SMI catalogue 2022 - Catalog - Page 53
HI VIS CLOTHING
HYDROSTATIC
HEAD LEVEL
Hydrostatic Head (HH) is a way of measuring how
waterproof a piece of fabric is. The manufacturer
will take a clear tube and clamp their material
over the bottom end. They will then fill the tube
slowly with water and watch to see how high the
column of water can get before the material lets it
drip through.
A Hydrostatic Head rating of 10,000mm
means that the column of water was 10 metres
(10,000mm) tall before the material leaked.
We have put the below icons against relevant
garments in this section to demonstrate the
relevant Hydrostatic Head Level Rating.
HH
HH
10,000
20,000
RATING
RATING
WATER PENETRATION
RESISTANCE
1. Minimum level of rain protection
2. Intermediate rain protection
3. Highest level of rain protection
EN ISO 20471 CLASS 1
Minimum background material
0.14m2, Minimum retro
reflective material 0.10m2.
Bands of retro reflective
material should not be less than
50mm wide
EN ISO 20471 CLASS 2
Bands of retro reflective material shall
not be less than 50mm wide. Minimum
background material 0.5m2 Minimum
retro reflective material 0.13m2
BREATHABILITY
1. Not classified as breathable under
EN 343
2. Intermediate level of breathability
3. Highest level of breathability
RIS-3279-TOM IS A HIGH
VISIBILITY STANDARD FOR
RAIL INDUSTRY
As opposed to the EU-Wide nature
of other EN standards. The aim is to
ensure that rail workers on or near the
trackside are sufficiently visible to trains
approaching at speed or any other
traffic. It was formerly known as
GO-RT 3279.
EN ISO 20471 CLASS 3
Bands of retro reflective material shall not be less than 50mm wide. Minimum
background material 0.8m2 Minimum retro reflective material 0.2m2
Class 3 garments must be worn on any carriageway with a speed limit of 50
mph or above.
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