PH Helmet respirator : British Army

'PH' or 'Tube' helmet respirator as issued to British Army troops from January 1916. The helmet is a simple bag made from a double thickness of unlined blue-grey woollen flannelette fabric with a side seam that widens at the bottom where it reaches the wearer's shoulders. The two layers of fabric are held together by a section of triangular stitching at the lower front and rear. The individual circular glass eyepieces are held in tin-plated steel frames. These frames have a threaded internal section which can be removed to allow the fitting of replacement lenses. The mouthpiece consists of a soldered tinplate tube with a brown leatherette sleeve over the tip, to prevent cuts or chafing to the wearer's lips. The tube passes through the front of the helmet, the exit point being reinforced on both sides by a ring of waterproofed canvas. The remains of a black rubber expiration valve are present on the external stub of the mouthpiece.

The 'PH' Helmet was introduced into British Army service at the start of 1916, as a modification the 'P' helmet which had been in use since autumn of 1915. The new respirator was similar in most ways to the earlier model, and was virtually identical in appearance. Both were based upon the even earlier 'Hypo' or 'Smoke' helmet, but were improved by the adoption of removable individual glass eyepieces to replace the large and fragile window, and by the use of flannelette fabric, which was found to be stronger and more resistant to gas than ordinary flannel. The most important improvement was the introduction of a tubular mouthpiece with a rubber non-return valve, which allowed expired air to be blown out, but prevented air (and gas) from being inhaled. This innovation overcame the greatest weakness of the 'Hypo' helmet, which had been prone to the accumulation of exhaled carbon dioxide in the many folds and hollows of the fabric. The 'P' helmet was designed to combat the anticipated German use of a new gas, 'Phosgene', and was soaked in a solution of sodium phenate, which, being slightly caustic, could cause irritation to the skin of the wearer. These helmets had been issued to all troops prior to the first German use of Phosgene on 19 December 1915. The 'PH' helmet added hexamine (hexamethyl tetramine) to the sodium phenate solution, as tests had shown it to be an excellent absorbent of Phosgene. The 'PH' helmet, or a development, the 'PHG' (which was fitted with inbuilt sponge rubber goggles to counteract the use of lachrymatory or 'tear' gases) were issued to all Australian troops on arrival in France, and remained in widespread service until replaced by the vastly superior Small Box Respirator at the end of 1916. While they were unpopular with users because of their complicated fitting procedure, (they were designed to be tucked inside the shirt and held in place by the tunic) and because they often burnt the skin of the wearer, they provided adequate protection.