FINAL DRAFT UGANDA 
STANDARD  
  FDUS 947-1
First Edition
2011-mm-dd
 
 
 Reference numbe r
FDUS 947-1: 2011
© UNBS 2011 
  
Handling of petroleum products and their derivatives — Part 1: 
Siting, design and construction of service stations 
 FDUS 947-1: 2011 
ii © UNBS 2011 – 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 2011  
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, in cluding 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: 256 414 505 995 
Fax: 256 414 286 123 
E-mail: unbs@infocom.co.ug  
Web: www.unbs.go.ug  FDUS 947-1:2011 
© UNBS 2011 – All rights reserved  iii
 Contents Page 
Foreword ...................................................................................................................... ...................................... vi  
1  Scope ......................................................................................................................... ............................. 1  
2  Normative re ferences .......................................................................................................... .................. 1  
3  Terms and de finitions ......................................................................................................... .................. 2  
4  Planning of service stat ion ................................................................................................... ................ 4  
4.1  Service stati on siting ........................................................................................................ .................... 4  
4.1.1 Environmental impact and fire hazard asses sments ........................................................................ 4  
4.1.2 Traffic impact  assessment ..................................................................................................... .............. 5  
4.2  Composition ................................................................................................................... ........................ 5  
4.3  Boundaries .................................................................................................................... ......................... 5  
4.4  Design specifications for service st ations .................................................................................... ..... 5 
4.4.1 General ....................................................................................................................... ............................ 5  
4.4.2 Design area speci fications .................................................................................................... ............... 6  
4.5  Service station forecourt area classi fication ................................................................................. ..... 7 
4.5.1 General ....................................................................................................................... ............................ 7  
4.5.2 Classified ar ea examples ...................................................................................................... ................ 7  
4.5.3 Protection of buildings wi th access to fo recourts .............................................................................  7 
4.5.4 Fuels other than class 1 products ............................................................................................. .......... 8 
5  Design and installation of underground tanks ................................................................................. 10 
5.1  Tanks design installati on and maintenance .....................................................................................  10 
5.1.1 Leakage de tection ............................................................................................................. .................. 10  
5.1.2 Steel tanks ................................................................................................................... ......................... 11  
5.1.3 Fibre reinforced  resin tanks .................................................................................................. ............. 11  
5.1.4 Ultra violet protection ....................................................................................................... .................. 11  
5.2  Site topography ............................................................................................................... .................... 11  
5.2.1 General ....................................................................................................................... .......................... 11  
5.2.2 Excavations ................................................................................................................... ....................... 11  
5.3  Corrosion prot ection .......................................................................................................... ................. 12  
5.4  Transportation and offloa ding of stee l tanks .................................................................................. . 12 
5.5  Transportation and offloading of  fibre reinforced tanks ................................................................. 12  
5.6  Back f illing .................................................................................................................. ......................... 12  
5.6.1 Stability ..................................................................................................................... ............................ 12  
5.6.2 Observation of  wells .......................................................................................................... ................. 12  
5.6.3 Backfill ma terial ............................................................................................................. ...................... 13  
5.7  Installation of tanks and method of backf illing with cohesive backfill mate rials ......................... 13  
5.7.1 General ....................................................................................................................... .......................... 13  
5.7.2 Water level ................................................................................................................... ......................... 13  
5.7.3 Excavation of  floor ........................................................................................................... ................... 13  
5.7.4 Tank insta llation ............................................................................................................. ..................... 14  
5.7.5 Ballast fill .................................................................................................................. ............................ 14  
5.7.6 Distribution of backfill ......................................................................................................................... 14  
5.7.7 Other mate rials ............................................................................................................... ..................... 14  
5.8  Installation of tanks and methods of backf illing with cohesionless b ackfill material ................. 15  
5.9  Holding down .................................................................................................................. ..................... 15  
5.9.1 General ....................................................................................................................... .......................... 15  
5.9.2 Saddles ....................................................................................................................... .......................... 15  
5.10 Concrete slab ................................................................................................................. ...................... 15  
5.11 Pipe connections and manholes on fibre-reinforced resin tanks .................................................. 16  
5.11.1 Pipe conne ctions .............................................................................................................. ................... 16  
5.11.2 Manhole constr uction .......................................................................................................... ............... 16  FDUS 947-1: 2011 
iv © UNBS 2011 – All rights reserved
 5.11.3 Pipes ......................................................................................................................... ............................16  
5.12 In-situ l eak test ............................................................................................................. ........................16  
5.13 Manufacturing and Installation ...........................................................................................................16  
