Slurry wear properties of pump lining materials

1. ELSEVI ER Wear 210 (1997) 211-219
WEAR
Slurry wear properties of pump lining materials
Yoshiro Iwai a Kazuyuki Nambu"
Fukui Universit.v, Fukui, 910, Japan
"Milsubishi Heat,)"h~dustries Ltd., Takasago, H.voga,676, Japan
Received 25 November 1996: aces:prod l I March 1997
Abstract
in order to study the slurry wear properties of elastomeric lining materials for sand, sludge and sewage pumps, several tests were carried
out under various test conditions with a slurry jet dev!ce and prototype pump. Preliminary tests were done with 13 materials including
polymers, metals and ceramic coatings. Polyurethane, fluid elastomer and rubber showed good wear resistance compared with the hard metals,
and were examined in detail. The test conditions were ,asfollows: jet velocity v (8-25 m s- I), impingement angle at(10°-90°), mean diameter
of silica sand d (42--415 p,m), and sand concentration by weight c (0.1-7 wt.%). The slurry wear rates of the polyurethane and the fluid
elastomer were maximum at the impingement angle of approximately 30°. The rubber showed almost the same wear rate regardless of
impingement angle. The slurry wear rate increased according to a power law of the jet velocity above a critical velocity and sand concentration.
As the particle size increased above a critical size at the same weight concentration, the wear rate first increased but then decreased. The
influence of impingement variables and particle variables observed using both test methods shows a similar tendency for each lining material.
so the slurry wear loss can be described with a single empirical equation. Comparing the slurry wear resistance of three lining materials, the
polyurethane showed the lowest resistance because it contained many pores which were produced during the lining process. The rubber
showed the highest slurry wear resistance which is probably related to its high tear strength. © 1997 Elsevier Science S.A.
Ke)~'ords: Slurry wear: Elastomeric lining material: Slurry jet test: Impingement variables: Particle variables
1. Introduction
Irrigation pumps used under sedimental abrasive condi-
tions are damaged by repeated impact of solid particles [ 1,2].
Such damage is called slurry wear and is an extremely serious
problem for the life and reliability of pump operations. The
slun), wear resistance of various materials is well known [3-
6]. Since slurry wear is affected by impingement variables,
particle variables and material variables, it is very difficult to
estimate the slurry wear resistance of a new material from
previous information. For these reasons, candidate slurry
wear resistant materials, especially coating materials, must
be selected empirically.
The recently developed elastomeric lining materials are
expected to be useful coatings for sand pumps, sludge pumps
and sewage pumps. Reliable experimental data and reports
of slurry wear phenomena for elastomeric lining materials
are less often reported than those of the hard metals [7,8],
so this study was done.
2. Slurry jet tests
2. I. Test apparatus and procedure
Fig. I shows a schematic view of the test apparatus. It
consists of several elements: a specimen holder, a nozzle to
0043-1648/97/$17.00 © 1997Elsevier Science S.A. All rights reserved
Pll $0043-1648 ( 97 ) 00055-0
jet out the test liquid, a tank and a stirrer to mix solid particles
in liquid, a cooler to maintain the desired liquid temperature.
a pump to circulate the test liquid and a valve to control liquid
rio':,'. The test piece was a plate of length 20 ram, width 30
mm and thickness 5 ram. The coating specimen was attached
1. Test piece 6. Stin~r
2. Nozzle (dia,3mm) 7. Cooler
3. Water bath 8. Pump
4. Test liquid 9. Valve
5. Tank
Fig. I. Schematic view of the slurryjet test apparatus.

2. 212 E lwai, K. Nambu I Wear 2I0 (I 997) 211-219
to a steel backing strip. The lining thickness was approxi-
mately 2.5 mm. The test piece was attached to the holder and
was set 20 mm above the exit of the nozzle.
The diameter of the nozzle was 3 mm and the flow velocity
was varied by adjusting the valve. The slurryjet velocity was
measured as follows: the sampling volume (here 1.5 l) of
flow was collected from the nozzle into a graduated beaker,
the volume was divided by the time of sampling and the area
of the nozzle exit to obtain the velocity. The maximum jet
velocity was about 25 m s- ~at the nozzle exit. The impinge-
merit angle of the jet relative to the test surface was varied
from 10° to 90°by tilting the SlX;cimenholder. The test liquid
was tap water containing silica sand of various size. The shape
of silica sand particles is shown in Fig. 2. The mean value of
maximum and minimum length (designated the mean diam-
eter) ranged from 42 Itm to 415 ttm and the aspect ratio of
angular ailica sand was about !.4. The density and the hard-
ness of the silica sand were 2.7 mg ram-3 and HV----750-
1280. The concentration of silica sand by weight was meas-
ured by sampling the slurry jet flow at the nozzle exit in each
test. The concentration could be adjusted from 0. ! to 7 wt.%.
