Circor IMO BK12DHZ User manual

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PRODUCT SERVICE MANUAL
FOR
BK12DHZ PUMPS
WARNING
This manual, and the GENERAL INSTRUCTION MANUAL SRM00046, should be read
thoroughly prior to pump installation, operation or maintenance.
Manual No. SRM00095 Rev 03 (20-0051) March, 2020

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READ ENTIRE PAGE BEFORE PROCEEDING
FOR THE SAFETY OF PERSONNEL AND TO PREVENT DAMAGE TO EQUIPMENT, THE FOLLOWING
NOMENCLATURE HAS BEEN USED IN THIS MANUAL:
DANGER
Failure to observe precautions noted in this box can result in severe bodily injury or
loss of life.
WARNING
Failure to observe precautions noted in this box can cause injury to personnel by
accidental contact with equipment or liquids. Protection should be provided by user
to prevent accidental contact.
CAUTION ATTENTION
Failure to observe precautions noted in this box can cause damage or failure of
equipment.
Non-compliance of safety
instructions identified by
the following symbol could
affect safety for persons:
Safety instructions where
electrical safety is
involved are identified by:
Safety instructions which
shall be considered for
reasons of safe operation
of the pump and/or
protection of the pump
itself are marked by the
sign:
ATTENTION
CONTENTS
SAFETY AND TABLE OF CONTENTS ………………………………………………...... 2
A. GENERAL INSTRUCTIONS ................................................................................ 3
B. INTRODUCTION................................................................................................... 3
C. DESCRIPTION OF THE PUMP ............................................................................ 3
D. PUMP MODEL IDENTIFICATION ........................................................................ 4
E. ORDERING INSTRUCTIONS .............................................................................. 4
F. OPERATION ........................................................................................................ 4
G. PARTS LIST ......................................................................................................... 5
H. PUMP MAINTENANCE (Disassembly, Assembly) ................................................ 6
SEAL DRAWING................................................................................................ 10
BOLT TORQUE CHART .................................................................................... 11
TROUBLESHOOTING ...................................................................................... 12
I. FIELD AND FACTORY SERVICE AND PARTS .................................................... 12
J. ASSEMBLY DRAWING ........................................................................................ 13-16
ATTENTION
If operation of pump is critical to your business, we strongly recommend you keep
a spare pump or major repair kit in stock at all times. As a minimum, a minor
repair kit (o-rings, gaskets, shaft seal and bearings) should be kept in stock so
pump refurbishment after internal inspection can be accomplished.

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A. GENERAL INSTRUCTIONS
Instructions found herein cover disassembly, assembly and parts identification of Series
BK12DHZ pumps.
NOTE: Individual contracts may have specific provisions that vary from this manual.
Should any questions arise which may not be answered by these instructions,
refer to General Instructions Manual, SRM00046, provided with your order. For
further detailed information and technical assistance please refer to Imo Pump,
Technical/Customer Service Department, at [phone].
This manual cannot possibly cover every situation connected with installation, operation,
inspection, and maintenance of equipment supplied. Every effort was made to prepare text of
manual so that engineering and design data is transformed into most easily understood
wording. Imo Pump must assume personnel assigned to operate and maintain supplied
equipment and apply this instruction manual have sufficient technical knowledge and are
experienced to apply sound safety and operational practices which may not be otherwise
covered by this manual.
In applications where equipment furnished by Imo Pump is to become part of processing
machinery, these instructions should be thoroughly reviewed to ensure proper fit of said
equipment into overall plant operational procedures.
WARNING
If installation, operation and maintenance instructions are not correctly and strictly followed and
observed, injury to personnel or serious damage to pump could result. Imo Pump cannot accept
responsibility for unsatisfactory performance or damage resulting from failure to comply with instructions.
B. INTRODUCTION
Instruction manual covers Series BK12DHZ Imo pumps. This series of pumps has been
designed for use in high pressure fuel oil applications. Model, and design construction of each
pump can be identified by designator code on pump nameplate. Definitions of model
designators are identified in Figure 1.
C. DESCRIPTION OF EQUIPMENT
BK12DHZ Series pumps are positive displacement, rotary screw pumps consisting of precision
bored housings that enclose a driven screw (power rotor) and four to eight intermeshing
following screws (idler rotors). These screws, when rotating, form a succession of closures or
cavities. As they rotate, fluid is moved axially from inlet port to outlet port in a continuous,
uniform flow with minimum fluid pulsation and pump noise.

