The reason is:

(1) Poor contact of ignition switch or adjustment knob;

(2) The ignition wire and electrode are detached;

(3) Short circuit caused by contact between ignition wire and combustion vessel or combustion vessel and another electrode;

(4) Poor contact between ignition wire and sample;

(5) Low oxygenation pressure;

(6) The moisture content of the sample is too high, the volatile matter is too low, and the sample particles are too large;

(7) Oxygen bomb leaks gas.