Design Considerations for Toxic Chemical and Explosives Facilities

Chapter 18

Electrostatic Studies in Army Ammunition Plants 1

2

3

William O. Seals , James Hokenson , and George Petino 1

Army Research, Development and Engineering Center, Dover, NJ 07801-5001 Southwest Research Institute, San Antonio, TX 78284 Hazards Research Corporation, Denville, NJ 07834 2

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3

One of the greatest hazards that exist in the manufacture of solid propellants, explosives, and pyrotechnic materials is dust explosions. At the different stages of manufacture, considerable quantities of dust can be produced. These unwanted quantities of dust are produced during the screening, drilling and packaging operations. In addition to posing a fire/explosive hazard, health problems for plant personnel can be serious. It is essential that the dust be removed safely from each operation. To accomplish this removal, exhaust fans are used to extract dust from the surrounding atmosphere and deposit it in transport ducts. The dust is then air carried through the ducts to a dry dust collector or passed through a water blanket for removal. The collision of dust particles with each other and the frictional forces upon each particle as it contacts the air can produce hazardous levels of electrostatic energy. Dusts which do not contain an oxidizer have an upper explosive limit. When these dust concentrations are s u f f i c i e n t l y high enough, the f u e l - a i r r a t i o of the cloud can produce an energetic reaction; therefore, dust concentration levels under dynamic flow i n a dust c o l l e c t i o n system were d e s i r a b l e . The i n t e r r e l a t i o n s of duct s i z e , dust concentration l e v e l s , and flow conditions that can produce hazardous i n i t i a t i n g and propagating reactions within the ducts needed to be addressed. This chapter w i l l discuss the evaluation of dust explosion potent i a l at various manufacturing operations i n three Army Ammunition Plants. The assessment of data from each plant w i l l be presented in detail.

Army Ammunition Plant Dust Evaluation Three Army Ammunition Plants were selected to evaluate whether dust explosions could occur i n their explosive materials manufacturing operations:

0097-6156/87/0345-0269$06.00/0 © 1987 American Chemical Society

Scott and Doemeny; Design Considerations for Toxic Chemical and Explosives Facilities ACS Symposium Series; American Chemical Society: Washington, DC, 1987.

TOXIC CHEMICAL AND EXPLOSIVES FACILITIES


270 1.

Louisiana ΑΑΡ, Shreveport, La.

2·

Longhorn ΑΑΡ, Marshall, Texas

3.

Lone Star ΑΑΡ, Texarkana, Texas

In each of these p l a n t s , the characterization of the dust ex p l o s i o n p o t e n t i a l was carried out by sampling transport ducts for explosive dust concentrations during an actual plant operation. The c r i t i c a l measurements taken were the q u a n t i f i c a t i o n of explo s i v e dust concentrations and l e v e l of e l e c t r i c energy generated from the e l e c t r o s t a t i c charge accumulations found i n the duct. In order to characterize the concentration of dust flowing i n s i d e a duct, a measured amount of dust must be extracted over a known period of time. This c o l l e c t i o n v e l o c i t y must be the same as the i n t e r n a l duct flow v e l o c i t y to avoid a l t e r i n g the d i s t r i b u t i o n of dust p a r t i c l e s i z e s . In addition, a number of sample points over the e n t i r e duct cross sectional area i s necessary to define the o v e r a l l dust concentration. This method of sampling, known as gravimetric sampling under i s o k i n e t i c conditions, was used to determine the dust concentrations at the various manufac turing areas i n the Army Ammunition P l a n t s .

Duct V e l o c i t y and Flow Rate To measure the i n t e r n a l flow v e l o c i t y i n the duct, dust samp l i n g was taken at various points along the v e r t i c a l diameter. A p i t o t s t a t i c tube and magnehelic gauge, shown i n Figure 1, was the equipment used f o r these measurements. The duct humidity, tempertaure, and s t a t i c pressure were measured to calculate the gas density. In determining the humidity, the wet and dry bulb temperature of a continuous sample stream was used. To prevent dust buildup on the wet bulb thermometer, an i n l i n e metal f i l t e r was inserted into the l i n e . Dust Concentration Dust samples were c o l l e c t e d by the p r o b e / f i l t e r configuration shown i n Figure 2. The f i l t e r used to trap the explosive dust was a 37mm p l a s t i c f i l t e r cassette. To monitor the actual flow r a t e , a rotometer was used. The c a l c u l a t i o n f o r each traverse point dust concentration was obtained from Ci

