Use absorption-free hose material
• Apply the test gas at the tip of the probe
• Use single gases, e.g. NO with nitrogen as the carrier gas
• Use the device “warmed up” (warm-up time at least 20 minutes)
• Zero with clean air after 20 minutes
• Maximum overpressure of the test gas: 12” WC;
better: unpressurised via bypass
• Pump flow in the unit >_ 0.5 l/min
• Apply the test gas for at least 7 minutes