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Ordinance on Safety and Health of Work under High Pressure

(Revised in terms of the Title March 19, 1977 by Ministry of Labour Ordinance No. 2)
Ministry of Labour Ordinance No. 40, September 30, 1972
Latest Amendments:
Ministry of Health, Labour and Welfare Ordinance No. 171 of July 16, 2001

In Japanese

Chapter V.  Recompressing Lock

(Installation of a Recompressing Lock)

Article 42. When the employer has workers engage in work in compressed air carried out under a pressure of 0.1 MPa or more or in diving operations at the depth of 10 m or more, he shall install a recompressing lock necessary for assuming first-aid treatment for compressed air workers subjected to high pressures or for diving workers, or shall assume measures use of which the said workers can make.

2.  When the employer installs the recompressing lock, he shall avoid the places given below:

(1)  Places or their vicinities in which to deal with dangerous substances (which correspond to the ones as listed in Attached Table 1 of the Cabinet Order, same as in the following), explosives and large amounts of combustible substances, or to store the substances described above.

(2)  Places which may happen to floods, snowslide, or landslide.

(Entry Prohibited)

Article 43. The employer shall prohibit those other than persons concerned from entering into the places therein the recompressing lock has been established or the places therein to operate the said recompressing lock, and shall put up notices to that effect at conspicuous locations.

(Operation of a Recompressing Lock)

Article 44. When the employer has the said workers operate the recompressing lock, he shall comply with the provisions given below:

(1)  The employer shall make inspection of air feeding equipment, air exhausting equipment, communication devices, and warning devices in terms of their operation status as installed in the said recompressing lock before operating the recompressing lock on a day, repair the equipment or devices if defective, and replace the defective with new ones when he finds anything wrong.

(2)  When compression is applied to workers, the employer shall not use pure oxygen.

(3)  Excluding required cases, the doors shall be kept unopened which are provided between main and sub-main rooms, and the barometric pressure in both the main and sub-main rooms shall be kept equal.

(4)  The employer shall have those who operate the recompressing lock always supervise the condition of compression and decompression, or the presence of other abnormalities.

2. When the employer does operate the recompression lock, he shall record the condition of compression and decompression applied at each occasion.


Article 45. The employer shall make inspection of the recompressing lock when it is installed, and subsequently at intervals shorter than a period of a month in terms of the items given below, and shall repair the said rooms or replace defective equipment or devices with new ones when he finds anything wrong in the equipment or devices:

(1)  Operational condition of the air feeding equipment and air exhausting equipment.

(2)  Operational condition of communication devices and warning devices.

(3)  Presence or absence of leakage of electricity.

(4)  Presence or absence of damage to electrical machines, equipment and wiring, and other abnormalities in the said machines, etc., or wiring.

2.  When the employer makes inspection of the equipment or devices in compliance with the provisions set forth in the preceding paragraph, he shall make a recording of the inspection results, and shall keep the recorded results in custody for a period of three years.

(Prohibition of Carrying Dangerous Substances, etc.)

Article 46. The employer shall prohibit dangerous substances, etc., liable to ignite or explosive substances or the substances which may form combustible substances if an increase is made in the temperature of the substances while they are being carried into the inside of the recompressing lock, and shall also put up a notice which states the said prohibition at the entrance of the recompressing lock.

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Table1 / Table2 / Table3