Tubes Handbook 18th Edition (EN) - May 2018

38| Dräger-Tubes & CMS-Handbook
When reading the concentration on a scaled tube, three different situations can be
encountered:
- the color indication ends at a right angle to the tube's longitudinal axis
- the color indication is oblique to the tube's longitudinal axis
- the end of the color indicatlon becomes very diffuse
When the color indication is at a right angel to the tube's longitudinal axis. the
concentration can be read directly against the scale (see example 1). If the color indication
is oblique (i. e. runs in a slanting direction to the tube’s longitudinal axis), then a long and
a short discoloration can be observed. In this case the average reading indicates the
concentration (see example 2). If the color indication become progressively diffuse, the end
of the discoloration may be difficult to evaluate. In this case the final edge of
the discoloration has to be read at the point where a faint discoloration is just visible
(see example 3)
100
200
400
100
200
400
800
800
1000
1000
n=10
100
400
1000
1500
2000
2500
3000
ppm
Average value
1500
2000
2500
3000
ppm
End of discoloration =
concentration
2000
3000
4000
D-1222-2009
Example 1
Example 2
Example 3