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D. PUMP MODEL IDENTIFICATION
This instruction manual covers Imo Series BK12DHZ pumps with rotor size 187, 250, 275, 312,
350 and 400. The model of each pump is identified on pump nameplate. Refer to Figure 1 and
Table 2 for instructional keys when using this manual.
FIGURE 1
E. ORDERING INSTRUCTIONS
When corresponding with Imo Pump regarding Series BK12DHZ pumps, refer to pump nameplate, this
instruction manual, and assembly drawing as instructed below:
1. From pump nameplate, record the pump model number, serial number and manufactured date.
2. Record instruction manual number, revision and date.
3. From the assembly drawing and/or parts list (table 2) in manual, provide IDP number(s) and names
for replacement part(s).
4. Give above information to your Imo service representative.
Imo sales and service representatives are listed herein and in General Instruction Manual, SRM00046.
F. OPERATION
F.1 LIQUID LIMITATIONS
Never operate with thin liquids such as solvents or water. The pump is designed for liquids having
general characteristics of oil.

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F.2 OPERATING LIMITS
CAUTION ATTENTION
Operating conditions, such as speed, fluid viscosity, temperature inlet pressure,
discharge pressure, filtration, duty cycle, drive type, mounting, etc., are interrelated.
Due to these variable conditions, specific application limits may be different from that
of operational limitations. Equipment must not be operated without verifying system’s
operating requirements are within pump’s capabilities.
Under no circumstances are following operating limits (specified in Table 1) to be exceeded
without specific approval from Imo Pump.
Table 1 – Normal Pump Operating and Structural Limits
MAXIMUM SPEED ...........................................................3600 RPM (Depending on Lead)
VISCOSITY ..............................................1 cSt Minimum – 3000 SSU (650 cSt) Maximum
MINIMUM – MAXIMUM LIQUID TEMPERATURE ........................ 0 to 250 F (-18 to 121 C)
MAXIMUM INLET PRESSURE ............................................................150 psig (10.3 Barg)
MAXIMUM DISCHARGE PRESSURE .......................... 2200 psig (103.4 Barg) Cont. Duty
FILTRATION ............................................... (See General Instruction Manual, SRM00046)
DRIVE .................................................................................................................... Direct only
MOUNTING ........................................................... Foot or Flange mounted in any attitude
G. PARTS LIST Table 2 – Pump Parts List
IDP QTY DESCRIPTION KIT IDP QTY DESCRIPTION KIT
1 1 Case 46 1 Inboard Cover
2 1 Inlet Head 47 4 Bearing Retaining Bolt
3 2 Vent Pin XX 48 1 Seal Seat Adapter
4 16 Cover Bolts (8 on 187,250 Size) 49 1 Ball Bearing X
6 1 Stop Pin 63 1 Power Rotor XX
7 1 Dyna Seal XX 66 1 90° Elbow (Not 187 &250)
8 2 Housing Retaining Ring XX 67 2 Pipe Plug (4 on 275)
9 1 Inlet O-Ring X 68 1 Nipple (Not on 187 and 250)
21 2 Suction Idler 69 1 Fitting (Not on 187 and 250)
22 1 Idler Stop XX 70 1 Elbow
23 2 Cups XX 71 1 Tubing
24 1 Discharge Housing XX 73 1 Suction Housing XX
25 1 Seal XX 74 1 Elbow (187 & 250 Only)
26 1 Tube 79 1 Floating BP Bushing XX
27 4 Tube O-Ring 81 1 Idler Stop Cap Screw
28 2 Housing O-Ring X 83 1 Seal Seat O-Ring X
29 1 Thrust Plate X 85 1 Pipe Plug (400 Size Only)
31 1 Key 90 2 Thrust Plate Spacers
35 2
Discharge Idlers (6 on 312 Size
& 2 on 400 size
)
XX 91 1 Thrust Plate Bolts
38 2
Seal Spacer
(
Not 187, 350 & 400 sizes
)
92 1 Thrust Balance Tube
42 2 Bearing Retaining Ring X 93 4 Middle Idlers (400 Size Only) XX
43 1 Bearing Retainer
X = Minor Repair Kit Items.
XX = Major Repair Kit Items. (Items marked (X) are included in Major Repair Kit).