The temperature of the liquid was kept between 25 and 30
°(2. The mass loss and profiles of the damaged surface were
measured at set intervals with a precision balance (sensitivity
0.Ol rag) and a stylus profilometer respectively.
2.2. Test materials
Fig. 2. Scanning aicmglmtogm~ of silica sand (mean diameter 323 ttm).
Thirteen materials were used in preliminary tests in the
impact slurry jet test apparatus. The test materials were high
polymer lining materials and coating materials, a martensitic
stainless steel (SUS,I03, !3Cr) as a reference metal, a high
chromium cast iron, and a duplex stainless steel cast alloy as
a representative of hard metal. The test results are summarized
in Table I. The conditions for these tests were as follows: the
test liquid was tap water containing 3.7 wt.% silica sand with
a mean diameter of 42 i~m, the slurry jet velocity was 15
m s- ' and the impingement angle was 90". The test duration
was 2 h, extended to 5 h when the wear rate was small. Some
of the elastomeric lining materials such as materials B, F and
H were very effective in resisting wear. These were therefore
selected for further testing. Their material properties are listed
in Table 2. The polyurethane m~d fluid elastomer were made
by two-liquid mixing, and the tubber was a synthetic soft
rubber. These materials are used in practice to repair worn
linings.
Table !
Results of preliminary slurry jet tests of 13 materials
Test piece Hardness Wear loss
HV ( 1.96 N) Shore A Shore D Mass loss (rag} Maximum wear depth (tim)
2h 5h 2h 5h
A SUS403 (plate) 213 - - 13.3 -
B Polyurethtme (soft) - 83 - 0 0
C Polyurethane (hard) - - 75 I0 -
D Polyurethane coating - 90 - 0 0"
E Polyurethane coating - - 67 71.7 -
F Fluid elastomcr - 85 - 0 0
G AIzOj + resin 30 - - 60.9 -
H Rub,bur - 62 - 0 0
I WC 982 - - 1.66 3.88
J Cr cast iren I 830 - - 1.77 4.43
K Cr cast iron 11 893 - - 0.60 1.50
L Duplex SOS 1 469 - - 4.23 10.6
M Duplex SUS It 346 - - 14.1
45
0 0
[80
13 33
933
0 0
725
0 0
5 i0
7 15
I 3
24 50
10
Test conditions: test velocity 15 m s- t, impingement angle 90°, diameter of silica sand 42 p.m, sand concentration 3.7 wt.%.
' Swelling.

3. Y.iwai,K.Nambu/Wear2lO(1997)211-219 213
Table 2
Properties of lining materials
Material Detail Density
(gem -.~)
Shorehardness A Tensile strength Tear strength
(MPa) (N cm- •)
Elongation
(%)
B Polyurethane Two-liquid mixture 0.57
F Fluid elastomer Two-liquid mixture 0.95
H Rubber Synthetic soft rubber 1.11
83 10 160 400
85 14 600 550
62 16 780 400
Implgament
j OlrecUon
0.5 h
polyurethane
!~'m Elastomer ~h
"~--~ ~ Oh
"1ram 23hh
~ h
}L sus.o3 r..".D.75h
d--323 IZm v=23 m/s
c=0.5 wt.9~ o =30 °
Fig.3. Profilesofthedamagedsurfaceforvarioustestdurations.
2.3. Experimental results
Additional impact slurry jet tests were done on the three
selected lining materials, together with a martensitic stainless
steel (SUS403) as a reference material, with a jet velocity
range v of 8-25 m s-', impingement angle a of 10°-90°,
mean diameter of silica sand d of 42-415 wm, and sand
concentration by weight c of 0.1-7 wt.%.
