Patent ID: 7713742

Claim:
A calibration gas delivery apparatus for delivering a selectively humidified calibration gas to a measurement probe, the apparatus comprising: a) a delivery conduit having a conduit inlet adapted to receive a carrier gas stream and a conduit outlet for delivering a calibration gas stream; b) a mass flow controller in the delivery conduit for controlling the flow of the carrier gas; c) a first injection unit having a first intake in fluid communication with a first reservoir and a first outlet in fluid communication with the delivery conduit, the first reservoir adapted to hold an ionic mercury solution, the first injection unit delivering the ionic mercury solution at a known flow rate in liquid form; d) a second injection unit having a second intake in fluid communication with a second reservoir and a second outlet in fluid communication with the delivery conduit, the second reservoir adapted to hold water as a humidificant, the second injection unit delivering the water at a known flow rate; and e) at least one vaporizer downstream of the first and second outlets and upstream of the conduit outlet for converting the ionic mercury solution and the water into vapor form and delivering a calibration gas including the carrier gas, ionic mercury, and water vapor to the conduit outlet, whereby the concentrations of the ionic mercury and water in the carrier gas are known.