Methods and systems for detecting barrier blockage in a gas detector are disclosed. In some embodiments, a gas detector comprises a barrier configured to define a sensing chamber of the gas detector. The gas detector further comprises a radiation detection system. The radiation detection system comprises a radiation source and a detector. The radiation detection system may be configured for generating output signals related to radiation transmitted through the barrier. The gas detector comprises a controller operatively connected to the radiation detection system. The controller is configured to: determine an amount of radiation transmitted through the barrier based on the output signals; and determine a condition of the barrier based on the determined amount of radiation, wherein the determined condition indicates whether the barrier is blocked.

The present disclosure provides a particle analyzer and a particle test control method and device thereof. A method comprises, acquiring a blood sample in a test location; preparing a diluted sample by the acquired sample; after acquiring a diluted sample, monitoring whether a pore blocking event occurs during a counting process; when the pore blocking event occurs, suspending the test of the sample, and performing an unblocking operation; and after the unblocking operation is completed, re-counting the same diluted sample without re-acquiring and re-diluting the blood sample by the impedance method after the unblocking operation.