β

"ru Qsi t Qsi t s i

8

i

where : C^ « Di Qsi si subscript w

58 β

t

Note:

β

dust concentration i n the duct. weight of dust collected on f i l t e r cassette. P °be sample flow r a t e . sampling time. i = value at the i traverse point. r

t

n


18.

Electrostatic Studies in Army Ammunition Plants

SEALS ET AL.

Κ Downloaded by STONY BROOK UNIV SUNY on October 6, 2017 | http://pubs.acs.org Publication Date: July 20, 1987 | doi: 10.1021/bk-1987-0345.ch018

1

T 0 T A L

PRESSURE LEAD LOW OR HIGH VELOCITY PRESSURE GAGES ON PANEL BOARD

STATIC PRESSURE LEAD

MALE ADAPTER DUCT PENETRATION

\/

/

/

7ψ

/

/

/ /

//

TYPICAL DUCT SURFACE

AIR

FLOW

Figure 1. Pitot-static velocity probe.


271


272


INLET DRILLED TO MATCH 1/4" T U B I N G

ACETATE FILTER WITH BACKING PAD

TO MEASUREMENT PANEL BOARD ROTAMETER

DUCT

Figure 2. Dust sampling probe.


18.

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273

E l e c t r o s t a t i c Instrumentation The charge density of dust transported through ducts and the resultant e l e c t r i c f i e l d s at the duct inner walls was monitored by a Monroe Electronics Inc., Model 171 e l e c t r i c fieldmeter. A l l the e l e c t r o s t a t i c sampling i n the f i e l d was performed i n c i r c u l a r crosssection ducts. Thus, the e l e c t r o s t a t i c f i e l d i n t e n s i t y , f o r t h i s geometry, can be determined from Poisson's equation using the c y l i n d r i c a l coordinate system.


Calibrations The Monroe E l e c t r i c F i e l d Meter was calibrated by using a v o l tage standard and a large p a r a l l e l plate capacitor. The e l e c t r i c f i e l d between the two p a r a l l e l plates i s calculated as a function of voltage across the plates. The calculated f i e l d i s used to deter mine the c a l i b r a t i o n constants. To c a l i b r a t e the charge density meter, simultaneous e l e c t r o s t a t i c measurements are made using the charge density meter and e l e c t r i c f i e l d meter. By comparing the simultaneous measurements under uniform space charge condi t i o n s , the transfer function f o r the charge density meter was determined from the e l e c t r i c f i e l d meter as the standard. The transfer function accounts f o r flow conditions, e f f e c t s of the medium being measured, and the c h a r a c t e r i s t i c s of the sampling hose. The transfer function determined was based upon Composition Β explosive dust flowing through 305m (100 f t . ) of 2.54cm (1 i n . ) diameter conductive hose at 9.4 1/s (20 cfm)

36.9 QlOpJ y

3

Q

η C/m

where C ~ gain of charge density instrument V = output voltage 3

η C/m

= 1.0 χ 10~

9

coulombs

Charge Density Measurements A charge density meter, shown i n Figure 3, designed and b u i l t by Southwest Research I n s t i t u t e was used to record the charge den s i t y measurements. This meter consisted of a sensor u n i t , control readout u n i t , and power supply. B a s i c a l l y , t h i s instrument operates by extracting a dust sample from a duct and then passing through the sensor u n i t . Here, a series of s t e e l screens trap the charge laden dust p a r t i c l e s . To avoid hazardous charge buildups i n the sensor, the charge i s removed from the s t e e l screens to ground. This creates a current flow that can be converted to voltages. I t i s t h i s voltage that i s recorded. Plant Sampling and Results Louisiana ΑΑΡ Two d i f f e r e n t process areas were selected at the Louisiana ΑΑΡ



274

for dust concentration and e l e c t r o s t a t i c charge accumulation determination. These areas were (1) the Composition Β screening and bin loading i n b u i l d i n g 1611 and (2) the 155mm s h e l l d r i l l i n g oper ation i n b u i l d i n g 1619.


