Suppressive shields

B. W. Je2ek, "Suppressive Shielding for Ha2ardous Munitions Production Operations" in Symposium on Processing Propellants, Explosives, and Ingredients, American Defense Preparedness Association (ADPA), Washington, D.C., 1977. 

Suppressive Shield Structural Design and Analysis Handbook, U.S. /Army Corps of Engineers, Huntsville, Div. No. HNDM-1110-1-2, 1977. 

King, An Overview of the Suppressive Shielding Program , Minutes of the 16th Explosives Safety Seminar, Vol 1, DOD Explosives Safety Board (Sept 1974), 91 — 139 9) I. Forsten,... 

Thresher, Applications of Suppressive Shielding in Hazardous Operation Protection , EM-TM-76-003 (June 1975)... 

Casey, Facility Design Reviews Program for Munitions Production Base Modernization and Expansion, Status Report , PATM 2178 (1975) 33) B.W. Jezek et al, Applications of Suppressive Shielding in Hazardous Operation Protection , Rept No EM-TR-76008, Edgewood Arsenal, APG (1975) 34) W.F. Nekevis et... 

Most gas pressure parameters for vented HE explosions apply for open vents and the special venting configurations developed for suppressive shields (Refs. 17 and 19). If vents are covered with blowout or frangible covers, the peak gas pressures are essentially the same as in unvented structures, but venting times and gas impulses can be altered (increased), depending on the vent area, mass per unit... 

Typical sections through vent panels evaluated in the suppressive shields program are shown in Fig. 36, together with definitions of vent area ratios which were found to correlate with attenuation of transmitted blast waves. 

Procedures for calculating vent area ratios for various structural configurations which have been used for suppressive shields are presented in Fig. 36. The procedures shown in Fig. 36 are believed to be self-explanatory, except possibly for the interlocked I-beams. The vent areas number 2 and 3 for this case are to take account of the two equal spaces b associated with each I-beam. 

The expression for peak overpressure in psi outside a suppressive shield is (Ref. 38)... 

R.G. Thresher, Suppressive Shielding of Explosive Facilities , Proceedings of the Sixth International Pyrotechnic Seminar, Univ of Denver (July 1978), 273-303 77) H. Treu-... 

Suppressive Shielding. See under Materials of Construction in Ammunition Plants in Vol 8, M42-R to M45-L... 

Studies aimed toward greater safety in TNT production include consideration of the use of suppressive shielding (Ref 26), design of conveyor belts without danger of detonation or propagation (Ref 40), and a study of the possible expl hazard from drowning tank material (Ref 18)... 

Ge detectors each provided with a cylindrical BGO + Nal Compton suppression shield. The conversion electrons were measured with two spectrometers each consisting of a mini orange filter and a Si(Li) detector. The transmission of the filter was optimized for detection of electrons with energies in the range 0.9- 1.3 MeV. For 196Pb the intensity of the E0 0t transition+in +... 

The y-ray spectra were taken with two Ge detectors both positioned at 135° with respect to the beam direction at the target position. One of the Ge detectors was provided with a BGO Compton suppression shield. 

Measurements were taken on 158Er at a total of 14 target-stopper distances. A portion of the total-projected spectra taken at four of the target-stopper separations is shown in Fig. 1. These spectra are of excellent statistical quality and reveal a favorable peak-to-background ratio in the 0° detector as a result of using the Compton suppression shield. 

A relatively new concept called suppressive shields is offered to provide protection to the area surrounding hazardous work with pyrotechnic and explosive material. At present, these operations are either limited to small quantities, widely dispersed, or segregated by barricades. Suppressive shields provide an alternative in the form of a vented steel enclosure. 

Since suppressive shields are full enclosures, they perform... 

Another particularly attractive feature of suppressive shields is that they are modular in design for quick erection and modification to provide maximum protection and flexibility. 

The Group 6 Shield illustrates a unique spherical design which is small and portable for use with laboratory quantities of primary explosives. The Group 5 Shield demonstrates the modular design concept that makes suppressive shields an attractive alternative to inflexible concrete barricades. 

Figure 3. General configuration of suppressive shield groups...

Group 3 Shield. The Group 5 Suppressive Shield is designed for use with pyrotechnic material ( ). 

One of the features that adds to suppressive shield utility is the modular design illustrated in Figure 8. The panels for the Group 5 Shield are laid out by the foundation ready for assembly. 

Figure 8. Group 5 suppressive shield panels ready for assembly...

Figure 11. Group 5 suppressive shield assembled, ready for test...

Instrumentation layout for the tests is shown schematically in Figure 12. Instrumentation for the Group 5 Suppressive Shield tests is tabulated in Table III. Burning time was measured using photocells in the shield wall. Thermocouples in the bulk pyrotechnic were used to obtain an indication when the material was completely burned. Static overpressure was measured on large charges to estimate confinement effects. Radiant heat flux outside the shield was measured with Keithley 86o flux meters. 

Methods do exist for estimating free field radiant flux, fireball diameter, and burning time for unconflned pyrotechnic material, but there is, at present, no method to compute attenuated thermal effects when a suppressive shield is used. Predictive models are needed ( 6). 

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