HSE
Health & Safety
Executive
The influence of preconditioning on
performance of side lever and compression
knapsack sprayers when subjected to the test
methods proposed by ISO DIS 19932-1
Prepared by
IC Consultants Limited
for the Health and Safety Executive
CONTRACT RESEARCH REPORT
409/2002
HSE
Health & Safety
Executive
The influence of preconditioning on
performance of side lever and compression
knapsack sprayers when subjected to the
test methods proposed by ISO DIS 19932-1
Evan Thornhill C Biol
and William Taylor C Biol
IC Consultants Limited
47 Princes Gate
South Kensington
London SW7 2QA
United Kingdom
It is critical to the safe use of knapsack sprayers that their operators are not unduly exposed to the
pesticide solutions that they are using. Leakage, spills whilst filling, non-approved concentrations of
solutions are all potential threats which may exist with new machines or appear after moderate use.
The ability to measure or assess these risks is the main basis for the development of an International
Standard; a document that will describe both how the tests are made [Test Methods] and what limits
should be acceptable [Performance Limits]. In this study, and in contrast to the earlier Health and
Safety Executive Contract 4179/S51.208, sprayers that have been subjected to simulated "use", were
compared with those that were unused. The range of sprayer types researched was also expanded
from just side lever versions to include compression sprayers too.
This second HSE study has shown that, with one UK make of sprayer, safety related matters were not
found to be worsened after 250 hours of simulated use. Levels of leakage, external deposits - and
other key measures - were not apparently influenced by preconditioning; the sprayers design and
quality of construction having a dominating effect over "use". In addition, as with the earlier HSE
contract, this research has once again raised the need to actually work through what has been
proposed by Working Groups since both Test Methods and Performance Limits can be seriously
faulted and may not then be enforceable. For example, it is clear that to pressure test plastic
compression sprayers to 4 times that for which they are rated, may not be reasonable or necessary; to
overfill some compression sprayers with integral funnels by 10% of their rated capacity [as a means of
contaminating external surfaces], may not lead to any outer surface contamination. Hence, the work
identified and then verified, some proposed test procedure changes. These observations - and others
embodied within this report - were successfully used at the Third Working Group Meeting on January
16 2001 to thereby modify the DIS into one that is likely to be more appropriate for UK conditions and
implementation.
This report and the work it describes were funded by the Health and Safety Executive. Its contents,
including any opinions and/or conclusions expressed, are those of the authors alone and do not
necessarily reflect HSE policy.
HSE BOOKS
© Crown copyright 2002
Applications for reproduction should be made in writing to:
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St Clements House, 2-16 Colegate, Norwich NR3 1BQ
First published 2002
ISBN 0 7176 2270 3
All rights reserved. No part of this publication may be
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in any form or by any means (electronic, mechanical,
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ii
CONTENTS
Page number
1
BACKGROUND
THE SPRAYERS
2
PRECONDITIONING
3
TEST METHODS
Pressure
5
Straps
8
Stability
9
Volumetric
10
External deposits
11
Internal residues
13
Leakage
14
Spillage
15
TEST SUMMARY
16
CONCLUSIONS
17
PHOTOGRAPHS
18 to 32
iii
iv
BACKGROUND
Manually operated sprayers - when used professionally - are expected to have a
working life of several hundred hours. During this time, the machines may undergo
changes that can affect their safety characteristics. Hence the new proposed
International Standard now makes some provision for preconditioning the machines
before they are tested; an aspect of research that has not previously been
systematically measured. However, the duration of the preconditioning period
remains debatable. Should it simulate a time scale that is appropriate to professional
use for a year [250 hours] or should it be just for a few hours [25 hours] to identify
manufacturing limitations?
In addition, the Draft International Standard is concerned with all types of manually
operated knapsack sprayers - including those which use built in pumps to store the
required energy as pressurised air - the compression sprayer. These machines have
also been largely ignored by researchers and Regulatory Bodies despite their
importance in professional and amateur markets as well as their specific categories of
risk assessment - such as Pressure Testing for which there is little substantive data.
This changed status of the Draft IS, to include preconditioning before testing of both
compression sprayers and side lever knapsacks, prompted the need for this study;
research that was conducted in order to ensure a stronger UK negotiating position at
the next Working Group meeting at BBA in Germany on January 16 2001.
