Interpretation Of Results - ThermoFisher Scientific GLD PRO Manuel D'utilisation

11.0 Interpretation of results

Figure 5 illustrates the leak detector's LED light response range. The greater the number
of red or yellow LED lights lit correlates in general to the size of the leak. NOTE: The
leak detector is not a quantitative device, rather it is designed to detect leaks in gas line
connections commonly associated with laboratory equipment.
Gas
Helium
Hydrogen**
Nitrogen
Argon
Carbon dioxide
Blue LED and all 3 yellow LEDs
and audible continuous alarm:
significant leak detected
Figure 5 – LED light response chart for the leak detector. A 1:1 ratio of I Probe : I Reference
indicates no leak present. Red LED lights indicate the presence of helium and/or hydrogen.
Yellow LED lights indicate the presence of nitrogen, argon, and/or carbon dioxide
**CAUTION: This unit is designed to detect TRACE AMOUNTS of hydrogen and rising from a small
leak in a non flammable environment, e.g., laboratory room air, etc. This unit is rated for use in a
non flammable atmosphere where the sample gas may become sufficiently high in concentration to
become explosive.
Tip drift
Tip drift is the phenomenon when a false LED light response is registered as the unit
is quickly turned or swept in dramatic arc movements. Tip drift is inherent to all dual
thermistor leak detector technology and is based in large part on the asymmetry of the
flow cells; shaking or tipping the unit influences the air flow profiles, which impacts the
rates of heat exchange. If the device is functioning normally, the LED light signal will return
to zero in 3–5 seconds after the unit is held still. In extreme cases, the unit may require
another "zero" cycle before using. To avoid tip drift, be sure to hold the unit steady while
making measurements.
10
Minimum Detectable
Leak Rate (atm cc / sec)
1.0 × 10
-5
1.0 × 10
-5
1.4 × 10
-3
1.0 × 10
-4
1.0 × 10
-4
Blue LED and 4 red LEDs:
small leak detected
Blue LED only:
no leak detected
Indicating
LED Light Color
Red
Red
Yellow
Yellow
Yellow
Blue LED and all 7 red LEDs
and audible continuous alarm:
significant leak detected