6  Pipe works a nd fittings ....................................................................................................... ................17  
6.1  Steel pipe and fitti ngs for welding ........................................................................................... ..........17 
6.1.1 General ....................................................................................................................... ...........................17  
6.1.2 Fittings ...................................................................................................................... ............................17  
6.1.3 Flanges ....................................................................................................................... ..........................17  
6.1.4 Gaskets ....................................................................................................................... ..........................17  
6.2  Threaded steel pipe and fittings .........................................................................................................17  
6.2.1 General ....................................................................................................................... ...........................17  
6.2.2 Fittings ...................................................................................................................... ............................17  
6.2.3 Flanges ....................................................................................................................... ..........................17  
6.2.4 Pipe threads .................................................................................................................. .......................17  
6.3  Non-metallic  piping............................................................................................................ ..................17  
6.3.1 Materi al ...................................................................................................................... ...........................17  
6.3.2 Fuel compatibility ............................................................................................................ ....................18  
6.3.3 Fuel permeability ............................................................................................................. ....................18  
6.3.4 Ultraviolet exposure .......................................................................................................... ..................18  
6.3.5 Primary delive ry pipes ........................................................................................................ ................18  
6.3.6 Vents ......................................................................................................................... ............................18  
6.3.7 Fill pipes .................................................................................................................... ...........................18  
6.3.8 Compressibility ............................................................................................................... .....................18  
6.3.9 Transition ............................................................................................................................... ...............18  
6.3.10 Shear-off valve ............................................................................................................... ......................18  
6.4  Installa tion .................................................................................................................. ..........................18  
6.4.1 Pipework ...................................................................................................................... .........................18  
6.4.2 Joint fitt ings ................................................................................................................ .........................19  
6.4.3 Incline on pi pe work .......................................................................................................... ..................19  
6.4.4 Jointing tape ............................................................................................................................... ..........19 
6.4.5 Buried pipe work .............................................................................................................. ....................19  
6.4.6 Welding ....................................................................................................................... ..........................19  
6.4.7 Pipework leak test............................................................................................................. ...................19  
6.4.8 Corrosion prot ection .......................................................................................................... .................19  
6.5  Dip pipes or gauging pipes .................................................................................................... .............19  
6.6  Suction pipes ................................................................................................................. ......................19  
6.7  Delivery pipes ............................................................................................................................... ........19 
6.8  Breather pipes or  vent pipes .................................................................................................. ............20  
7  Fillers, pumps a nd drainage ................................................................................................... ............20  
7.1  Fillers ....................................................................................................................... .............................20  
7.1.1 General ....................................................................................................................... ...........................20  
7.1.2 Filler box .................................................................................................................... ...........................20  
7.2  Pumps and di spensers .......................................................................................................... .............21  
7.2.1 General ....................................................................................................................... ...........................21  
7.2.2 Dispensers and di spensing pumps ............................................................................................... ....21 
7.2.3 Specific requ irements ......................................................................................................... ................21  
7.3  Drainage and in tercepto rs ..................................................................................................... .............22  
7.3.1 Surface water ................................................................................................................. ......................22  
7.3.2 Containment separation ........................................................................................................ ..............23  
7.3.3 Sewage ........................................................................................................................ ..........................23  
7.3.4 Washing of vehicles ........................................................................................................... .................23  
7.4  Overfill pr otection ........................................................................................................... .....................24  
8  Electrical inst allation ....................................................................................................... ....................24  
8.1  General ....................................................................................................................... ...........................24  
8.2  Electric cables ............................................................................................................... .......................25  
8.3  Buried cables ................................................................................................................. ......................25  
8.4  Sleeve pipes .................................................................................................................. .......................25  
8.5  Non-explosion-protec ted equipment ............................................................................................. ....25 FDUS 947-1:2011 
