Permissible pressure units including the torr 1) and its conversion

Make notes under the following headings. Then use your notes to talk about it.

Follow-up Activity

Study the suggested key answers to the previous tasks.

1. The Main Vacuum Technology Processes and Their Purposes.

2. Vacuum Impregnation Advertisement.

3. Nanotube and Its Advantages.

4. Merits of John Dalton and William Crooks in Vacuum Science.

5. Nanotechnology Applications and Prospects.

TABLE I

Unit	N·m^-2, Pa ^2)	mbar	bar	Torr
1 N·m (= 1 Pa)		1·10^-2	1·10^-5	7,5·10^-3
1 mbar			1·10^-3	0,75
1 bar	1·10^5	1·10^3
1 Torr		1,33	1,33·10^-3
1) The torr is included in the table only to facilitate the transition from this familiar unit to the statutory units N · m^-2, mbar and bar. In future the pressure units torr, mm water column, mm mercury column (mm Hg), % vacuum, technical atmosphere (at), physical atmosphere (atm), atmosphere absolute (ata), pressure above atmospheric and pressure below atmospheric may no longer be used. Reference is made to DIN 1314 in this context.   2) The unit Newton divided by square meters (N · m^-2) is also designated as Pascal (Pa): 1 N · m^-2 = 1 Pa. Newton divided by square meters or Pascal is the SI unit for the pressure of fluids.   3) 1 torr = 4/3 mbar; fl torr = 1 mbar.

TABLE II

Abbrev.	Gas	C*= λ·p [cm * mbar]
H2	Hydrogen	12,00 · 10^-3
He	Helium	18,00 · 10^-3
Ne	Neon	12,30 · 10^-3
Ar	Argon	6,4 · 10^-3
Kr	Krypton	4,8 · 10^-3
Xe	Xenon	3,6 · 10^-3
Hg	Mercury	3,05 · 10^-3
O2	Oxygen	6,5 · 10^-3
N2	Nitrogen	6,1 · 10^-3
HCI	Hydrochloric acid	4,35 · 10^-3
CO2	Carbon dioxide	3,95 · 10^-3
H2O	Water vapor	3,95 · 10^-3
NH3	Ammonia	4,6 · 10^-3
C2H5OH	Ethanol	2,1 · 10^-3
Cl2	Chlorine	3,05 · 10^-3
Air	Air	6,67 · 10^-3
Mean free path I Values of the product c* of the mean free path λ for various gases at 20 °C.

Vocabulary Terms And Abbreviations Used
In Vacuum Engineering

Дата добавления: 2014-12-26