1
The Sprayers
Cooper Pegler compression and side lever knapsack sprayers were donated by Hardi
International to this project, were individually coded and manufacturer's number
recorded [Table 1]. However, during the development of data for Pressure Testing it
was realised that research with other makes would be most useful too and these were
purchased separately. These sprayers were normal commercial products in all aspects
except one; the two types of side lever knapsacks were made of a more translucent
plastic in order to facilitate the new need to measure the tank contents [see Volumetric
Tests]. This change will be part of Hardi's normal production in the future.
In this report the identity of these other sources of sprayer are not disclosed
and all sprayers have assumed a code that numerical follows on from that used in the
previous study; HSE Contract Research Report 4179/S51.208.
Table 1: The Identification Code for the sprayers used in this contract
Code
HSE 8
HSE 9
HSE 10
HSE 11
HSE 12
HSE 13
HSE 14
HSE 15
HSE 16a
HSE 16b
HSE 17
HSE 18
HSE 19
HSE 20
HSE 21
HSE 22
Make
Cooper Pegler
Cooper Pegler
Cooper Pegler
Cooper Pegler
Cooper Pegler
Cooper Pegler
Cooper Pegler
Cooper Pegler
Type
Capacity Manufacturer No.
C5 Maxi Pro Compression 5 litres
846249
C8 Maxi Pro Compression 8 litres
846250
CP3 Series 2000
20 litres
846361
CP15 Classic
15 litres
646255
C5 Maxi Pro Compression 5 litres
C8 Maxi Pro Compression 8 litres
CP3 Series 2000
20 litres
846321
CP15 Classic
15 litres
846255
Compression
5 litres
Compression
8 litres
Mesto/CP Falcon Compression
5 litres
Cooper Pegler C5 Maxi Pro Compression 5 litres
846249
Cooper Pegler C8 Maxi Pro Compression 8 litres
846250
Cooper Pegler CP 3 Series 2000
20 litres
846361
Compression
5 litres
Compression
6 litres
2
The Preconditioning of Sprayers
The method
Assemble the sprayer following the manufacturer's instructions. Hand check for normal tightness the
filling cap, gland nut and other operator controlled couplings.
The lever operated knapsack sprayer, filled to 75 % of its nominal capacity, is securely supported by
its straps on a device described in 4.3. Water is pumped by the action of the device on the sprayer
through a manifold with nozzle(s) providing a minimum output of 72 litres per hour at ca. 3 bar with a
maximum of 35 strokes a minute. The sprayed water is collected in a separate tank so that it can siphon
back into the sprayer under test just before the pump completely empties the sprayer tank. The test is
continued for 25 hours [or 250 hours; a time limit yet to be agreed].
Cut-off valve test device consists of a frame to fix the hand held part of the valve and a unit for moving
the valve lever to open it periodically with an induced flow at the prescribed rate and pressure. It is
proposed to operate the valve with the spray liquid at a pressure of ca. 3 bar using a frequency of
15 cycles/min for a total duration of 25 000 cycles.
Compression sprayers are subjected to cycles that alternate between the recommended maximum
working pressure and no pressure for 10 000 cycles.
Comments from this HSE Study 2
Whether these types of sprayers should be preconditioned or not remains the biggest
problem in the development of an acceptable IS for knapsack sprayers. It has been
argued that this inclusion is an unnecessary precedent; that none - or few- other
Standards have preconditioning as a requirement. In contrast, the opposite view is that
these sprayers may pose undue risk to the operator if they fail during use. The issues
which need to be resolved are whether preconditioning is relevant and acceptable for
this specific Standard. Is preconditioning a normal IS practice and if it is, what is a
reasonable period for preconditioning? Some argue that if preconditioning is needed
then a few hours will identify latent faults whilst others justify a time scale that
reflects the machines likely life. Regulatory Working Group Members have been
asked to clarify these points.
Some details on the preconditioning study
Two compression sprayers [HSE 8 and 9] and two side lever knapsack sprayers [HSE
10 and 11] were preconditioned; side levers for the longer - 250 hours - time scale
proposed. These four preconditioned machines, and four identical ones that were "as
new", were then subjected to the Test Methods that follow in this report to establish
whether "use" would influence Performance Limits. It was hoped that if there was no
effects attributable to preconditioning then it demonstrates that this demand should
not be a restraint to the developing Standard. Hence, the need for preconditioning
would not be a technical restraint to its inclusion in a Standard. However, although
tests for 250 hours are expensive, they are likely to be critical if poorer machines
and/or design faults are to be identified.