Building 1611 Bulk Composition Β explosive i s received i n 27.4 kg (60 lb) boxes and conveyed to the second f l o o r . The explosive i s dumped on a shaker and screened to remove foreign matter. In t h i s opera t i o n , a considerable amount of dust i s generated. The dust i s contained by vented hoods above the shaker and transferred into 30.5 cm (12.0 i n . ) ducts. The screened material then drops through a duct to a loading hopper on the f i r s t f l o o r . The explosive dust generated by t h i s process i s removed through a 10.2 cm (4.0 i n ) duct. The 12 inch and 4 inch ducts are connected i n a Y configuration that leads into a 12 inch duct to a wet c o l l e c t o r . This c o l l e c t i o n system i s shown i n Figure 4. The cleanout openings i n the ducts that f a c i l i t a t e the removal of dust accumulations were used as the sample c o l l e c t i o n areas. To record the dust v e l o c i t y , probes were i n s t a l l e d i n the duct. One of the most e s s e n t i a l features of t h i s probe was i t s round bottom which prevented disturbances i n the flow during normal operations· B u i l d i n g 1619 The d r i l l i n g operation, which provides a recess f o r the i n s t a l l a t i o n of a fuze i n a 155mm s h e l l , was performed i n b u i l d i n g 1619. An a i r driven d r i l l i s used to put a recess i n the Composi t i o n Β that has been encased i n the nose. The dust generated from t h i s operation i s removed by suction through a 5.1 cm (2.0 in) l i n e to a Hoffman primary dust c o l l e c t o r . Downstream of the primary c o l l e c t o r i s a secondary c o l l e c t o r used to take any excess not trapped i n the primary c o l l e c t o r . Two sample areas were selected f o r study as shown i n Figure 5. Dust Concentration Measurements In both b u i l d i n g l o c a t i o n s , the v e l o c i t y p r o f i l e indicated duct f l o e turbulence. The d r i l l i n g operation o f b u i l d i n g 1619 had flow v e l o c i t i e s and negative s t a t i c pressures that were s i g n i f i c a n t l y higher than the operations i n b u i l d i n g 1611. These differences can be attributed to the duct diameters, s i z e s , and number of dust cleanouts found i n the two removal systems. Sampling of the dust concentration was made at the centerline and one point above and one point below the c e n t e r l i n e . A close inspection of the data indicated that a higher dust concentration was observed at the bottom of the duct with e s s e n t i a l l y constant l e v e l s from the top of the duct to the centerline. Dust concentrations were three orders of magnitude higher f o r the d r i l l i n g operation i n 1619 than obtained i n the hopper loading operation of 1611. This was to be anticipated when one analyzed the two types of a c t i v i t y . I t had been found that the d r i l l i n g of 48 s h e l l s would accumulate 11.34 kg (25 l b s ) of explosive dust.



SEALS ET AL.


Figure 3. Charge density sensor.

SHAKER TABLE

HOPPER LOADING

SAMPLE LOCATION No. 1

30.5CM DUCT

Φ .

ELBOW DOWN ELBOW HORIZONTAL 30.5CM DUCT


SECOND FLOOR DUCTING FIRST FLOOR DUCTING

t SAMPLENo.LOCATION 3 WET DUST COLLECTOR

Figure 4. Dust and electrostatic sampling location in the Composition Β screening and bin loading operation of Building 1611, Louisiana ΑΑΡ.


