The typical application for bump testing or calibrating your instrument using an NRC regulator requires a fixed flow 0.5 litre/min regulator, a bit of tubing; a calibration cup; your gas mixture; and you are good to go.
There is nothing wrong with that, provided you are using the correct flow rate, regulator material and tubing. If your instrument has an internal pump, then you should be using the On-Demand Flow Regulator.
There are several regulators which can be used with NRC gas mixtures. Here are a few ideas for making your bump test or calibration system more efficient and functional.