Span Calibration accessing the setup menus with the MODE button as discussed in Section 6.7 below. LEL only Type of calibration gas (standard) has changed significantly. LEL calibration gas maybe based on several different response standards methane, propane and pentane are the most common. If using anew cylinder of calibration gas, make sure that the type and amount of combustible gas is identical to that of the previous bottle. Honeywell Analytics offers calibration gases in Methane, Propane Equivalent and Pentane Equivalent. Dead sensor. Replace sensor. Instrument problem. Contact the local service center. Refer to the phone number on page ii of this manual.