The Initial Blow Down is performed with oil free, dry nitrogen NF grade. The blow down should be completed prior to the installation of system components (outlets, inlets, sensors, switches, relief valves, manifolds and source equipment). The initial blow down insures that any large particulate matter is blown out after the installation of the distribution piping.

 

The Initial Pressure Test is performed on each section of the piping after the installation of the station outlets and inlets, but before the installation of the components of the distribution system that could be damaged by the test pressure (pressure switches, sensors, relief valves, etcetera). The pressure must be 1.5 times the system working pressure and not less than 150 psig for pressure gases and 60 psig for vacuum. The pressure must be maintained until each joint has been examined for leakage, which is usually done by using soapy water.

 

The Cross Connection Test is an important part of every installation. Completing this test allows the Installer to confirm that the correct medical gas or vacuum will be dispensed at the proper station outlet or inlet. During this test each piping system is individually pressurized with oil free, dry nitrogen NF grade to 50 psig. After the system is pressurized, each station outlet or inlet is tested to determine if the test gas is being dispensed only from the piping system being tested.

 

The Piping Purge Test is another test which allows the Installer to eliminate particulate matter from the distribution piping. During the test the Installer must purge each outlet with an intermittent high volume flow of test gas until it produces no discoloration on a clean white cloth. The purging is completed at the closest outlet or inlet and continues to the furthest outlet or inlet within the zone.

 

The Standing Pressure Test for Positive Pressure Medical Gas Piping must be completed after successful completion of the initial pressure testing and after the installation of all system components (outlet and inlet faceplates, sensors, etcetera). The test is conducted using oil free dry nitrogen NF grade at 20 percent above the normal operating pressure for a 24 hour period. There must be no change in the test pressure after 24 hours other than changes due to ambient temperature.

 

The Standing Vacuum Test for Vacuum Systems is also completed after the initial pressure testing and installation of all system components. The test must be conducted between 12” Hg and full vacuum. During the test the vacuum source must be disconnected from the piping system. No changes in the vacuum other than changes due ambient temperature are allowed for a period of 24 hours.

Once all the above tests have been completed by the Installer, the system verification can be completed by an ASSE 6030 Professional Qualifications Standard for Medical Gas Systems Verifier.

 

The Installer performed tests are an important part of the installation process for any medical gas installation.
 
Are you getting what you paid for?
 

By:

 

Jay D’Agostino

NITC/ASSE 6020 Medical Gas Inspector