It was noted - during the preconditioning routine that one manufacturing issue
- would have to be resolved. An inappropriate pressure control spring in the Classic a diaphragm sprayer - did not permit it to discharge spray liquid at the target flow rate
3
and pressure. Whilst these flow rate demands for these sprayer designs are close to the
compromise of operator effort/maximum performance, it is known to be
commercially possible and should be rectified.
……………………………………………………………………………..
An informal note on the problem of flow rate from the CP 15 Classic; a
diaphragm pumped knapsack sprayer
This new CP15 Classic [HSE 11] was fitted with a high specification pressure gauge
and used the lowest output nozzle with which it is supplied - a hollow cone. Only 2
bars was achieved on H setting and on the L setting, a little above 0.5 bars. Pumping
faster resulted in the pressure relief valve being activated and the introduction of
pressure surges which the operator would avoid.
An older [about 10 years] CP 15 Classic that was known to have met this need was
used to repeat the observations. On H setting, 3 bars and on L 2 bars was possible. It
was difficult to manually reach 3 bars but it was possible. The new valve assembly
was fitted to the old sprayer and, this time, 3 bars and 0.7 bars for the H and L
respectively were possible. Then, with the old valve in the new sprayer, 2.5 bars and
1.4 bars respectively for H and L could only be achieved by the operator.
These results suggest that the valve [spring] change has the greatest effect [and offers
the greatest scope for improvement] but other - unknown as yet - factors may have
been contributing as well.
Classic Sprayer: New
Old
H setting:
L setting:
3 bars
2 bars
<2 bars
0.5 bars
New with old valve
2.5 bars
1.4 bars
Old with new valve
3 bars
0.7 bars
Another valve spring, sent by the manufacturer, was fitted and 3 bars pressure was
possible. However, the manufacturer may like to note that at about 2.0 bars, the valve
was beginning to lift and allows the spray solution to bypass the discharge hose
assembly; a minor problem but the operator does have to expend more energy than is
needed. Both manufacturers and Regulatory Bodies should note that these
unintentional changes can be made and should be more closely monitored in the
future to ensure the full performance of the product.
…………………………………………………………………………………………..
4
Pressure Tests
The Method
Note that these tests are hydrostatic and not pneumatic. The sprayer is to be filled with water to its
rated capacity.
Connect the outlet of the trigger valve with a pressure supply device.
Subject the sprayer to 4 times the maximum rated pressure.
Comments from this HSE Study 2
The term - Burst test - that was originally suggested, has now been changed to
the more appropriate one - Pressure Test. In addition, the evidence of this study has
shown that 4 times the rated - was not realistic nor is it likely to be capable of being
reached by the operator who, with existing compression sprayers can not manually
reach such high pressures nor have common access to external sources of that
capacity, either. Finally, pressure relief valves [PRV] are designed now to be tamper
proof to the operator and the combination of all these points demanded a rethink of
this critical - but badly worded - Test Method and Performance Limit. It was agreed to
change the wording to
Subject the sprayer to 1.43 times the maximum rated pressure or until the pressure relief valve
operates.
-
and thereby capture all these points and meet new EU requirements that are being
developed elsewhere that could influence this IS.
Some specific measurements whilst Pressure Testing
Two compression sprayers [HSE 12 and 13] were filled with water and connected to
the pressure testing device. Both the Hardi C5 and the C8 burst at 12 bars before the
pressure could reach four times [16 bars] that for which they are rated [4 bars]. This
simple observation prompted a much more comprehensive study then that which was
planned; the origin and basis of this Performance Limit now being questioned.
The first step was to establish whether this observation was atypical of the
manufacturing range or is a feature of construction material. A range of plastic and
metal compression sprayers were gained and a more systematic set of measurements
made [Table 2]. Pressure at which the relief valve opens, the maximum an operator
can reach and then when it fails to hold liquid were all noted and individually
described.
HSE 16a was a 6 year old [but not used] 5 litre industrial version that had been
preconditioned at IPARC and [we believe] rated for 3 bars was pressurised when
filled with water. Whilst it was still holding water at 7 bars - it was swelling into a
round shape and would be unusable. At 11 bars it burst.
