Flofab MCST Series User manual

August 21, 2021
Rev. 1
INSTALLATION, OPERATION, AND
MAINTENANCE MANUAL
WITH PARTS LIST
MCST SERIES PUMPS
Flo Fab Inc.
www.flofab.com
MODELS
MCST-6

Manual - MCST Series
- 1 -
RECORD YOUR PUMP MODEL AND SERIAL NUMBER
Please record your pump modelandserialnumber in the spaces provided
below. Your Flo Fab distributor needs this information when you require parts or
service.
Pump Model:
Serial Number:
Flo Fab Inc.
www.flofab.com

Manual MCST Series
- 2 -
TABLE OF CONTENTS
INTRODUCTION
...................................................................................................................... - 4 -
SAFETY SECTION A
................................................................................................................- 6 -
INSTALLATION SECTION B
............................................................................................... - 8 -
Pump Dimensions
..................................................................................................... - 8 -
PREINSTALLATION INSPECTION
.............................................................................. - 9 -
POSITIONING PUMP
........................................................................................................ - 9 -
Lifting
............................................................................................................................. - 9 -
Mounting
.....................................................................................................................- 10 -
Clearance
.................................................................................................................... - 10 -
SUCTION AND DISCHARGE PIPING
.........................................................................- 10 -
Materials
..................................................................................................................... - 10 -
Line Configuration
.................................................................................................. - 10 -
Connections to Pump
.............................................................................................- 10 -
Gauges
..........................................................................................................................- 11 -
SUCTION LINES
............................................................................................................... - 11 -
Fittings
.........................................................................................................................- 11 -
Strainers
......................................................................................................................- 11 -
Sealing
..........................................................................................................................- 11 -
Suction Lines In Sumps
......................................................................................... - 12 -
Suction Line Positioning
.......................................................................................- 12 -
DISCHARGE LINES
......................................................................................................... - 13 -
Siphoning
....................................................................................................................- 13 -
Valves
........................................................................................................................... - 13 -
Bypass Lines
.............................................................................................................. - 14 -
AUTOMATIC AIR RELEASE VALVE
..........................................................................- 15 -
Theory of Operation
...............................................................................................- 15 -
Air Release Valve Installation
.............................................................................- 15 -
ALIGNMENT
......................................................................................................................- 16 -
Coupled Drives
......................................................................................................... - 17 -
Drive Belts
..................................................................................................................- 18 -
OPERATION SECTION C
....................................................................................................- 20 -
PRIMING
.............................................................................................................................- 20 -
STARTING
.......................................................................................................................... - 21 -
Rotation
.......................................................................................................................- 21 -
OPERATION
...................................................................................................................... - 21 -
Lines With a Bypass
................................................................................................- 21 -
Lines Without a Bypass
.........................................................................................- 21 -
Leakage
........................................................................................................................- 22 -
Liquid Temperature And Overheating
............................................................- 22 -
Strainer Check
.......................................................................................................... - 22 -
Pump Vacuum Check
............................................................................................. - 23 -
STOPPING
.......................................................................................................................... - 23 -
Cold Weather Preservation
................................................................................. - 23 -
BEARING TEMPERATURE CHECK
........................................................................... - 24 -

Manual MCST Series
- 3 -
TROUBLESHOOTING SECTION D
.................................................................................- 25 -
PREVENTIVE MAINTENANCE
................................................................................... - 26 -
PUMP MAINTENANCE AND REPAIR SECTION E
.................................................. - 28 -
PERFORMANCE CURVE
................................................................................................- 28 -
ILLUSTRATION
................................................................................................................ - 29 -
PARTS LIST
........................................................................................................................- 30 -
PUMP AND SEAL DISASSEMBLY AND REASSEMBLY
...................................... - 31 -
Back Cover and Wear Plate Removal
.............................................................. - 32 -
Rotating Assembly Removal
............................................................................... - 32 -
Impeller Removal
.................................................................................................... - 34 -
Seal Removal
............................................................................................................. - 34 -
Shaft and Bearing Removal and Disassembly
..............................................- 34 -
Shaft and Bearing Reassembly and Installation
..........................................- 36 -
Seal Installation
........................................................................................................- 37 -
Impeller Installation and Adjustment
.............................................................- 40 -
Rotating Assembly Installation
..........................................................................- 41 -
Back Cover and Wear Plate Installation and Adjustment
....................... - 42 -
PRESSURE RELIEF VALVE MAINTENANCE
.........................................................- 43 -
Final Pump Assembly
............................................................................................ - 43 -
LUBRICATION
.................................................................................................................. - 44 -
Seal Assembly
........................................................................................................... - 44 -
Bearings
...................................................................................................................... - 44 -
Power Source
............................................................................................................ - 45 -
WARRANTY
............................................................................................................................ - 46 -

