HIGH-VISIBILTY
Definition:
High-visibility clothing is any
clothing worn that has highly reflective properties or a color that is easily
discernable from any background. Orange hunting vests are a popular example of
high-visibility clothing.
In other words, High visibility clothing in good
condition is important to alert motorists that there are workers on, or near,
the road. It assists to create a safer workplace for employees.
Ø What types are there?
AS 4602, High Visibility Safety
Garments, notes three different classifications for garments.
A short description of each
classification, with some indicative illustrations -
A.
Class D:
·
Outdoor daytime use only.
·
Fluorescent or other non
retro-reflective1 high visibility material.
B.
Class N:
·
Night time use only.
·
Retro-reflective material on a
‘non-specified’ background.
C.
Class D/N:
·
Day or night use.
·
Combination of fluorescent and
retro-reflective material.
·
Where retro-reflective strips are
applied to a garment, they should be 50 mm wide (not 25 mm).
Ø What type should be using?
There are many different products
available, including clothing with high visibility panels, safety vests, and
overalls / jump suits.
Environmental
factors may include:
Ø Temperature (heat / cold)
Ø Lighting and visibility (day / night / artificial / twilight / rain /
fog)
Task factors
may include ensuring that:
Ø A non-flammable garment is worn whilst completing hot works.
Ø Works being undertaken near rail lines meet the specific requirements
for this application.
Ø It is also important to remember to check that the vest being worn does
not blend in with background colours.
The importance of Hi Visibility Clothing in some
workplaces
There are certain
workplaces that have very many hazards and employees are required to wear high
visibility clothing to ensure that they remain safe. In workplaces such as
construction sites, transport companies, warehouses, factories and roadwork, it
is crucial to wear hi visibility clothing for your own safety. The hi
visibility clothing will prevent employees from getting cuts, chemical and
biological hazards, static electricity and high voltages.
The clothing is more
visible during the night and for daytime work, the bright clothing can be worn
on the main body. The high visibility clothing also protects employees in
situations when it too hot. The material used prevents the heat from outside
from affecting the body.
There are many employees
who are killed each year while some are seriously injured at work especially in
vehicle related incidents. The most common are situations where a pedestrian is
struck by a forklift or a lorry that is reversing. In this cases, the driver
does not see the person if they are not wearing any high visibility clothing.
The use of high visibility
clothing greatly improves the visibility of the people in a workplace which
reduces the risks of accidents and improves safety. There are laws that are in
place to ensure that the employers ensure the safety and health of their
employees is well taken care of. The high visibility garments are provided by
employers and if the employees do not use them they are liable for prosecution
if n accident occurs.
There high visibility
clothing includes vests, t-shirts, trousers, jackets, hats and coveralls. The
type of clothing that is used in a workplace will be determined by the ambience
and lighting that is available in the area and conditions such as fog and snow.
There are jobs that will
only require you to wear a waistcoat but some require full body high visibility
clothing. If you are a maintenance worker or work in an area that has many
moving vehicles, it is advisable to get the full body ones. This ensures that
you are visible as possible to the driver.
Some occupations involve
workers being out in very adverse weather and the high visibility clothing
ensures that the workers are well protected from these conditions. Workplaces
that are very dark are a potential hazard and hi visibility clothing is
necessary. The amount of clothing that the worker puts on will also be
determined by the lighting situation. Traffic police and civil engineers work
in environments that are full of vehicles and this increases the risk of
accidents. They should wear high visibility clothing to ensure that the drivers
can spot them from a distance to avoid any accidents. This is very important if
it is on a foggy day or its snowing.
There are various standards
that are used to determine which hi visibility clothing is suitable for a
specific workplace. Workers should use the right type to ensure that they are
well protected from the hazards that are presented in their workplaces.
Safety Jackets
Most of the safety jackets
have a reflective strip that reflects light in conditions of low visibility.