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H. PUMP MAINTENANCE
WARNING
Failure to observe precautions while installing, inspecting and maintaining pump can
cause injury to personnel from accidental handling of liquids that may harm skin or
clothing, or fire hazard risks from flammable liquids, or injury from high pressure fluid jets.
DANGER
BEFORE working on equipment, make sure all power to equipment is disconnected and
locked-out.
H.1 GENERAL COMMENTS
NOTE: Part number identifiers (IDP’s) contained within parenthesis such as (10) refer to circled
numbers shown on assembly drawings.
H.2 TOOLS REQUIRED
Procedures described in this manual require common mechanics hand tools, a torque wrench, dial
indicator and suitable lifting device (such as) slings, straps, etc.
H.3 DISASSEMBLY PROCEDURES
SPECIAL NOTE: To service mechanical seal and ball bearings ONLY perform H.3, Steps
1, 6, 7,8 and 9 and H.4, Steps 8, 9, 10 and 11 ONLY.
CAUTION
Fluid leakage from disassembly of pump may make floor slippery and cause personal injury.
1. Close suction and discharge piping to pump and remove pipe plug (67) to drain unit. Remove
seal piping (71). Remove pump from driver, coupling and base plate. Remove coupling hub
and key (31).
2. Remove bolts (4) and inlet head (2). Remove O-ring (9) from inlet head (2).
3. Remove thrust plate (29), and oil balance tube (92) with O-rings (27) by removing hex bolts
(91) and thrust spacers (90). Remove O-rings (27) from tube (92).
4. Remove cups (23) from suction idlers (21).
5. Remove suction idlers (21) by unscrewing them from inlet end of pump. Remove remaining
idlers (35) from housings (73, 24) by rotating power rotor (63) in a counter-clockwise direction.
CAUTION
Do not permit idlers (21, 93, and 35) to drop as they emerge from housings (73, 24).
6. Remove bolts (47) and bearing retainer (43).
7. Remove assembled power rotor (63). Removal of power rotor (63) includes removal of Truarc
rings (42), ball bearing (49), seal seat adapter (48), spacer (38) and mechanical seal (25).

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8. Disassemble power rotor (63) as follows: See Figure 1 for seal drawing.
a. Using a flat nosed tool, such as a screw driver, remove Truarc rings (42) located on both
sides of ball bearing (49) from grooves in power rotor (63).
b. Sealed ball bearing is assembled to power rotor (63) with a light press fit. Ball bearing (49)
may be removed by using a bearing puller or a vertical arbor press. When using press, two
pieces of key stock are to be placed through openings of mechanical seal seat adapter (48)
underneath ball bearing (49) on both sides of power rotor shaft. Key stock should be long
enough to support power rotor (63) as it is placed in press. Press ram is to be positioned
against power rotor (63) coupling end face. Gently press power rotor (63) through ball
bearing (49). Ensure power rotor (63) does not fall to floor once ball bearing (49) is off of its
diameter.
c. Remove seal seat adapter (48) from power rotor (63), then remove mechanical seal
stationary seat from seal seat adapter (48). Loosen set screws on mechanical seal rotating
assembly body and remove from power rotor (63). Remove spacer (38) from the power
rotor (63).
9. Remove O-ring (83) from inboard end cover (46).
10. Remove bolts (4) and inboard cover (46) from case (1).
11. Remove O-ring (28) from inboard cover (46).
12. Remove idler stop (22) from inboard cover (46) by removing bolts (81).
13. Remove floating balance piston (79) from inboard cover (46).
14. Remove stop pin (6) and Dyna seal (7) from case (1).
15. Remove housing snap rings (8) from case (1).
16. Remove housing (24) from case (1) and O-ring (28) from housing (24).
CAUTION
Do not permit housing (24) to drop as it is removed from pump.
17. Remove tube (26) from housing (24 or 73), and O-rings (27) from tube (26).
18. Remove aligning vent pins (3) from housing (24 or 73).
19. Remove housing (73) from case (1).
CAUTION
Do not permit housing (73) to drop as it is removed from pump.
H.4 PUMP ASSEMBLY PROCEDURE
Note: Prior to reassembly of pump, all parts should be cleaned and inspected for nicks and burrs.
Replace all worn or damaged parts. Imo Pump recommends replacement of all O-rings (9,
27, 28, 83), Dyna Seal (7), mechanical seal (25) and ball bearing (49) when these parts are
disturbed from their previously installed positions. Coat all parts with light lubricating oil to
assist in assembly.