Fig. 3 shows examples of profiles of the damaged surface
which were measured at the same location in a longitudinal
direction at various test durations, The test conditions were
v ---23 m s- ', a = 30°, d-- 323 wm and c = 0.5 wt.%. The
worn surface of SUS403 was very smooth, but the worn
surfaces of lining materials were rougher, before and after
the test. The difference in worn depth at the deepest position
400 "
t o P ~
v=23rn/s • Elastomer
f= a--30° • Rubber
"[ d=323pm [3 SUS403
" 300 ~0.5~/
ID
to 200
lO0, n
0 1 2 3 4
Time , hour
Fig. 4. Variation of wear depth as a function of test duration.
was measured and then designated as a maximum wear depth
at each test interval.
Fig. 4 shows the variation of maximum wear depth of each
material with test duration. The wear depth increased linearly
with test duration except in the initial stage of testing. The
slope of the linear part of the wear curve was calculated by
means of the least-squares method, and is defined as the wear
rate (lzm h-I) in this study. The volume wear rates were
determined by measuring the mass of the specimen before
and aftec testing. Examples of the relationship between the
wear rate by depth and the wear rar~ by volume under various
conditions are shown in Fig. 5. The polyurethane and
SUSd03 show linear relationships with correlation coeffi-
cients of 0.93 and 0.97 respectively. The wear depth rates are
used in discussions of slurry wear behaviour in this section.
Fig. 6 shows variations in wear rate as a function of
impingement angle at v=23 m s-', d=323 izm and c=0.5
wt.%. The wear rate of the fluid elastomer and rubber were
approximately i/10 the wear rate of the polyurethane and
SUS403. The wear rate of SUS403 increased to a peak value
at about ot=45 ° and decreased with further increase in
impingement angle. The polyurethane and the fluidel~tomer
showed similar tendencies, but the angle at which the wear
rate became maximum was approximately 30°. The wear rate
of the rubber was almost the same regardless of the impinge-
ment angle. HereaRer, the wear rates of test materials arc
compared at an impingement angle of 30°.
The relationshipbetween the wear rate and slurryjet veloc-
ity are shown on a logarithmic scale in Fig. 7. The wear rate

4. 214 E Iwai,K. Nambu/ Wear210 (1997)211-219
. . . . l ....
r o ~ I gllama,~um
0 A Polyurethane
I . .• & Rubber
" aoo 10= ~ ¢ sus4o3
¢=O.~.H
-
~2oo .,~ lo1
O-- lO 2O 3O
Wear volume rate , rnm3/h
1200. . . . .
fo_ ,/ .... ,...........,~ 1000 100 1 102
Velocity v, m/s
:X II00~ / " Fig. 7. Relationship between wear rate andjet velocity.
~ ,
E soo rate of the fluid elastomer and rubber were negligible for the
particle size of 91 ttm at the maximum jet velocity in this
~ [ ***/* apparatus, The critical velocities Voand velocity factor are
400 summarized in Table 3. The critical velocity diminishes with
~x)L ,A- increasing particle size. However, the velocity factor is inde-
5 pendent of particle size and takes values between I and 3.
=,, . . . . , . , . Fig. 8 shows the relationship between the wear rate and
0- lO 2o 3o 40 ~o
particle size at a particle concentration of 0.5 wt.%. The
Wear volume rate , mrnS/h
Fig. 5. Relationship between wear rate by volume and wear rate by depth
for polyurethane and SUS403.
4001/I- v=2am/s o Polyurethane
d=,.%'~t=m • Rubber
300 c.o.swt.~ _ o sus4o~
, T.T .-. T . ,= ~
0 30 60 90
Impingement angle a, degree
Fig. 6. Variations of wl,ar rate as a function of impingement angle at t= 23
ms -I.
increased according to a power law with velocity for both
particle sizes used in the test. The exponent (designated the
velocity factor) was calculated by the least-squares method
from the experimental data. The jet velocity below which the
wear rate was hardly measurable (approximately 5 ltm h- I)
was called the critical velocity vo for slurry wear. The wear
elastomeric materials did not wear at particle sizes less than
a given value although the wear rate of SUS403 was meas-
urable. This particle size is designated the critical particle size
and is 208, 91 and 42 Ixm for the fluid elastomer, rubber and
polyurethane. As the particle size became larger above a
critical size, the wear rate increased but then was smaller with
the 415 ttm particle size. Since the weight content of silica
sand was kept constant for all particle sizes in thisexperiment,
the number of particles which struck the specimen surface
during the test duration became smaller with larger particle
size.
