Gas detection instruments with internal pumps should not use a standard pressure regulator.
The negative aspect of using a positive pressure regulator on an instrument with a pump is that you are pressurising both the sensors and the pump, where there is a slight chance that the diaphragm of the pump could be ruptured.
The main problem with using pressure regulators is that gas can be forced into the sensor capillary at a higher than normal rate if the positive pressure from the gas flow is not sufficiently relieved. This will cause the response of the sensor to be artificially high during calibration and therefore have the final response reduced after calibration. The use of "T" assemblies can resolve this issue if used properly but they are often misused.
The ODFR-1001 from CAC Gas & Instrumentation is an on demand flow regulator specially designed to be used with gas detection devices and docking stations with internal pumps. The regulator provides the exact amount of gas the instrument pump requires and eliminates the need for gas sample bags, flow meters or special tubing assemblies.
The ODFR-1001 maximises the efficiency of the calibration process making it quick and easy for the user. Further, it minimises the consumption of calibration gas as the instrument determines flow rate and usage.
With a dynamic flow range of 0.3litres/min to 3.0liters/min the ODFR-1001 can be used for many different gas calibration applications. With the addition of flow splitters, the regulator can be used for multiple instruments or docking stations provided the maximum flow range is not exceeded.
For all of the reasons noted above, the use of the ODFR-1001 is the "best practice" for calibrating instruments with internal pumps.