7.3 System Verification: The Verifier's Test Sequence

Who Verifies, and When

The Verification Tests

1. Standing pressure test

Piping is held at operating line pressure for 10 minutes. After the system is filled with nitrogen or source gas, the source valve and all zone valves are closed. The piping must show no decrease in pressure after 10 minutes. Any leaks are found, repaired, and retested.

2. Cross-connection test

The verifier proves again, independently, that each outlet is connected to the right system. One accepted method is individual pressurization:

1. Reduce all medical gas and vacuum systems to atmospheric pressure.
2. Disconnect every test gas source except the one system being checked.
3. Pressurize that gas system with test gas to 50 psi.
4. With adapters matching each outlet label, check every station outlet and inlet in all systems. Test gas must come only from the system being tested.
5. Disconnect the source, return that system to atmospheric pressure, and repeat for each system.

3. Valve test

Each valve is tested to confirm it controls only the outlets and inlets, zones, or areas named on its label. A zone valve labeled for Rooms 401-404 that also shuts off Room 405 fails.

4. Alarm test

Every master, area, and local alarm signal is tested for proper function and correct labeling. Examples include changeover, reserve, line pressure high and low, vacuum low, dew point, and CO.

5. Piping purge test

A heavy, intermittent purging of the pipeline removes any remaining particulate left by construction.

6. Piping particulate test

7. Piping purity test

For each medical gas system, purity is verified with nitrogen NF or the system gas:

• The outlet most remote from the source is tested for total non-methane hydrocarbons and halogenated hydrocarbons, and the results are compared with the source gas.
• The difference may not exceed 5 ppm of total non-methane hydrocarbons, or 5 ppm of halogenated hydrocarbons.
• Moisture at the outlet may not exceed 500 ppm, or an equivalent pressure dew point of 10°F (-12°C) at 50 psi.

Halogenated hydrocarbons are tracked because some degreasers and refrigerants contain them. Finding them at the remote outlet but not at the source points to contamination introduced during construction.

8. Final tie-in, operational flow, and concentration tests

Section 7.4 covers these: leak tests and purges at connections to live systems, flow and pressure drop at every outlet and inlet, and gas concentration at every source and outlet.

9. Medical air purity test

At the medical air compressor source, the verifier analyzes the air for the contaminants NFPA 99 limits before it is supplied to patients. This confirms that the compressor plant, dryers, filters, and intake produce medical air of the required quality.

10. Labeling and source equipment verification

The verifier confirms that labeling and valve identification meet the code. The verifier also confirms that the source equipment works before it is put into service: gas supply manifolds with their changeover and alarms, medical air compressor systems, and medical-surgical vacuum systems.

Reports

Inspection and testing reports go directly to the party that contracted for the testing. That party passes them through channels to the responsible facility authority and anyone else who requires them. Reports must contain detailed listings of all findings and results. Some plumbing codes, such as the California Plumbing Code, also require a report delivered to the AHJ before the system is accepted.

How the Installer Helps Verification Go Smoothly

• Deliver the witnessed test forms on day one.
• Have every outlet faceplate installed and labeled, and every zone valve box labeled on the outside.
• Make sure the alarm wiring is complete and the alarm panels are labeled.
• Make the purge and test ports on zone valves and source equipment accessible.
• Keep nitrogen in the system and openings sealed until verification starts.

The diagram after this text summarizes the sequence.