DRAFT UGANDA STANDARD  
  DUS 2159 -1 
First  Edition  
2019 -mm-dd 
 
 
 Reference number  
DUS nnnn-n: yyyy 
© UNBS yyyy  
  
Hydraulic Fluid  — Performance Classifications  — Part 1: 
General  
 DUS 2159 -1: 2019  
ii © UNBS 2019  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS yyyy  
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without  prior written 
permission from UNBS.  
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail:  info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2159 -1:2019  
© UNBS 2019  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 Base Oil  ................................ ................................ ................................ ................................ ..................  2 
4.1 Group I  ................................ ................................ ................................ ................................ ....................  2 
4.2 Group II  ................................ ................................ ................................ ................................ ...................  2 
4.3 Group III  ................................ ................................ ................................ ................................ ..................  2 
4.4 Group IV  ................................ ................................ ................................ ................................ .................  2 
4.5 Group V  ................................ ................................ ................................ ................................ ..................  2 
5 General classification  ................................ ................................ ................................ ...........................  2 
5.1 Viscosity  ................................ ................................ ................................ ................................ .................  2 
5.2 Performance  ................................ ................................ ................................ ................................ ...........  2 
Bibliography  ................................ ................................ ................................ ................................ ........................  5 
 
. DUS 2159 -1: 2019  
iv © UNBS 2019  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established under Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Ugan da Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a given field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other in terested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC 16, Petroleum , Subcommittee 
SC 1, Petroleum  and Petrochemical . 
DUS 2159  consists of the following parts, under the general tit le Hydraulic Lubricating Fluid  — Performance 
Classifications :  
  Part 1 : General  
  Part 2 : Specifications for categories HH, HL, HM, HV and HG  
  Part 3: Specifications for hydraulic fluids in categories HFAE, HFAS, HFB, HFC, HFDR and HFDU  
  Part 4 : Specifi cations  for hydraulic fluids in categories  HETG, HEPG, HEES and HEPR  DUS 2159 -1:2019  
© UNBS 2019  – All rights reserved  v 
 Introduction  
The choice of suitable hydraulic fluids  is critical for the lifetime, operational safety and efficiency of hydrostatic 
components and gears.  
The selection of the appropriate  hydraulic fluid for a specific application can be made only when the different 
features of the lubricants and the task and conditions under which the machine is to operate are taken into 
consideration.  
This draft standard outlines the current performance  classifications as applicable to ISO classification. Current 
hydraulic oil categories that may be deemed obsolete by the ISO classification system during the course of 
the application of this standard shall be considered obsolete as well . 
 DRAFT UGANDA STANDARD  DUS 2159 -1: 2019  
 
© UNBS yyyy – All rights reserved  1 
 Hydraulic flui d — Performance Classifications  — Part 1: 
General  
1 Scope   
This Draft Uganda Standard covers classification of hydraulic fluids used in hydraulic systems.  
This classification system does not include automotive brake fluids or aircraft hydraulic fluids  
NOTE  The consumer should refer to the owner’s or operator’s manual for recommended category of hydraulic fluids  
to be used in a specific  hydraulic systems . 
This specification defines only new hydraulic fluids before they are installed in the hydraulic system.  
This specification defines specific types of hydraulic fluids . It does not include all hydraulic fluids . Some oils 
that are not included may be satisfactory for certain hydraulic applications . 
2 Normative references   
The following referenced documents referred to in the text in such a way that some or all of their content 
constitutes requirements of this document. For dated references, only the edition cited applies. For undated 
references, the latest edition of the referenced document (including any amendm ents) applies.  
ISO 3448, Industrial liquid lubricants — ISO viscosity classification  
DUS 2159 -2:2019 Hydraulic lubricating fluid — Performance Classifications — Part 2 Specifications for 
categories HH, HL, HM, HV and HG ISO 12922, Lubricants, industrial oil s and related products (class L) — 
Family H (Hydraulic systems) — 
DUS 2159 -3:2019 Hydraulic lubricating fluid — Performance Classifications — Part 3 Specifications for 
hydraulic fluids in categories HFAE, HFAS, HFB, HFC, HFDR and HFDU  
DUS 2159 -4:2019 Hydra ulic lubricating fluid — Performance Classifications — Part 4 Specifications for 
categories HETG, HEPG, HEES and HEPR  
3 Terms and definitions   
No terms and definitions are listed in this document.  
ISO and IEC maintain terminological databases for use in s tandardization at the following addresses:  
— ISO Online browsing platform: available at http://www.iso.org/obp  DUS 2159 -1: 2019  
2 © UNBS yyyy – All rights reserved  
 4 Base Oil  
Fully formulated hydraulic fluids shall consist of a blend of a base fluid and an additive package. These base 
fluids shall be catego rized into five groups types ; API groups I, II, III, IV and V  
4.1 Group I  
Group I base oils classified as  being  less than 90 percent saturates, greater than 0.03 percent sulfur and with 
a viscosity -index range of 80 to 120.  
4.2 Group II  
Group II base oils  classified  as being more than 90 percent saturates  less than 0.03 percent sulfur and with a 
viscosity index of 80 to 120 . 
4.3 Group III  
Group III base oils classified as being greater than 90 percent saturates, less than 0.03 percent sulfur and 
have a vis cosity index above 120. . 
4.4 Group IV  
Group IV base oils  classified as polyalphaolefins (PAOs). These synthetic base oils are  made through a 
process called synthesizing . 
4.5 Group V  
Group V base oils classified as all other base oils, including silicone, p hosphate ester, polyalkylene glycol 
(PAG), polyolester, biolubes, etc. These base oils are at times mixed with other base stocks to enhance the 
oil’s properties . 
5 General classification  
Hydraulic fluid shall be classified according to viscosity grade and performance . 
5.1 Viscosity  
The viscosity of the hydraulic fluid shall be classified basing on the ISO viscosity classification, as per 
designations indicated in DUS ISO 3448.  
5.2 Performance  
Hydraulic fluid shall be classified according to performance base d on  the classification as indicated in the 
table below.  
 
