A fluid control system (600, 800, 900, 1000) for pulse delivery of a fluid, the system (600, 800, 900, 1000) comprising: a flow channel; an isolation valve (690, 890, 930, 1090) to initiate and terminate a pulse of fluid from the flow channel; and a mass flow controller, MFC, (610, 810, 910, 1010), including a control valve to control flow of fluid in the flow channel, a flow sensor to measure flow rate in the flow channel, and a dedicated controller to control flow of fluid through the control valve based on feedback from the flow sensor, and switching of the isolation valve (690, 890, 930, 1090), to control a mass of fluid delivered during the pulse of fluid, wherein the flow sensor comprises a flow restrictor within the flow channel and positioned between the control valve and the isolation valve (690, 890, 930, 1090), an upstream pressure sensor configured to detect an upstream pressure in the flow channel at an upstream position between the control valve and the flow restrictor, and a downstream pressure sensor configured to detect a downstream pressure in the flow channel at a downstream position between the flow restrictor and the isolation valve (690, 890, 930, 1090), the flow sensor measuring flow rate based on the upstream pressure and the downstream pressure, wherein the dedicated controller is connected to the isolation valve (690, 890, 930, 1090) to control switching of the isolation valve (690, 890, 930, 1090) to initiate and terminate the pulse, wherein the dedicated controller is configured to determine an estimated number of moles of fluid delivered as a function of i) the flow rate measured by the flow sensor, ii) the detected pressures, and iii) a targeted pulse-on period, and wherein the dedicated controller is configured to control the flow through the control valve and the switching of the isolation valve (690, 890, 930, 1090) based on the estimated number of moles of fluid delivered, the flow through the control valve being controlled by adjusting, during the pulse, a flow set point of the control valve based on feedback of the estimated number of moles of fluid delivered during the pulse in order to precisely deliver a desired number of moles within the targeted pulse-on period for each pulse. a flow channel; an isolation valve (690, 890, 930, 1090) to initiate and terminate a pulse of fluid from the flow channel; and a mass flow controller, MFC, (610, 810, 910, 1010), including a control valve to control flow of fluid in the flow channel, a flow sensor to measure flow rate in the flow channel, and a dedicated controller to control flow of fluid through the control valve based on feedback from the flow sensor, and switching of the isolation valve (690, 890, 930, 1090), to control a mass of fluid delivered during the pulse of fluid, wherein the flow sensor comprises a flow restrictor within the flow channel and positioned between the control valve and the isolation valve (690, 890, 930, 1090), an upstream pressure sensor configured to detect an upstream pressure in the flow channel at an upstream position between the control valve and the flow restrictor, and a downstream pressure sensor configured to detect a downstream pressure in the flow channel at a downstream position between the flow restrictor and the isolation valve (690, 890, 930, 1090), the flow sensor measuring flow rate based on the upstream pressure and the downstream pressure, wherein the dedicated controller is connected to the isolation valve (690, 890, 930, 1090) to control switching of the isolation valve (690, 890, 930, 1090) to initiate and terminate the pulse, wherein the dedicated controller is configured to determine an estimated number of moles of fluid delivered as a function of i) the flow rate measured by the flow sensor, ii) the detected pressures, and iii) a targeted pulse-on period, and wherein the dedicated controller is configured to control the flow through the control valve and the switching of the isolation valve (690, 890, 930, 1090) based on the estimated number of moles of fluid delivered, the flow through the control valve being controlled by adjusting, during the pulse, a flow set point of the control valve based on feedback of the estimated number of moles of fluid delivered during the pulse in order to precisely deliver a desired number of moles within the targeted pulse-on period for each pulse.