MTH PUMPS D91 SERIES User manual

Section
D91
Page 501
Dated
June 2004
D91 SERIES
Pump Manual
HORIZONTAL CLOSE COUPLED

UNIT INSPECTION
Inspect the unit for damage. Report
any damage to freight carrier im-
mediately. Check motor nameplate to
make sure voltage and phase match
the available power supply.
INSTALLATION
Locate the pump as close to the
liquid source as possible. Protect
the pump from freezing. The pump
should be located at a low point to
keep the impeller submerged at all
times. Always leave room around the
pump for servicing and ventilation.
Units may be installed horizon-
tally, inclined, or vertically. All piping
should be independently supported
and
never
forced into fi tting, this will
cause undue stress and could cause
binding within the pump.
SUCTION PIPING
Always use pipe that is the same size
or one size larger than the suction
size of the pump. NEVER use pipe
smaller than the pump suction size.
The D91EF has a 2” NPT suction and
we recommend a section of pipe 20
inches long as the lead suction pipe.
See Typical Piping Diagram fi gure
1-1. This allows for a smooth even
entry of liquid into the impeller. We
also suggest installing a gate valve
and a union so the pump can easily
be isolated for servicing.
CAUTION -Never use the suction iso-
lation valve to throttle the pump.
Make sure all joints are tight. Avoid
air pockets. If an eccentric pipe
reducer is used, make sure it is
installed straight side up. Air in the
suction line can cause the pump to
cavitate. Always make sure suction
pipe and fi ttings are independently
supported.
NEVER
use the pump to
act as pipe support, this could make
the pump bind or break.
DISCHARGE PIPING
Always use pipe that is the same
size or one size larger than the
discharge size of the pump. If you
use pipe smaller than the 1 1/2”
NPT discharge on the D91EF, the
pumping capacity will be diminished.
We recommend a section of pipe 15
inches long as the lead pipe out of
the pump discharge. A check valve,
gate valve and a union should also
be installed in the discharge line for
pump throttling and servicing. See
Typical Piping Diagram fi gure 1-1.
Make sure the discharge line is well
supported. NEVER use the pump as
pipe support.
ELECTRICAL CONSIDERATIONS
Electrical supply must be a separate
branch circuit with fuses or circuit
breakers. Install a disconnect switch
as close to the pump as possible.
Wire in accordance with the National
Electric Code and local codes where
applicable.
CAUTION -Always disconnect electri-
cal power when handling the pump or
controls.
Motors must be wired for proper
voltage. Motor wiring diagram is on
the motor nameplate. Single-phase
motors are usually furnished as dual
voltage 115/230/1/60. Three phase
motors are usually furnished as tri
voltage 208/230/460/3/60. All three
phase motors require a magnetic
motor starter and thermal overload
protection. Single-phase motors up
to and including 1 horsepower have
built in thermal protection. Check
motor nameplate to confi rm overload
protection is built in. All single-phase
motors above 1 HP require magnetic
starters and thermal overload protec-
tors. Always limit your wire size so
the maximum voltage is no more than
10% of motor nameplate voltage at
the motor leads. If this voltage drop
is exceeded, motor and pump life will
be greatly diminished.
MOTOR ROTATION
The correct motor rotation (when
viewed from the motor end of the
pump) is clockwise. Pop cap off the
back of the motor; the motor shaft is
now exposed for viewing. Switch the
power on and off quickly and observe
the motor shaft. If the rotation is
counterclockwise change any two
motor leads on a three-phase motor.
Single-phase motors are nonrevers-
ible.
PUMP STARTUP
Make sure the suction gate valve
is wide open; when the pump is in
operation this valve should never be
throttled. Open the discharge gate
valve about 1/4 open. This will prime
the pump and force air out.
NEVER
Figure 1-1

