7 in the Chemical laboratory I
I
I
the 10 ft./lb. impact. T h e tempered glass of 4 was quite superior. Goggles which withstood 7.5 ft./Lb. impacts were 6, 7, 13, 14 and 15. For 10 ft./lb. impacts, only 13, 14 and 15 passed the
Evaluation of ContemDorarv Safetv Glasses, Goggles, and Face Shields
Material a n d thickness Safety Glasses 1. Acrylic "Clipon" 0.070 in. 2. Acrylic "visitors" 0.100 in. 3. Glasses 0.140 in. 4.
Glasses 0.145 in.
5.
Glasses 0.155 in,
Goggles 6. Glass lens 0.120 in. 7.
8.
"Multiply" lens 0.052 in. Vinyl 0.052 in.
9.
Acrylic 0.085 in.
10.
Acetate 0.060 in.
-Impact 7.5 ft./lb."
a t 1 0 feet-10 ft./lb..
Lens cracked a n d broken loose Lens shattered, p a r t broke loose Lens shattered a n d broke loose Pellet flattened N o cracks N o cracks Lens shattered Pellet flattened b u t did not N o cracks break loose Pellet flattened Dented Penetrated Three radial cracks Penetrated Radial cracks t o edge Dented
Penetrated b o t h 11. Acetate double 0.030 in. & 0.060 in. Radical cracks 12.
Acetate 0.040 in.
13. Polycarbonate 0.062 in. 14.
Polycarbonate, double 0.040 in.
15.
Polycarbonate 0.062 in.
Figure 1. MuItpeTarget Holder.
,eature
same trance time of spray displayed from thehigh front-and impact atresisthe tavce. The buyer should insist on goggles and pmtection with high impact against spray-sueh as and 15, Faee shield tests recommended acetate of at least 0 . 0 6 0 thickness, palycarbonate, and possibly "Multiply." In addition to the high impact resistance of 18 and 22 the buyer should insist on windows wide enough to protect the ears fmm side attack and long enough to protect the neck,
Department of Chemistry, Viilanova University, Villanova, Pa. 19085
Table I.
t.
test. All but one of the goggles tested provided ventilation of some kind. only 14 and 15 had vents that did not allow en-
G. N . Quam, Research and Development Division and, J a m e s S h e a ,
*This investigation was supported by Research Grant OH00300 from the National Institute for Occupational Safety and Health, Public Health Service, U. S. Department af Health, Education, and Welfare.
a
Edited by N O R M A N V. STEERE, 140 Melbourne Ave., 5:E. Minneapolis, Minn. 5541 4
CXI. Impact Resistance Tests of Contemporary Safety Glasses, Goggles, and Face Shields*
The person delegated to purchase safety glasses, goggles, and face shields for lahoiatary workers should know what specifications are important, and what may he critical. Suppliers are using,sueh expressions as "shatter-proof glass, "plastic," "light weight," "comfortable," and "style." Ohviously we select eye and face shields for protection against missiles and sprays. Faee shields should afford effective coverage as well. We can rely on skilled industrial designers for style and comfort. Materials used vary widely in impact resistance. Once we have discovered the very high impact resistance and transparent materials we must choose thicknesses that meet the specific requirements. In Table I some typical contemporary commercial devices were subjected to impact tests. We have deliberately omitted company names. The first column names the material, and thickness of lenses or windows. Columns two and three state the effect of a 7.5 ft./lb. and a 10 ft./lb. impact, respectively. The fourth column cites the ventilation and spray deflection of goggles, and the effect of glass missiles on face shields. Safety glasses are not specifically designed to ward off sprays. Numbers 4 and 5 of Table I withstood the 7.5 ft./lb. impact without cracking and 4 also withstood
'''
Penetrated. F o u r radial cracks Dented in.
D e n t in first Slight bulge in second Dented in.