© UNBS 2011 – All rights reserved  v
 8.6  Accredited electricians and certifi cation of electr ical work ........................................................... 25  
8.6.1 Electricians .................................................................................................................. ........................ 25  
8.6.2 Electrical inst allations....................................................................................................... .................. 25  
8.6.3 Certific ation ................................................................................................................. ......................... 25  
8.7  Emergency ..................................................................................................................... ...................... 25  
8.8  Hazardous installations ....................................................................................................... ............... 25  
9  Operation and maintenan ce of filling stations .................................................................................  26 
9.1  Marking of equipment .......................................................................................................... ............... 26  
9.2  Notice and labels ............................................................................................................. .................... 26  
9.3  Fire-fighting equipment ....................................................................................................... ............... 26  
9.3.1 Portable and mobile fire exti nguishers ........................................................................................ ..... 26 
9.3.2 Fire hoses .................................................................................................................... ......................... 26  
9.3.3 Couplings ..................................................................................................................... ........................ 26  
9.3.4 Fire alarms.................................................................................................................... ........................ 27  
9.3.5 Colour identification of fire-fighting equipment .............................................................................. . 27 
9.3.6 Employees for fi re-fighting ................................................................................................... .............. 27  
9.4  Protection and welfar e of personnel ........................................................................................... ...... 27 
9.4.1 Safety and prot ection measures ................................................................................................ ........ 27 
9.4.2 Contact with petr oleum products ............................................................................................... ....... 28 
9.5  Repairs and al terations ....................................................................................................... ................ 28  
9.5.1 Permits ....................................................................................................................... .......................... 28  
9.5.2 Equipment ..................................................................................................................... ....................... 28  
9.5.3 Pipelines, pumps and valves ................................................................................................... ........... 29  
9.5.4 Hot work ...................................................................................................................... ......................... 29  
9.5.5 Electrical eq uipment........................................................................................................... ................. 29  
9.5.6 Plant ......................................................................................................................... ............................. 29  
9.6  Personnel safety .............................................................................................................. .................... 29  
9.6.1 Supervision ................................................................................................................... ....................... 29  
9.6.2 Use of casual and contractors' labour ............................................................................................... 29  
9.7  Removal or abandonment of tanks and pipe  work .......................................................................... 29  
9.7.1 Removal ....................................................................................................................... ......................... 29  
9.7.2 Abandonment ................................................................................................................... ................... 30  
9.8  Registration .................................................................................................................. ........................ 32  
Annex A (normative)  Design and constructi on of tanks ......................................................................... .... 33 
A.1 General ....................................................................................................................... .......................... 33  
A.2 Interceptors a nd drainage ..................................................................................................... ............. 33  
A.3 Used oil and solvent w ashings (paraffins) ..................................................................................... .. 34 
Annex B (normative)  PUR fo am-forming systems and foams for filling abandoned tanks and 
pipework — Test met hods ....................................................................................................... ........... 35  
B.1 Tests for foam-fo rming systems ................................................................................................ ........ 35 
B.1.1 Determination of viscosity at (25 ± 1) °C of  the components (isocyanate and polyol) of a 
foam-forming  system ........................................................................................................... ............... 35  
B.1.2 Determination of foaming characteristics at (25 ± 1) °C: cream time, string time and rise 
time .......................................................................................................................... ............................. 35  
B.2 Determination of foam properties ...................................................................................................... 36  
B.2.1 Foam samples .................................................................................................................. .................... 36  
B.2.2 Density of foam ............................................................................................................................... ..... 36 
B.2.3 Closed-cell content ........................................................................................................... .................. 36  
B.2.4 Compressive strength........................................................................................................... .............. 37  
Annex C (normative)  Design criteria for interceptors (gravi ty separators) ............................................... 38  
C.1 General ....................................................................................................................... .......................... 38  
C.2 Design procedure .............................................................................................................. .................. 38  
C.3 Example ....................................................................................................................... ......................... 39  
Bibliography .................................................................................................................. .................................... 42  
 FDUS 947-1: 2011 
vi © UNBS 2011 – All rights reserved
 Foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry  of Tourism, Trade and 
Industry established under Cap 327, of the Laws of Uganda.  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 A limentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS Agr eements of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a gi ven field or area and consists of representatives of 
consumers, traders, academician s, manufacturers, governme nt and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committ ee 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.  
