1. The differences between the testing of
type 3 (liquid jet test) and type 4 (liquid
spray test) for protective clothing are
important to define. This overview
provides information on the core
differences.
Picture the scene: A sales advisor (SA) at a
PPE distributor is taking a phone call from a
safety officer (SO) at a chemical plant.
SA: “Good Morning, how can I help you?”
SO: “Ah, hello I need to get some clothing
to protect against chemicals.”
SA “Okay, we have clothing for type 3 and
4, or type 5 and 6 protection – which do
you need?”
SO: “Oh, Type 3 and 4 please.”
At this point we’ll leave their conversation
as I want to focus on why so often a
decision is made to purchase a garment
that is approved to type 3 and type 4, and
also why so many garments in the
marketplace are manufactured and
approved to both type 3 and type 4.
A good place to start is with ISO
16602:2007 Protective clothing for
protection against chemicals —
Classification, labelling and performance
requirements which is the international
standard that details the classification of
each type (as well as other related
requirements).
The table below provides an overview of
the types in ISO 16602 and those that we’ll
discuss further are highlighted:
We can instantly see that there is a key
difference in the testing between type 3
(Liquid jet test) and type 4 (Liquid spray
test), so let’s look at the tests in more
detail. Both tests require some pre-
treatment and work simulation activities to
take place, but as these are the same for
both tests and are detailed in ISO 16602 &
EN ISO 14605, we’ll not cover them here.
Type 4 (Liquid spray test) – ISO 17491-
4:2008
Test methods for clothing providing
protection against chemicals.
Determination of resistance to penetration
by a spray of liquid (spray test).
This test takes the form of four sprinkler or
shower type sprays of liquid being directed
at an individual dressed in the garment.
The liquid is made up of water, a surfactant
(to lower the surface tension and therefore
allow the water to flow more easily into
any gaps in the garments), a dye and if
needed a stabilising agent for the dye.
The test subject is dressed in
undergarments and an absorbent coverall
underneath the garment to be tested. The
absorbent coverall is also used to
determine the 'calibration stain' required in
the test parameters before the test begins.
The outer garment is worn as per the user
instructions and any instructions to tape
the garment (usually at the wrists, ankles
and around a full face mask – but may also
include taping the front zip assembly).
The test subject stands on a turntable
within the test chamber which rotates at a
speed of one revolution per minute. The
spray is then activated for a period of one
minute and the test subject performs
certain tasks: moving their arms backwards
and forwards and also lifting each foot in
succession to a height of 20cm and placing
it back down (30 times within the minute)
to simulate walking.
At the end of the process, the garments
and any other PPE are carefully removed
and any staining on the absorbent coverall
is measured and noted on the test report.
What’s your type?
Workwear
12 Reference guide to the British Safety Industry 2016
What’s Your Type?
1a 1b 1c 2 3a 4a 5 6a
5.4 Leak tightness X X X
5.5 Inward leakage X
b
X X
5.6 Liquid jet test X
5.7 Liquid spray test X
5.8 particle aerosol inward leakage test X
5.9 Limited liquid spray test X
6.5 Permeation resistance X X X X X X
6.6 Resistance to penetration by liquid under pressure X
d
6.7 Particulate penetration resistance
e
6.8 Liquid penetration resistance X
6.9 Liquid repellency X
a
b
c
d
e
General
performance
Sub clause
in ISO
16602
Specific performance test(s)
Type of chemical protective clothing
Classification by type of chemical protective clothing
A test for evaluating the performance of protective clothing materials against particles is not recommended at this time
Whole
chemical
protective
clothing
integrity
Chemical
resistance of
protective
clothing
material
c
When not providing coverage of the torso, arms and legs, Types 3, 4 and 6 clothing are partial body protective clothing meeting only the material
chemical resistance requirements for the respective type.
Applicable to Type 1b chemical protective suits when the face piece is not permanently attached to the suit
Applicable to primary material used in construction of chemical protective clothing item: may or may not be applicable to seams (see Clause 7)
Either permeation resistance test or test for resistance to penetration by liquid under pressure shall be applied
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2. Workwear
Reference guide to the British Safety Industry 2016 13
The test report is then compared against
EN ISO 14605:2005 +A1:2009 Protective
clothing against liquid chemicals —
Performance requirements for clothing
with liquid-tight (Type 3) or spray-tight
(Type 4) connections, to determine whether
the amount of the test liquid that has
penetrated the garment indicates a pass
(less than or equal to three times the total
calibrated stain area).
Type 3 (Liquid jet test) – ISO 17491-
3:2008
Test methods for clothing providing
protection against chemicals.
Determination of resistance to penetration
by a spray of liquid (Jet test).
Many of the same protocols are observed
in the type 3 testing as in the type 4
testing, the same calibration process, the
same test liquid prepared in the same
manner, the same type of undergarments
and absorbent coverall are worn and again
the garment is worn according to the user
instructions, along with any relevant taping
(wrists, ankles etc).
The difference is in the test process itself;
for type 3 testing a jet of the test liquid is
directed specifically at potential weak areas
in the construction of the garment, areas
where a liquid is most likely to penetrate:
• Zip flaps (a jet of liquid will be sprayed at
an angle to try to force it open)
• The back of the neck and crotch where
several seams may join resulting in a
potentially weak area
• Under the arms which might often suffer
stress and weakness.
The jet is sprayed at a distance of one
metre at the specified pressure. As with the
type 4 test, comparison of any staining is
made against the calibration stain and EN
ISO 14605:2005 to determine if the
garment achieves a pass.
Back to the original question: 'What’s your
type?'. If, as a potential user of these
garments a risk assessment has indicated
that you need protection against a spray
based hazard, why would garments that
are also suitable for jet type hazards be
selected?
Is it perhaps that:
• EN ISO 14605 steers the manufacturer
towards producing garments that are
type 3 and 4 because the standard
covers both?
• It’s easier for manufacturers to certify
their garments to type 3, knowing that
by achieving this, they’re almost
guaranteed to be granted certification
for type 4 as well?
• It’s easier for the end user, knowing that
they have a garment that is tested
beyond what they will likely require?
Most people believe the answer is 'yes',
however let’s consider why this may not be
the case and the benefits in purchasing a
garment that is certified to type 4 only.
The key factors are of course comfort and
protection. In general terms, the greater
protection offered by a garment, the lower
the comfort of the garment, so:
• There may be a wider range of style
options available in a type 4 only
garment - such as separate jacket and
trousers - or a simplified design coverall
• The garment could potentially be less
complex and therefore easier, safer (and
possibly quicker) to don and doff
• Garments approved to type 3 may have
been designed to resist permeation of
more aggressive chemicals, which could
mean that the fabrics used may be
thicker or denser, potentially leading to
heat stress complications for the wearer.
• Price! A garment approved to type 3 will
undoubtedly cost more than a garment
approved solely to type 4.
The correct garment can of course only be
determined by a comprehensive risk
assessment, not only of the hazard faced
during the work process but also
considering any risks inherent in the
environment, heat stress issues, and also in
the doffing procedure (oftentimes one of
the highest risks to the individual).
So next time you look to purchase
chemically protective garments, rather than
settling for a one size fits all solution, why
not ask yourself: ‘What’s my type?’ and
check whether your chosen manufacturer
can offer you a solution that meets your
requirements, rather than a 'one-size fits
all' solution.
Diagram 2: Example of type 3 testDiagram 1: Example of type 4 test
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