276

TOXIC C H E M I C A L A N D EXPLOSIVES FACILITIES E l e c t r o s t a t i c Measurements


B u i l d i n g 1611 E l e c t r i c f i e l d and charge d e n s i t y measurements were r e c o r d e d at e a c h sample l o c a t i o n i n b u i l d i n g 1611. T y p i c a l measurements a r e shown i n the F i g u r e 6. I n t h e s t r i p c h a r t r e c o r d i n g s , e a c h peak i n t h e e l e c t r i c f i e l d t r a c e s , c o r r e s p o n d s to when C o m p o s i t i o n Β was dumped on the s h a k e r . The l a g c o r r e s p o n d s t o the l e n g t h o f time t a k e n f o r t h e d u s t t o be t r a n s p o r t e d t h r o u g h 30.5m (100 f t . ) o f sampling hose. I n s p i t e o f t h i s d e l a y , one can see t h a t t h e r e i s e x c e l l a n t agreement between t h e two i n s t r u m e n t s f o r t h e d u r a t i o n of e a c h p u l s e and a r r i v a l t i m e . B u i l d i n g 1619 The d u c t d i a m e t e r s were 5.1 cm (2.0 i n ) ; t h u s , i n s t r u m e n t a t i o n was l i m i t e d t o t h e c h a r g e d e n s i t y meter f o r c o l l e c t i n g d a t a . Shal low d r i l l i n g charge d e n s i t y measurements were made a t l o c a t i o n s 4 and 5 i n F i g u r e 5. The magnitude o f t h e c h a r g e a t e i t h e r o f t h e s e p o i n t s showed no s i g n i f i c a n t d i f f e r e n c e s . S i n c e the charge d e n s i t y s i g n a l was dependent upon t h e o p e r a t o r , no p r e d i c a b l e c h a r a c t e r i s t i c s c o u l d be r e n d e r e d from one s i g n a l t o another from the random loadings. Charge

and Energy L e v e l s

A l t h o u g h t h e c h a r g e d e n s i t y l e v e l s i n b u i l d i n g 1619 a r e two o r d e r s o f magnitude g r e a t e r than found i n b u i l d i n g 1611, t h e e n e r g y l e v e l s a r e a l l a p p r o x i m a t e l y o f t h e same magnitude. T h i s i s based upon t h e energy l e v e l dependent upon t h e d u c t d i a m e t e r . The l e v e l s l e v e l s o f e n e r g i e s found a t t h e s e l o c a t i o n s were many o r d e r s o f magnitude s m a l l e r t h a n t h e r e p o r t e d i g n i t i o n e n e r g i e s f o r Compo s i t i o n B. Longhorn ΑΑΡ Longhorn ΑΑΡ i s i n v o l v e d i n t h e manufacuture o f t h e 4.2 i l l u m inating flares. Two s i t e s , b u i l d i n g s B-7 and 34Y, were s e l e c t e d f o r d u s t and e l e c t r o s t a t i c measurements. I n b u i l d i n g B-7, 4.2 aluminum c a n d l e s a r e p r o c e s s e d ; w h i l e , i n B u i l d i n g 34-Y, w h i t e s i g n a l f l a r e s a r e manufactured. P r o c e s s i n g o f 4.2 i l l u m i n a t e c o n s i s t s o f m i x i n g t h e composi t i o n , w e i g h i n g , c o n s o l i d a t i o n , removal o f a c a r b o a r d p l u g , a d d i n g a p r i m e r s t a g e , and p a c k a g i n g . A s c h e m a t i c o f t h i s p r o c e s s i n g o p e r a t i o n i n B u i l d i n g B-7 i s i l l u s t r a t e d i n F i g u r e 7. The same m a n u f a c t u r i n g p r o c e s s s t e p s f o l l o w e d i n b u i l d i n g B-7 a r e found i n B u i l d i n g 34-Y. The s a m p l i n g a r e a s f o r B u i l d i n g 34-Y are shown i n F i g u r e 8.

Duct V e l o c i t y , F l o w R a t e s , and Dust C o n c e n t r a t i o n Measurements The p r o c e s s e s m o n i t o r e d were n o t c o n t i n u o u s ; t h e r e f o r e , t h e


18.

SEALS ET AL.


277

DRILL CUBICLES

if

PALLET OF 155mm SHELLS


ru SAMPLE LOCATION No. 4

VACUUM PUMP

Figure 5. Dust and electrostatic sample locations in the drilling operation of Building 1619, Louisiana ΑΑΡ.

