OBTURATOR

Hiift-loch, n. obturator foramen, -nerv, m. sciatic nerve. 

Obturate. To stop or close an opening so as to prevent escape of gas. To seal, as with delay elements... 

Obturation. A process that seals the breech of a gun and prevents the escape of propint gases at the time of firing. In all modem firearms, light and medium artillen7, it is effected by the momentary expansion of the brass or copper cartridge case... 

In separate-loading ammo, obturation is achieved by a special device, called an Obturator... 

Obturator Pad. Pad of tough plastic material, forming part of an Obturator (qv)... 

Obturator Spindle. Part of the breechblock assembly of a gun which fires separate-loading ammo. It extends thru the breechblock and holds in position the various parts of the Obturator (qv), while permitting the breechblock independent rotation around these parts Ref OrdTechTerm (1962), 207-R... 

The reproducibility of the time of a delay element is related to the reproducibility of the primer used for initiation. The times of short" obturated delay elements are very sensitive to variation in primer output (Refs 7 12). Although primers of this type have been additionally tested for blast and gas vol, some opinions have held that, provided the priming mixt is maintained within the prescribed limits, the output is a mere reflection of the pellet wt... 

Regional block, a form of anesthesia that includes spinal and epidural anesthesia, involves injection near a nerve or nerve plexus proximal to the surgical site. It provides excellent anesthesia for a variety of procedures. Brachial plexus block is commonly used for the upper extremity. Individual blocks of the sciatic, femoral, and obturator nerves can be used for the lower extremity. An amount that is close to the maximally tolerated dose is required to produce blockade of a major extremity. 

Detonation Velocity-Confinement and Obturation Relationship. Accdg to W.G. Penney (as quoted by Dunkle, Ref 8, p 209), deton rate of condensed phase expls is related to charge diam in the same way as confinement. The two relationships are equivalent, because the outer portions of a detonating chge give effective confinement to the central region... 

Accdg to Dunkle (Ref 8, p 206), confinement and obturation of expls in rigid tubes leads to an increase in deton velocity and this has been explained by various investigators on the basis of the hydrodynamic theory of detonation... 

Detonation Velocity, Influence of Confinement on. See Detonation Velocity -Confinement and Obturation Relationship... 

Since in the anvil-type of primer the cup is not pierced, obturation (sealing) is obtd after the primer is fired, because the entire cup is pressed into cartridge cavity. Such primers are also known as obturated type, to distinguish them from the unobturated type, which is usually employed as an "explosive-train element" in fuzes. This type and some obturated types employed in fuzes are described in Ref 4, Part F... 

The complete round (cartridge) of small arms ammunition (except for the shotgun), employing one of the center-fire obturated type primers is represented in Fig 32... 

A fiber rotating band and a plastic obturator are assembled on the outside of the proj near the base of the sabot. During proj flight, the tracer burns for a minimum of 2.5 seconds. The sabot discards upon leaving the gun muzzle (with velocity of 4850fps) by setback, centrifugal and air-pressure forces. The sheathed core penetrates the target by kine-... 

There are two types of fuze primers "unobturated " and "obturated". Obturated primers contain an anvil, while unobturated do not contain it. Following are examples of unobturated fuze primers a) Instantaneous Stab Fuze Primers... 

Percussion fuze primers described below belong to "obturated types... 

The elements A B of Fig 1-46 are obturated column types, while C is vented column type, D vented ring type and E pressure type delay (Ref 23, pp 5-1 to 5-18)... 

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