Committee membership 
The following organisations were represented on the Technical Committee for Petroleum Standards, 
UNBS/TC 16/SC 2, during the dev elopment of this standard: 
• Delta (U) Ltd 
• Kampala City Council 
• Kobil (U) Ltd 
• Kyambogo University 
• Makerere University 
• Ministry of Energy and Mineral Development 
• Ministry of Gender Labour and Social Development 
• Ministry of Works and Transport 
• National Council of Science and Technology   
• National Environment Management Authority 
• Total (U) Ltd 
• Uganda National Bureau of Standards 
 FINAL DRAFT UGANDA STANDARD FDUS 947-1: 2011
 
© UNBS 2011 – All rights reserved  1
 Handling of petroleum products and their derivatives — Part 1: 
Siting, design and construction of service stations  
1 Scope 
1.1 This Final Draft Standard covers the siting, design a nd construction of service stations, installation and 
operation of equipment in service stations for  handling, storage and dispensing of petroleum products and 
their derivatives, other  than equipments used in transportation. 
1.2 A design will meet the requirement of this standard if it complies with any of the approved standards 
listed in normative reference. However, such standar d will be used in it’s entirety where applicable. For 
example, the product classification of one standard cannot be used in combination with design of another 
standard. 
1.3 This standard does not cover the installation of pr essurized storage tanks such as liquefied petroleum 
gas (LPG) storage vessels.  
2 Normative references 
The following referenced documents are indispensable for the application of this document. For dated 
references, only the edition cited applies. For undated references, the latest edition of the referenced 
document (including any amendments) applies. 
FDUS ISO 844, Cellular plastics — Determination of compression properties   
FDUS ISO 1209-1, Determination of flexural properties — Part 1: Basic bending test  
FDUS ISO 1209-2, Determination of creep behaviour — Part 2: Flexural creep by three-point loading  
FDUS ISO 3219, Plastics — Polymers/resins in the liquid state or as emulsions or dispersions — 
Determination of viscosity using a rotational viscometer with defined shear rate   
FDUS ISO 4590, Cellular plastics — Determination of volume  percentage of open and closed cells of rigid 
materials   
FDUS ISO 845, Cellular plastics and rubbers — Determination of apparent density  
FDUS ISO 7-1, Pipe threads where pressure-tight joints ar e made on the threads — Part 1: Designation, 
dimensions and tolerances  
DUS 974(API RP 1604), Closure of underground petroleum storage tanks.  
US 159, Specification for steel pipes for water and gas suitable for screwing  
FDUS 951-1:2011, Glass-reinforced polyester-coated steel tanks for the underground storage of 
hydrocarbons and oxygenated solvents and intended for burial horizontally  
DUS 951-2:2011, Fibre-reinforced plas tics (FRP) tanks for buried (undergroun d) storage of petroleum product   
2 © UNBS 2011 – All rights reserved
 DUS 947-2, The storage and handling of liquid fuel – Part 2: Larger consumer installations 
 DUS 956, Steel pipe flanges. 
 DUS 975, The electrical components of free-standi ng power-operated dispensing devices for flammable 
liquids.  
DUS 962 Symbolic safety signs – Part 1:  Standard signs and general requirements.  
DUS 955-2, Welding – Part 3: The fusion welding of steel  (including stainless steel): Tests for the approval of 
welding procedures and production welds DUS 963, Cathodic protection of buried and submerged structures.  
DUS 961, Welded steel tanks for oil storage  DUS 960, The wiring of premises.  DUS 976, Identification colour marking – Part 1: General.  
US ISO 7165:2009 Fire fighting — Portable fire extinguishers — Performance and construction 
US 534, Occupational health and safety m anagement systems — Specification 
The application of the National Building Regulations 
3 Terms and definitions 
For the purposes of this standard, the following terms and definitions shall apply. 
