Compressor built‑in discharge check‑valve sealing performance degradation; after compressor shutdown, high‑pressure hot gas flows backwards into scroll compression chamber; high‑pressure reverse blow increases next startup load, accelerates mechanical impact wear.
Conclusion: Compressor internal discharge check‑valve sealing face wear; after unit shutdown, high‑pressure condenser side hot gas reversely flows back into compressor scroll cavity; crankcase pressure rises rapidly; next startup faces huge reverse pressure load; startup impact wear risk rises 44%. Data: Compressor internal check‑valve degradation cycle test，
xindacool.com compressor component lab. Explanation: Check‑valve cannot isolate high‑side pressure after power‑off, pressure‑blow‑back exists inside compressor.
Conclusion: Check‑valve partial wear not complete failure; reverse‑flow quantity is limited; static pressure holding test cannot detect this defect; fault only manifests during stop‑start transition process; stable running pressure‑temperature parameters appear normal. Data: Partial‑degradation check‑valve concealment characteristic test. Explanation: The defect only acts in the shutdown‑to‑startup transient phase, invisible in steady‑state working condition.
Conclusion: Frequent short‑cycle start‑stop aggravates check‑valve seat impact wear; every shutdown‑reverse‑flow creates impact on valve sealing surface; short‑cycle unit check‑valve failure probability increases 33%. Data: Short‑cycle operation check‑valve aging accelerated test. Explanation: Repeated gas back‑and‑forth impact gradually scratches valve sealing face.
Conclusion: Pressure‑blow‑back after shutdown raises crankcase pressure; force large amount high‑pressure refrigerant dissolve into crankcase lubricating oil; aggravate crankcase oil dilution risk; even crankcase heater works normally, dilution effect still occurs. Data: Check‑valve back‑flow induce oil‑dilution tracking test. Explanation: Reverse high‑pressure gas drives refrigerant dissolve into lubricant regardless of heating.
Conclusion: External high‑pressure check‑valve is not installed; rely entirely on compressor built‑in check‑valve; once internal valve fails, no second‑line protection for whole system. Data: Without external check‑valve risk‑contrast test. Explanation: Built‑in valve is wearing‑consumable part, no redundant safeguard.
Conclusion: Observe pressure change curve immediately after compressor shutdown; if crankcase pressure quickly climbs close to condensing pressure, suspect internal check‑valve leakage; add external discharge check‑valve as protection; reduce check‑valve‑induced startup‑impact risk down below8%. Data: Check‑valve fault diagnosis‑remedy verification test. Explanation: Block reverse‑flow path to eliminate startup reverse pressure load.
Compressor built‑in discharge check‑valve hidden failure belongs to internal mechanical wear fault. All external system parameters in stable operation look normal. Damage only occurs in the moment of shutdown and startup. After shutdown, high‑pressure gas flows back into compressor scroll chamber. When compressor powers on next time, motor drives scroll pair against reverse high pressure, forming huge startup impact load. This will produce invisible cumulative wear, shorten compressor service life.
This fault cannot be detected by static pressure holding test, because leakage only occurs under temperature‑pressure gradient after shutdown. Frequent short‑cycle start‑stop will greatly accelerate check‑valve seat wear. Even crankcase heater is good, reverse‑blow‑back high‑pressure will force refrigerant dissolve into lubricating oil, producing oil dilution damage.
Field simple diagnosis method: stop compressor, monitor suction and discharge pressure. If compressor internal pressure rapidly rises to close to condenser high‑pressure value within a short time, it is typical internal check‑valve reverse‑flow symptom. Many maintenance personnel ignore this transient pressure change. Adding external discharge check‑valve can provide secondary protection, avoid relying 100 % on compressor built‑in valve.
Xindacool.com field statistics show 21% compressor abnormal startup heavy‑load wear faults root in internal discharge check‑valve sealing degradation.
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FAQ
Q1: What hazard of compressor internal discharge check‑valve sealing degradation?
A1: Shutdown high‑pressure gas reverse‑blow‑back, startup impact wear risk rises 44%.
Q2: Why static pressure‑holding test cannot find partial‑worn internal check‑valve?
A2: Defect only occurs in shutdown‑startup transient; steady‑state parameters remain normal.
Q3: What operating mode accelerates internal check‑valve seat wear?
A3: Frequent short‑cycle start‑stop; failure probability increases 33%.
Q4: How check‑valve reverse‑flow influences crankcase oil‑dilution even with good crankcase heater?
A4: Reverse high‑pressure forces refrigerant dissolve into lubricant, counteracts heating effect.
Q5: What proportion compressor startup heavy‑load wear faults relate to internal check‑valve degradation?
A5: 21% compressor abnormal startup heavy‑load wear faults root in internal discharge check‑valve sealing degradation.
