hp20mdl1sm-rev0621
Model HP20 High Pressure •
17
sandpiperpump
.
com
HG-CF-1194-A - 12.02.10
Page 8
Read these instructions
c o m p l e t e l y , b e f o r e
installation and start-up. It
is the responsibility of the purchaser to
retain this manual for reference.
F ai l ure t o c om pl y wi t h t he
recommendations stated in this
manual will damage the pump, and
void factory warranty.
IMPORTANT!
SERVICE
The following sections give a general
overview on how to service all
models of BLAGDON Diaphragm
Pumps. For details on individual part
numbers, quantities, materials, etc.,
please consult the parts list supplied
with the pump.
NOTE :
Before commencing
any service or maintenance work
on the pump, ensure that the air
supply has been disconnected or
isolated.
AIR VALVE SYSTEMS
PNEUMATIC TYPE
Remove the 4
screws securing the valve block to
the valve chest, together with any
associated gaskets or seals.
Remove slide valve plate & slide
valve from the valve block assembly.
Clean all parts thoroughly and
inspect for excessive wear, replacing
where necessary.
The slide valve and valve plate
contact faces should be flat and free
from scratches. A light polishing on a
flat surface with a fine abrasive paper
will remove most scratches.
If excessive wear is suspected in the
valve block bore or valve carrier,
remove the valve block plugs and
withdraw the valve carrier. Check
valve block plug o-rings for wear or
attack & replace where required.
Clean the valve carrier & valve block
bore with white spirits to remove any
oil films.
NOTE :
T h e n o m i n a l
diametrical clearance between the
valve carrier and the valve block
block bore should be 0.05 -
0.0
9mm. A clearance in excess of
this will cause the valve system to
run erratically.
Apply a light grease to the valve
block plug O-rings when re-
assembling into the valve block bore.
Any damage to the O-ring may cause
the valve system to malfunction.
Re-assemble the valve block
assembly & re-torque in accordance
to the settings shown in the parts list.
In the event of a complete air-side
overhaul, the pump should be dis-
assembled down to the centre
section assembly as described later
in the “Wet
-
Side Overhaul” section.
With the valve block assembly
dismantled, remove the inner covers
where appropriate.
A careful note of the position of all
related seals and gaskets should be
made to facilitate re-assembly.
Remove diaphragm shaft bushes,
where appropriate, and check all
seals and „O‟ rings for wear or
d a m a g e . I f w o r n , r e p l a c e
immediately.
NOTE:-
The integrity of the
diaphragm shaft seals is essential
for the correct functioning of all
pneumatically actuated valve
systems.
Check the diaphragm shaft for
excessive wear as this will result in
premature seal failure. Replace as
required. Lubricate all components
and re-assemble as detailed above,
in reverse order. Ensure the correct
position of all components detailed in
all sectional assembly drawings.
WET-SIDE OVERHAUL
REPLACING BALL VALVES
Remove discharge manifold from
pump assembly together with
associated valve balls, seats and „O‟
rings.
NOTE :-
The orientation of the
valve seat relative to the valve ball
should be noted as incorrect
positioning may result in a
performance loss.
Turn pump through 180
o
and remove
the suction manifold. Clean and
inspect the components. Check for
any wear or damage and replace as
required.
NOTE :-
Ball or valve seat wear
may result in loss of performance
and suction lift.
Re-assemble the valve balls/seats
and ensure manifolds are adequately
torqued to the settings shown in the
parts list.
R E P L AC I N G D I AP H R A G M S
Remove both suction and discharge
manifolds as detailed in the previous
section, removing all ball valves,
seats and „O‟ rings.
Loosen and remove both outer
covers from the pump assembly.
The orientation of the covers should
be noted so as to facilitate re-
assembly.
Holding one of the frontplates in a
vice, („soft jaws‟ should be fitted), or
with an adjustable spanner, loosen
and remove the frontplate from the
opposite end. Remove the
diaphragm, backplate and bumpstop
from diaphragm shaft.
Carefully withdraw the diaphragm
shaft from the centre section and
hold the free end in a vice, holding
between the flats machined on the
end. Loosen and remove the
frontplate and remove the diaphragm
together with backplate and
bumpstop (where fitted).
NOTE :-
Care should be taken with
all plastic, coated and hygienic
pumps, so that the surface of the
frontplate is not damaged.
Thoroughly clean all parts and check
for wear, damage, swelling, cracking,
delamination and chemical attack.
Replace components where required.
NOTE :-
Rubber diaphragms
should be replaced if they are
worn to such an extent that the
fabric re-enforcing is evident on
the surface of the diaphragm.
For pumps fitted with PTFE
diaphragms, a light coating of grease
should be applied to the back-up
diaphragm prior to re-assembly.
Before re-assembly, it is advisable to
check the condition of the diaphragm
shaft seal/‟O‟ rings for wear or attack.
If either is evident, it is recommended
that they be replaced.
Assemble the diaphragms onto the
shaft in a reverse sequence to their
removal. Care should be taken as to
the orientation of the diaphragm
relative to the front and back plates.
All diaphragms have “AIR SIDE”
molded onto one side. The backplate
must be fitted adjacent to the AIR
SIDE of the diaphragm.
4: AIR
END
