Flow controller and pressure regulator:

The measurement and control of carrier gas, flow is necessary for both column efficiency and for qualitative analysis. The more constant the flow rates, the more precise and accurate the outputs. The column flow rates of carrier gas in conjunction along with temperature will determine the retention time of qualitative aspect of every sample solute. The flow rate must have certain features. It must be stable, reproducible and convenient. Stability is essential for accurate results, reproduceability for precision and convenient parameter adjustment to optimise results. For these purpose, a specially designed flow controller or pressure controller is used to manage precise and accurate flow rates for column carrier gas or for auxillary gases required for detector operation.

Figure demonstrates as to what will happen if column carrier gas flow rate is decreased from previous setting. All peaks have shifted to longer retention times and have an apparent loss of peak height The base of each peak is also wider, therefore, individual peak areas remain constant

Figure:  Effect of decreased flow rate