This presentation explains the science behind high-speed oil flushing and 12 practical points to improve the cleaning of lubrication and hydraulic oil systems.

1. 12 Points to Improve Your Oil
Flushing for a Clean System

2. 12 Points to Improve your Oil Flushing
for a Clean System
• High Speed Oil Flushing Importance
• Rationale
• 12 Points to Improve High Speed Oil Flushing

3. LOAD
Dynamic Clearance
1 μm
Clearance 9 μm
Lubrication Films are Microscopic

4. Size Comparison
Average human
Hair
70 μm
Rust particle
40 μm
Sand Particle
50- 2000 μm
Bacterium
1.5 μm
100 mesh
149 μm
Journal Bearing
Lubrication Film
125 - 0.5 μm

5. Typical Dynamic (Operational) Clearances
Variable Volume Piston Pumps
CYLINDER
BARREL
5 – 40 μm

6. Typical Dynamic (Operational) Clearances
Variable Volume Piston Pumps
VALVE PLATE
0.5 – 5 μm
CYLINDER
BLOCK

7. Typical Dynamic (Operational) Clearances
Ball Bearing
0.1 – 0.7 μm

8. Typical Dynamic (Operational) Clearances
Mechanical Seal
0.3 – 1.6 μm
Between Faces
0.05 – 0.5 μm
Seal and Shaft

9. Conclusion:
Particles, specially microscopic
particles impair lubrication films in
hydraulic or lubrication systems, for
this reason systems need to be clean

10. Oil Flushing Purpose:
The oil flushing purpose is to remove
any debris in the system that may
impair or reduce the operating life of a
lubrication or hydraulic fluid powered
system. Frequently during the oil
flushing procedure, the oil is also
purified.

11. High Velocity Oil Flushing
In this technique the unwanted
particles in a lubrication or power oil
system are removed using a turbulent
or high velocity oil flow and then,
capture in a filter.
System Internal Surface
Particles

12. High Velocity Oil Flushing
In this technique the unwanted
particles in a lubrication or power oil
system are removed using a turbulent
or high velocity oil flow and then
capture in a filter.
System Internal Surface
Particles
High velocity and turbulent flow will flush
the particles

13. The purpose of a high velocity in a oil flush is keep the particles
suspended. A high velocity means turbulence. A turbulent flow has
velocity fluctuations in a very unstable pattern. The changes in
velocity and directions will keep the particles suspended and will
drag them into the stream.

14. Boundary Layer
Turbulent flow is like rapids, the main stream will
move fast and chaotic, but close to the river edge,
the velocity is slow and eventually zero.
Image Source: https://upload.wikimedia.org/wikipedia/en/b/b5/Rapids.jpg
• High Velocity
• Low velocity
• Zero velocity

15. Boundary Layer
• Like the rapids, the flow inside of a pipe will have a microscopic layer with no
flow stuck to the pipe wall and a free stream moving quickly.
• If a microscopic particle reaches the boundary layer it will settle on the
bottom of the pipe.
Bottom
Bottom

16. If the particles settle on the bottom, How do I
fight back?
Flush it anyway!
More flow means more velocity, more
turbulence and better result.

17. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

18. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

19. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and a better result.

20. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

21. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

22. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

23. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

24. If the particles settle on the bottom, How do I
fight back?
Flush anyway!
More flow means more velocity, more
turbulence and better result.

