i-MO CIRCOR BK6DHZ(C)-250 User manual

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PRODUCT SERVICE MANUAL
BK6DHZ(C)-250, 275, 312 and 400 PUMPS
WARNING
This manual, and the GENERAL INSTRUCTION MANUAL, SRM00046,
should be read thoroughly prior to pump installation, operation or
maintenance.
MANUAL NO. SRM00096 REV 04
(
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 ..............................................................................................6
H. SEAL DRAWING ........................................................................................................9
H. TORQUE TABLE ........................................................................................................10
I. TROUBLESHOOTING, FIELD AND FACTORY SERVICE AND PARTS ....................11
J. ASSEMBLY DRAWING ..............................................................................................12 thru 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
BK6DHZ(C)-250, 275, 312 and 400 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, CA-1, 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 BK6DHZ(C)-250, 275, 312 and 400 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
BK6DHZ(C)-250, 275, 312 and 400 pumps are positive displacement, rotary screw pumps
consisting of a precision bored housing that encloses a driven screw (power rotor) and two
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 BK6DHZ(C) pumps with rotor size 250, 275, 312 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 BK6DHZ(C) pumps, refer to pump
nameplate, this instruction manual, and assembly drawing as instructed below:
1. From pump nameplate, record pump model number, serial number and manufactured date.
2. Record instruction manual number, revision and date.
3. From 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
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 ...............................1500 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 1 – Pump Parts List
IDP QTY DESCRIPTION KIT IDP QTY DESCRIPTION KIT
1 1 Case 47 4 Bearing Retaining Bolt
2 1 Inlet Head 48 1 Seal Seat Adapter
4 16
Inlet and Inboard Cover Bolts
(8 on Size 250) 49 1 Ball Bearing X
6 1 Stop Pin 63 1 Power Rotor XX
7 1 Dyna Seal XX 66 1 90° Elbow (400 size only)
8 2 Housing Retaining Ring XX 67 2 Pipe Plug
9 2 Inlet & Inboard Cover O-Ring X 68 1 Nipple (400 size only)
21 2 Idler XX 69 1 Fitting (400 size only)
22 1 Idler Stop XX 70 1 90° Tube Fitting
23 2 Cups XX 71 1 Tubing
24 1 Housing XX 74 1 90° Tube Fitting (250 Only)
25 1 Seal X 79 1 Floating BP Bushing XX
27 2 Seal Return Tube O-Ring X 81 1 Idler Stop Cap Screw
28 1 Housing O-Ring X 83 1 Seal Seat O-Ring X
29 1 Thrust Plate XX 90 2 Thrust Plate Spacers
31 1 Shaft Key 91 2 Thrust Plate Bolts
38 1 Seal Spacer (Not 400 size) 92 1 Thrust Balance Tube
42 2 Bearing Retaining Ring X 93 2 Balance Piston Spacer
(
400
)
size C-face onl
y)
43 1 Bearing Retainer 94 1 BP Spacer Bolts (400 size C-face only)
46 1 Inboard Cover
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, figures 3 through 6 and Table 2.
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 – Use correct assembly drawing pertaining to your
pump size and whether pump is a C-face or foot mount type.
SPECIAL NOTE: To service mechanical seal and ball bearing ONLY perform H.3,
Steps 1, 6, 7 8 and 9 and H.4, Steps 6, 7, 8, and 9 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 oil balance tube (92).
4. Remove cups (23) from idlers (21).
5. Remove idlers (21) by unscrewing them from inlet end of pump
CAUTION
Do not permit idlers (21) to drop as they emerge from housing (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 2 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 (49) 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). (On size 400, C-face unit
removal of inboard cover (46) also removes balance piston spacer (93) and BP spacer
installation bolts (94). These two parts need not be removed from balance piston since
they are not wearing parts and will not be supplied with major kit.)
11. Remove O-ring (28 or 9) 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.
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.
Note: Bolts (81) 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, following procedure is mandatory assembly practice.