These jackets are however of no use in habitats where there is no incident
light, for example a mine or a dark street or railway track, as shown in Fig 1.
To
overcome this shortcoming of the reflective type of jackets, we have developed
a photo-luminescent
fabric. Strips of this fabric can be cut and stitched on jackets along
with the reflective strips so that these become visible during night under very
poor visibility conditions in the absence of an incident light as shown in Fig
2.
Fluorescence, Phosphorescence and Glow in the Dark pigments: When an electron absorbs light energy, it
is usually excited to a higher energy level in the first excited state S1 as
shown in Fig 3, before rapidly relaxing to the lowest energy level. This
event is termed vibration relaxation or internal conversion and occurs in
about a picoseconds or less. The decay straight from the S1 state to the So
state after the internal conversion is termed as fluorescence.
Phosphorescence decay is similar to fluorescence, except that the electron
undergoes a spin conversion into a triplet state T1 instead of the lowest
singlet excited state So' a process known as intersystem crossing. The
stability of the first triplet excited state T1 is what determines whether a
material is fluorescent or phosphorescent. Fluorescence occurs if this
excited state is relatively unstable and phosphorescence occurs if it is
relatively stable. This however is an inherent property of the material and
cannot be changed. Thus phosphorescence is a much slower process than fluorescence.
Fig 3: Jablonski diagram to
differentiate between fluorescence and phosphorescence Glow in
the Dark pigments usually contain two types of components; one being the
fluorescent dye and the other the phosphorescent compound. What happens is
that the phosphorescent material absorbs light and emits it slowly as a pale
blue light. Then the pale blue light is absorbed by the fluorescent dye and
emitted as a green or red light depending on the dye used. The most commonly
used phosphorescent material is zinc sulfide mixed with copper. The green
fluorescent dye is mostly sodium fluorescein and the red fluorescent dye is a
Rhodamine. Since fluorescence is a much faster process than phosphorescence,
the phosphorescent material forms the source and the fluorescence material
takes up the role of the device for energy consumption (Fig 4). Fig 4: Chemical structure of
fluorescent dyes present in glow in the dark pigments
Sodium fluorescein
Rhodamine B High visibility clothing for construction side All railway tracks require
maintenance. It is rare for a rail service to be suspended during routine
jobs, which means people have to work in close proximity to busy lines,
albeit with train speed restrictions implemented in areas subject to working.
To increase the visibility or conspicuity of workers, a number of actions can
be taken. Warning lamps and signalling devices may indicate work activity.
However, these do not indicate the location of individual workers. To achieve
this, personal protective equipment (PPE) is required. On the UK railway network the
wearing of high visibility clothing has become a mandatory requirement for
all persons associated with track or lineside working. Railway workers may find themselves carrying out maintenance work on
track, where no trains are running – called 'Green Zone working'. However,
much work is undertaken on active railways, during day and night, and under
different weather conditions. Under such circumstances, known as 'Red Zone
working', the dangers are real and ever present and it is important that the
highest levels of visibility are maintained. The main feature of high
visibility clothing is that it is made from materials that aid conspicuity by
day and night. To enhance the visibility of a wearer during the day, garments
are made from fluorescent materials of standard colours. The visibility of a
person is aided at night by the inclusion of retroreflective tapes within the
construction of a garment. Retroreflective materials reflect a high
proportion of light back towards it’s point of origin. There is a large range of high
visibility clothing available. However, there is a particular specification
for clothing that is allowed to be worn on the UK rail network. The
specification is set out in Railway Group Standard GO/RT 3279:2008, a
document that defines the ‘minimum requirements for high visibility clothing
for being conspicuous on the lineside or on or near the line’. The document
also sets out special requirements for the high visibility clothing of Rail
Incident Officers, who may be on a track following accidents. High
visibility Clothing Being highly visible under both
day and night-time conditions is an essential requirement in many situations.