- 4 -
Manual MCST Series
INTRODUCTION
Thank You for purchasing an FloFab pump. Read this manual carefully to learn
how to safely install and operate your pump. Failure to do so could result in
personal injury or damage to the pump.
Because pump installations are seldom identical, this manual cannot possibly provide
detailed instructions and precautions for every aspect of each specific application.
Therefore, it is the responsibility of the owner/installer of the pump to ensure that
applications not addressed in this manual are performed only after establishing that
neither operator safety nor pump integrity are compromised by the installation.
Pumps and related equipment must be installed and operated according to all
national, local and industry standards.
If there are any questions regarding the pump or its application which are not
covered in this manual or in other literature accompanying this unit, please contact
your FloFab distributor, or the FloFab Company:
Flo Fab Inc.
www.flofab.com
For information or technical assistance on the power source, contact the power
source manufacturer's local dealer or representative.

Manual MCST Series
- 5 -
HAZARD AND INSTRUCTION DEFINITIONS
The following are used to alert maintenance personnel to procedures which require
special attention, to those which could damage equipment, and to those which could
be dangerous to personnel:
Immediate hazards which WILL result in
severe personal injury or death. These
instructions describe the procedure
required and the injury which will result
from failure to follow the procedure.
Hazards or unsafe practices which
COULD result in severe personal injury
or death. These instructions describe the
procedure required and the injury which
could result from failure to follow the
procedure.
Hazards or unsafe practices which
COULD result in minor personal injury or
product or property damage. These
instructions describe the requirements
and the possible damage which could
result from failure to follow the
procedure.
NOTE
Instructions to aid in installation, operation, and maintenance or which clarify a
procedure.

- 6 -
Manual MCST Series
SAFETY SECTION A
This information applies to the MCST Series basic pumps. FloFab has no control
over or particular knowledge of the power source which will be used. Refer to the
manual accompanying the power source before attempting to begin operation.
This manual will alert personnel to known procedures which require special
attention, to those which could damage equipment, and to those which could be
dangerous to personnel. However, this manual cannot possibly provide detailed
instructions and precautions for each specific application or for every situation that
might occur during maintenance of the unit. Therefore, it is the responsibility of the
owner, installer and/or maintenance personnel to ensure that applications and/or
maintenance procedures not addressed in this manual are performed only after
establishing that neither personal safety nor pump integrity are compromised by
such applications or procedures.
Before attempting to open or service the
pump:
1. Familiarize yourself with this manual.
2. Disconnect or lock out the power source to
ensure that the pump will remain
inoperative.
3. Allow the pump to completely cool if
overheated.
4. Check the temperature before opening any
covers, plates, or plugs.
5. Close the suction and discharge valves.
6. Vent the pump slowly and cautiously.
7. Drain the pump.
This pump is designed to handle most
non-volatile, non-flammable liquids
containing specified entrained solids. Do not
attempt to pump volatile, corrosive, or
flammable materials which may damage the
pump or endanger personnel as a result of
pump failure.
After the pump has been positioned, make
certain that the pump and all piping
connections are tight, properly supported and
secure before operation.