run the pump dry. Rotating parts wilI
eventually seize and mechanical seal
damage may occur.
NEVER
run the
pump at shutoff conditions. Energy
from the motor is imparted to the
liquid which is converted to heat. The
liquid may fl ash to vapor causing the
pump to burst.
Once the pump is started and run-
ning adjust the discharge gate valve
to your desired pressure. Make sure
there are no leaks in pump connec-
tions and piping. Check your motor
amps to make sure the motor is
running within its rated capacity. The
pump should be running smooth with
no vibration or excessive noise.
MAINTENANCE
The bearings in the close-coupled
motor are sealed and permanently
greased. No other greasing is
required. Periodic 6-month checks
of the unit should be made to make
sure the unit runs smoothly at its de-
sired performance. If possible keep a
log of the suction pressure, discharge
pressure and motor amps. Over a
period of time this information can tell
you if the pump parts are starting to
wear. If a problem arises check the
troubleshooting section for guidance.
If the problem cannot be rectifi ed call
your local distributor or the factory.
PUMP DISASSEMBLY
1. Shut disconnect off. Always make
sure the power to the pump is off.
2. Close suction and discharge gate
valves.
3. Drain the pump by removing the
top and bottom 1/8 NPT plugs on the
casing
4. Remove the motor hold down
bolts.
5. Remove the four bolts that hold the
adapter to the casing.
6. Slide back pull out assembly out
of casing, it may be necessary to pry
them apart.
7. Remove the casing o-ring and set
it aside. Inspect it to make sure it’s
not cut. Clean the o-ring groove on
the casing.
8. Remove the impeller cap screw.
2
1
3
4
5
6
7
8
9
1
0
1
1
1
4
1
5
1
2
1
3
9. The back of the motor will have a
small cap on it, pry it off. This reveals
the end of the motor shaft which has
a screwdriver slot or fl ats on it.
10. Remove the impeller. Use a
screwdriver or a wrench to hold the
exposed motor shaft. Carefully grab
the impeller (be careful not to cut
yourself on any sharp edges) and
turn it counterclockwise. It may be
very hard to get the impeller free.
11. Remove the mechanical seal
rotating elements.
12. Remove the four bolts holding the
adapter to the motor. The adapter,
which still has the stationary mem-
bers of the seal in it, will now pull off
the motor.
13. Remove the stationary member
of the seal and clean all the parts. Be
very careful not to scratch the seal
face, this will cause the seal to leak.
14. To reassemble follow the direc-
tions in reverse.
D91EF Bronze Fitted
1 FE19DGNISAC NORITSAC03SSALC 41004 1
SSARB 51004
2
MJ481-3419ARETPADA
NORITSAC03SSALC
61004
1
MJ512-3129ARETPADA 71004
MJ652-4529ARETPADA 42004
MJ481-3419ARETPADA
SSARB
81004
MJ512-3129ARETPADA 91004
MJ652-4529ARETPADA 32004
3MJ512-34119DRELLEPMI EZNORBNOCILIS 50003 1
MJ623-45219DRELLEPMI EZNORBNOCILIS 60003
4
MJ512-341LAESLACINAHCEM
N-ANUB 301-S
1
TPE 401-S
NOTIV 501-S
MJ623-452LAESLACINAHCEM
N-ANUB 601-S
TPE 701-S
NOTIV 801-S
5MJ512-341EVEELS SSARB 00001 1
MJ623-452EVEELS 10001
6 G
NISACGNIR-O
N-ANUB 461-S
1TPE 561-S
NOTIV 661-S
7
MJ512-341REHSAWGNIR-O
N-ANUB 141-S
1
TPE 241-S
NOTIV 341-S
MJ623-452REHSAWGNIR-O
N-ANUB 441-S
TPE 541-S
NOTIV 641-S
8
MJ512-341RELLEPMIGNIR-O
N-ANUB 531-S
2
TPE 631-S
NOTIV 731-S
MJ623-452RELLEPMIGNIR-O
N-ANUB 831-S
TPE 931-S
NOTIV 041-S
9MJ512-341REHSAWRELLEPMI SSARB 20001 1
MJ623-452REHSAWRELLEPMI 30001
01 MJ512-341WERCSPACRELLEPMI SSARB1X61-8/3 02057 1
MJ623-452WERCSPACRELLEPMI SSARB1X31-2/1 73057
11 MJ512-341YEK LEETSSSELNIATS 40001 1
MJ623-452YEK 50001
21 GULPEPIP SSARBTPN8/1 54896 5
31 GULPEPIP SSARBTPN4/1 58586 2
41 MJ481-341WERCSPAC LEETS1X61-8/3 13991 4
MJ512-312WERCSPAC LEETS1X31-2/1 75991
51 WERCSPAC LEETS4/11X31-2/1 85991 8
61 ROTOM --- --- 1

TROUBLESHOOTING
A.) PUMP WILL NOT RUN
1.) Circuit breaker is open
2.) Thermal overload has tripped
3.) Improper voltage supplied to the
motor
4.) Wiring connections are loose
5.) Blown fuse
6.) Pump controls in off position
7.) Motor wired improperly
8.) Motor is defective
B.) GPM CAPACITY IS LOW
1.) Pump is not throttled correctly
2.) Pump is running backwards
3.) Pump has lost its prime
4.) The impeller was sized wrong -the
diameter is too small
5.) Impeller is worn -clearance
opened up
6.) Air or gas in the liquid
7.) NPSHA is to low
8.) Piping is undersized
9.) The impeller has a vane or vanes
plugged with debris
10.) A strainer is partially plugged
11.) Pump is undersized for the
system
12.) Phase loss -one leg of a 3-phase
motor went out
C.) EXCESSIVE NOISE/VIBRATION
1.) Rotating parts are binding
2.) Pump is cavitating
3.) Defective motor
4.) Pump is running backwards
5.) Air or gas in system
6.) Impeller is plugged with debris
7.) Pump or piping is loose
8.) Pump is not throttled correctly
- running wide open