I could get writers cramp on this topic.
And Yes California has done a nice job, on trying to follow this code section.
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Before the Final Tie-In / The 24 Hour Standing Installer Testing Shall Be With:
1) Positive Pressure Systems With NF Nitrogen Gas Only.
2) Negative Pressure Systems With A Separated Vacuum Unit (i.e. not the new medical vacuum or existing vacuum pump).
NFPA 99 The 2012 -2021 Editions Chapter 5 - Installer-Performed Tests.
5.1.12.2.6.7  The 24-hour standing pressure test of the positive pressure system shall be witnessed by the (authority having jurisdiction or its designee for the 2012 code / added for the 2018 & 2021 ASSE 6020 or 6030). A form indicating that this test has been performed and witnessed shall be provided to the verifier at the start of the tests required in 5.1.12.3. (Tested with NF N2)
5.1.12.2.7.6 The 24-hour standing pressure test of vacuum system shall be witnessed by the (authority having jurisdiction or its designee for the 2012 code / added for the 2018 & 2021 ASSE 6020 or 6030). A form indicating that this test has been performed and witnessed shall be provided to the verifier at the start of the tests required in 5.1.12.3. (Tested with Vacuum)
(Inspections shall be performed by a party other than the installing contractor.)
NFPA 99 The 2018 & 2021 Editions Chapter 5
Installer-Performed Tests & System Inspection.
NEW Section: 5.1.12.3 System Inspection
5.1.12.3.1.1 System inspections shall be performed prior to concealing piping distribution systems in walls, ceilings, chases, trenches, underground, or otherwise hidden from view.
5.1.12.3.1.2 The test gas shall be nitrogen NF.
5.1.12.3.1.3 Inspections shall be conducted by a party technically competent and experienced in the field of medical gas and vacuum pipeline inspections and testing and meeting the requirements of ASSE 6020, Professional Qualifications Standard for Medical Gas Systems Inspectors, or ASSE 6030, Professional Qualifications Standard for Medical Gas Systems Verifiers.
(Inspections shall be performed by a party other than the installing contractor.)
5.1.12.3.2.1 The initial pressure tests performed by the installing contractor shall be witnessed by an ASSE 6020 inspector, an ASSE 6030 verifier, or the authority having jurisdiction or its designee. A form indicating that this test has been performed and witnessed shall be provided to the verifier at the start of the tests required in 5.1.12.4.