The two instruments most used are the Q200 and the Miran SapphIRe. While both are quality instruments, they have some functional differences.
The Miran uses a large volume of air for it’s sampling. As such it is often preferred by those doing the EN test since it has a multiport collector and reads the average from the airstream. When a Miran detects a leak, the concentration builds to the peak and then falls off. So when plotted it looks something like this.
So as you are scanning, you will pass a leak but there is slight delay by the time the leak shows up on the graph. While the peak value between the two instruments seem very similar, the leak curves look different.
A Q200 looks more this
There is less of a time delay from detecting the leak to reaching the peak. Where this is particularly useful is when troubleshooting or doing R&D. It makes it easier to isolate the exact area of leakage.
Many think that the Q200 can not be used for the EN test but it can.
With the addition of a pump to collect the airflow and submit it to a sampling port you can effectively use the Q200 for the EN test.