Fig. 9 shows the relationship between the wear rate and
silica sand concentration for the particle sizes 91 and 323 Itm.
The wear rate is proportional to the sand concentration to
some power. The exponents (designated the concentration
factor) are summarized in Table 3. The concentration factors
are less than 1.0.
The important particle variables may include the effects of
the number and the size of particles on the ,,,,'ear rate. The
damage due to a single particle of silica sand of each size can
be determined by combining data from Figs. 8 and 9. The
number of particles that struck the surface during a unit time
may be estimated in the following way,
(number of particles)
(area of nozzle exit) × (jet velocity) x (concentration)
('tr/6) × (panicle diameter)3× (density of particle)

5. Y.Iwai. K. NmnbuI Wear210 (1997) 211-219 215
Table 3
Summary of impingement and particle variables obtained by the slurry jet tests
Impingement vmiable ( a = 30°, c = 0.5 wt.% )
Critical velocity r,) (m s- ' ) Velocity factor (c--rn)"
d=91 pm d=323 p.m d=91 p.m d=323 ixm
Panicle variable (t~=23 m s- '. =z=30~)
Critical diameter d, (gm),
c-~ 0.5 wt.%
Concentration factor c"
d=9l tim d=323 p.m
Polyurethane 13 8,5 3.3
Fluid elastomer > 23 15 -
Rubber > 23 11 -
SUS403 10 8.5 2.7
r 0 Polyurethane
l ~ Elastomer
--I- ° / ~E I. v,,2am/s / c~
ro-_3o° I /-~
I
" fO0 20]3 300 400
3,2 42 0.72 0.46
2.9 209 - 0.46
1,3 9 ! - 0.49
2.8 42 0.53 0+65
IO 4
0
Mean diameter of particle d, IJ m
Fig. 8. Relationship between wear rate and particle size.
91 323IJm
oum z~ Polyu,ethane / ' /
<D & Elastomer ~ O
100¢ • i Flubl~t
j= [] C, SUS403 : x ~
0=30" ~ "
5oo .--~
0 2 4 6
Concent;ation c, wt.9~
Fig. 9. Relationship between wear rate and silica sand concentration.
Fig. 10 shows the relationship between the wear rate and
the number of impacting particles during a unit time (here,
second). When the wear rates are compared at the same
impacting rate of particles, the wear rate becomes larger for
larger particle sizes. From this figure, the wear rate due to
impacts of a given number of particles (here, l0 s number)
can be compared. The results for each material are shown in
Fig. 1I; they plot as straight lines on a logarithmic scale.
91 tim 3231.Lm
o---30"
,~E 103 in O sus403
--i
~ 102
t,-
03
101
10;03 104 105 106 107
Number of particle, l/see.
Fig. 10. Relationship between wear rate and the number of impaciing par-
ticles during a unit lime (.second).
t0 4 • //
~:~ O Polyumti~
E • R.bber
77 !1~--05
%
~.101
b.,
10i01 102 I0a
Mean diameter of particled, I~m
Fig. 1i. Relationship between wear rate due to impacts of IO" particles and
mean diameter of silica sand.
Since their exponents are 3.3, 3.1, 2.7 and 3. i for the poly-
urethane, the fluidelastomer, the rubber and SUS403, respec-
tively, the wear rate is proportional to the mean diameter of
p',,'ticles to the power of approximately 3. This may indicate

6. 216 E lwai,ft. Nambu/ Wear210(1997)211-219
that the wear damage is affected by the (mass) X (velocity),
i.e. kinetic energy of each particle. From these results, it is
concluded that slurry wear ii-,creases in unit time with an
increase in both the size and the number of particles.
Polyurethane
& Benehtestofanactualpump
3.1. Test apparatus
Fig. 12 shows a sketch of the test apparatus. It consisted
of a mixing tank, suction line, a test pump, discharge line and
an orifice for flow regulation. Three sampling pipes were
installed in order to examine the sand concentration at upper,
bottom and horizontal sections of the discharge pipe.
The test pump was a horizontal, mixed flow, open type
impeller with four blades. The rotating speed was controlled
by a cycle changer. The rated capacity of this pump was 2.8
m3 rain- *and the rated total bead was 7.2 m at rotating speed
of 1750 rev min- i. The orifice was calibrated using an elec-
tromagnetic flow meter in the line before slurry wear tests
were done.
