The installation and commissioning of medical gases shall be carried out in accordance with the relevant documents of the YY/T0186～0187-94 standards.

(1) In accordance with the requirements of the design drawings, prepare the construction organization measures, the project progress schedule, and the equipment and material supporting tables.

(2) Clear the construction site, and verify the diameters and flow velocity requirements of the various gas pipelines against the design drawings. Check the reserved openings and coordinate their spatial positions with other disciplines.

(3) Install the supports and hangers. After the various gas pipelines are in position (the main and concealed pipelines are laid first, followed by the branch pipelines), first inspect each pipeline section separately, carry out pressure tests and leak checks, and then commission the entire system. Keep complete records of all commissioning and testing methods and their results, compile them into lists and registers, and have them signed and acknowledged by the client, the supervision unit, the quality inspection department, and other relevant organizations, for future reference and for archiving upon completion and handover.

1) Pressure strength test. High-pressure pipes must undergo a strength test, which may be performed by the hydraulic (water pressure) method: apply a pressure greater than 1.5 times the maximum working pressure; if the pressure is held for 5 min without dropping, the test is passed. After the strength test, the pipes and fittings must be cleaned again and reinstalled in position; the welding reliability of the pipes must also be tested by sampling a proportional number of welds for flaw detection. If any weld fails, after repair, sample and test twice as many welds as in the previous round; if there are still failures, after another repair, sample and test twice as many as in the previous round again; if they pass, acceptance can be granted. If there are still failures, all pipelines in the entire system must be refabricated until acceptance is passed.

2) Leak test. The pressure shall be held for 24 h at the maximum working pressure of the gas type used, with the average hourly leakage not exceeding the specified total system leakage rate (generally ≤0.15%/h for positive pressure and ≤1.8%/h for negative pressure); calculate it using the following formula:

$$A = frac{100}{t}left[1-(P2T1/P1T2)right] tag{8.1}$$

Where: $A$ — average hourly leakage rate (pressure rise rate for negative pressure) (%);

$P1$ — pressure at the start of the test (MPa);

$P2$ — pressure at the end of the test (MPa);

$T1$ — absolute temperature at the start of the test (℉);

$T2$ — absolute temperature at the end of the test (℉);

$t$ — test duration (h). 3) For the negative pressure suction system, the suction rate at each connector should be tested. A bucket may be filled with water, and then the suction tube inserted into the bucket to measure the rate, which is calculated using the following formula:

$$B = V/t tag{8.2}$$

where: $B$ — suction rate (L/min);

$V$ — volume of the bucket (L);

$t$ — test duration (min).

One point to be clarified here: water is used for this test because it is impossible to use blood or other related liquids with relatively high viscosity; water has to be used instead, so as to provide a relative assessment of the performance of the suction system.

(4) Inspect the equipment arriving on site, complete the registration, and proceed with the equipment installation. Carry out acceptance inspection of the installed equipment and connect it to the pipe network according to the various different gases and their related equipment. After passing inspection, conduct acceptance of the entire system. Upon passing, both parties sign, and after compiling the completion documents, the handover is performed.

(5) The contact areas between the various gas pipelines and the supports/hangers shall be treated with static-conducting and anti-static corrosion measures in accordance with the requirements of relevant national codes and standards; all gas pipelines entering each operating room must be safely grounded (as required on page 11 of drawing collection 97SD567).

(6) Gases supplied to the clean operating department shall be provided with alarm devices and pressure-regulating devices, and the oxygen supply shall have the function of automatically cutting off the gas source in the event of a fire.