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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 for pump size in torque table, Chart 1.
3. Complete tightening fastener to torque value determined in 2.
1. Install O-ring (28) in groove of housing (24).
2. Install 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 housing snap rings (8) in case (1).
4. Install balance piston (79) on inboard cover (46). Install idler stop (22) on inboard cover
(46) with cap screws (81). Torque bolts to proper value for pump size in torque table,
Chart 1. Install O-ring (28 or 9) on inboard cover (46).
5 Install inboard cover (46) on case (1) using bolts (4). Be sure seal return (70) is facing
up. Torque bolts to proper value for pump size in torque table, Chart 1.
6. 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
seal stationary seat in seal seat adapter (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 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).
7. Install O-ring (83) in seal bore of inboard cover (46).
8. Install assembled power rotor (63) in pump, centering all parts as they enter inboard
cover (46). Align one of openings in seal seat adapter (48) over drain in inboard cover
(46).
9. Install bearing retainer (43) on inboard cover (46) using bolts (47). Torque bolts to
proper value for pump size in torque table. Chart 1.

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10. Install idlers (21) into housing (24) by meshing threads with power rotor thread and
screwing them into housing idler bores.
11. Install cups (23) to ends of suction idlers (21).
12. Install O-rings (27) on oil balance tube (92) and oil balance tube (92) in housing (73).
13. 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, Chart 1.
14. Install O-ring (9) to groove in inlet head (2).
15. Install inlet head (2) using bolts (4). Torque bolts to proper value for pump size in torque
table, Chart 1.
16. Install seal piping (71) and drain plug (67).
Note: Inlet head (2) can be rotated 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, Chart 1. Reconnect seal piping (71).
17. Install coupling hub key (31). Install and align pump and driver as specified in General
Instruction Manual, SRM00046.
FIGURE 2 – Mechanical Seal
Torque Table - Chart 1

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Pump Frame Size Bolt Description (IDP #) Torque
250 Inlet Bolt (4) 200 ± 10 Lb-Ft (270 ± 14 N-m)
Thrust Plate Bolt (91) 30 ± 5 Lb-Ft (40 ± 7 N-m)
Inboard Cover Bolt (4) 200 ± 10 Lb-Ft (270 ± 14 N-m)
Idler Stop Bolt (81) 50 ± 5 Lb-in (68 ± 7 N-m)
Bearing Retainer Bolt (47) 22 ± 5 Lb-Ft (30 ± N-m)
275 Inlet Bolt (4) 80 ± 5 Lb-Ft (108 ± 7 N-m)
Thrust Plate Bolt (91) 30 ± 2 LB-FT (40 ± 3 N-m)
Inboard Cover Bolt (4) 80 ± 5 LB-Ft (108 ± 7 N-m)
Idler Stop Bolt (81) 20 ± 2 Lb-Ft (27 ± 3 N-m)
Bearing Retainer Bolt (47) 35 ± 2 LB-Ft (47 ± 3 N-m)
312 Inlet Bolt (4) 100 ± 5 Lb-Ft (135 ± N-m)
Thrust Plate Bolt (91) 60 ± 5 Lb-Ft (80 ± 7 N-m)
Inboard Cover Bolt (4) 100 ± 5 Lb-Ft (135 ± 7 N-m)
Idler Stop Bolt (81) 35 ± 2 Lb-ft (48 ± 3 N-m)
Bearing Retainer Bolt (47) 44 ± 5 Lb- Ft (60 ± 7 N-m)
400 Inlet Bolt (4) 205 ± 10 Lb-Ft (278 ± 17 N-m)
Thrust Plate Bolt (91) 60 ± 5 Lb-Ft (80 ± 7 N-m)
Inboard Cover Bolt (4) 205 ± 10 Lb-Ft (278 ± 17 N-m)
Idler Stop Bolt (81) 50 ± 5 Lb-in (68 ± 7 N-m)
Bearing Retainer Bolt (47) 44 ± 5 Lb- Ft (60 ± 7 N-m)
H.5 SPECIAL TESTING INSTRUCTIONS
After pump has been reassembled with major kit, it is recommended that a break-in
test be performed to allow idlers to polish into babbitt housing bores. For 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 five minutes.

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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 event users prefer 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.