Pressure-insensitive mass flow controller

A method of preventing a mass flow controller from participating in crosstalk in an array of mass flow controllers, comprising the steps of:

• supporting an array of process fluid control assemblies on a pallet, each of the fluid control assemblies including a combination valve, a first pneumatic valve downstream of the combination valve, a mass flow controller downstream of the first pneumatic valve, and a second pneumatic value downstream of the mass flow controller;
• moving a handle of the combination valve of at least one of the fluid control assemblies from a disabled position in which the valve is not responsive to a pneumatic signal to an enabled position in which fluid flows when the pneumatic signal is present;
• directing the pneumatic signal to the combination valve of at least some of the fluid control assemblies to enable fluid flow through the at least some of the fluid control assemblies;
• flowing toxic, corrosive or flammable fluid through the combination valve of the at least some of the fluid control assemblies;
• flowing the toxic, corrosive or flammable fluid through the first pneumatic valve of the at least some of the process fluid control assemblies;
• flowing the toxic, corrosive or flammable fluid through the mass flow controller of the at least some of the fluid control assemblies;
• sensing and providing a signal indicative of a fluid pressure of the toxic, corrosive or flammable fluid inside of the mass flow controller with a pressure sensor contained within the mass flow controller, wherein the pressure sensor is positioned and the flow path from an inlet to the pressure sensor is configured such that the pressure sensor is sensitive to rapid pressure perturbations at the inlet of the mass flow controller;
• providing a signal indicative of a fluid flow inside of the mass flow controller with a flow sensor contained within the mass flow controller, wherein the flow sensor is positioned downstream of the pressure sensor;
• determining an adjustment for a control valve in response to a rapid pressure perturbation at the inlet of the mass flow controller using the signal indicative of the fluid pressure and the signal indicative of the fluid flow, the determining to effectively avoid overcompensation for the rapid pressure perturbation, the control valve contained within the mass flow controller downstream of the pressure sensor and the flow sensor;
• adjusting the control valve based on the determined adjustment, so that the mass flow controller effectively avoids overcompensating for the rapid pressure perturbation;
• flowing the toxic, corrosive or flammable fluid through the second pneumatic valve of the at least some of the fluid control assemblies;
• mixing the toxic, corrosive or flammable fluid from the at least some of the fluid control assemblies in a main manifold;
• flowing the mixed fluid stream from the main manifold through a manifold outlet;
• flowing an inert fluid through a fluid inlet;
• enabling a third valve downstream of the fluid inlet and disabling a fourth valve downstream of the third valve such that the inert fluid flows through the third valve, through a fluid line downstream of the fluid inlet and upstream of the fourth valve, through a purge manifold downstream of the fluid line, and from the purge manifold into the first pneumatic valve of the at least some of the fluid control assemblies to purge the at least some of the fluid control assemblies;
• and
• enabling the fourth valve such that the inert fluid flows through the third valve, through the fourth valve and from the fourth valve into the main manifold to flush the main manifold.