P helmet

The historical link between the use of HMT to alleviate or prevent the effects of phosgene is a long one. In designing respirators to defend against phosgene during WWI, a range of compounds was examined. For example, soda lime (a mixture of sodium hydroxide and calcium hydroxide) proved effective, while phenol and sodium phe-nolate were also effective and British Phenolate Helmet (P Helmet) was first used on December 15, 1915. This was followed by the Phenolate Hexamine Helmet (PH Helmet) from early 1916 onwards. The PH Helmets comprised a flannel sack which had been dipped in a mixture of... 

In June 1915, 2,500,000 Hypo Helmets were issued - bags of flannel which had been chemically impregnated against chlorine. The bags were placed over the head and tucked into the collar two eyepieces cut into the front and made of celluloid enabled the wearer to peer out at the scene around him. In the autumn the British added modifications - the helmet was better impregnated and a rubber exhaust tube was added. Nine million of these P Helmets were issued by December. 

The P Helmet had been hastily improvised to provide protection against phosgene, another chemical used in the dye industry, whose potential as a war gas had been noticed by the Allies in the summer of 1915. The helmet arrived at the front in the nick of time. 

Ambulance men drilling in the standard British gas mask, the P Helmet , July 1916. The bag of flannel made the face sweat and the chemical which impregnated it then ran, stinging the eyes and trickling down the neck. In addition to the discomfort, the masks often leaked, the eyepieces cracked, and a lethal amount of carbon dioxide could build up inside the helmet. 

By the fall of 1915, the War Department finally became interested in providing American troops with some form of a protective mask. By then, the British already had the P helmet, a flannel bag treated with sodium phenate and sodium hyposulfite that fitted over the head and was effective against chlorine and phosgene gases. The Germans were slightly ahead with a rubberized facepiece, unbreakable eyepieces, and a drum canister.24... 

Fig. 3-4. Warfare in the chemical age. (a) British soldiers at the Battle of the Somme appear to be wearing PH helmets in this photograph dated July 1916. (b) The PH helmet was an improved version of the earlier hypo and P helmets in which air was inhaled and exhaled through the fabric. The PH helmet incorporated an expiratory valve, and the cloth was impregnated with chemicals designed to destroy phosgene (the active agent was hexamethylenetetramine). This protective mask was stiflingly hot, and prolonged wear resulted in car-...

During the autumn, the combatants intensified their research into gas warfare. An account among the papers of Foulkes states that In November 1915, a most valuable document had been obtained giving a list of enemy gases, including phosgene which was to be employed in Flanders early in December and in this connection it was stated that the enemy hoped to cause 10000 casualties ." The Allies had also decided on the introduction of phosgene, and a new respirator -the P helmet - had been developed in anticipation. 

Belanger, P.L. Elesh, E. (1980) Health Hazard Evaluation Determination, Bell Helmets Inc., Norwalk, CA (Report No. 79-36-646). Cincinnati, OH, National Institute for Occupational Safety and Health... 

As a precaution should fire occur, the workers should be provided either with protective helmets, equipped with a fresh air supply, or with masks and absorbers, and they should also wear protective clothing of asbestos or thick wool. If a violent fire occurs, the building must be evacuated, since to remain in an atmosphere containing a high concentration of nitrogen dioxide, even for a short time, is very dangerous. This is discussed in more detail on p. 407. 

Uses Was used in World War I in the so-called P, H. helmets as a protection against phosgene gas. 

In a series of studies, Bell et al. assessed the effects of ephedrine mixtures on performance, and found measurable improvement. One and one-half hours after ingesting a placebo (P), caffeine (C) (4 mg/kg), ephedrine (E) (0.8 mg/kg), or caffeine and ephedrine, 12 subjects performed a 10-km run while wearing a helmet and backpack weighing 11 kg. The trials were performed in a climatic suite at 12-13°C, on a treadmill where the speed was regulated by the subject. V02, VC02, V(E), HR, and rating of perceived exer-... 

Jin P L. The development research of the new safety helmet. China Personal Protective Equipment, 2001,... 

Krzeminski, D.E., Goetz, J.T., Janisse, A.P., Lippa, N.M., Gould, T.E., Rawlins, J. W., Piland, S. G., 2011. Investigation of linear impact energy management and product claims of a novel American football helmet liner component. Sports Technol. 4, 65-76. 

The chemistry of these polymers was extended to terphthaloyl chloride and p-phenylenediamine, resulting in the commercialization of Kevlar fiber. Kevlar (structure shown below) is ideally suited for ballistic vests and high impact helmets because of its strength and the fact that it is as strong as steel but at one-fifth the... 

There are some cormnon misconceptions regarding combat helmet testing. One common misconception concerns the existence of National Institute of Justice (NIJ)-certified Level IDA helmets. The Nil Standard for Ballistic Helmets 0106.1 only certifies up to Level II for ballistic-type helmets. The only comprehensive Level IIIA testing protocol for helmets in the LIS is the H. P. White Helmet Test Procedure (HPW-TP-0401.01B). Additionally, the NIJ Standard does not provide arty information on how to measure blunt trauma deformation a standard operatingprocedure to assess trauma-related injury to the wearer. Testing protocols of NIJ Standard 0106.01 are employed by many manufacturers for testing helmets up to Level IDA (Nielsen, 2008 Scheetz et al., 1973). 

Scheetz, H. A., Corona, B. M., Ellis, P. H., Jones, R. D., Randall, R. B. Method for Human Factors Evaluation of Ballistic Protective Helmets , Report AD-774833, Human Engineering Laboratory, Aberdeen Proving Ground, Maryland. 

Yetham, L. A., Godfreg, P. M., Chinn, P. B. Materials for Motorcycle Crash Helmets a Finite Element Parametric Study. Plastics. Rubber and Composite Processing and Applications 1994 22 215-21. 

Figure 3. Three of the modules comprising methionine synthase. At the top center is the Bi2- binding fragment [651-896], a structure with two domains, one a four-helix bundle that serves to cap the cofactor, and the other an a/p fold that interacts with the lower face of the corrin macrocycle and binds the nucleotide tail of cobalamin. Measurements of the rates of photolysis of the C0-CH3 bond indicate that the cap domain covers the upper face of the corrin in the substrate-free form of the intact enzyme (7). On the lower right is the activation domain [897-1227] with bound AdoMet. This helmet-shaped single domain is an unusual fold with no resemblance to other well-characterized AdoMet-binding domains (8). On the lower left is the structure of the methyltransferase AcsE from Moorella thermoaceticum, which we take as a surrogate for the folate-binding domain of MetH.

Dionne, J.P., El Maach, 1., Shalabi, A., Madris, A., 2003. A method for assessing the overall impact performance of riot helmet. J. Appl. Biomech. 19, 246-254. 

Under high bending stresses, semicircular cracks (half of penny shaped crack of radius a) initiate at the surface of the PMMA. For this geometry, V = 2/n. Taking for PM M A as 1 M Pa mi, calculate the minimum crack size that could initiate catastrophic fracture in a window of the thickness that you recommend, when the helmet is at its maximum operating depth. Assume p = 1030kg/m for seawater. Visual inspection can be relied upon to detect cracks if a > 2 mm. At what depth do cracks of this size initiate catastrophic fracture in the window that you have designed ... 

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