Varian 990 dCLD II, Operation Manual

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Model 990 dCLD II Component Leak Detector
C-2
C.3 Terminology
The following terminology has application throughout this manual:
Flow
std cc/sec One cubic centimeter of gas per second at a pressure differential of
one standard atmosphere (760 torr at 0° C).
atm cc/sec One cubic centimeter of gas per second at ambient atmospheric
pressure and temperature (used interchangeably with
std cc/sec
because the difference is insignificant for leak testing purposes).
Rate-of-Rise In vacuum systems this is defined as the rate of increase of absolute
pressure per unit time, with the vacuum pump isolated from the
system, and is the sum of actual inleakage and internal outgassing.
Rate of rise is usually expressed in torr or microns (millitorr) per
hour. The flow rate should be expressed in torr-liters/second.
Conversions 1 std cc/sec* 0.76 torr-liter/sec
1 torr-liter sec* 1.3 std cc/sec
1 std cc/sec 9.7 x 10
4
micron cubic feet per hour or
practically 10
5
micron CFH (
µ
CFH)
1
µ
CFH practically 10
−
5
std cc/sec
*for practical purposes, equal
Numerical
Notation-Exponential
System Most leak rates of commercial significance are very small fractions
of a std cc/sec. Therefore minus powers of ten are used as a conve-
nient system of numerical shorthand.
Table C-1 below shows the relationship of exponents and multipliers (to the base 10) to the
arithmetic form, and the equivalent result.
Table C-1 Decimal Notation
Multiplier x 10
n
Arithmetic Form Result
1 x 10
2
= 1 x 10 x 10 = 100
1 x 10
1
= 1 x 10 = 10
1 x 10
o
= 1 = 1
1 x 10
−
1
= 1 x 1/10 = .1
1 x 10
−
2
= 1 x 1/10 x 1/10 = .01
5 x 10
−
3
= 5 x 1/10 x 1/10 x 1/10 = .005
5 x 10
−
7
= 5 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 = .0000005
5 x 10
−
9
= 5 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 x 1/10 = .000000005