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.
When producing a specialty gas mixture, most of the time taken to manufacture it goes into cylinder preparation to ensure that the mixture is stable. This is the single most important aspect in a quality gas mixture. If what comes out of the cylinder is not what is described on the label it will result in a poor calibration. Much time, testing, and research is invested in the development of techniques related to the interaction with cylinders and valves, solely to ensure the stability of mixtures. In general, it includes:
Purging is an important part of a good calibration procedure and should always be practised when handling dangerous gases. Purging ensures that you have control over which gases are in your gas delivery system, and therefore which gases are being exposed to internal components, sensors, or other equipment. It also helps to prevent unwanted reactions from taking place, which can greatly increase the service life of related components.
The GDS-100 Gas Distribution System was originally designed to provide an efficient method of utilizing high pressure/large volume gas mixtures with gas detection docking stations.
Although excellent for this application the GDS-100 has also proven to be a beneficial stand-alone system for both calibration and bump testing applications.
The ODFR-1001 is an On-Demand Flow Regulator providing flows between 0.3 – 3 litres per minute.
This regulator is ideal for calibrating or testing process analysers which have an internal pump to draw in the gas sample.
The on-demand flow regulator is available in a low pressure version, for use with disposable gas cylinders up to 70 bar, and a high pressure version, for cylinders with pressure up to 300 bar. Both versions work identically.
In order to deliver gases from a cylinder to the point of use, a gas delivery system is used. This can be as simple as a single cylinder regulator or a complex system involving a manifold, pipelines, line regulators, outlet points, or a long list of many other components.
However your system is designed, there will be many gas-tight connections. In this article, we’ll focus on one type of fitting: tapered thread fittings.
Step: 1: Pressure or Flow
All high-pressure regulators are designed to accept incoming pressure of 150bar+ from the cylinder. This makes them a high-pressure regulator. But what do you require on the outlet of the regulator. What does your instrument/analyser/GC require? Pressure or flow?
Typically, a gas detection instrument will require flow (0.5l/min) where a gas analyser may require pressure at 1 or 2 bar. The instrument, analyser or GC will dictate what is required.
Once this is determined then we can continue.