Manual MCST Series
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Do not operate the pump without the guards
in place over the rotating parts. Exposed
rotating parts can catch clothing, fingers, or
tools, causing severe injury to personnel.
Do not remove plates, covers, gauges, pipe
plugs, or fittings from an overheated pump.
Vapor pressure within the pump can cause
parts being disengaged to be ejected with
great force. Allow the pump to cool before
servicing.
Do not operate the pump against a closed
discharge valve for long periods of time. If
operated against a closed discharge valve,
pump components will deteriorate, and the
liquid could come to a boil, build pressure,
and cause the pump casing to rupture or
explode.
Death or serious personal injury and damage
to the pump or components can occur if
proper lifting procedures are not observed.
Make certain that hoists, chains, slings or
cables are in good working condition and of
sufficient capacity and that they are
positioned so that loads will be balanced and
the pump or components will not be damaged
when lifting. Suction and discharge hoses and
piping must be removed from the pump
before lifting. Lift the pump or component
only as high as necessary and keep personnel
away from suspended objects.

Manual MCST Series
- 8 -
INSTALLATION SECTION B
Review all SAFETY information in Section A.
Since pump installations are seldom identical, this section offers only general
recommendations and practices required to inspect, position, and arrange the pump
and piping.
Most of the information pertains to a standard static lift application where the pump
is positioned above the free level of liquid to be pumped.
If installed in a flooded suction application where the liquid is supplied to the pump
under pressure, some of the information such as mounting, line configuration, and
priming must be tailored to the specific application. Since the pressure supplied to
the pump is critical to performance and safety, be sure to limit the incoming pressure
to 50% of the maximum permissible operating pressure as shown on the pump
performance curve.
For further assistance, contact your FloFab distributor or the FloFab Company.
Pump Dimensions
See Figures 1 for the approximate physical dimensions of the pump.
OUTLINE DRAWING
Figure 1. Pump Model MCST-6

Manual MCST Series
- 9 -
PREINSTALLATION INSPECTION
The pump assembly was inspected and tested before shipment from the factory.
Before installation, inspect the pump for damage which may have occurred during
shipment. Check as follows:
a. Inspect the pump for cracks, dents, damaged threads, and other obvious damage.
b. Check for and tighten loose attaching hardware. Since gaskets tend to shrink after
drying, check for loose hardware at mating surfaces.
c. Carefully read all warnings and cautions contained in this manual or affixed to the
pump, and perform all duties indicated. Note the direction of rotation indicated
on the pump. Check that the pump shaft rotates counterclockwise when facing
the impeller.
Only operate this pump in the direction
indicated by the arrow on the pump body and
on the accompanying decal. Refer to
ROTATION in OPERATION, Section C.
d. Check levels and lubricate as necessary. Refer to LUBRICATION in the
MAINTENANCE AND REPAIR section of this manual and perform duties as
instructed.
e. If the pump and power source have been stored for more than 12 months, some
of the components or lubricants may have exceeded their maximum shelf life.
These must be inspected or replaced to ensure maximum pump service.
If the maximum shelf life has been exceeded, or if anything appears to be abnormal,
contact your FloFab distributor or the factory to determine the repair or
updating policy. Do not put the pump into service until appropriate action has been
taken.
POSITIONING PUMP
Lifting
Pump unit weights will vary depending on the mounting and drive provided. Check
the shipping tag on the unit packaging for the actual weight, and use lifting
equipment with appropriate capacity. Drain the pump and remove all
customer-installed equipment such as suction and discharge hoses or piping before
attempting to lift existing, installed units.
Death or serious personal injury and damage
to the pump or components can occur if
proper lifting procedures are not observed.
Make certain that hoists, chains, slings or
cables are in good working condition and of
sufficient capacity and that they are positioned

Manual MCST Series
- 10 -
so that loads will be balanced and the pump or
components will not be damaged when lifting.
Suction and discharge hoses and piping must
be removed from the pump before lifting. Lift
the pump or component only as high as
necessary and keep personnel away from
suspended objects.
Mounting
Locate the pump in an accessible place as close as practical to the liquid being
pumped. Level mounting is essential for proper operation.
The pump may have to be supported or shimmed to provide for level operation or to
eliminate vibration.
Clearance
It is recommended that 18 inches (457 mm) of clearance be provided in front of the back cover to
permit removal of the cover and easy access to the pump interior. A minimum clearance of 11 inches
(279,4 mm) must be maintained to permit removal of the cover.
.
SUCTION AND DISCHARGE PIPING
Pump performance is adversely effected by increased suction lift, discharge elevation,
and friction losses. See the performance curve and operating range shown in
SECTION E to be sure your overall application allows pump to operate within the
safe operation range.
Materials
Either pipe or hose maybe used for suction and discharge lines; however, the
materials must be compatible with the liquid being pumped. If hose is used in suction
lines, it must be the rigid-wall, reinforced type to prevent collapse under suction.
Using piping couplings in suction lines is not recommended.
Line Configuration
Keep suction and discharge lines as straight as possible to minimize friction losses.
Make minimum use of elbows and fittings, which substantially increase friction loss.
If elbows are necessary, use the long-radius type to minimize friction loss.
Connections to Pump
Before tightening a connecting flange, align it exactly with the pump port. Never pull
a pipe line into place by tightening the flange bolts and/or couplings.

