Section 34. No person shall install or use, or cause to be installed or used, any tank or other receptacle for the storing of compressed air at any pressure exceeding 50 pounds per square inch, except when attached to locomotives or street or railway cars or trackless trolley vehicles, or to motor vehicles for use in operating such vehicles or their brakes or body-lifting apparatus unless the owner or user of such tank or other receptacle holds a certificate of inspection issued by the department, certifying that the tank or other receptacle has been duly inspected within the preceding 2 years, or unless the owner or user holds a policy of insurance upon the tank or other receptacle issued by an insurance company authorized to insure air tanks within the commonwealth, together with a certificate of inspection from the department. The provisions of this section shall not apply to any such tank or other receptacle used by divers if such tank or other receptacle is inspected by the refilling agency. This section shall be inapplicable in case of the installation or use of a receptacle temporarily holding oil and air and used for the purpose of lifting automobiles or operating hydraulic machinery, but only if said receptacle is approved by the board as being of a type which conforms to recognized standards of engineering practice as such standards apply to receptacles designed for such purpose and as meeting the requirements of regulations referred to in section thirty-five which regulations are hereby made applicable to such receptacles for this purpose.

Portable tanks and bottles containing compressed air used for breathing purposes while combatting fires or used in rescue operations in contaminated areas; and storage tanks and mechanical filling systems used to fill such portable tanks and bottles shall be exempt from the provisions of this section; provided, that such tanks, bottles and mechanical filling systems bear the stamp of approval from the Interstate Commerce Commission or have been inspected and approved by an inspector of the division who is authorized to make such inspections. All such storage tanks and mechanical filling systems must meet recognized national standards of safety and purity; and provided, further, that such portable tanks and bottles must also be hydrostatically tested every five years as required by the department.

Tanks used in and as part of electrical substations owned or operated by an electric company, as defined in section 1 of chapter 164, shall be exempt from this section if: the tanks bear the stamp of the American Society of Mechanical Engineers; the electrical substation is enclosed, locked and inaccessible to the public; and the tanks are inspected and maintained in accordance with industry standards as determined by the board of boiler rules.