HSE 16b - a new 8 litre 3 bar rated model - was purchased which at 3.5 bars leaked
past the [sealed] valve, the pump at 6.5 bars with the pump seal failing at 8 bars. The
cause of failure was the O ring being extruded out of its fitting. Maximum operator
pressure attainable was 4 bars.
5
Table 2: Critical pressures measured on some manual compression sprayers; bars.
Code Pressure relief valve
- rated - actual
HSE 12 4
3.8
HSE 13 4
3.9
HSE 18 4
3.8
HSE 16a 3
3.3
HSE 16b 3
3.5
HSE 22 3
3.2
HSE 21
2.8
HSE 17
6
Operator maximum
5.5
3.9
4.7
4
4
8.6
No longer useable
12
12
12
8
13
13
19
In attempting to reach the maximum pressure an operator is likely to reach manually,
it became clear that design of pumping handle and robustness of its design would
influence this value. For example, the maximum values achieved by the two models
of HSE 16 were governed by the strength of the pump rod whilst another one [not
reported here] had a round pump handle that hurts the operator as he tries to overpressurise the system.
Cooper Pegler C5 [HSE 12] and C8 [HSE 13]: These are rated for 4 bars and the
relief valves lifted at 3.8 and 3.9 bars respectively. The maximum pressure the
operator could generate was 5.5 bars. With relief valves sealed, both burst at 12 bars.
A further C5 [HSE ?] burst at 11 bars.
HSE 22: This 6 litre compression sprayer is 3 bar rated and the relief valve lifted at
3.2 bars. Maximum pressure achieved by operator with sealed valve was 4 bars. The
test was stopped at 13 bars when the pump seal extruded past its retaining channels.
The tank itself showed no sign of failure.
HSE 21: This compression sprayer was not rated but was fitted with a colour
indicating relief valve which lifted at 2.8 bars. At 13 bars, major leaks were caused
past the handle seal. Its pump handle design does not allow it to be pumped with
much force and the operator could only reach 4 bars. This model is made of a hard
[non-swelling] plastic and is not likely to extrude under pressure. However another
Model with a rounded spherical knob-like handle could only allow the operator to
reach 3 bars.
Mesto 5 litre or CP Falcon: HSE 17 was the only metal, stainless steel manually
compressed sprayer used in these Pressure Tests. After 5 litres of water was added, it
took 100 pumps by the operator to reach 6 bars and the pressure relief valve lifting.
The valve was sealed and pumping continued until the operator could not apply a
higher pressure than 8.6 bars. The sprayer was filled with water and pressurised on the
rig. At 18 bars the plastic seal of the pressure gauge was violently ejected due to
distortion but without leakage. At 19 bars there was considerable leakage past the
trigger valve assembly and at 40 bars, whilst still not bursting, the tank base was
6
completely convex and - on later examination - we could see that the internal pump
had collapsed such that it could not be removed from the tank. It is worth noting that
despite the use of 40 bars pressure, the hose remained intact. So although there were
some concerns at testing the complete sprayer - rather than just the tank - this
modified procedure is a more complete and thorough test, it is easier to make the
necessary connections and it is commercially realistic.
It was also noted that some pressure relief valves [PRV] had excellent safety features
that made sealing for the Pressure Test very difficult.
Notes: The more common 'softer' plastic types expand at about 10 bars whilst the
more rigid plastic may sustain 13 bars. However, the softer material is used since it is
likely to withstand impact damage. Pumps are made from harder plastic and the tanks
when pressurised expand away from this component to cause leakage at this interface.
Sometimes the O ring is forced out; more commonly this occurring where the pump
retaining threads are flattened at two opposing points - a design introduced to permit
pressure relief without excessive liquid loss on opening.
The original British Standard was written suggesting that 4 times the rated pressure is
a reasonable threshold limit for these machines to reach but the origin of this proposal
is not clear. It appears that other specification writers have adopted the same criteria
without checking the authenticity of this claim. There are standards for hoses which
have such limits but not for tanks. Hoses have Proof pressures of 2x and burst of 4 x.
It has also been suggested that the operator could accidentally seal the relief valve
and/or use an external pressure supply. Are metal types better and does the type of
plastic used influence this characteristic? The Hardi C5 and C8 are considered to be a
better design and construction then many and so we felt determined that this very
important safety issue should be thoroughly and completely resolved.
