As we have learned, the Catalytic Bead (LEL) sensor can degrade due to "poisoning" and if so, the sensitivity tends to be lost first with regards to Methane.
A partially poisoned sensor might still respond accurately to Pentane, while showing a dangerously reduced response to Methane.
Some manufacturers offer an "equivalent" mixture of calibration gas (Methane) to address this condition.
Contact the instrument manufacturer for specific information and guidance on the potential effects to their technology.