Manual MCST Series
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Lines near the pump must be independently supported to avoid strain on the pump
which could cause excessive vibration, decreased bearing life, and increased shaft
and seal wear. If hose-type lines are used, they should have adequate support to
secure them when filled with liquid and under pressure.
Gauges
Most pumps are drilled and tapped for installing discharge pressure and vacuum
suction gauges. If these gauges are desired for pumps that are not tapped, drill and
tap the suction and discharge lines not less than 18 inches (457,2 mm) from the
suction and discharge ports and install the lines. Installation closer to the pump may
result in erratic readings.
SUCTION LINES
To avoid air pockets which could affect pump priming, the suction line must be as
short and direct as possible. When operation involves a suction lift, the line must
always slope upward to the pump from the source of the liquid being pumped; if the
line slopes down to the pump at any point along the suction run, air pockets will be
created.
Fittings
Suction lines should be the same size as the pump inlet. If reducers are used in
suction lines, they should be the eccentric type, and should be installed with the flat
part of the reducers uppermost to avoid creating air pockets. Valves are not normally
used in suction lines, but if a valve is used, install it with the stem horizontal to avoid
air pockets.
Strainers
If a strainer is furnished with the pump, be certain to use it; any spherical solids
which pass through a strainer furnished with the pump will also pass through the
pump itself.
If a strainer is not furnished with the pump, but is installed by the pump user, make
certain that the total area of the openings in the strainer is at least three or four times
the cross section of the suction line, and that the openings will not permit passage of
solids larger than the solids handling capability of the pump.
This pump is designed to handle up to 3 inch (76,2 mm) diameter spherical solids.
Sealing
Since even a slight leak will affect priming, head, and capacity, especially when
operating with a high suction lift, all connections in the suction line should be sealed
with pipe dope to ensure an air-tight seal. Follow the sealant manufacturer's
recommendations when selecting and applying the pipe dope. The pipe dope should

Manual MCST Series
- 12 -
be compatible with the liquid being pumped.
Suction Lines In Sumps
If a single suction line is installed in a sump, it should be positioned away from the
wall of the sump at a distance equal to 1 1/2 times the diameter of the suction line.
If there is a liquid flow from an open pipe into the sump, the flow should be kept
away from the suction inlet because the inflow will carry air down into the sump, and
air entering the suction line will reduce pump efficiency.
If it is necessary to position inflow close to the suction inlet, install a baffle between
the inflow and the suction inlet at a distance 1 1/2 times the diameter of the suction
pipe. The baffle will allow entrained air to escape from the liquid before it is drawn
into the suction inlet.
If two suction lines are installed in a single sump, the flow paths may interact,
reducing the efficiency of one or both pumps. To avoid this, position the suction inlets
so that they are separated by a distance equal to at least 3 times the diameter of the
suction pipe.
Suction Line Positioning
The depth of submergence of the suction line is critical to efficient pump operation.
Figure 2 shows recommended minimum submergence vs. velocity.
NOTE
The pipe submergence required may be reduced by installing a standard pipe increaser
fitting at the end of the suction line. The larger opening size will reduce the inlet
velocity. Calculate the required submergence using the following formula based on the
increased opening size (area or diameter).

