Quality
Waterjet Newsletter – 06/24/2008
Effectiveness
of Helmet and Face Shield For Waterjetting
Protection Katakura and Guo*
presented a research study in this subject, aiming to provide data necessary
for establishing industrial safety standards. A waterjet
with a diameter of 0.2 mm and up to 200 MPa
pressure was used in this study. Commonly used industrial safety helmets were
cut in halves and then impacted with the jet at different angles, different
stand-off distances, and different pressures. The helmet is made from
fiber-reinforced plastics (FRP). Its thickness varies between 1.4 mm and 2.8
mm. The face shield was simulated with 2 mm thick acrylic resin plates. The
time from the jet exiting the nozzle till penetration was recorded with a
hand-operated stop watch. Jetting was stopped after 30 seconds if no
penetration occurred. The results are summarized as
follows: o
No penetration occurred on the helmet within 30 seconds of
impact if the jet is 200 mm away, shotting at the
front of the helmet, and the pressure is below 40 MPa.
o
Penetration occurred 100% on the helmet within 30 seconds
of impact if the jet is only 100 mm away, shotting
at the front of the helmet, and the pressure is above 100 MPa.
o
When the pressure reached 200 MPa,
the helmet was penetrated at the weakest spot within 30 seconds when the jet
was at 350 mm or within 10 seconds when the jet was at 320 mm. The helmet was not penetrated within
30 seconds when the jet was 410 mm or further away. o
The chance of penetration is higher if the jet hits the
side (instead of front) of the helmet. o
The jet aiming at an angle (instead of perpendicular to
the target surface) has a lower chance of penetration. o
The simulated Their conclusion was that the
commercially available helmets and face shields are useful protective devices
if the jet is kept at a suitable distance away. *
Katakura, H. and Guo, C. (2006) Research on
personal protective devices for water jetting operation --- performance of
head and face protectors, Proceedings of the 8th Pacific Rim
International Conference on Water Jet Technology, Oct. 10-12, Qingdao, China,
Paper 42. Beyong High Pressure l
Dr. Lydia Frenzel
will host a workshop on “Coatings Removal and Surface
Preparation by WaterJet Methods with emphasis on
Flash Rust” on August 18, 2008 at Megarust, |
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