(a) ELECTRIC FIELDMETER OUTPUT

-**| |-*-5SEC

UJ CO

Û S -120 LU

Ο

Ο

S

0 (b) CHARGE DENSITY METER OUTPUT

-H

h*-5SEC

Figure 6. Electrostatic measurements at Building 1611 in 30.5-cmdiameter duct at Location 1.



278


TYPICAL VACUUM EXHAUST INLETS

NOTE: CONSOLIDATION PRESS EXHAUST INLET ALWAYS OPEN. ALL OTHER INLETS INTERMITTENTLY OPENED AND CLOSED DURING OPERATION

CARDBOARD DISK REMOVAL

ΛΑ/" Figure 7. Dust and electrostatic sampling locations in 4.2 aluminum candle production process in Building B-7, Longhorn ΑΑΡ.

SAMPLE LOCATION^

10 HP HOFFMAN WET DUST COLLECTOR

^SAMPLE LOCATION

Ô

Ό

20 HP HOFFMAN WET DUST COLLECTOR

Figure 8. Dust and electrostatic sampling locations in the signal flare production process in Building 34-Y, Longhorn ΑΑΡ.


18.

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AL.


279

consistency i n the measured values was poor. This was attributed to intermittent vacuuming performed at the d i s c r e t i o n of the oper ator. Only the i n l e t s on the consolidation press had i t s dust vacuumed continuously.


E l e c t r o s t a t i c Measurements The small 2.0 i n . ducts i n buildings B-7 and 34-Y l i m i t e d the instrumentation studies to the charge density meter. The same locations cited f o r dust v e l o c i t y and flow rate sampling points were used f o r these measurements. At t h i s l o c a t i o n , pyrotechnic materials are processed. These materials d i f f e r from the Composi t i o n Β that was used i n the o r i g i n a l c a l i b r a t i o n of the charge density meter. As a consequence of not using the pyrotechnic material with the e l e c t r i c fieldmeter to c a l i b r a t e the charge den s i t y meter, only r e l a t i v e charge l e v e l s can be inferred from the data. While these small diameter ducts produced high charge l e v e l s , the energy l e v e l s i n the transport system were small. P o s i t i v e and negatively charge species were found to co-exist. The p o s i t i v e charges occured from the intermittent vacuum at the weigh s t a t i o n and the negative charges from the continuous vacuuming at the consolidation presses. Building B-7 A t y p i c a l charge density waveform from the sample 6 l o c a t i o n r e f l e c t s the dust taken during the vacuum operation at the d i s k removal s t a t i o n . As seen i n Figure 9, the charge can be e i t h e r p o s i t i v e or negative. Typical p o l a r i t y charge reversals can be attributed to the transfer of image charges. Building 34-Y Sampling points i n Building 34-Y were selected near two wet c o l l e c t o r s of two independent vacuum c o l l e c t i o n systems. I t was i n t e r e s t i n g to note that the dust c o l l e c t e d at these points were granular and larger i n size than dusts collected at any of the other plants analyzed. Apparently there i s s u f f i c i e n t moisture or v o l a t i l e content to cause the f i n e magnesium and aluminum p a r t i c l e s to agglomerate i n t o large p a r t i c l e s . The charge magni tudes were observed to be higher i n the morning. As the tempera ture increased i n the afternoon, t h i s charge magnitude was seen to decrease. Moisture condensate formed on the duct surfaces as the temperature changed. These moisture and temperature v a r i a t i o n s may have contributed to the decreased charge l e v e l s . The dust from the weighing and pressing s t a t i o n s of Bay 103 were sampled at l o c a t i o n 8. Again, the sampling of dust was per formed by the operator i n a random fashion. This random operation produced unpredictable charge density waveforms. The charge density l e v e l s are quite high, but the energy l e v e l s are low. These low l e v e l s are attributed to the small duct diameters and dependency of the energy upon the duct radius to the f i f t h power. The energy l e v e l s at b u i l d i n g 34-Y are approximately an order of


280


magnitude lower than those observed at building B-7. This lower order was due to the agglomeration of the aluminum composition that occurred i n building 34-Y.