Protection against sprayb
Nane Nane None None
None
Lens shattered b u t remained Vents open t o in frame all sides D e n t e d a n d three Vents open t o radial cracks all sides Penetrated. Larger hole and many Vents open t o cracks all sides Vents open t o all sides Dented. T h r e e Vents open t o radial cracks all sides Larger holes N o ventilaa i d cracks tion provided Vents open t o all sides Deeper d e n t Simple perforationtop and sides Deener d e n t Vents open t o baEk only Dented in. Wide vents o n top and sides. Open t o back only (Continued on page A861
Volume 51, Number 2. February 1974
/
A85
Table I. Evaluation of Contemporary Safety Glasses. Goggles, and Face Shields (continued)
--
Material and thickness
Imoact a t 10 feet-7.5 ft./ll;: 10 ft./lb.a
Face Shields
16. Acetate 0.020 in.
Penetrated Many cracks
Protection aeainst sprayb
-
Effecto f Gloss Missiles' Windows badly shattered and
17. Acetate 0.040 in.
Penetrated and cracked
18. Acetate 0.060 in. 19. Acrylic 0.100 in.
Dented only
roughened Four long cracks Roughened Roughened only Cracked and roughened
Penetrated Radical cracks Split top to bottom Dented Cracked very slightly
20.
"Multiply" 0.045 in.
21.
Vinylite 0.045 in.
Penetrated Radial cracks
22.
Polyearbonate 0.062 in.
Dent
in.
Deeper dent
Roughened One circular crack and hole Roughened and cracked Roughened only
"Impacts were delivered by 16 gr. pellet from Sheridan air gun. bVents that open to front and perforations allow spray to enter and possibly reach the eyes. cGlaas fragments fired from glass missile "cannon."
Table II.
Ballistic Tests. 22-cal. Short. 10 ft. Muzzle to Target
T e s t plates in target frame
N u m b e r of 0.062 in. plates penetrated
P l a t e which defeated t h e bullet
Acetate Acrylic* Polycarhonateb Vinvlite
6 (all w i t h radial cracks) 24 (all shattered) 4 (no cracks) 2 1 (all shattered)
7 t h (slight dent) 2 5 t h (slightly cracked) 5 t h (dented l/ta in.) 22nd (cracked)
oPlexiglas bLexan o r Merlon a s demonstrated by a sound-color movie (1). To further evaluate plastics available in sheet form a 22-caliber short bullet was used for the ballistic test (about 80 ft./Lh.). Twentyseven test plates, each 0.060 in. thick, were placed in the multiple target holder, Figure 1, and fired a t ten feet from rifle muzzle to the first plate. Tahle II shows the results which placed polycarhonate as a superior impact-resistant plastic. This study was repeated with only four 0.125 in. test plates of the first three plastics.
First and second d a t e s were cracked. Bullets were defeated by the third plate. Acrylic. All plates were penetrated. In order of penetration the holes were of diin., and '% ameters in., ' X e in., in. Polyearbonate. First two plates were penetrated without cracking. Bullets caused dents in third plate.
Acetate.
window. Ballistic tests of this combination have shown that the inner 0.093 in. window was very slightly dented (2). Polycarhonate lenses of goggles used for routine laboratory use should be increased to 0.093 in. thickness. For added impact resistance to equal that of the face shield above a 0.187 in. lens was attached by a brass center bolt and stabilized by two cemented small plastic blacks above each lens, Figure 2. The ballistic test plates indicate penetration of the 0.187 in. outer plate and a very slight dent in the 0.093 in. inner plate. When only mild impacts are anticipated the outer 0.187 in. reinforcement may he removed for both the goggles and the face shield. The huyer can always order a numher of reinforcement elements for those special operations requiring higher impact resistance. We hope manufacturers will increase the margin of safety by moving up to 0.093 in. polyearbonate for routine laboratory practice. The 0.187 in. reinforcement element should always be availahle.
CONCLUSIONS
BALLISTIC TESTS OF EXPERIMENTAL LENSES AND WINDOWS Goggles should always be worn along with a face shield because of the times when the faee shield window is pushed upward for relief. The goggle lenses should then be of impact resistance equal to that of the face shield. A face shield has been made to withstand an impact of 80 ft. Ih. (22 cal. short) by developing a douhle window of 0.093 in. thick polycarbonate with a reinforcement of an outside 0.187 in. thick polycarbonate
T h e huyer of goggles and face shields must he concerned with the material and thickness of lenses and windows. Ventilation is essential for goggles but of more importance the vents must he designed to defeat the passage of sprays into the eyes of the wearer. The faee shield must provide good coverage of the face and the neck and ears from missiles and sprays.
LITERATURE CITED
Safety
I Figure 2. Goggles and Ballistic Tests-22 short^.
cal.
...
feature