3.1 
acceptable: 
acceptable to the parties concluding the purchase contract, but in relation to the certification mark and to 
inspections carried out by approving authority, acceptable to the U ganda National Bureau of Standards 
3.2 
approved:  accepted by the appropriate approving authority 
3.3 
approving authority:  appropriate of the following: 
a) in terms of the Occupational Health and Safety  Act 2006, the Commissioner Occupational health and 
Safety Act, Ministry of Gender Labour and Social Development; 
b) in terms of petroleum supply act  2003, the Commissioner Petroleum Supply Department, Ministry of 
Energy and Mineral Development; 
c) in terms of the Uganda National Bureau of Standards Act 1993, The Executive Director Uganda 
National Bureau of Standards; 
d) in terms of Weights and Measures Act 1993 Cap 93, The Executive Director  Uganda National Bureau 
of Standards;  
e) in terms of the Environmental Act 1995,The Exec utive Director National Environmental Management 
Authority; and 
f) the local authorities concerned. FDUS : 2011 
© UNBS 2011 – All rights reserved  3
  947-1
3.4 
backfill material:  
clean, sieved subsoil or sand of specified grading 
3.5 
competent person:  
person who has the necessary knowledge of and ability with  regard to the particular process or type of plant 
and equipment to which this standard refers, to render  him capable of the work involved, and who has been 
duly authorized (in writing) by the approving author ity to perform a specific and identified task 
3.6 
dispenser:  
unit that consists of one or more meters and one or more hoses and that is fed from a remote pump.  
3.7 
dispensing pump:  
unit that consists of one or more meters and one or mo re hoses and that has its own pump(s) within the unit 
3.8 
responsible engineer:  
engineer who is registered under Engineer registration  act (1969) of Uganda as amended under decree no. 10 
of 1977 
3.9 
fibre-reinforced resin steel tank:  
steel tank that has a fibre-reinforced resin coating on the outside of the tank 
3.10 
fibre-reinforced resin tank:  
tank made from a number of fibre glass strands (re inforcement) bound together using a resin and catalyst  
3.11 
filler:  
point for filling the tank with product 
3.12 
filler box:  
box surrounding the filler point 
3.13 
flash point:  
temperature at which a liquid ignites  
3.14 
holiday test defect:  
lining or coating defect where the coating is so thin or the coating material has been so degraded or so 
contaminated that the defect is registered by a su itable holiday detector (cor rectly used and set at an 
appropriate voltage) and that the protective pr operties of the lining or coating are impaired 
3.15 
oxygenates:  
generic term for products such as methanol, ethanol, isopr opanol, tertiary, butyl alcohol, tertiary methyl butyl 
ether and tertiary amyl methyl ether 
3.16 
rapid drainage system:  
system that allows drainage of spillage from the fille r box to the relevant underground tank and that is 
controlled by a suitable valve  
4 © UNBS 2011 – All rights reserved
 3.17 
submersible pump:  
remote pump that feeds one or more dispensers and that is either completely submer sed in the product or has 
its rotating parts submersed in the product within a tank 
3.18 
service station:  facility constructed under this standard that offers su fficient capabilities to handle  the storage of petroleum 
products (fuels and lubricants) in underground tanks, of individual tank capacity not exceeding 85 m
3 and 
offering total storage capacity not exceeding 200 m3, and dispensing them to final consumers 
3.19 
filling station 
facility constructed under this standar d that offers sufficient capabilities to handle t he storage of automotive 
fuels within underground tanks of individual capacity not exceeding 85 m3 and total facility capacity not 
exceeding 200 m3 and dispensing it to final consumers units 
3.20 
forecourt 
open area in a service/filling station where automobiles stop to refuel 
 
3.21 
tank farm 
area where one or more petroleum products tanks are sited 
4 Planning of service station 
4.1 Service station siting 
4.1.1 Environmental impact and fire hazard assessments 
Hydrocarbons are volatile under certain conditions  and contain or can easily form harmful chemical 
compounds, making them prone to environmental destruction and fire hazards. The siting of service stations is 
therefore paramount not only in facilit ating marketing but is also vital in the aspects of protection from fire 
hazards, destruction of environment and disruption to other operations. Awareness to the approving authority 
on the following shall therefore be made by submis sion of environmental impact assessment, before 
construction of service station begins: 
a) location of site in respect  to other existing or planned developments, water bodies, areas of fragile 
ecosystem and other risk areas that could be expos ed in the event of accidental spillage; 
b) access to various facilities within the servic e station for effective and efficient operation and 
maintenance; 
c) fall of ground in respect to various sources of i gnition and other risky operations, that may render the 