 
 
 DUS 2159 -1: 2019  
© UNBS yyyy – All rights reserved  3 
 Table  1 — Classification of hydraulic fluids  
 
Code 
letter  General 
applications  Particular 
applications  More 
specific 
applications  Composition 
and 
properties  Symbol  
ISO-L Typical  
applications   
Rem arks International 
Standard  
H Hydraulic 
Systems  Hydrostatic   Non-inhibited 
refined mineral 
oils HH    
DUS 2159 -
2:2019  
 Refined 
mineral oils 
with improved 
anti- rust and 
anti-oxidation 
properties   
HL   
  
Oils of HL type 
with improved 
anti-wear 
properties   
 
HM General 
hydraulic 
systems 
which include 
highly loaded 
compo - nents   
 Oils of HM 
type with 
improved 
viscosity/ 
temperature 
proper - ties  
HV Construction 
and marine 
equipment   
Applications 
where 
environmen - 
tally 
acceptable 
fluids  
are requested  Triglycerides  HETG  General 
hydraulic 
systems   DUS 2159 -
4:2019  
Polyglycols  HEPG  
Synthetic 
esters  HEES  
Polyalphaolefin 
and other 
synthetic 
hydro - carbons   
HEPR  
 
 
 
 
Hydraulic 
slideway 
systems   
 
 
Oils of HM 
type with anti -
stick/slip  
properties   
 
 
 
 
HG Machines 
with 
combined 
hydraulic and 
plain bearing 
way 
lubrication 
systems 
where 
vibration or 
intermittent 
sliding (stick/ 
slip) at low 
speed is to be 
minimised  These 
fluids are 
intended 
to be  
multi -
func- 
tional but 
they do 
not 
function 
success - 
fully 
under all 
hydrau - 
lic 
applica - 
tions   
 
 
 
 
DUS 2159 -
2:2019  DUS 2159 -1: 2019  
4 © UNBS yyyy – All rights reserved  
  
Applications 
where  
fire-resistant 
fluids  
are required   
 
Oil in water 
emulsions   
 
HFAE   Typically 
more 
than 95 
% mass 
fraction 
of water.   
 
 
 
 
 
DUS 2159 -
3:2019   
Chemical 
solutions in 
water   
 
HFAS   Typically 
more 
than 95 
% mass 
fraction 
of water.  
 
 
Water in oil 
emulsions   
 
HFB  Typically 
more 
than 40 
% mass 
fraction 
of water.  
 
Water polymer 
solutions   
 
HFC  Typically 
more 
than 35 
% mass 
fraction 
of water.  
Synthetic fluids 
containing no 
water and 
consisting 
phosphate 
esters   
HFDR    
Synthetic fluids 
containing no 
water and of 
other 
composition   
HFDU    
 DUS 2159 -1: 2019  
© UNBS yyyy – All rights reserved  5 
 Bibliography  
[1] ISO 6743 -99, Lubricants, industrial oils and related products (class L) — Classification — 
Part 99: General  
 DUS 2159 -1: 2019  
© UNBS yyyy – All rights reserved  7 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of the UNBS Certification Mark is governe d by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certification mark scheme of the Uganda Nation al Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 2159 -1: 2019    
 
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© UNBS 2019 – All rights reserved