가스 Conversion Factor란 무엇인가?

1. 가스 Conversion Factor란 무엇인가?

MFC(Mass Flow Controller, 가스유량제어기)에서 같은 설정값으로 여러가지 다른 종류의 가스를 흘릴때 가스의 종류에 따라서 흐르는 부피가 다르다.
가스의 종류에 따라 다른 부피를 질소의 부피로 나누어 준값을 그 가스의 Conversion Factor라고 합니다.

예를들어 O2의 C.F=0.9779라면 어떤 MFC에서 질소가 100cc/min흐르는 설정에 대해서 CO2는 97.79cc/min 흐른다는 의미입니다.
사용자 입장에서 볼때도 Conversion factor를 알고 있다면 N2용 MFC를 구매한후 여러가지 다른 가스에도 적용할수 있다. 
실제로 MFC생산 회사에서도 N2로 교정하기 때문에 Conversion factor가 정확하다면 다른 문제는 없다.

 

2. Actual Flow Rate of Gas

 

                    Actual Flow Rate of Gas = Flow Rate  x  Correction of Nitrogen Fact

다음 표에는 열 기반 MFC의 질소와 관련된 다양한 가스에 대한 이론적 가스 보정 계수가 나열되어 있습니다. 
질소 보정과 공정 가스의 실제 흐름 사이에 비선형성이 존재할 수 있습니다.

 

Gas	Symbol	Specific Heat, CP cal/g°C (비열)	Density g/l @ 0°C (밀도)	Conversion Factor
Air	- - -	0.24	1.293	1
Ammonia	NH3	0.492	0.76	0.73
Argon	Ar	0.1244	1.782	1.39
Arsine	AsH3	0.1167	3.478	0.67
Boron Trichloride	BCl3	0.1279	5.227	0.41
Bromine	Br2	0.0539	7.13	0.81
Carbon Dioxide	CO2	0.2016	1.964	0.70*
Carbon Monoxide	CO	0.2488	1.25	1
Carbon Tetrachloride	CCl4	0.1655	6.86	0.31
Carbon Tetraflouride (Freon - 14)	CF4	0.1654	3.926	0.42
Chlorine	Cl2	0.1144	3.163	0.86
Chlorodifluoromethane (Freon - 22)	CHClF2	0.1544	3.858	0.46
Chloropentafluoroethane (Freon - 115)	C2ClF5	0.164	6.892	0.24
Chlorotrifluoromethane (Freon - 13)	CClF3	0.153	4.66	0.38
Cyanogen	C2N2	0.2613	2.322	0.61
Deuterium	D2	1.722	0.1799	1
Diborane	B2H6	0.508	1.235	0.44
Dibromodifluoromethane	CBr2F2	0.15	9.362	0.19
Dichlorodifluoromethane (Freon - 12)	CCl2F2	0.1432	5.395	0.35
Dichlorofluoromethane (Freon - 21)	CHCl2F	0.14	4.592	0.42
Dichloromethysilane	(CH3)2SiCl2	0.1882	5.758	0.25
Dichlorosilane	SiH2Cl2	0.15	4.506	0.4
1,2-Dichlorotetrafluoroethane (Freon - 114)	C2Cl2F4	0.16	7.626	0.22
1,1-Difluoroethylene (Freon - 1132A)	C2H2F2	0.224	2.857	0.43
2,2-Dimethylpropane	C5H12	0.3914	3.219	0.22
Ethane	C2H6	0.4097	1.342	0.5
Fluorine	F2	0.1873	1.695	0.98
Fluoroform (Freon - 23)	CHF3	0.176	3.127	0.5
Freon - 11	CCl3F	0.1357	6.129	0.33
Freon - 12	CCl2F2	0.1432	5.395	0.35
Freon - 13	CClF3	0.153	4.66	0.38
Freon - 13 B1	CBrF3	0.1113	6.644	0.37
Freon - 14	CF4	0.1654	3.926	0.42
Freon - 21	CHCl2F	0.14	4.592	0.42
Freon - 22	CHClF2	0.1544	3.858	0.46
Freon - 23	CHF3	0.176	3.127	0.5
Freon - 113	C2Cl2F3	0.161	8.36	0.2
Freon - 114	C2Cl2F4	0.16	7.626	0.22
Freon - 115	C2ClF5	0.164	6.892	0.24
Freon - 116	C2F6	0.1843	6.157	0.24
Freon - C318	C4F8	0.1866	8.93	0.164
Freon - 1132A	C2H2F2	0.224	2.857	0.43
Helium	He	1.241	0.1786	1.45
Hexafluoroethane (Freon - 116)	C2F6	0.1843	6.157	0.24
Hydrogen	H2	3.419	0.0899	1.01
Hydrogen Bromide	HBr	0.0861	3.61	1
Hydrogen Chloride	HCl	0.1912	1.627	1
Hydrogen Fluoride	HF	0.3479	0.893	1
Isobutylene	C4H8	0.3701	2.503	0.29
Krypton	Kr	0.0593	3.739	1.543
Methane	CH4	0.5328	0.715	0.72
Methyl Fluoride	CH3F	0.3221	1.518	0.56
Molybdenum Hexafluoride	MoF6	0.1373	9.366	0.21
Neon	Ne	0.246	0.9	1.46
Nitric Oxide	NO	0.2328	1.339	0.99
Nitrogen	N2	0.2485	1.25	1
Nitrogen Dioxide	NO2	0.1933	2.052	**
Nitrogen Trifluoride	NF3	0.1797	3.168	0.48
Nitrous Oxide	N2O	0.2088	1.964	0.71
Octafluorocyclobutane (Freon - C318)	C4F8	0.1866	8.93	0.164
Oxygen	O2	0.2193	1.427	0.993
Pentane	C5H12	0.398	3.219	0.21
Perfluoropropane	C3F8	0.194	8.388	0.17
Phosgene	COCl2	0.1394	4.418	0.44
Phosphine	PH3	0.2374	1.517	0.76
Propane	C3H8	0.3885	1.967	0.36
Propylene	C3H6	0.3541	1.877	0.41
Silane	SiH4	0.3189	1.433	0.6
Silicon Tetrachloride	SiCl4	0.127	7.58	0.28
Silicon Tetrafluoride	SiF4	0.1691	4.643	0.35
Sulfur Dioxide	SO2	0.1488	2.858	0.69
Sulfur Hexafluoride	SF6	0.1592	6.516	0.26
Trichlorofluoromethane (Freon - 11)	CCl3F	0.1357	6.129	0.33
Trichlorosilane	SiHCl3	0.138	6.043	0.33
1,1,2-Trichloro - 1,2,2-Trifluoroethane (Freon - 113)	CCl2FCClF2 or C2Cl3F3	0.161	8.36	0.2
Tungsten Hexafluoride	WF6	0.081	13.28	0.25
xenon	xe	0.0378	5.858	1.32