facility insecure; 
d) drainage system especially how it links up with the drainage system of the Local Authority; 
e) location of existing boreholes, aquifers or ar tesian wells with 500 m where an analysis of hydrogen 
sulphide and hydrocarbon will periodically be done; and 
f) soil types and the depth down to the first impermeable layer.  FDUS : 2011 
© UNBS 2011 – All rights reserved  5
  947-1
4.1.2 Traffic impact assessment 
A service station is a major generator of road traffic c ongestion and as such presents a high degree of traffic 
on the road section onto which it is sited. This determines the number of stations t hat can be permitted on any 
section of the road or high way in any section of t he city. The objective is to keep traffic to minimum and 
therefore, the following shall be observed in siting service stations: 
a) service stations shall be sited at distance of not less than 1000 m from each other on the same 
section of the single carriage road, this applies to either side of the dual carriage road;  
b) a service station shall not be located opposite a br eak or opening in the central verge of dual carriage; 
c) a filling station shall not be sited too close to an intersection to a tr affic island on the main road. The 
minimum distance between an access to a service stat ion and the tangent of a traffic island shall be 
80 m; 
d) no siting of stations shall be allowed on road cu rves and bends and shall not be located adjacent to 
residential houses; and 
e) the minimum distance of a property line (Service station) from the centre line of the single carriage 
road must not be less than 15 m. 
4.2 Composition  
The service station shall compose of  such structures, equipment and inst allations designed and constructed in 
such a way as to make the facility efficient in handlin g the storage and dispensing of petroleum products, with 
no damage to the environment and able to offer safety and hygiene to personnel. A service station layout shall 
therefore be composed of but not lim ited to the following structures: 
• forecourt,  
• tank farm, 
• buildings, and 
• entrances and exits 
4.3 Boundaries  
In respect to the surroundings environment, appropriate boundary fencing shall be provided for the interest of 
security of the station and the surrounding environment. For a service station in an urban setting, an 
appropriate wall fence in brick/blockwork bonded by cement –sand mortar) raised at least 1.8 m high shall be 
erected around the station excluding  the frontage, all subject to the local authorities approval.  
4.4 Design specifications for service stations 
4.4.1 General 
Plans submitted for approval to the approving autho rity shall be endorsed by a responsible engineer who 
hereby certifies that such plans comply with the prov isions of this standard a nd other relevant government 
laws or regulatory measures existing at the time .  
6 © UNBS 2011 – All rights reserved
 4.4.2 Design area specifications  
4.4.2.1 Total service station coverage area  
The total area required will depend on forecourt area, t he size and orientation of the building and, tank farm 
area (depending on number and capacity of installed unde rground tanks). To allow for turning of vehicles and 
to avoid traffic congestion within the station area, the minimum area of a service station shall be set as 
follows. 
a) the minimum size for a filling station shall be 30 m x 30 m; however, in intensely developed areas the 
frontage can be relaxed after investigation subject to  approval of the relevant authority(ies). This area 
excludes area required for other services other than storage and dispensing petroleum products 
(motor fuel); and 
b) the minimum size for a serv ice station (filling station with a service bay) sh all be 1 200 m2, with the 
frontage of not less than 30 m; 
c) every service station shall pr ovide for one parking space for each of its four employees with a 
minimum of two-car parking space and, where addi tional service(s) exist, the parking space shall be 
enough to accommodate the additional vehicles as re quired by the national building regulations.  
4.4.2.2 Forecourt specification  
The service station forecourt shall be  a non-slippery surface structure, constructed of materials that are 
impermeable to, and cannot react with petroleum products. Preferred materials are but not limited to concrete  
The minimum area of service station forecourt wi ll depend on number of pumps dispenser or dispenser 
islands. Dispenser islands in a forecourt shall be designed  and laid in such a way to provide a driveway of not 
less than 6 m on either side. Consequently, adjacent dis penser islands shall be separated from each other by 
6 m.   
The hazardous area around the dispenser islands s hall be covered with a canopy extending outside a 
minimum of 1.5 m on all sides and raised as to comply with building regulations.  The slope of the forecourt shall be maintained between 1: 50 and a maximum 1:20 in hilly places, fixed in such 
a way that effluent flows to appropri ate channels and not to the road.  