It was noted that none of the hoses failed during the tests.
Manual compression sprayers have been know to be pressurised from external sources
- usually garage compressors. Whilst modifications such as this one are beyond the
immediate scope of this Standard - they have been considered in this report.
A Schrader valve is fitted to make this easier pressurising possible but in doing so
raises the fear of tank failures/explosions. However, these compressors are normally
ran to deliver 7 bars as a maximum but are used more typically at 5 bars; pressures
within the range that has been tested.
German regulations [TUV] fixed 4 x max working pressure for plastic tanks and 5 x
for metal tanks as a burst limit and accept that they may be irreversibly damaged. A
new EU guideline for pressurised containers sets the limit at 1.43 x the rated pressure.
Conclusion on pressure testing: The proposed 4 x rated pressure is not readily
achievable with most common designs. The origin for this IS value may be TUV or
refer to that IS for hoses and this became accepted by BS without challenging its
feasibility.
It is suggested that
since operators can not raise pressures greater than 10 bars in practice
external pressure sources that are readily available are not likely to exceed 10
bars either
a 10 bar pressure maximum limit is the more appropriate one to adopt for this
test.
7
Strap Tests
1.1.1
Straps
The test shall be performed with the test equipment described in 4.5. The sprayer tank is to be filled to
its nominal capacity.
Each and every load bearing strap is to be tested separately. An equivalent test that subjects the straps
to the same force may be used.
Comments from this HSE Study 2
The sprayers filled to their rated capacity were held by individual straps and dropped
onto a 75 mm wide very strong bar. This technique contrast with that we used in our
first HSE contract which lifted the sprayer by its main structure and allowed it to drop
onto the strap being tested; a technique that permits a far greater drop distance.
Dropping these sprayers for 300 mm resulted in no apparent damage and they would
pass the test. However, some observations were also made after a drop height of 600
mm and whist the C5 and C8 would still pass, it could be seen that the triangular strap
retaining clips were beginning to be opened up; a minor fault that the operator could
rectify.
The rig used comprised a solid vertical board positioned between two strong tables
supporting the horizontal bar. A vertical measure secured to the board allowed the
researchers to determine release height for the machines.
8
Stability Test
1.1.2
Stability
The sprayer is to be placed in all orientations with its base on an incline of 10 % (= 5.7°) described in
4.12.
The test is to be performed with an empty and full tank.
Comments from this HSE Study 2
A solid board was inclined at 10%. Sprayers filled to their rated capacity and when
empty were placed at four orientations on this board to gauge their stability.
All filled sprayers would pass this stability test and were uninfluenced by
preconditioning.
The two compression sprayers [HSE 8 and 9] when empty and orientated with their
strap facing down the slope were at their stability limit and would fail.
However, conformity with other Standards was raised at the January 16 2001 meeting
and it has been agreed to raise the incline for testing to 15%; a requirement of BBA,
EN 907 as well as EN 1553.
The introduction of this slope is likely to lead to the failure of the Series 2000 and the
C5/C8 compression sprayers.
9
Volumetric Test
1.1.3
Volumetric scale
Using the volumetric scale, it shall be possible to determine the volume of the tank contents.
Comments from this HSE Study 2
This was introduced - without query - as a new requirement since the earlier HSE
contract identified some machines as being wrongly rated; two makes were under
capacity and, whilst being filled, over flowed. Liquid levels in many tanks can not be
read.
The Test Method was adopted at the January 16 2001 meeting.
In this study the manufacturers tank contents marks on the test machines were
highlighted in black. Water was poured into the machines using 2 [and where
necessary at the end] and 1 litre aliquots with a calibrated 2 litre measuring cylinder.
These liquid levels were marked in red and recorded photographically. The disparity
between the manufacturer's mark for rated capacity, and the actual volume, were
determined [Table 3].
Finally, the volume of liquid that is available as spare tank capacity - after it had been
charged to the manufacturers rated mark - was also measured. Compression sprayers
that had been subjected - or not - to the Pressure Test were used to establish whether
high internal forces had distorted their capacity.