25. To achieve a turbulent flow the velocity of
liquid in the pipe must be higher than:
Calculations based on Turboflow R&O 32 (lubricant oil) at 70⁰C on
Sch. 40 pipe, Reynolds number=3000
nps V [ft/s] V [m/s] Q [gpm] Q [m3/h]
1/2 9.8 3.0 9 2.11
3/4 7.4 2.3 12 2.78
1 5.8 1.8 16 3.57
1 1/2 3.8 1.2 24 5.47
2 2.9 0.9 31 7.03
3 2.0 0.6 46 10.42
4 1.5 0.5 60 13.68
5 1.2 0.4 76 17.15
6 1.0 0.3 91 20.61

26. A High Velocity Oil Flushing – The
Devil is in the Detail

27. 1.- Consider your oil Flushing in the Design
Stage.
• For example if a manufacturer
requires to install a filter or
strainer for the oil flushing in the
return pipe at oil reservoir, we
may need to include a pipe spool
in the design
Drawing Source: Ecol Poland, https://youtu.be/kzOEtRxZrNs

28. Design without pipe spool for
oil flushing Pipe spool
Filter installed for
oil flushing
Strainer installed
for oil flushing
Drawing Source: Poland, https://youtu.be/kzOEtRxZrNs

29. 1.- Consider your oil
Flushing in the Design
Stage.
Other examples are: Necessary
connections only for flush purposes, or
drains.

30. 2. Does your contractor
Have a
quality
program?
Provide an
specific
procedure
for approval
in advance?
Have
trained and
experienced
technicians?

31. Excessive foreign objects or debris
3.-BeforetheoilFlushing,inspectthesystem
andplanaccordingly Air Blow
Welding Slag or rust
Chemical
Cleaning
Water or moisture
Air Blow & Dry,
Dehydrators

32. Chemical Cleaning
(removes only deposits)
Varnish
3.-BeforeoilFlushing,inspectthesystem
andplanaccordingly
Deep media filtration
Ion exchange
Electrostatic Filtration

33. 4. Select the proper size
equipment
• Pump big enough to provide turbulent flow on largest pipe diameter
• Heater to heat the oil up 70⁰C approximately in 2 hours
• Filters rated for smaller particles than those installed in the system
for regular operation.

34. 5. Avoid sudden
changes on
cross-sectional
flow area
6x1 reducer
6x1x4 tee

35. 5. Avoid sudden
changes on cross
sectional flow
area
Remove orifice plate, control valves, system
filter media or any other restrictions

36. 4”
1 1/2”
2”
6”
Drawing Source: Ecol Poland, https://youtu.be/kzOEtRxZrNs

37. 6. Flush from top to the
bottom
Few particles are dragged
by the stream
Most of the particles are
dragged by the stream

38. Run-Down Tank
Rotating
Equipment
Pump
Oil
Reservoir
Flushing direction*
* Requires more than one
flow pattern during flushing.
Flushing patterns may be
different than oil flow
direction during normal
operation.

39. 7. Eliminate
dead legs larger
than 6 diameters
A dead Leg is any section of the pipe without
flow
Closed branch no flow

40. FlowSpeedm/s

41. 8. Inspect the cleaning
equipment and be cautious
about it
Cast iron
or carbon
steel
Rented
equipment
Are hoses
clean and
dry?

42. 8. Inspect the cleaning
equipment and be cautious
about it
Threaded
Fittings
Calibration
of critical
instruments
No-fully
drainable
tanks

43. 9. Document
Turbulence

44. 10 Highlight
P&IDs and
include them in
the procedure
• Show flow paths
• Operated valves (opened, closed,
cycled, partially open)
• Removed or isolated components
• Temporary cleaning equipment

45. 11. Boost your flush
Hammer
on welds
Inject
nitrogen
or air
Reverse
Flow

46. 11. Boost your flush
Use
vibrators

47. 12 Plan your
sample
• Sample from a high turbulent flow
• Sample downstream
• Sample far from filters
• Sampling procedure

48. Conclusion:
There is not a silver bullet for a
successful oil flushing. A successful oil
flushing is a result of taking care of
many details.

49. To know more:
• Pall Corporation Filtration e-book
• ISO 4406 Hydraulic fluid power — Fluids —
Method for coding the level of contamination by
solid particles
• ANSI/API STANDARD 614 Lubrication, Shaft-sealing
and Oil-control Systems and Auxiliaries

50. For the original presentation with
animations, questions or
comments, contact
Mauricio Gonzalez
Mauriciog.career@gmail.com