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Note: Bolts (81) (except for 187 rotor size) have Nylok threads. Torque stated on appropriate
assembly drawing for bolt (81) does not include additional torque to install fasteners
containing nylok inserts. Torque required for first application is much higher than for
subsequent applications. To ensure required preload on Nylok fastener is achieved for
each application, the following procedure is mandatory assembly practice.
1. Using a suitable torque wrench, install fastener in mating piece until Nylok insert is
completely engaged. Note torque required.
2. Add torque measured in step1. to torque value on assembly drawing.
3. Complete tightening fastener to torque value determined in 2.
1. Install O-ring (28) in groove of discharge housing (24).
2. Install discharge housing (24) in pump case (1), from suction end of case, aligning groove in
housing (24) to stop pin hole in case (1). Install stop pin (6) with Dyna Seal (7) in case (1).
3. Install O-rings (27) on oil balance tube (26) and oil balance tube (26) in discharge end of inlet
housing (73). Install vent pins (3) in same end of inlet housing (73).
4. Install assembled inlet housing (73) in case (1), ensuring that oil balance tube (26) and vent
pins (3) engage holes in discharge housing (24).
5. Install housing snap rings (8) in case (1).
6. Install balance piston (79) on inboard cover (46). Install idler stop (22) on inboard cover (46)
with cap screws (81). Torque cap screws to proper value for pump size in torque table Figure
2. Install O-ring (28) on inboard cover (46).
7. Install inboard cover (46) on case (1) using bolts (4). Be sure seal return is facing up. Torque
bolts to proper value for pump size in torque table figure 2.
8. Assemble power rotor (63) and mechanical seal (25) as follows (see seal insert Figure 2).
a. Install O-ring in groove of mechanical seal (25) stationary seat. Install mechanical
stationary seat in seal spacer (48) ensuring that spring pin is properly positioned to engage
slot in seal seat.
b. Install spacer (38) on power rotor (63) when required.
c. Install mechanical seal (25) rotating assembly on power rotor (63) next to spacer (38).
Tighten set screws.
d. Wipe mechanical seal rotating and stationary faces with a clean, lint free cloth before
assembling faces together.
e. Install assembled bearing spacer (48), with stationary seat, to power rotor shaft next to
mechanical seal rotating face.
f. Install inner Truarc ring (42) in groove of power rotor (63).
g. Press bearing (49) on power rotor (63), pressing only on inner race of ball bearing (49) until
it is located next to inner Truarc ring (42).
h. Install outer Truarc ring (42) in groove of power rotor (63).

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9. Install O-ring (83) in seal bore of inboard cover (46).
10. Install assembled power rotor (63) in pump, centering all parts as they enter inboard cover
(46). Align one of openings in spacer (48) over drain in inboard cover (46).
11. Install bearing retainer (43) on inboard cover (46) using bolts (47). Torque bolts to proper
value for pump size in torque table figure 2.
12. Install idlers (35, 21) into housings by meshing threads with power rotor thread and screwing
them into housing idler bores.
13. Install cups (23) to ends of suction idlers (21).
14. Install O-rings (27) on oil balance tube (92) and oil balance tube (92) in inlet housing (73).
15. Install thrust plate (29) to pump case (1) with spacers (90) and thrust plate bolts (91), ensuring
that pin hole in thrust plate (29) engages tube (92) in suction housing (73). Torque bolts to
proper value for pump size in torque table figure 2.
16. Install O-ring (9) to groove in inlet head (2).
17. Install inlet head (2) using bolts (4). Torque bolts to proper value for pump size in torque table
Figure 2.
18. Install seal piping (71) and drain plug (67).
Note: Inlet head (2) can be rotated and repositioned in 90° increments to suit suction piping.
To change inlet position, disconnect seal piping (71), remove bolts (4) and rotate inlet
head to desired position. Install bolts (4) and Torque bolts to proper value for pump
size in torque table figure 2. Reconnect seal piping (71).
19. Install coupling hub key (31). Install and align pump and driver as specified in General
Instruction Manual, SRM00046.
H.5 SPECIAL TESTING INSTRUCTIONS
After pump has been reassembled with a major kit, it is recommended that a break-in test be
performed to allow idlers to polish into babbitt housing bores. For this test, pump should be run to
maximum required working pressure starting from 300 psig (20.7 Barg), in 200 psig (13.8 Barg)
increments, holding each pressure for five minutes.

