Abstract: A method and apparatus according to the present invention monitors an emission gas, such as a carbon monoxide gas, from an emission source, such as a carbon monoxide source, by periodically sensing a concentration level of emission gas, such as carbon monoxide, in ambient air and generating a signal corresponding to the sensed concentration level of the emission gas. In response to the signal, a percent blood concentration value of the emission gas is determined. The calculated blood concentration value is compared to a threshold value, and if greater than the threshold value, the source of emission gas, such as carbon monoxide gas, is disabled. The blood concentration value can be determined on a predetermined time interval, and at least in part, can be based on a prior blood concentration value in combination with a current blood concentration value.

Abstract: A pressure relief valve assembly for an air conditioning system of a vehicle includes a compressor hose block having an inlet port and an outlet port. The inlet port is for connection to a low pressure gas and the outlet port is for connection to high pressure gas of the air conditioning system. The compressor hose block also has a connecting port interconnecting the inlet port and the outlet port. The pressure relief valve assembly further includes a valve disposed in the connecting port to allow the high pressure gas to pass from the outlet port to the inlet port when a pressure of the high pressure gas reaches a predetermined level.