3.2. Test procedure
Three of the four blades were coated, each with one of the
three lining materials, and the fourth was bare cast iron for
reference. The silica sand had a mean particle diameter of
205 IJ.m. In the case of pump operation, the flow velocity,
which corresponds to the peripheral speed of the impeller,
was 16 and 20 m s-*, and the impingement angle, which
depends on the flow rate, was 0° and 5°. Two silica sand
concentrations used in the tests were 3.7 and 10 wt.%, which
was checked every 2 or 3 h during continuous operation. The
test duration was 50 h and wear progression was examined
at 10, 25 and 50 h.
I[
t° t,Sxiag talc
2. ,Sactio,line
3. Test pump
4. Dischargeline
5. Oz~xe
6. Motor
Z Totq~ motor
Fig. 12.Schematicviewofthetestapparatususinganactualpump.
0 h
Flow of
ater
50h
v-16 m/s
c~=O °
d--205 pm
C-10 wt. %
Fig. !3.Thesurfacesofa testimpellerlinedbypolyurethanebeforetesting
andafteroperationfor50h.
3.3. Experimental results
Photographs of the surfaces of the polyurethane before
testing and after 50 h of operation are shown in Fig. 13.
Surface damage was greatest at the leading edge. The shapes
of the leading edges were replicated by resin at various stages
of wear and compared with the original shapes as shown in
Fig. 14. The most severe slurry wear occurred on the bare
cast iron, whereas the lined impellers showed slight loss. The
wear volumes ,,,,'erecomputed from the difference between
original and worn profiles. Fig. 15 shows the variations of
wear volume with test duration: it increased almost linearly.
The wear of the rubber and the fluid elastomer were almost
the same, but the polyurethane was worn twice as much as
the rubber and the fluid elastomer. The slope of the line was
calculated as the slurry wear rate.
Fig. 16 shows the variation of wear rate as a function of
velocity, impingement angle and sand concentration respec-
tively. The effects of these variables on the wear rate could
not be determined exactly because the experimental data were
limited. Nevertheless, it is seen that there was no dependence
on impingement angle with the rubber but there was with the
polyurethane and the fluid clastomer. If we assume the power
law relationship between wear loss and blade velocity and

7. Y. lwai. K. Nombu / Wear 210 ¢1997) 211-219 217
a a'
Upper
f,~:-''- ,.--- J~surface
CCL. --
~:'--~--~-"~"c-"....:..------..-~.z.. 9mLower
Cast iron surface
Polyurethane
g
Elastorner ~ O h
-.......... 1Oh
~-~25 h
- - - - - - 5 0 h
Rubber 5, mmj
Fig. 14. Variationof surfaceprofilesofthe leadingedgeof the lip (profiles
show thedamagealongthe linea-a' as shownin Fig. 13).
E
¢/)
mlO00
o
0,)
E,,-z
o Potyur~
@ El&~omer /
• Rubber /
V=16Ills
1500 o--O"d=205 um
. C - - 1 ~
0 10 20 30 40 50
Time , hour
Fig. 15. Variation of slurry wear volume with test duration.
sand concentration in the actual pump are similar to that in
the slurry jet tests, the exponents of the power law of these
variables can be calculated. These values are summarized in
Table 4.
4. Discussion
Comparing impingement variables and particle variables
obtained by both the slurryjet tests and pump tests (Tables 3
and 4), the variations ¢f the factors for the three lining mate-
rials show similar tendencies. The slurry wear loss can be
described with an empirical equation of the type
E
50
~ IO
o = 0°
/
~w
v.IBrn,~
lOI
OIJ ! ! ,i a
110 so o
v~oc~, m/s /bz~e,doame
3O /
o -0" /
2O
00 g1'015
GoncenVatlon,wt.%
Fig. 16. Relationship between wear rate and velocity, impingement angle
and silica sand concentralion.
Table 4
Summary of variables obtained by bench tests of a pump
Impingementvariable
Velocity factor d"
(cz==0°, c ==3.7 wt.%.
d = 205 p.m)
Panicle variable
Concentrationfactorc"'
(v=16ms-r.a=O °,
d= 205 ttm)
Polyurclhan¢ 2.4 0.62
Fluidelastomer 2.1 0.59
Rubber 1.3 0.32
(wear) cc(t, - t,o)"C"(d- do) 3
Here, vo and m are dependent on the particle size but n is
independent. When comparing materials, the rubber wears
the least and is associated with a high value of vo and low
value of n.