4.4.2.3 Tank farm specification 
The area where underground tanks are installed shall be clearly separated from the forecourt, well protected 
and maintained. In intensely developed areas, tank farm s can be integrated within the forecourt subject to 
approval of approving authority after ensuring that suffi cient structures have been included in the design to 
prevent the deformation of tanks by various loads.  
The tank farm area will depend on the number and size of installed underground tanks estimated as per 
specifications in 5.2.2.2. 
4.4.2.4 Buildings specifications 
Each service station shall include buildings, construct ed in conformity with building and construction standards 
and regulations existing at the time, to serve but not limited to functions of office block, sanitary wash rooms, 
canopy, generator house and service station store. 
Buildings shall be constructed of inflammable mate rials and their wiring systems shall conform to Ministry of 
Works and Transport; Electrical Installations and Equipment in Buildings Regulation 2004.  FDUS : 2011 
© UNBS 2011 – All rights reserved  7
  947-1
4.4.2.5 Exits and entrances 
The entrances and exits to the service station shall be of sufficient size and be positioned in such a way that 
drivers are not obstructed from othe r road users by structures and features within and in the neighbourhood. 
In detail, the following shall be considered: 
a) minimum width of the entrance and exit s including the side walk shall be 9.0 m; 
b) maximum angle of intersection of the drive way with the street pavement shall be 45 °; 
c) minimum distance of the dr iveway to any exterior property line shall be 6 m; and 
d) minimum distance between kerbs sites shall be 9 m ( width of entrances). 
4.5 Service station forecourt area classification  
4.5.1 General 
The equipment of the forecourt under normal open area co nditions shall comply with the requirements in 4.5.2 
to 4.5.4.  
4.5.2 Classified area examples  
The direct classification examples for typical service station conditions are given in figures 1 to 5. These 
classification examples shall also be applied to non-retail dispensing sites. The Zone 2 areas indicated cover 
the possibility of localized hazardous areas being present for short per iods, with such areas being well 
ventilated under open area conditions. 
The classified areas indicated relate to the inst allation of fixed electrical equipment and shall not be 
considered as extending beyond an unpierced wall, r oof or other vapour barrier or solid partition.  
4.5.3 Protection of buildings with access to forecourts  
Kiosks, sales rooms, storage rooms, restrooms and other  buildings with openings to a hazard zone shall be 
classified according to that zone at the same height  throughout the building. Such buildings shall be well 
ventilated and heating apparatus shall be positioned in such  a way that it is not possible to have a source of 
ignition in a hazardous area during normal operations or in the event of an outside spillage. 
Fixed heating shall only be of the type where the surface temperature does not exceed 100 °C and all staff 
shall be warned against introducing any  other type of portable appliance.  
Wherever possible, kiosks or other types of buildings  shall not be within any hazardous area. Further care 
shall be taken not to introduce sources of ignition into hazardous locations, for example, cold drink dispensers 
and fridges, electrical signage, sound systems or  uncertified portable credit card readers.  
8 © UNBS 2011 – All rights reserved
   
  
Figure 1 — Underground tank with class I flammable liquids or class II and III combustible liquids at 
temperatures at or above their flash points, with gravity filling 
4.5.4 Fuels other than class 1 products  
The requirements in 4.5.2 to 4.5.3 apply to the handling of  class I products, for example, petrol type fuels. It 
shall be noted that this standard does not distinguish in its design and constructional features between 
dispensing units for class I (PMS) and class II (AGO and BIK) products. Such class II products do not cause a 
hazardous area outside dispensers, but the in side area classification remains the same.   
 
Figure 2 — Underground tank with class II and III combustible liquids at temperatures below their 
flash points, with gravity filling 
 FDUS : 2011 
© UNBS 2011 – All rights reserved  9
  947-1
 
 
Figure 3 — Low hose dispenser with vapour barrier 
 
 
Figure 4 — High hose metering pump/dispenser — without sight glass and with vapour barrier  
10 © UNBS 2011 – All rights reserved
 
 
Figure 5 — Workshop with pit 
Construction and installation of underground tanks, pipe wo rks, pump dispensers and electrical installation 
and other equipment are covered in details in next sections 
5 Design and installation of underground tanks 
5.1 Tanks design installation and maintenance  
Tanks shall be situated at suitable di stances from buildings, roadways or other structures as to comply with 
the relevant provisions of building and civil engineering regulations (this is covered in DUS- 947-2 and national 
construction and building regulations ) 
5.1.1 Leakage detection  
5.1.1.1 Fuel leakage detection 
Tanks of Individual capacity exceeding 30 m3 shall be fitted with an appropriate leakage detection facility 
corresponding to either of the following forms or empl oying appropriate technology subjected to approval of 
the approving authority. 
