METHOD OF CONTROLLING A POWERED AIR PURIFYING RESPIRATOR

摘要

A method of controlling a powered air purifying respirator blower system to detect a low air pressure high airflow event is disclosed. The blower system comprises a fan powered by an electric motor, controlled by an electronic control unit for delivering a forced flow of filtered air to a user. The electronic control unit has a plurality of data points representing events defining an acceptable operating range in terms of different characteristics of the blower system stored therein. The method comprises sampling a characteristic that represents the operating condition of the blower to obtain a sampled data point; comparing the sampled data point and the stored data point representing a low air-pressure high airflow event, for the same characteristic; repeating the sampling during a fixed time period, and if the comparing step indicates the low air-pressure high airflow event has been reached for the majority of the time period; activating an alarm. Use of a respirator employing the method to deliver a forced flow of filtered air to a contained user environment is also disclosed.