Since the slurry jet test may serve as a laboratory test for
assessing slurry wear properties of materials, the damaged
surfaces obtained by the slurry jet test were studied in detail.
Fig. 17 shows scanning electron microphotographs of the
surfaces taken before and after tests. For the polyurethane,
which showed the highest wear rate, there are many pores on
the worn surface. The material which covers pores was found
to fracture quickly. The si',~ and the number of pores were
measured from the photographs. Their mean diameter and
distribution density were about 80 izm and 1500 per mmz,
consequently the ratio of the area of pore to that of the worn
surface exposed to impact was 0.4-0.5. Very probably, many
pores were produced in the bulk during the lining process of
the polyurethane, which caused the high wear rate. For the
fluid elastomer, few pores can be seen on the worn surface
although there are many pores on the original surface. The
surface was damaged by ploughing type abrasion. For tic
rubber, shear type wear occurred uniformly on the worn sur-
face. The rubber seems to tear off by repetitive scratching
due to the edges of particles, because of its high ability to

8. 218 E Iwai, K. Nambu / Wear 210 (1997) 211-219
Poly~ethane
Elaston~
Rut~¢¢
Fig. !7. Scanningelectronmicroplm(ograFhsof the surfacesbeforeandafter
tests,
absorb impact energy and also to stretch considerably before
failure. As a result, the slurry wear of the rubber is only
influenced slightly by the impingement angle and velocity.
Comparing the mechanical properties of the three lining
materials, the tear strength is much higher for the rubber and
the fluid elastomer than for the polyurethane although their
hardness and tensile strengths are similar. Therefore, we can
conclude that the rubber owes its high slurry wear resistance
to its high tear strength.
$. Conclusions
Slurry wear tests of elastomeric lining materials were car-
tied out in a slurry jet apparatus and in a prototype pump,
The following conclusions were obtained,
!. Fluid elastomer and rubber showed higher wearresistance
than martensitic stainless steel and hard metals,
2. The slurry wear rates of the polyurethane and the fluid
elastomer became maximum at the impingement angle of
approximately 30°, The rubber showed almost the same
wear rate regardless of impingement angle.
3. The slurry wear rate increased according to a power law
with jet velocity above a critical velocity and with sand
concentration.
4. As the particle size above a critical value increased at
constant weight particle concentration, the wear rate first
increased but then decreased.
5. The impingement variables and particle variables
obtained by both test methods show similar tendencies for
.
the three lining materials. The slurry wear loss can be
described by an empirical equation of the type
(wear) or. ( v -- Vo)nC~( d- do) 3
where Voand m are dependent on the particle size but n is
independent.
The polyurethane contained many pores in the bulk from
the lining process, resulting in the highest wear rate o~the
three lining materials. The rubber apparently owed its
highest slurry wear resistance to its high tear strength.
Acknowledgements
A part of this study was supported by Hosokawa Powder
Technology Foundation. The authors are grateful to Dr T.
Honda (Fukui University) and also for the help of Mr H.
Yamauchi, Y. Kumazaki and Y. Aoki who were students at
Fukui University.
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Biographies
Yoshiro lwai graduated from Fukui University in 1972 and
from the Postgraduate School, Kyoto University, in 1977. He
received a doctor's degree in engineering from Kyoto Uni-
versity in 1980. He was a lecturer from 1978 to 1982 and an
associate professor from 1982 to 1991 at Fukui University.
Since 1991 he has been a professor in the Department of
Mechanical Engineering at Fukui University. He worked as
a visiting assistant professor with Dr F.G. Hammitt at the

9. Y. iwai. g. Nambu / Wear 210 ¢! 997) 2 ! !-2 i 9 2 |9
University ofMichigan in 198I. His research interestsinelude
wear and cavitation erosion of various materials and lubri-
cation diagnostics using an optical particle sensor.
Kazuyuki Nambu graduated from the Departmentof Mechan-
ical Engineering, Kyoto University, in 1973. He received a
Master ofEngineeringdegree from Kyoto Universityin 1975,
Presently he is a mechanical engineering department project
manager with Mitsubishi Heavy Industries Ltd., Takasago
Machinery Works. He has been engaged in the development
and design of large pumps for irrigation, transportation and
waterworks.