Defence against gas : 1927 : Provisional / by command of the Army Council ; the War Office, 17th June, 1927.
- Date:
- 1927
Licence: Public Domain Mark
Credit: Defence against gas : 1927 : Provisional / by command of the Army Council ; the War Office, 17th June, 1927. Source: Wellcome Collection.
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![wppruy JO 5. Size.—In general it is found that oe per cent. of individuals can be fitted satisfactorily with- normal {size 3 facepieces. In some cases, however, where the eye to chin distance is far from the normal, an outsjze may be required. | TEMSEES inn g factor is whether Ener eBieCE oe cto Jewel onthe fack€uch that satisfactory vision is obtained when the facepiece is correctly adjusted. In most cases a gas-tight fit is obtained irrespective of size, but incorrect sizing will lead to considerable diminution in efficiency owing to discomfort and loss of field of vision. 6. Harness tension.—Since fit does not depend directly upon the harness 9f the-dacepiece, the aim should be to main- tain the harness bts loose as is consistent with stability of the facepiece on the face. Correct harness tension is there- fore best obtained by first loosening the elastics to within an inch of their ends and then, with the facepiece on the face, gradually tightening up until a satisfactory tension is obtained, observing that fit invariably tends to improve when the face- piece has been worn a short time. Any tendency to leak, which, if anywhere, usually occurs in the temp]ggregion, So as a rule be overcome by loosening the adjacent Or 6tFaps so as to give the fitting surface at this point greater freedom cdo, dake up its own shape in contact with the skin. The other may then require a corresponding tightening A Gdn If the pull of the elastics as a whole is too loose, the facepiece will be found to shift on the face on vigorous and repeated turning of the head. If the pull is too tight, pressure marks will usually be visible on the wearer’s face, especially. on the forehead, after a short period of wear. AN bte- ereecaeee “Tt 61 o—SHerieSs pee ae carsied-out, the wearer should remove the facepiece and put it on again to confirm that a satisfactory fit hgs been gbtained. After completion of fitting the ieaen oe oh BE ee Eeeg without authority from the gas officer or instructor. 8. Correct adjustment, size and harness tension are checked by:— i. Visual examination. ii. Gas chamber test. gO 5 9. Visual examination.—The fitting surface should provide a band of varying width in definite contact with the skin all round the face. If this band contact is discontinuous at any point the fit is unsatisfactory. When such lack of contact is suspected, confirmation can often be obtained by light pressure of the fingers on the stockinet covering this fitting band. A feeler gauge of metal or bone for insertion between the fitting surface and the skin is also often of assistance.](https://iiif.wellcomecollection.org/image/b32182363_0099.jp2/full/800%2C/0/default.jpg)