Manual MCST Series
- 13 -
Figure 2. Recommended Minimum Suction Line Submergence vs. Velocity
DISCHARGE LINES
Siphoning
Do not terminate the discharge line at a level lower than that of the liquid being
pumped unless a siphon breaker is used in the line. Otherwise, a siphoning action
causing damage to the pump could result.
Valves
If a throttling valve is desired in the discharge line, use a valve as large as the largest
pipe to minimize friction losses. Never install a throttling valve in a suction line.
With high discharge heads, it is recommended that a throttling valve and a system
check valve be installed in the discharge line to protect the pump from excessive
shock pressure and reverse rotation when it is stopped.
If the application involves a high discharge
head, gradually close the discharge throttling
valve before stopping the pump.

Manual MCST Series
- 14 -
Bypass Lines
Self-priming pumps are not air compressors. During the priming cycle, air from the
suction line must be vented to atmosphere on the discharge side. If the discharge line
is open, this air will be vented through the discharge. However, if a check valve has
been installed in the discharge line, the discharge side of the pump must be opened to
atmospheric pressure through a bypass line installed between the pump discharge
and the check valve. A self-priming centrifugal pump will not prime if there is
sufficient static liquid head to hold the discharge check valve closed.
NOTE
The bypass line should be sized so that it does not affect pump discharge capacity;
however, the bypass line should be at least 1 inch in diameter to minimize the chance of
plugging.
In low discharge head applications (less than 30 feet or 9 meters), it is recommended
that the bypass line be run back to the wet well, and located 6 inches below the water
level or cut-off point of the low level pump. In some installations, this bypass line may
be terminated with a six-to-eight foot length of 1 1/4 inch I.D. smooth-bore hose; air
and liquid vented during the priming process will then agitate the hose and break up
any solids, grease, or other substances likely to cause clogging.
A bypass line that is returned to a wet well
must be secured against being drawn into the
pump suction inlet.
It is also recommended that pipe unions be installed at each 90°elbow in a bypass
line to ease disassembly and maintenance.
In high discharge head applications (more than 30 feet, an excessive amount of
liquid may be bypassed and forced back to the wet well under the full working
pressure of the pump; this will reduce overall pumping efficiency. Therefore, it is
recommended that an FloFab Automatic Air Release Valve be installed in the
bypass line.
FloFab Automatic Air Release Valves are reliable, and require minimum
maintenance. See AUTOMATIC AIR RELEASE VALVE in this section for installation
and theory of operation of the Automatic Air Release Valve. Consult your AMOS
distributor, or contact the FloFab Company for selection of an Automatic Air Release
Valve to fit your application.
If the installation involves a flooded suction such as a below-ground lift station. A
pipe union and manual shut-off valve may be installed in the bleed line to allow
service of the valve without shutting down the station, and to eliminate the
possibility of flooding. If a manual shut-off valve is installed anywhere in the air
release piping, it must be a full-opening ball type valve to prevent plugging by solids.
If a manual shut-off valve is installed in a
bypass line, it must not be left closed during
operation. A closed manual shut-off valve may

Manual MCST Series
- 15 -
cause a pump which has lost prime to continue
to operate without reaching prime, causing
dangerous overheating and possible explosive
rupture of the pump casing. Personnel could
be severely injured.
Allow an over-heated pump to cool before
servicing. Do not remove plates, covers,
gauges, or fittings from an over- heated pump.
Liquid within the pump can reach boiling
temperatures, and vapor pressure within the
pump can cause parts being disengaged to be
ejected with great force. After the pump cools,
drain the liquid from the pump by removing
the casing drain plug. Use caution when
removing the plug to prevent injury to
personnel from hot liquid.
AUTOMATIC AIR RELEASE VALVE
Theory of Operation
When properly installed, an FloFab Automatic Air Release Valve will permit air
to escape through the bypass line and then close automatically when the pump is
fully primed and pumping at full capacity.
Some leakage (1 to 5 gallons [3.8 to 19 liters]
per minute) will occur when the valve is fully
closed. Be sure the bypass line is directed back
to the wet well or tank to prevent hazardous
spills.
* Consult the manual accompanying the Air Release Valve for additional information
on valve installation and performance.
Air Release Valve Installation
The Automatic Air Release Valve must be independently mounted in a horizontal
position between the pump discharge port and the inlet side of the discharge check
valve (see Figure 3 ). The inlet opening in the Air Release Valve is equipped with
standard 1-inch NPT pipe threads.

