13.12 Notification to manufacturer of approval or disapproval. After the Bureau has considered the results of the tests, a formal report of the approval or disapproval of the mask will be supplied to the applicant by the Director of the Bureau of Mines in writing. No verbal reports will be made. If the device passes all requirements the formal report will be unaccompanied by any test data or detailed results of tests. The results of tests of gas masks that fail to pass the requirements shall not be made public but shall be kept confidential, except that the person submitting the apparatus will be informed of the details of the failure with a view to possible remedy of the defects in gas masks submitted in future.*+

13.13 Requirements for Bureau of Mines approval. To obtain the approval of the Bureau of Mines a gas mask must pass successfully the following inspection and tests:

(a) Color and markings. Distinctive colors and markings to indicate the purpose of each canister are required to safeguard the wearers. The colors required are indicated in the following table:

All colors used shall be such as to be clearly identified by the user and clearly distinguishable one from another. The color coating used shall offer a high degree of resistance to chipping, scaling, peeling, blistering, and fading and to the effects of chemical fumes, smokes, gases, moisture, and dusts in the ordinary atmospheres to which they may be exposed under normal conditions of storage and usage.

For chemical smokes or fumes the canister shall be of a color to indicate the purpose of the absorbent material contained and shall be striped with a strongly contrasting color, either black or white, one half inch in width. The stripes may be so placed to indicate the number and position of the filters. Type N canisters, for protection in air against all gases, vapors, and smokes, need have no stripes on the red color.

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*For statutory and source citations, see note to § 13.0.

On each canister shall appear in bold letters a brief statement to show the purpose of the canister, for example:

This statement may be made part of the approval label, or it is permissible to attach a metal plate bearing the proper inscription in raised or distinct letters, or to stamp the statement into the metal of the canister with a male or female die. The statement may be permitted if marked with decalcomania or stenciled with paint; or paper labels may be used. The latter must be attached with heatproof cement.

The case in which the gas mask is kept also must have the same statement indicated conspicuously in bold letters. The distinctive color or colors may be that of the letters themselves or that of the background, or part of the design, in such fashion that the distinctive colors are prominent.

(b) Materials. The gas mask and equipment must be constructed in all its parts of materials obviously suitable for the purpose they must serve. This applies to the fabric, rubber, metal, chemical, and other parts.

(c) Design and construction. The excellence of design and mechanical construction, as well as the workmanship, will be considered. This will be done with regard to safety to the wearer, freedom of his movements and his vision, the fit of the face and headpieces, and the comfort afforded under all conditions of use. There also will be considered the ease with which canisters or other parts of necessarily short life may be replaced by fresh parts and the tightness of the whole apparatus, with a view to insuring the wearer against leaks of unpurified air both before and after such changes have been made. Masks and respirators fixed in cases, hermetically sealed, or otherwise arranged to preserve them, will be considered with regard to ease of access and readiness in emergency and the suitability and efficacy of the cases.

(d) Facepiece test. Two men wearing the gas masks will enter a room containing 1 percent of ammonia; if necessary, a canister for ammonia will be attached to the mask for this test. Ten minutes will be spent in work designed to provide observation on freedom of movement permitted, freedom from leaks, and comfort allowed the wearer. The time will be divided as follows:

5 minutes: Walking, turning head, dipping chin.

5 minutes: Pumping air with a tire pump to a pressure of 25 pounds into a gas cylinder of about 1 cubic foot capacity.

To meet approval it will be necessary that no ammonia comes through the mask during the test and that no undue discomfort be experienced because of the fit or other mechanical features of the gas

mask.

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Should the mask be of a type without a facepiece it may be tested by wearing it in its appropriate atmosphere, other than ammonia, in a manner to provide information substantially the same as the preceding in regard to its ability to protect the wearer.

(e) Resistance to flow of air. (1) Before and after the chemical tests described under paragraph (f), the pressure drop of air passing through the canisters at a rate of 85 liters per minute will be determined in inches of water-column height. At no time must the resistance exceed 3.0 inches of water.

(2) The resistance to flow of air of the complete mask and canister, to inhalation and to exhalation, will be determined on a mechanical apparatus, the rate of air flow being 85 liters per minute continuous flow. The resistance to inhalation must not exceed 3.5 inches, and the resistance to exhalation must not exceed 1.5 inches of water pressure. (f) Canister tests-Type A: Acid gases. Nine canisters, separated from the facepieces and harness, will be tested on a chemical testing apparatus under the following conditions:

Humidity: 50-percent relative humidity.

Temperature: Room temperature (approximately 25° C.).
Rate of flow of gas: 32 liters per minute, continuous flow.

Tested in this way, the life or service time of each canister must be at least 30 minutes. The end of the life will be the time at which a test shows 5 parts per million of chlorine, hydrogen cyanide, or sulphur dioxide in the air coming from the canisters.

The additional tests described under paragraphs (g) and (h) are also required.

Type B: Organic vapors. Three canisters, separated from the facepiece and harness, will be tested on a chemical apparatus under the following conditions:

Vapor used for testing: Carbon tetrachloride.

Concentration of carbon tetrachloride in air: 5,000 parts per million.

Humidity: 50-percent relative humidity.

Temperature: Room temperature (approximately 25° C.).

Rate of flow of gas: 32 liters per minute, continuous flow.