While the hazards may be common to many professions, the working environments
where high-visibility garments are worn are extremely varied. This is
represented in the different designs of high-visibility clothing currently
available, ranging from vests used by warehouse operatives to water-resistant
jackets and trousers worn by highway maintenance workers or railway
engineers. ·
EN 471 clause 4 – garment design EN471 addresses a number of
design criteria such as the minimum visible area of the various material
types and the positioning and minimum width of the retroreflective material. ·
EN 471 clause 5 – background material The background material
consists of coloured fluorescent fabric intended to be highly conspicuous
during daylight conditions (fluorescent materials give off light when light
is shone onto them). EN 471 details three specific colour requirements –
‘yellow’, ‘orange-red’ and ‘red’. These are defined by colour ‘coordinates’
measured using a spectrophotometer both before and after a treatment intended
to assess the durability of the material to fading when exposed to sunlight.
Other treatments include colour fastness to rubbing and perspiration,
washing, hot pressing and bleaching. In addition to colour measurement, EN
471 includes tests for the strength of the fabric, resistance to water
ingress (a hydrostatic head test) and its breathability (an important
property that influences garment comfort) using a skin model test apparatus. ·
EN 471 clause 6 – retroreflective
material Night-time or low light level
visibility is achieved using retroreflective material, which ‘bounces’ light
from discrete light sources (e.g. vehicle headlights) directly back to the
source. Testing is carried out at a range of incident angles on both new
material and material which has been subjected to various pretreatments, such
as abrasion, flexing, folding at cold temperature, exposure to extreme
temperature variation, washing and/or dry cleaning and simulated rainfall. ·
Certification In Plant study of
High Visibility fabric Above fabric specification : Weave : Satin ( to improve
reflection ) Fabric P/C blends composition: 1. Polyester = In
Warp wise 2. Cotton = In
Weft wise ·
Polyester
fiber dyed with Fluorescent Disperse Dyes. ·
Cotton
dyed with reactive / vat dyes. Process Route Grey Issue
Singing +
Desizing (Enzymatic)
Heat setting for polyester
Scouring +
Bleaching
Mercerization
Souring Dyeing
Finishing
(Normal + Sanfo.)
Physical and
chemical Test (after finishing)
Inspection
and Packing Dying
Process Route: Special type of luminous Disperse dyes (Fluorescent dyes) are taken in
a and P/C blend fabric is padded together with 30% to 40% squeezing
expression. After this the fabric is dried. At this time Disperse dyed are fixed
in the polyester. After this the fabric is send on CDR (Continues Dyeing range) machine.
At this time the fabric is padded with vat dyes (With Hydro + NaOH) in soluble
form. The cotton is dyed with Vat dyes. After Dyeing is over the fabric is oxidized to convert vat dyes in
original insoluble form by Hydrogen Peroxide (H2O2). After this the fabrics is washed and send for finishing. Generally
normal finish is applied. ·
Fabric
then sends for Physical and chemical testing. Physical Test: Ø Tearing strength Ø Tensile strength Ø Seam slippage strength Ø Abrasion Ø Cover Factor Ø Pilling Ø GSM Ø EPI x PPI Ø Warp x Weft (Count) Chemical Test: Ø Washing Fastness Ø Water Fastness Ø Perspiration Fastness (
Acid + Alkali) Ø Sublime Fastness Detail on dying process
route New
high visibility Nomex ProVis solution for industrial workers: |
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Retro Reflective Stripe
Some High Visibility Vest
Reference:
o
http://www.fibre2fashion.com/news/textile-news/newsdetails.aspx?news_id=83595
o
http://www.fibre2fashion.com/industry-article/12/1187/self-illuminated-safety-jackets1.asp
o
http://www.textileglossary.com/terms/high-visibility-clothing.html
o
www.workcover.vic.gov.au
***
Hi Visibility Clothing are a life saver. Be careful that you buy them from a reliable store and please read the care instructions while washing them
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