When work is not in progress, the entrance should be blocked. When work is inprogress, the standby person should ensure that unauthorized persons do not enter the restricted area. Purging and ventilation. Purging of the confined space to remove contaminants should be done before entry by means of a high rate of general ventilation. Atmospheric testing is then in order.
Atmospheric testing is then in order.
The main environmental, or engineering, control of suspected or known contaminants during operations is general ventilation. Design of the system will vary. Continuous general ventilation is recommended for most operations where contaminants are generated. This may be supplemented or replaced by local exhaust ventilation. Monitoring of contaminants during operations is indicated if there is doubt about the effectiveness of controls.