Tested in this way, the life or service time of each canister must be at least 30 minutes. The end of the life will be the time at which a test shows 5 parts per million of carbon tetrachloride in the air coming from the canister.

The additional tests described under paragraphs (g) and (h) are also required.

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Type C: Ammonia. Three canisters, separated from the facepiece and harness, will be tested on a chemical testing apparatus under the following conditions:

Concentration of ammonia in air: 20,000 parts per million, or 2 percent by

volume.

Humidity: 50-percent relative humidity.

Temperature: Room temperature (approximately 25° C.).

Rate of flow of gas: 32 liters per minute, continuous flow.

Tested in this way, the life or service time must be at least 20 minutes. The end of the life will be the time at which the air, after passing through the canister, contains 100 parts per million, or 0.01 percent by volume, of ammonia.

The additional tests described under paragraphs (g) and (h) are also required.

Type D: Carbon monoxide. Carbon monoxide gas masks and respirators are divided into two classes: Class 1, gas masks for high degree of protection during a period of 2 or more hours; and class 2, self-rescue respirators, small, light masks or respirators for carrying in the pocket or on the belt to protect for one-half hour or more for the purpose of enabling escape from a place should carbon monoxide arise. The test requirements are:

Class 1 and class 2. Six canisters or parts containing the absorbent or catalyst, separated from the facepiece and harness, will be tested on a chemical-testing apparatus under the following conditions:

(1) Number of canisters, 3; gas used for testing, carbon monoxide; concentration of carbon monoxide in air, 10,000 parts per million, or 1 percent by volume; humidity, 50-percent relative humidity temperature, room temperature (approximately 25° C.); rate of flow of gas, 32 liters per minute, continuous flow.

(2) Number of canisters, 3; gas used for testing, carbon monoxide; concentration of carbon monoxide in air, 5,000 parts per million, or one-half percent by volume; humidity, 100-percent relative humidity, at 0° C. temperature, temperature of melting ice, 0° C., produced by immersing the canister in a bath of ice and water. The incoming air will be cooled by passing it through tubes leading through the ice water to the canister. The rate of flow of gas is 32 liters per minute, continuous flow.

Tested in this way, the life or service time will be that time at which a total quantity of carbon monoxide amounting to 960 cc. for class 1 (equivalent to 0.05 percent uniform outflow for 1 hour) or 640 cc. for class 2 has penetrated the mask. Under conditions (1) this life must be at least 4 hours for class 1 or 1 hour for class 2; under conditions (2) the life must be at least 1 hour for class 1 and 30 minutes for class 2.

Carbon monoxide canisters of class 1 must also have a means of showing when the useful life of the canister has ended, because the gas is itself odorless and tasteless; this may be done by causing an increase in resistance to breathing as moisture is absorbed, by allowing a definite increase in weight as moisture is taken up, by a mechanical device to measure the amount of air breathed, or by other suitable

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method. Tests of such methods will be arranged by the Bureau to suit the particular case, and special caution labels may be required for these canisters.

Type E: Smoke, dust, and mist filters when included in canisters for gases and vapors. When a gas-mask canister is designed to give protection against smokes, dusts, and mists in combination with gases and/or vapors, it must meet the following additional requirements:

Class 1. Three filters will be tested on a smoke-testing apparatus under the following conditions:

Fume used, tobacco smoke; rate of flow of gas, 85 liters per minute; length of test, 5 minutes.

Tested in this way, the filter must retain at least 95 percent of the passing tobacco smoke at the end of the 5-minute period.

Class 2. Six filters will be tested on a smoke-testing apparatus and by man-tests as follows:

(i) Tobacco-smoke test. Number of canisters, 2; rate of flow of gas, 85 liters per minute; length of test, 5 minutes.

Tested in this way, the filters must retain at least 50 percent of the passing tobacco smoke at the end of the 5-minute period.

(ii) Cotton-smoke man-test. Number of canisters tested, 2. Nature of test: Two men will wear the masks in a room of about 1,000 cubic feet capacity, filled with the smoke from the smudge burning of 1 pound of cotton waste. If the masks are not made with canisters suitable for the absorption of the gases generated by this test, such canisters shall have been attached to or placed in series with the canisters containing the filters to be tested. The men will remain 10 minutes in the room if the canisters fulfill the following requirements:

No discomforting irritation of the respiratory system or eyes is to be experienced by either man; this requirement is necessary for approval.

(iii) Tin tetrachloride man-tests. Number of canisters, 2.

Nature of test: Two men stationed outside of a chamber of about 1,000 cubic feet capacity, in which is an atmosphere containing 500 parts per million by volume of tin tetrachloride fumes, will breathe the atmosphere from the chamber through the canisters. If necessary, a canister for absorbing acid gases will be attached to the filters or canister under test. The man will continue the test for 20 minutes if the filters fulfill the following requirement:

No discomforting irritation is to be experienced by either man; this requirement is necessary for approval.

These tests are designed to determine the adequacy of the device for protection and comfort in emergency situations and not to establish the adequacy of protection under situations where there is repeated daily exposure to dust, fume, and mist hazards. No canister will be approved under this part for dust, smoke, or fume and mists alone. All filters for this purpose and for canisters designed for general dust hazards, particularly poisonous dusts, must meet the requirements of Part 14.

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