Table 3: Volumes of spray liquid within the spray tanks when filled to their rated
capacity and the available spare capacity; mls of spray solution
HSE Code:
Sprayer:
Rated capacity; litres
19
C8
8
11
Classic
15
5500 8600
+10 +7.5
5600 8640
+12 +8
14980
-1.4
Spare capacity; mls: 2200 1840
Tank spare volume; % 40
21
2100 1800
38 21
4020
27
Actual content:
Error; %
8
C5
5
9
C8
8
18
C5
5
10
Series 2000
20
19460
-3
2230
11
Pressure testing compression sprayers may have slightly increased the tanks capacity.
Rated side lever knapsack volumes can be very accurate but those used on the
compression sprayer would permit about 10% too much liquid to be used. All tanks
had at least a 5% excess capacity [head room] beyond the maximum content point and
would meet BBA requirements.
10
External deposits
1.1.4
External surface deposit
The external surfaces of the sprayer has to be washed with a non-ionic surfactant aqueous solution of
0.5% , rinsed with clean water and then dried. The lid or the air pump, respectively, is to be removed.
Put the filter basket into a polythene bag and tighten the bag such that it presents a flat surface within
the filling orifice. Fit the basket into the filling orifice. For compression sprayers, fit a rubber bung, or
similar device, into the filling orifice.
A volume of test liquid, that equates to a tenth of the sprayer’s nominal capacity, shall be poured [at a
rate equivalent to the sprayers rated capacity being discharged in one minute] using the device
described in 4.7 with it's outlet placed 100 mm above the filling orifice such that it simulates
overfilling. The filter basket or the rubber bung, respectively, shall be removed and the sprayer drained
for 1 minute.
Comments from this HSE Study 2
Some compression sprayers have integral funnels which will hold more than the 10%
of its rated capacity; a severe limitation to the Test Method is then posed since there
would be no further contamination of external surfaces such as those of the tank.
Further tests with this Method were abandoned, for in addition to the above problem,
there is seepage between the funnel and spray liquid container which is likely to mask
the intended values. The funnel fitting was removed to try and improve its sealing
properties but any attempt made leakage worse. These fittings appear not to be
designed as true liquid seals but to merely help to channel spray liquid through the
narrow orifice of the container.
Other techniques had to be considered. For example, four compression sprayers had
their orifice sealed by using a pump with a cut off handle. Traced liquid was poured
into the funnel and then a further 10% of its rated capacity poured onto that traced
liquid. We attempted to drain the liquid back into the tank by slackening the pump
and then measure all external deposits [Table 4]; but there were difficulties.
Table 4: External spray deposits on compression sprayers with sealed filling orifices;
mls of spray solution
Sample 1
II
Non preconditioned
C5
C8
9
33
9
33
Preconditioned
C5
C8
33
21
34
21
In a preferred second technique, preconditioned machines [washed in 0.5% non ionic
surfactant using the harder surface of a green kitchen sponge then washed in clean
water and allowed to dry] were also compared to non-preconditioned.
These tests were made with the upper lip of the funnel of the compression sprayers
and the filling basket of the side lever knapsacks sealed across with plastic so that the
10% of the sprayers capacity was poured onto it and then drained over it. However, it
11
does seem as if much of the spray is reflected away from the sprayer itself. Pouring
was made from a bucket. The preconditioned side lever machines retained less than
those which were not whilst the compression sprayer results appear less clear.
Table 5: External spray deposits on the non preconditioned and preconditioned
sprayers; mls of spray solution
Non preconditioned
C5 C8 Classic Series 2000
Sample I 16 20
43
63
II 16 20 43
69
Preconditioned
C5 C8 Classic Series 2000
27 17
21
43
26 17
21
43
This modified Test Method seems reasonable and was adopted at the January 16 2001
meeting. The only concern is whether spray liquid is reflected away from contact with
retained liquid in the filling orifice to the same degree as that from a tight plastic
surface.
The form of preconditioning, to which these machines were exposed, showed little - if
any - effect on surface retention; volumes appear to be more influenced by shape and
orientation of surfaces rather than its finish.
12
Internal residues
1.1.5
Internal residues
The sprayer shall be filled with water or test liquid, fixed in the recommended operating position but
with hose and lance in a horizontal spraying position.
The cut-off valve shall be immediately closed when the spray pattern is disrupted.
The amount of liquid remaining in the sprayer is to be determined.
