(1) Qhov siab tsis tshaj 2000 meters;
(2) Qhov kub ntawm qhov nruab nrab ib puag ncig tsis siab tshaj 40 degree thiab tsis qis dua -10 degree;
(3) The relative humidity of the air is not more than 85 percent (when the medium temperature is 20 degree ±5 degree );
(4) Qhov chaw tsis muaj hmoov av conductive;
(5) Tsis muaj kev puas tsuaj ib puag ncig;
(6) Ib puag ncig uas tsis muaj roj thiab vapors uas tuaj yeem corrode hlau thiab rwb thaiv tsev;
(7) Hauv qhov chaw uas tsis muaj nag lossis daus;
(8) Lub dav hlau ntsug yog inclined tsis ntau tshaj 5 degrees thiab tsis muaj kev vibration hnyav thiab poob siab.