thePetroStreet

Thank you, Irish and dexter for yr input.
Correct me if i am wrong, :
The Type I test is using actual gas (the job gas), and there are limited deviations permitted as per table 3.1
The type II test, allows to test the compressor on any other available gas, as long as the specifics, such as Mol Wt, pressure, temp, etc are within the permitted deviations range?
Could you also tell me if the standard also specifies a time for which these tests need to be performed. I have also heard of ASME PTC 10 "modified" would you have any information on this?
Thanks,

Your interpretation is correct.
I recommend you to go through the attach article. A genuine practical approach for PTC-10.

First of all please do understand that ASME PTC-10 is only a "thermodynamic performance" test criteria, means it focus on process / operation related performance only, expected from specific machine. It has nothing to do with mechanical balancing or any other mechanical related issues. Please refer to API-617 for such tests.
ASME PTC-10 recommends test for atleast 15 minutes after the stabilization of process conditions, for a single operating point compressor. Any how if it is variable speed compressor with different operting points, then PTC doesn't implies any limit of time.

P.S. Modified ASME PTC-10 is not a standard, not internationally accepted codes. It is basically recommendation by some researchers based on limitation in PTC-10 on reality grounds. It may differ from vendor to vendor and from customer to customer.