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Figure 2 – Torque Table
Pump Frame Size Bolt Description (IDP #) Torque
Inlet Bolt (4) 90 ± 5 Lb-Ft (122 ± 7 N-m)
187
Thrust Plate Bolt (91) 130 ± 10 Lb-In (176 ± 13 N-m)
Inboard Cover Bolt (4 or 93) 90 ± 5 Lb-Ft (122 ± 7 N-m)
Idler Stop Bolt (81) 27 ± 2 In-Lb (37 ± 3 N-m)
Bearing Retainer Bolt (47) 130 ± 10 Lb-In (176 ± 13 N-m)
250
Inlet Bolt (4) 160 ± 10 Lb-Ft (217 ± 13 N-m)
Thrust Plate Bolt (91) 30 ± 2 Lb-Ft (40 ± 3 N-m)
Inboard Cover Bolt (4 or 93) 250 ± 15 Lb-Ft (340 ± 20 N-m)
Idler Stop Bolt (81) 65 ± 5 Lb-Ft (88 ± 7 N-m)
Bearing Retainer Bolt (47) 22 ± 2 Lb-Ft (30 ± 3 N-m)
275
Inlet Bolt (4) 60 ± 5 Lb-Ft (80 ± 7 N-m)
Thrust Plate Bolt (91) 30 ± 2 Lb-Ft (40 ± 3 N-m)
Inboard Cover Bolt (4 or 93) 110 ± 10 Lb-Ft (150 ± 13 N-m)
Idler Stop Bolt (81) 18 ± 2 Lb-Ft (24 ± 3 N-m)
Bearing Retainer Bolt (47) 45 ± 5 Lb- Ft (60 ± 7 N-m)
312
Inlet Bolt (4) 100 ± 5 Lb-Ft (135 ± 7 N-m)
Thrust Plate Bolt (91) 60 ± 5 Lb-Ft (80 ± 7 N-m)
Inboard Cover Bolt (4 or 93) 130 ± 10 Lb-In (176 ± 13 N-m)
Idler Stop Bolt (81) 35 ± 2 Lb-Ft (47 ± 3 N-m)
Bearing Retainer Bolt (47) 45 ± 5 Lb- Ft (60 ± 7 N-m)
350
Inlet Bolt (4) 180 ± 10Lb-Ft (245 ± 20 N-m)
Thrust Plate Bolt (91) 60 ± 5 Lb-Ft (80 ± 7 N-m)
Inboard Cover Bolt (4 or 93) 180 ± 10 Lb-Ft (245 ± 20 N-m)
Idler Stop Bolt (81) 65 ± 5 Lb-Ft (88 ± 7 N-m)
Bearing Retainer Bolt (47) 45 ± 5 Lb- Ft (60 ± 7 N-m)
400
Inlet Bolt (4) 150 ± 10 Lb-Ft (203 ± 13 N-m)
Thrust Plate Bolt (91) 45 ± 5 Lb- Ft (60 ± 7 N-m)
Inboard Cover Bolt (4 or 93) 220 ± 15 Lb-Ft (298 ± 20 N-m)
Idler Stop Bolt (81) 35 ± 2 Lb-Ft (47± 3 N-m)
Bearing Retainer Bolt (47) 35 ± 2 Lb-Ft (47± 3 N-m)

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I. TROUBLESHOOTING
For assistance with troubleshooting see General Instruction Manual, SRM00046.
J. FIELD AND FACTORY SERVICE AND PARTS
Imo Pump maintains a staff of trained service personnel that can provide pump installation, pump start-
up, maintenance/overhaul and troubleshooting supervision as well as installation and maintenance
training.
Our factories provide maintenance as well as overhaul and test facilities in the event user prefers to
return pumps for inspection or overhaul. Pumps that have been factory-overhauled are normally
tested and warranted “as-new” for a period of one year from date of shipment. For either field service or
factory overhaul assistance, contact your local Imo Sales Office or representative at Technical/Customer
Service Department in Monroe, NC, USA.
Most pumps have repair kits available. Minor Repair Kits are used to repair leaking seals, bad bearings
and/or for re-assembly after pump tear-down. They include (as applicable) pump shaft seals, packing,
all gaskets/O-rings and bearings. Major Repair Kits are sufficient to rebuild completely worn-out pumps
to “as-new” condition. They include all parts found in Minor Repair Kits plus all major internal parts
subject to wear. Since kits have all necessary parts, it is preferred that they be purchased rather than
selecting individual parts. When parts are individually selected from Parts List, some needed
components are often overlooked. In addition, mixing worn or used parts with new parts risks rapid
wear and shortened service life from new parts.

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CIRCOR
1710 Airport Road
PO Box 5020
Monroe, NC USA
28111.5020
Tel: [phone]
Email: [e-mail]
Web: www.circorpt.com
© 2020 CIRCOR Pumps North America, LLC. All rights reserved.