Use the air pressure setting recommended by the manufacturer. This usually requires a dedicated compressor which powers only the stunner. CO2 Stunning - Trouble Shooting Guide Reasons for return to sensibility 1. Low CO2 concentration. Increase the gas concentration.
Exposure time is too short.
Slow down the number of pigs or birds which are moved through the system. The time between exit from the CO2 chamber and bleeding is too long. To prevent recovery from the anesthesia, bleed the animals more quickly. Poor bleeding technique. If animals show signs of return to sensibility after bleeding the person doing the bleeding may need more training.