Lonestar ΑΑΡ The burster facing operation (building 04-M-40) and a grenade pressing operation (building B-46) were sampled at Lonestar ΑΑΡ for dust and e l e c t r o s t a t i c s * These operations were s i m i l a r i n nature as those performed i n Building 1619 at Louisiana ΑΑΡ and the press ing operation at Longhorn ΑΑΡ. The vacuum exhaust and dust c o l l e c t i o n system i s i l l u s t r a t e d for buildings 04-M-40 and B-46 i n Figure 10 and 11 respectively. In building B-46, three separate operations are performed: c o n s o l i dation, demachining, and cone swagging. A rotary press i s used to consolidate A-5 explosive into a grenade. To pick up the dust from t h i s pressing operation, f l e x i b l e rubber hoses (2.0 in.) are used. These l i n e s are then connected to a s t a i n l e s s steel l i n e that runs into a wet c o l l e c t o r .

Dust Measurements The flow rates and s t a t i c processes are approximately the same for a l l vacuum l i n e s . The v e l o c i t y p r o f i l e does show turbulence i n both processes. Except f o r the d r i l l i n g operation i n the Louis iana ΑΑΡ, the dust concentrations at location 10 and 11 were the highest recorded. In location 10, the dust concentration was more concentrated at the bottom, while the top and centerline concentrations were f a i r l y uniform. Of the three operations i n building B-46, higher dust concen trations were generated by the demachining operation. F a i r l y constant concentrations were found across the duct. This can be attributed to the high duct flow v e l o c i t i e s .

E l e c t r o s t a t i c Measurements The operations studied were limited to the charge density meter because of the small ducts. The dust collected from the rotary d r i l l and facing machine at location 10 had the highest charge l e v e l s measured i n the entire testing program. I t soon became apparent i n the i n i t i a l start up of the sampling that the s t e a d i l y increasing charge l e v e l s would exceed the measurement range of the charge density meter. At t h i s point, the flow rates through the charge density meter were reduced from 9.4 /s (20 cfm) to 7.1 / s ( 1 5 cfm). The peak measurements for the two flow rates were than compared. The charge density meter transfer function at a flow rate of 7.1 /s (15 cfm) was found to be - 156.8

V _100 I V

0

nC/nr


18.

SEALS ET AL.

g_ LU t*i

û |


+4000 0


(a) CHARGE DOUBLET

LU «

+3600 0

1 (b) POSITIVE PULSE

- H h*-5 SEC

Figure 9. Charge density measurements at Building B-7 at Sample Location 6.

Figure 10. Vacuum exhaust ducting and dust collection system for burster facing operation in Building 04-M-40.


281


282


CONSOLIDATION ROTARY PRESS

CONE SWAGGING PRESS

DEMACHINING AREA

Φ


\

g)


."Y"CONNECTION


L WET DUST COLLECTORS

Figure 11. Vacuum exhaust and dust collection system for grenade press operation in Building B-46.


18.


SEALS ET AL.

283


B u i l d i n g B-46: D i s t i n c t and unusual waveforms were observed from A-5 explosive dust c o l l e c t e d at l o c a t i o n 14 when the explosive m a t e r i a l i s dumped from a bucket i n t o a rotary press hopper. P o s i t i v e and negative charge species were found with the predominance of charge being negative i n p o l a r i t y . D i s t i n c t charge doublets r e s u l t each time a bucket i s emptied. With the deposition of a negative charge i n the press hopper, the opposite image charge i s retained by the pow der remaining i n the bucket. As the bucket i s completely emptied, the negative charge reaches i t s maximum and then begins to diminish. As a r e s u l t of t h i s a c t i o n , the charge reverses i t s p o l a r i t y · This phenomenon i s completed when the image charge doublet of the opposite p o l a r i t y i s formed and returns to zero when the bucket i s empty. Charge and Energy Levels Building 04-M-40 recorded the highest density l e v e l s of any of the sample locations measured. In a d d i t i o n , the highest readings were also always obtained when the sample was withdrawn from the bottom of the duct. Summary of Plant Sampling A summarization of a l l the data c o l l e c t e d at the three Army Ammunition Plants i s given i n Table 1· The maximum values obtained at each sample l o c a t i o n have been l i s t e d i n t h i s t a b l e . Although the r e s u l t s from the d i f f e r e n t processes are d i f f i c u l t to compare, these q u a l i t a t i v e observations can be made. ° Sampling i n small diameter vacuum ducts resulted i n higher vacuum pressures, flow v e l o c i t i e s , dust concentrations and charge d e n s i t i e s , but lower flow r a t e s . ° Higher charge d e n s i t i e s , dust concentrations, and energy l e v e l s were found i n processes involving d r i l l i n g , and facing operations of explosive. 0