Manual MCST Series
- 16 -
Figure 3. Typical Automatic Air Release Valve Installation
Connect the valve outlet to a bleed line which slopes back to the wet well or sump.
The bleed line must be the same size as the outlet opening or larger, depending on
which Air Release Valve is being used. If piping is used for the bleed line, avoid the
use of elbows whenever possible.
NOTE
For multiple pump installations, it is recommended that each Air Release Valve be fitted
with an independent bleeder line directed back to the wet well. If multiple Air Release
Valves are installed in a system, do not direct bleeder lines to a common manifold pipe.
Contact your FloFab distributor or the FloFab Company for information
about installation of an Automatic Air Release Valve for your specific application.
ALIGNMENT
The alignment of the pump and its power source is critical for trouble-free
mechanical operation. In either a flexible coupling or V-belt driven system, the driver
and pump must be mounted so that their shafts are aligned with and parallel to each
other. It is imperative that alignment be checked after the pump and piping are

- 17 -
Manual MCST Series
installed, and before operation.
NOTE
Check Rotation , Section C , before final alignment of the pump.
When mounted at the FloFab factory, driver and pump are aligned before
shipment. Misalignment will occur in transit and handling. Pumps must be
checked and realigned before operation. Before checking alignment, tighten the
foundation bolts. The pump casing feet and/or pedestal feet, and the driver mounting
bolts should also be tightly secured.
When checking alignment, disconnect the
power source to ensure that the pump will
remain inoperative.
Adjusting the alignment in one direction may
alter the alignment in another direction. check
each procedure after altering alignment.
Coupled Drives
When using couplings, the axis of the power source must be aligned to the axis of the
pump shaft in both the horizontal and vertical planes. Most couplings require a
specific gap or clearance between the driving and the driven shafts. Refer to the
coupling manufacturer's service literature.
Figure 4. Aligning Spider Type Couplings
Figure 5. Aligning Non-Spider Type Couplings
Align spider insert type couplings by using calipers to measure the dimensions on the
circumference of the outer ends of the coupling hub every 90°. The coupling is in
alignment when the hub ends are the same distance apart at all points (see Figure 4 ).
Align non-spider type couplings by using a feeler gauge or taper gauge between the
coupling halves every 90°. The coupling is in alignment when the hubs are the same

Manual MCST Series
- 18 -
distance apart at all points (see Figure 5 ).
Check parallel adjustment by laying a straightedge across both coupling rims at the
top, bottom, and side. When the straightedge rests evenly on both halves of the
coupling, the coupling is in horizontal parallel alignment. If the coupling is misaligned,
use a feeler gauge between the coupling and the straightedge to measure the amount
of misalignment.
Drive Belts
When using drive belts, the power source and the pump must be parallel. Use a
straightedge along the sides of the pulleys to ensure that the pulleys are properly
aligned (see Figure 6 ). In drive systems using two or more belts, make certain that
the belts are a matched set; unmatched sets will cause accelerated belt wear.
MISALIGNED:
SHAFTS NOT PARALLEL
MISALIGNED:
SHAFTS NOT IN LINE
ALIGNED:
SHAFTS PARALLEL AND
SHEAVES IN LINE
Figure 6. Alignment of V-Belt Driven Pumps
Tighten the belts in accordance with the belt manufacturer's instructions. If the belts
are too loose, they will slip; if the belts are too tight, there will be excessive power
loss and possible bearing failure. Select pulleys that will match the proper speed ratio;
overspeeding the pump may damage both pump and power source.
Do not operate the pump without the guard in
place over the rotating parts. Exposed rotating
parts can catch clothing, fingers, or tools,
causing severe injury to personnel.
DRIVE BELT TENSIONING
General Rules of Tensioning
For new drive belts, check the tension after 5, 20 and 50 hours of operation and

Manual MCST Series
- 19 -
re-tension as required (see the following procedure for measuring belt tension).
Thereafter, check and re-tension if required monthly or at 500 hour intervals,
whichever comes first.
Ideal drive belt tension is the lowest tension at which the belt will not slip under peak
load conditions. Do not over-tension drive belts. Over-tensioning will shorten both
drive belt and bearing life. Under-tensioning will cause belt slippage. Always keep
belts free from dirt, grease, oil and other foreign material which may cause slippage.