ISO/TR 21784:2018

TECHNICAL ISO/TR
REPORT 21784
First edition
2018-09
Plain bearings — Spray nozzle type
directed lubrication for tilting pad
bearings
Titre manque
Reference number
ISO/TR 21784:2018(E)
©
ISO 2018

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ISO/TR 21784:2018(E)

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© ISO 2018
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ii © ISO 2018 – All rights reserved

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ISO/TR 21784:2018(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviated terms . 1
5 Reduction effect of power loss by spray nozzle type directed lubrication systems.2
6 Lubrication system . 4
6.1 Tilting pad thrust bearing . 4
6.2 Tilting pad journal bearing . 5
7 Oil supply system of spray nozzle type directed lubrication . 6
7.1 General . 6
7.2 Tilting pad thrust bearing . 6
7.3 Tilting pad journal bearing . 7
7.4 Oil flow . 7
7.5 Oil supply pressure . 8
8 Structure of oil inlet and outlet (drainage) on nozzle type directed lubrication .8
8.1 Tilting pad thrust bearing . 8
8.2 Tilting pad journal bearing .10
Bibliography .12
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ISO/TR 21784:2018(E)

Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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electrotechnical standardization.
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described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
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This document was prepared by Technical Committee ISO/TC 123, Plain bearings, Subcommittee SC 7,
Special types of plain bearings.
Any feedback or questions on this document should be directed to the user’s national standards body. A
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ISO/TR 21784:2018(E)

Introduction
These days, rotating machines such as turbines, generators, compressors, pumps, etc. tend to be
increasing in speed and reducing in size. Bearings used in such machines can cause large power losses,
which not only degrades machine performance but also results in the associated cooling system being
larger in size. Directed lubrication type bearings can reduce the power loss significantly. They are
energy-saving bearings that can simplify facilities and improve plant efficiency.
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TECHNICAL REPORT ISO/TR 21784:2018(E)
Plain bearings — Spray nozzle type directed lubrication for
tilting pad bearings
1 Scope
Directed lubrication is an advanced technology that is capable of reducing the power loss and improving
the performance of tilting pad type bearings. Unlike flooded lubrication, where the bearing components
remain permanently submerged in an oil filled housing, with directed lubrication the components are
not submerged and the oil is delivered from an external source directly to the working surfaces of
the tilting pads after which it falls freely away to be drained from the bottom of the housing. There
are several alternative methods of realising the benefits of directed lubrication in tilting pad bearing
designs. As an example, this document specifies a spray nozzle type directed lubrication system where
lubricant is supplied to each pad through nozzles mounted between the pads in tilting pad thrust and
journal bearings. The design concept of this type of lubrication is described.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Symbols and abbreviated terms
For the purposes of this document, the following symbols apply.
Table 1 — Symbols and units
Symbol Explanation Unit
B Thrust collar width m
tc
c Specific heat capacity of lubricant J/(kg·K)
p
D Diameter of discharge oil hole m
d
d Hole diameter of nozzle m
h
K Coefficient of oil flow rate 1
Q
n Number of holes per nozzle 1
h
n Number of nozzles per bearing 1
n
P Power loss W
p Oil supply pressure Pa
en
3
Q Total oil flow rate m /s
3
Q Oil flow rate per nozzle m /s
n
ΔT Oil temperature rise K
3
ρ Density of lubricant kg/m
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ISO/TR 21784:2018(E)

5 Reduction effect of power loss by spray nozzle type directed lubrication systems
The effect of power loss reduction by the spray nozzle type directed lubrication system is shown with
regard to tilting pad thrust bearings. The power loss of tilting pad thrust bearings arranged for floo
...