Liquid Slugging is where extreme cases of Flooded Start or Liquid Flood Back occur.When large quantities of liquid refrigerant enter the compressor and then mix with the lubricating oil in the compressors sump.
The resulting liquid/oil mixing and diluting, then creates major amounts of liquid and oil
droplets in a frothy foam mixture.
During extreme cases, this foam/oil/liquid mixture can be carried into the suction gallery
and then through the suction valves and into the cylinder.
This “Wet” mix will wash the cylinder lubricant away and can also cause the valve reeds to break.
Due to this liquid /oil mixture carrying non compressible particles this can cause the valve plate to deflect to the point where it breaks.
The Suction valve plate will show
small dents or even holes through the plate.The valve plate then falls into the cylinder and on to the piston crown.
As the piston travels up to the top of the cylinder during the compression cycle the valve plate is
then smashed up into the discharge valve plate.
This can cause a hole to be punched through the piston crown and damage to the discharge valve assembly occurs as there is almost no clearance between the top of the piston crown and the discharge valve, which gives the compressor its high efficiency rating.
The discharge valve assembly can also be completely smashed to pieces in certain instances.
In very extreme cases of slugging, the cylinder can be virtually filled with liquid and can cause con rod breakages and even broken crankshafts have been the result of hydraulic lock in the cylinder.
This is more in Flooded Start /Slugging instances.
Remember
Compressors are designed to pump refrigerant in its vapour form only, NOT LIQUID !
The action of the compressor is
1) The compressors piston as it travels down the cylinder pulls low pressure suction vapour from the evaporator,
through the suction valve reed and into the cylinder.
2) The piston as its travels back up the cylinder will compress this low pressure suction vapour, as this LP vapour
is compressed, its pressure and temperature rises.
3) This compressed vapour is now pumped out through the discharge valves as a High pressure discharge
vapour, which then passes to the condenser.
4) The compressor works OK
When compressors try to pump liquid
1) If liquid refrigerant returns to the compressor, as it gets drawn into the suction gallery, it then passes through
the suction valve.
2) The liquid being a solid mass will make the suction valve bend and sometimes break.
3) Liquid will then enter into the cylinder which will then have its lubrication washed away.
4) This will cause scoring to the cylinder walls and pistons.
5) The piston as it travels down the cylinder will draw this liquid and vapour into it chamber.
6) As the piston travels up the cylinder, the piston hits the solid liquid mass as it cannot compress it.
7) This solid mass is then driven up against the suction valve and also driven up into the discharge valve.
8) Again the solid mass of liquid will open and defl ect the discharge valve plate against its limit stop and again the valve plate can get smashed to pieces.
9) Pieces of valve plate will then fall down into the cylinder, and the piston as it travels up the cylinder will try to compress the bits of valve plate.
10) This then can smash the piston
11) Under worse case scenario the cylinder can fi ll with liquid and hydraulic lock the piston which can break the con rod or even break the crankshaft.
Typical Causes of Slugging
See Liquid Flood Back & Flooded Starts
Preventative Measures Required
See Liquid Flood Back & Flooded Starts
Typical Damage to Compressor parts
1) Damaged Suction and/or Discharge Valve Reeds and springs or Valve assembly
2) Damaged Piston Crowns
3) Scoring to cylinder bores, pistons and rings
4) Broken Con rods (No scoring to big end bearings)
5) Broken crankshaft
Source : http://www.danfoss.com
9 komentar:
Pak James, AC compressor saya 1 PK pada saat start-up kok tidak bisa lancar yah berdengung seperti tertahan, kemudian saya coba untuk mengganti condensor baru dengan kapasitas yang sama tapi masih juga seperti itu, kawatir kondensor baru kurang bagus saya membeli dua condensor tapi tetap sama kedua duanya.
Kemudian saya coba jumper paralel dua condensor tsb dan bisa jalan dan suaranya pun halus, tapi kelemahannya berakibat ampere menjadi tinggi 5 s/d 7 dan tentu compressor menjadi panas, lalu akhirnya saya matikan dan menunggu sampai compressor dingin kembali.
Setelah dingin saya coba star-up ternyata masih berdengung dan susah hidup, jadi mau tidak mau setiap mau menyalakan AC saya harus jumper condensor dan temperature saya set di 16 deg C agar compressor bekerja terus.
Mohon saran pak James dan terimakasih sharing ilmu-nya.
Achang
Untuk Pak Achang, kemungkinan mekanik kompresornya macet atau tidak ada keseimbangan tekanan pada saat unit dimatikan.
coba pergunakan starting kapasitor dan Potensial relay untuk membantu gerak putar motor.
Pak James, terimakasih sarannya. Berapa ukuran Starting Capacitor yang pas dan terus terang saya belum pernah install starting capacitor dan potensial relay, adakah diagram untuk itu? atau hanya di pasang serie antara staring capacitor dan potensial relay?
Termakasih pak James, saya akan coba lagi
Untuk Pak Achang anda bisa Download skema pemasangannya disini http://www.electrica.it/file_pdf/electrica_rva.pdf
untuk starting kapasitornya bisa anda gunakan ukuran 120 - 150 MFD.
Untuk lebih jelasnya Run atau R pada terminal kompresor masuk ke kaki salah satu terminal starting relay dan runing kapasitor dan kaki terminal staring kapasitor yg satunya masuk ke nomer 1 pada potensial relay.
Terminal no 5 pd potensial relay disambungkan pada terminal overload kompresor dan terminal no 2 dihubungkan pada S terminal kompresor dan kaki runing kapasitor yg satunya.
anda bisa melepas overload atau tetap menggunakannya, karena didalam potensial relay jg terdapat overload pengaman motor.
Pak James,
Terimakasih informasinya.
AC saya sudah normal kembali.
Total yang di keluarkan cuma Rp. 135,000 rupiah saja untuk pembelian Starting capacitor dan Potential relay, tadinya saya berfikir harus ganti compressor 1PK yang harganya satu jutaan lebih.
Fungsi potential relay sepertinya menggantikan posisi saya yang harus jumper capacitor setiap kali compressor start-up dan mencabutnya setelah compressor running he he he, belum lagi resiko kesetrum dan percikan ledakan pada saat release energy.
Hanya saja saya salah beli starting capacitor yang 80 - 108 MFD, tapi masih bisa start juga sih.
Anyway, thanks allot ya pak James
Kalau masih bersedia sharing ilmu-nya tentu saya akan bertanya kembali.
Salam
Sama-sama Pak Achang.
Sore Pak James
Mau tanya seputar masalah ac kaset yang saat ini sedang kami alami.
Ditempat kami ada ac kaset LG LTUC368DLE1 dengan kap 35.827 btu,kondisi saat ini Display sensor pada indoor lampu merahnya berkedip,kristal sensornya pun nampaknya rusak karena tidak berfungsi,jadi unit indoor maupun outdoornya mati/tidak on.
Menurut bapak,permasalahannya ada dimana ya pak?apakah disensor displaynya?atau termistornya?atau motor pumpnya?
Modul indoor sdh diganti,termistor jg sdh diganti,motor pump gada mslh,tp tetap msh begitu,lampu merah berkedip dan unit indoor maupun outdoor mati.
Menurut bpk,dimana kira-kira masalahnya?
Sebelumnya terima kasih pak James.
Arif
Untuk sdr Arif, untuk mengetahui permasalahan tersebut, anda bisa lihat kode error ac LG.
bila display tidak menunjukan huruf kode kesalahan berarti yang dilihat adalah kedipan lampunya.
anda bisa lihat di menu atas yang bertuliskan "fault code".
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