An apparatus for verifying input gases used in anesthesia gas control equipment, the apparatus comprising: a chamber adapted to receive a gas, the chamber including: an inlet to receive the gas; and a vent to exhaust the gas; a pressure sensor arranged to measure pressure within the chamber; a gas control coupled to the inlet, the gas control configured to fill a first gas and a second gas into the chamber at respective times, wherein one of the first and second gas is oxygen gas and wherein the other of the first and second gas is nitrous oxide gas, and wherein the inlet is connected to an intake designated to receive the oxygen gas and an intake designated to receive the nitrous oxide gas, the gas control operable to: fill the chamber with the first gas to a defined begin pressure; and fill the chamber with the second gas to the defined begin pressure; and microprocessor circuitry, coupled to the pressure sensor, the microprocessor circuitry operable to: observe pressure in the chamber at a first time period, measured with the pressure sensor , to identify a first elapsed time to exhaust the first gas from the chamber, via the vent , and reach a defined end pressure; observe pressure in the chamber at a second time period, measured with the pressure sensor , to identify a second elapsed time to exhaust the second gas from the chamber, via the vent , and reach the defined end pressure; and identify a difference between the first gas and the second gas, based on a time difference between the first elapsed time and the second elapsed time. a chamber adapted to receive a gas, the chamber including: an inlet to receive the gas; and a vent to exhaust the gas; an inlet to receive the gas; and a vent to exhaust the gas; a pressure sensor arranged to measure pressure within the chamber; a gas control coupled to the inlet, the gas control configured to fill a first gas and a second gas into the chamber at respective times, wherein one of the first and second gas is oxygen gas and wherein the other of the first and second gas is nitrous oxide gas, and wherein the inlet is connected to an intake designated to receive the oxygen gas and an intake designated to receive the nitrous oxide gas, the gas control operable to: fill the chamber with the first gas to a defined begin pressure; and fill the chamber with the second gas to the defined begin pressure; and fill the chamber with the first gas to a defined begin pressure; and fill the chamber with the second gas to the defined begin pressure; and microprocessor circuitry, coupled to the pressure sensor, the microprocessor circuitry operable to: observe pressure in the chamber at a first time period, measured with the pressure sensor , to identify a first elapsed time to exhaust the first gas from the chamber, via the vent , and reach a defined end pressure; observe pressure in the chamber at a second time period, measured with the pressure sensor , to identify a second elapsed time to exhaust the second gas from the chamber, via the vent , and reach the defined end pressure; and identify a difference between the first gas and the second gas, based on a time difference between the first elapsed time and the second elapsed time. observe pressure in the chamber at a first time period, measured with the pressure sensor , to identify a first elapsed time to exhaust the first gas from the chamber, via the vent , and reach a defined end pressure; observe pressure in the chamber at a second time period, measured with the pressure sensor , to identify a second elapsed time to exhaust the second gas from the chamber, via the vent , and reach the defined end pressure; and identify a difference between the first gas and the second gas, based on a time difference between the first elapsed time and the second elapsed time. <EOS>