Comments from this HSE Study 2
Table 6: Internal residues of the complete sprayer; mls of spray solution
Non preconditioned
C5 C8 Classic Series 2000
Sample I 38 83
160
160
II 37 83
159
160
With pressure control valve:
Preconditioned
C5 C8 Classic Series 2000
45 40
159
88
45 40 158
88
I 121
II 121
At 1 bar: 162
162
Sprayers were discharged at maximum pressure - with straight hose and lance - until
spray pattern disrupted. However, the nozzle used was discharging at about 17
mls/sec to make the above judgement very critical and could influence reproducibility
of data. Despite this difficulty, preconditioning may not influence the result for their
appears to be not one dominant change between the two sprayer sets [Table 6]. Fitting
a pressure control valve is reputed to retain more internal residues - if compared to
one that is pumped beyond the point used in this Test Method. However, if both the
preconditioned and non- preconditioned are stopped when the spray sheet collapses
then there may be little difference. Changing pressure settings in the Classic from
high [3 bars] to low [2 bars] also made no difference when following this Test
Method.
BBA requirements are for internal residues to not exceed 1.5% of the rated capacity
or 250 mls - which ever is the greater. All these machines met that requirement. The
January 16 2001 meeting did not adopt a suggestion to measure tank and whole
sprayer residues as separate values.
13
Leakage
Fill the sprayer with water and the tracer dye to the nominal capacity. Manually pressurised
compression sprayers are to be set to their maximum nominal pressure. Operate the sprayer such that
all functions have been in use. Place the sprayer on a bench and allow its lance assembly with hose and
closed trigger valve to freely hang. Leave the sprayer for 5 minutes and examine for leakage. Escaped
liquid can be caught in a suitable container – holding a known volume of clean water – and any less
obvious leaks can be removed with complete sprayer immersion.
Samples of the water with the tracer dye that has leaked, together with that washed from all external
surfaces, can be quantified and leakage rates calculated.
Repeat the test with the sprayer in a horizontal (strap side down) position for 1 minute.
Comments from this HSE Study 2
It had been earlier decided by WG 5 that the Impact Test was made before this
one for Leakage. This sequence did not introduce too many difficulties with this range
of machines [Table 7]. Despite both skirts on the Series 2000 braking, the sprayer
could be supported manually during the vertical hold position. It was observed that
the side lever knapsacks can emit a small jet of liquid through the vent valve on
impact. Hence, if it is decided to use a contrived drop [within a dedicated test rig] then
great care will be needed to ensure that any spray liquid losses - as a consequence of
the impact - are retrievable from within that rig.
Table 7: Leakage from preconditioned and non preconditioned sprayers after the
Impact [dropped from 600 mm] Testafter 5 minutes in vertical position; mls of spray solution
Non preconditioned
C5 C8 Classic Series 2000
Sample I 1.2 1.4 2.2
3.3
II 0.9 1.2 2.2
3.4
Preconditioned
C5 C8 Classic Series 2000
0.6 0.6
1.4
1.5
0.5 0.5 1.4
1.5
after 1 minute strap side down; mls of spray solution
Non preconditioned
C5 C8 Classic Series 2000
Sample I 0.5 0.4 1.8
2.7
II 0.4 0.4 1.9
2.7
Preconditioned
C5 C8 Classic Series 2000
0.4 0.4 5.8
3.7
0.2 0.4 5.7
3.8
There was no obvious leakage from the tanks but there was some from the
vent valves on the side lever knapsacks. Because the machines had been immersed in
the tracer solution [for earlier Tests] and despite being washed, some small volumes
of this liquid could still be seen coming from the straps. These small volumes may
account for the absence of zero values. Preconditioning and dropping the sprayers
does not appear to be associated with leakage.
14
Splashes from filling
1.2.1
Filling rate
The dry sprayer, placed centrally on the polythene sheet, is filled up to its nominal capacity, using the
device described in 4.7 within 60 s.
All splashed liquid is collected and determined.
Comments from this HSE Study 2
A bucket was used to pour the liquid within the specified time [30 seconds for the
compression sprayers] but noted that if these 10 litre buckets were near full then there
was splash at start up. In order to avoid this cause of inaccuracy, smaller volumes in
the buckets were used - 3x5litres and 4x 5 litres for the 15/20 litre capacity side lever
sprayers respectively; a problem that the BBA design of liquid supply for these tests
may be shown to overcome. This care with the split volumes in the bucket then
avoided start-up splash. Splashed liquid was recovered from the outside of the
machines and in the immediate work area. Splash - only as a consequence of filling can result in quite small volumes with this make of sprayer [Table 8]. However, in
commercial reality, spill volumes could readily be dominated by the skill of the
operator and his choice/use of mixing container.
