Maag S Series, Installation, Operation & Maintenance Manual

Page: 7 / 16

MAAG-14000-E-02EMEA
5
S SERIES TWIN SCREW PUMPS
S E C T I O N X
I N S TA L L AT I O N
PIPING SYSTEM
Since the pump’s basic operating parts are designed to be affixed
on the two screws, extremely close running clearances exist
between the screws and the body; therefore, it is very important
to have the piping (especially the suction-side piping) cleaned
thoroughly before connecting the piping to the pump flanges .
After the pump unit has been installed and secured on its
foundation, pipe connections may be installed .
NOTE: Please see pump outline drawing for location of all pipe
connections, flange sizes and other notes pertinent to piping .
Pipes should be as short and direct as possible . Use long radius
elbows to change direction when needed .
When laying the suction and discharge piping and other supply
lines, there must be at least 1 .2 times the overall pump length
(without drive unit) in front of the gear casing of the pump .
Suction piping must be at least the same size of the inlet diameter; it
is acceptable if the suction pipes are one class larger than the inlet .
For example, if the size of the inlet is 150 mm (6 in), the suction
pipes should be 200 mm (8 in) . The pipe diameter [length of pipe
should be four (4x) times that of the pipe’s diameter] is used to
connect the suction pipes and the inlet . Discharge piping should
be the same size as the diameter of the outlet .
All major piping parts, including suction pipes, discharge pipes,
valves and strainers, should be supported independently and
installed properly to avoid any unnecessary strain on the pump .
The piping flanges must be properly aligned with the pump
flanges . To check alignment, insert flange bolts through the pipe
and pump flange . If bolts are easily moved within the bolt holes
and if flange faces are parallel with each other, the piping is
properly aligned .
If the pump is required to operate with suction lift, the suction
piping system must be properly made in relation to the original
design .
NOTE: NPSHa of suction piping must be larger than pump's NPSHr .
The pump cannot be expected to overcome deficiencies in the
suction piping system, such as narrow/thin runs of suction piping,
numerous elbows, valves and excessively high points above pump
suction, etc . In such cases, cavitation will invariably occur and the
pump may not operate at normal capacity .
Pump and pump accessories should be kept apart by valves to avoid
any force while pressure testing or washing the piping system .
PIPING SYSTEM ACCESSORIES
SUCTION STRAINERS
Maag suggests that suction strainers be installed on the suction
side of the pump at least temporarily until the new system is
deemed clean of solid residue . The screen area of the strainer should
be as large as possible . Generally, the strainer screen should be
constructed of 40 meshes, and 20 or 10 meshes for high-viscosity
applications . The net screen area should be approximately
5 to 8 times the flow cross-sectional area of the suction pipe .
However, if the viscosity of the media is in excess of 200 mm
2
/s,
then approximately 10 to 20 times the pipe cross-sectional area
is suggested for the net screen area . The maximum differential
pressure is 0 .1 bar (1 .5 psi) . The strainer on the suction side can be
used to prevent solids from entering into the pump and causing
damage to certain parts . Install pressure gauges on either side of
the strainer to indicate when the strainer should be cleaned . The
installed strainer should be easy to maintain and clean .
Generally, strainers can be used on all liquids except for those of
an extremely high viscosity . In these cases, the strainer cannot be
installed, therefore piping and accessory cleaning is mandatory .
CHECK VALVE
If the discharge piping system is subject to a high static head
and if the fluid handled flows back into the pump cavity when
stopping the pump, a check valve should be installed . This valve
will prevent hydraulic shock acting upon the pump, and most
importantly, it allows for separately starting the pump in a parallel
connection system .
PRESSURE-LIMITED VALVE
Pressure relief valves should be installed between the discharge
valve and the discharge flange of the pump in order to protect
both the pump and the piping systems . The relief valve should
match the pressure and capacity of the pump, and can lead
the released fluid back to the source of supply . As positive
displacement pumps, Maag pumps are equipped with a pressure-
limited valve to prevent pressure from building up . The starting
pressure of the pressure-limited valve should be 1 .5 bar (21 .8
psi) higher than the pump’s rated pressure . If the discharge pipe
is restricted or shut off, the pressure of the pump will build up
rapidly and the pressure-limited valve will be opened . However,
only when 30% to 50% of fluid is released back to the suction, will
the parts of the pump be protected from being badly damaged .
Therefore, all valves should be kept open while the pump is in
operation . The pressure-limited valve on the pump cannot be
adjusted by capacity or pressure .
GAUGES
A suitable meter
must be installed to monitor and control the pump
while in operation . The vacuum gauge and pressure gauge can be
separately installed on the inlet and outlet piping near the pump .
COUPLING ALIGNMENT
Coupling angle deviation, radial deviation and axial clearance
should be kept at a minimum in order to prevent noises, vibration
and to reduce wear and tear on bearings and couplings .
NOTE: Coupling axial clearance, per specifications, should be
within 2 mm to 5 mm (0 .08 in . to 0 .2 in .) . If using special coupling,
please consult with the manufacturer’s regulations .
Maag pump aggregate (including driver, base-plate and other
accessories) has been aligned (coupling) prior to delivery . However,