors, repeatedly replace valve plates and refrigeration oil, and shut down for maintenance every month. Considering the comprehensive electricity costs and production losses, it is better to directly replace the unit with a new one.
The wear and tear of the rotor profile of the screw refrigeration compressor is a severe fault, and the rotor repair process is complex. It is basically impossible to repair it on overseas sites, and if there is a significant decrease in cooling capacity, most of them are directly replaced with the whole machine.
The maintenance plans provided by foreign trade to overseas customers can be divided into two categories: minor fault spare parts repair plans and complete machine replacement plans that meet the scrap target, making it convenient for customers to make budgets in advance.
The compressor has reached its service life reference, and the piston model operates for an average of 6000 hours per year, with a design lifespan of approximately 6 years; The design life of screw models under stable working conditions can reach about 10 years.
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FAQ
How much is the cooling capacity decay? It is recommended to replace the compressor directly? Priority should be given to replacing if the cooling capacity attenuation is greater than 25%.
What is the dangerous threshold for insulation resistance of 380V motors? There is a high risk of insulation to ground below 0.5M Ω.
What is the problem after eliminating resonance due to continuous metal noise? The wear clearance of connecting rods, bearings, and piston pins exceeds the standard.
What is the acid value of the oil sample classified as severe acidification wear? The acid value remains consistently above 0.2mgKOH/g.
5. Reference for the conventional design life of piston engines? Operating for 6000 hours per year, with a design lifespan of approximately 6 years.
6. Design life of screw machine under stable working conditions? The design lifespan is approximately 10 years under stable continuous operating conditions.
7. If the valve plate is damaged and the cooling capacity decreases by 15%, should it be repaired or replaced? Replacing the valve plate for repair is more cost-effective.