Table 8: The volume of waste liquid from splashes during filling of the
preconditioned sprayers; mls of spray solution
C5 C8 Classic Series 2000
3.4 3.2 9.4 5.2
3.1 2.3 10.5 5.2
15
TEST SUMMARY
Two key issues are hopefully resolved with this study.
The Test Methods proposed within the next stage of this developing Standard a DIS - have been appraised, modified and largely accepted by WG 5 for UK use.
The impact of prior "use" of sprayers on likely Performance has been
measured.
Many Test Methods had to be modified as a consequence of this the second
HSE study. Pressure testing of compression sprayers to 4 x was not commonly
attainable, neither were such pressures likely to be achieved by the operator or by use
of normally available external forces - such as those from a garage's compressor.
Sprayers should be dropped by their straps onto the retaining bar rather than being
held by its main body if dropping is to simulate likely accidental release. Stability
testing needs to be aligned with parallel Standards which require a 15% slope rather
than 10%. Volumetric requirements were introduced without query and the Test
Method used is acceptable; values generated show that spray liquids can be read and
volumes measured with some accuracy. Determining external deposits demanded a
major change of Test Method before it could be made applicable to compression
sprayers. The BBA constant flow device is likely to improve reproducibility with
these measures as well as those in the Filling Test. Splashes from this latter action - it
is now concluded - may be more dependent on the operator rather than the machine.
The researchers now believe that it is his skill and/or poor use of the mixing bucket
that is the largest contributing factor to this risk in the work place. Internal residues
can be readily quantified and, surprisingly, use of pressure control valves or
contrasting working pressures may not influence the final volume. Leakage remains a
critical measure of risk assessment and, with the make of sprayer used in this study,
quantities were not influenced by being dropped; despite some structural damage with
one particular model. However, if contrived drops are adopted - using test rigs that
encompass the machine - it will have to be shown how spray liquid that may be
ejected through the vent valve are caught.
Reproducibility of data has been queried by WG 5 Members and it was the
task of this reports authors to consider whether this could be an issue with the Impact
and Strap Test. Many observations were therefore made and recorded on video film of
sprayers making impact. Impact points were influenced by where the operator held
the sprayer; some had dedicated holding points whilst others could only be supported
and carried by their straps. In addition the weight distribution of some sprayers is
much biased to one side or the back or front of the sprayer. These design
considerations were shown to dominate the attitude of the sprayer as it fell and its
subsequent point of impact. A vertical fall and a uniform impact on the base was not
observed. It is therefore being proposed by the UK WG 5 Members that sprayers are
dropped in the Impact Test from two release points; one from a dedicated holding
point [if available] and one from its straps. If no dedicated carrying point exists then
they should be released twice from the straps.
16
CONCLUSIONS
Preconditioning this one make of sprayer had no - or little - observable or
measurable impact on their performance using Test Methods [albeit, for necessity
modified] currently proposed for the DIS. The factors that dominate the sprayers'
performance are more likely to be related to their design and initial build quality;
intrinsic demands that ensure the subsequent safety related issues that have been
considered in this HSE funded study are met. We concluded that it is commercially
feasible to make sprayers that can be preconditioned for a reasonable length of time
and still pass this sequence of Tests. Hence, preconditioning sprayers should be within
the scope of this International Standard.
Without preconditioning, inferior makes of sprayer both from within the EU,
and more likely from countries that are beyond, will more readily comply with a
weaker IS and, thereby, place UK operators at risk. Having now determined that at
least one, but more likely many, better quality European made knapsack sprayers
could easily cope with this length of preconditioning, the final proof would be to
establish the likely inadequacies of some of these possible non EU imports; a further
research stage that ideally should be taken soon.
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Printed and published by the Health and Safety Executive
C1.25
05/02
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Printed and published by the Health and Safety Executive
C30 1/98
Printed and published by the Health and Safety Executive
C1.25
05/02
ISBN 0-7176-2270-3
CRR 409
£20.00
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