Low flow v e l o c i t i e s prevented uniform dust concentrations i n the ducts. (This was r e f l e c t e d i n the dust buildup at duct cleanouts)· 0

Batch operations have periods of high and low loading densi t i e s . This indicates that the gravimetric method of sampling, dependent on the t o t a l mass of dust c o l l e c t e d over a given period, can only r e f l e c t average concentrations. Instantaneous concentra tions may be s i g n i f i c a n t l y higher. ° Minimum explosive concentration f o r explosive and pyrotechnic dusts have been reported* i n the range of 40 to 1000 gm/mm, (40 to 1000 o z / f t ) . With the exception of l o c a t i o n 5 i n B u i l d i n g 1619 at Louisiana ΑΑΡ, a l l the dust concentrations determined f o r the various plants were below the maximum average concentrations. 3

3



SAMPLED

ALUMINATE

ALUMINATE

B L D G 34-Y: 8

9

A-5

A-5

13

14

COMP Β

11

A-5

COMP Β

10

B L D G B-46: 12

BUILDING 04-M-40:

LONESTAR Α Α Ρ

ALUMINATE

ALUMINATE

6

7

B L D G B-7:

LONGHORN Α Α Ρ

COMP Β

5

5.1

5.1

5.1

7.6

5.1

5.1

5.1

5.1

5.1

5.1

5.1

30.5

COMP Β

COMP Β

3

B L D G 1619: 4

10.2

COMP Β

COMP Β

2

30.5

(CM)

DUCTDIA

B L D G 1611: 1

LOUISIANA Α Α Ρ

MATERIAL

SAMPLING

LOCATION

6.30

5.80

4.70

8.90

3.30

4.20

3.00

4.90

0.47

3.80

-

68.00

4.90

63.00

3

(M /MIN)

FLOW R A T E

-50.80

-50.80

-50.80

-76.20

-50.80

-101.60

-88.90

-108.00

-127.00

-152.40

-

-2.29

-2.29

-2.29

80

80

75

80

79

89

89

89

88

-

75

72

63

62

(°F)

TEMP

63

63

82

70

67

50

36

42

6

35

-

36

50

41

(%)

REL HUMIDITY

0.180

0.660

0.820

13.800

26.000

1.400

12.100

6.300

0.900

330.000

-

0.115

1.610

0.093

3

DUST CONCENTRATION (GM/M )

+19.600

-5,170

-4.890

94,000

140,000

+1,030

+3,500

-11,100

+7,750

+11.100

+14,800

-287

+184

-232

3

CHANGE DENSITY (nC/M )

1.790

0.125

0.112

315.000

698.000

0.005

0.057

0.570

0.280

0.570

1.020

3.000

0.005

2.430

(pJ)

ENERGY

•MAXIMUM V A L U E S MEASURED DURING THE PLANT SAMPLING

STATIC PRESSURE (MM Hg)

Table 1. Summary of Measurements Taken During the Plant Sampling*


Κ) 00

18.

SEALS ET A L .


285

° Minimum i g n i t i o n energies for explosive and pyrotechnic dusts were reported i n the range of 0.2 and 8.0 j o u l e s . Maximum energy l e v e l s calculated from the charge density measurements were a l l very low. (maximum energy l e v e l of 7 0 0 ^ * J ) . This was an unusually high reading f o r Building 04M-40. The highest maximum energy l e v e l was i n Building 1611 at Louisiana ΑΑΡ which read 3.0 M J . ° The charge density appears to be approximately proportional to the peak mass flow rate (duct flow r a t e , Q, times the maximum dust concentration) i n the duct.


R E C E I V E D May 1 5 , 1 9 8 7


Design Considerations for Toxic Chemical and Explosives Facilities

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