ULTIMA X
®
Series
GB
59
7.4 ULTIMA XE – ATEX Performance Approval
The lower explosive limits [LEL] of the gases and vapours in following table were
taken from EN 60079-29-1:2007. For gases and vapours not listed in
EN 60079-29-1:2007, the lower explosive limits [LEL] were taken from the Chem-
safe [Dechema, Frankfurt] data base. Local regulations may specify different LEL
values; always ensure the correct values are used.
It is recommended that the ULTIMA XE zero is calibrated using clean air, free of
flammable gas, and calibration gas of approximately 50 % LEL in air of the gas be-
ing monitored. The table shows the ULTIMA XE flammable gas sensor relative re-
sponse to various gases and vapours when calibrated using 50 % LEL Propane in
air. For non-safety related applications the ULTIMA XE flammable gas sensor may
be calibrated using the relative response factors shown in the table and 50 % LEL
Propane in air. When using relative response factors for gas calibration, deviations
of up to ±20 % of the true gas concentration can be expected.
Reference Calibration Example for 50 % Methanol:
Arsine 10 % FS 10 % FS
Germanium 10 % FS or 2 ppm 10 % FS
Silane 10 % FS or 2 ppm 1 % FS or 2 ppm
Diborane 10 % FS or 2 ppm 1 % FS or 2 ppm
Fluorine 10 % FS or 2 ppm 5 % FS or 2 ppm
Bromine 10 % FS or 2 ppm 5 % FS or 2 ppm
Gas Linearity Repeatability
When monitoring flammable gas in safety related applications the
ULTIMA XE must be calibrated with a known concentration of the gas
being monitored.
(1) Relative response factor for Methanol from the ta-
ble in this chapter
= 0.79
(2) Propane calibration gas concentration being used = 0.89 Vol% C
3
H
8
(3) Propane volume concentration for 100 % LEL = 1.7 Vol%
(4) Propane calibration gas concentration in % LEL
% LEL = 0.89 Vol% C
3
H
8
x
100 % LEL
= 52.4 % LEL
1.7 Vol% C
3
H
8
(5) Gas calibration set point = 52.4 % LEL x 0.79 = 41.4 % LEL
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