Pulsed mass flow measurement system and method

A method for measuring a pulsed mass flow rate of gas passing from an upstream source of gas to a downstream process chamber through an on/off type valve of the source of gas, comprising:

• connecting the source of gas to the process chamber through a passageway;
• dividing the passageway into an upstream portion and a downstream portion using a flow restrictor device;
• measuring pressure within the upstream portion of the passageway;
• measuring temperature within the upstream portion of the passageway;
• and
• calculate a mass flow rate through the passageway using the pressure measurements and the temperature measurements in the upstream portion of the passageway.

A system for measuring a pulsed mass flow rate of gas passing from at least two upstream sources of gas to a downstream process chamber, comprising:

• a passageway for connecting the sources of gas to the process chamber;
• a temperature probe providing measurements of temperature of the passageway;
• a flow restrictor device dividing the passageway into an upstream portion and a downstream portion;
• a pressure transducer providing measurements of pressure within the upstream portion of the passageway;
• and
• a computer processing unit (CPU) connected to the pressure transducer and the temperature probe and programmed to receive pressure measurements from the pressure transducer, receive temperature measurements from the temperature probe, and calculate a mass flow rate through the passageway using the pressure measurements and the temperature measurements.