a) Electrical  — A water/hydrocarbon sensitive probe positioned in the base of the tank at the time of 
manufacture.  This probe sets on an alarm shall it det ect product out of the primary tank, or water into 
the secondary tank. 
b) Mechanical  — A 50 mm diameter drop tube installed at the time of manufacture, running from the top 
to the bottom of the tank and into the interstitial spac e. A float switch fixed to the inside of the tube can 
trigger a warning light and indicate product or water into the interstitial space. 
c) Vacuum test  — A negative 35 kPa vacuum test, held for 30 min, is used to detect a leak in the 
interstitial space. 
d) Volume change  — The interstitial space is f illed with a fluid such as tri-et hylene glycol (steel tanks) or 
brine (fiber-glass tanks) at the time of manufacture. A leak in either the inner or the outer skin causes 
a volume change detected by a level indi cator located at the top of the tank FDUS : 2011 
© UNBS 2011 – All rights reserved  11
  947-1
5.1.1.2 Water detection 
Water may enter the primary tank from loose tank top fittings.  Water shall be detected by periodically wiping 
water-finding paste onto the bottom of the tank dipstick where a change of colour indicating the depth of water 
present or by an appropriate technology subject to approval.  
Some more sophisticated double wall tanks may be fitted with  an electronic sensor in the interstitial space to 
detect the presence of water.  
5.1.2 Steel tanks  
Steel tanks and fibre reinforced steel tanks s hall comply with requirement of DUS 951-2.  
5.1.3 Fibre reinforced resin tanks These shall comply with the requirement of standard FDUS 951-1, and all materials used in contact with the 
tank shall be compatible with fibre reinforced resin. 
5.1.4 Ultra violet protection  
While on site before installation fibre reinforced tanks sh all be protected against ultra violet radiations by 
acceptable means. 
5.2 Site topography  
5.2.1 General 
Each contractor or installer shall be in possession of an approved plan before excavation of the site starts 
(see building regulations) fully approved by the inspecti on authority and marking of the plan shall be evident 
NOTE This is not a requirement for g eneral maintenance and emergency works to existing service stations for which 
no major modification has been done 
5.2.2 Excavations  5.2.2.1 All the excavation shall be carried out in approv ed manner to comply with the requirement of 
Occupational Health and Safety Act 2006 as well as the required specification in building and civil engineering 
standards  
5.2.2.2 The depth of excavation measured downwards from  the proposed finished ground level or from 
the top of the finished drive way surface shall be at least equal to the sum of tank diameter and,  
a) at least 150 mm for the depth of the bedding layer plus 
b) at least 750 mm for the depth of the overlay.  
The width and length shall be in accordance with the tank plan dimensions plus the clearance of at least 500 
mm all around. 
5.2.2.3 The difference between tanks in a single excavation shall be at least 500mm 
5.2.2.4 The contactor or installer shall use suitable equipm ent to keep the exaction free of visible water 
during construction period. No part of excavation shall intersect a line projected at downwards at 45
0 from the 
outer edge of the structural foundation, unless the exac tion is approved by and under the strict control of a 
suitably qualified and recognized engineer.  
12 © UNBS 2011 – All rights reserved
 5.3 Corrosion protection  
When cathodic protection of the tanks and pipe works is needed, it shall be provided in accordance with DUS 
963 Where cathodic protection is installed within hazardous location, the safety parameter laid down in DUS 965 shall be strictly adhered to. 
5.4 Transportation and offloading of steel tanks  
5.4.1 The manufacturer or supplier shall not permit loading or transport of the tank unless suitable 
equipment is available and used 
5.4.2 During transportation, the tanks shall rest of s and bags or any other suitable padding and shall be 
held down with webbing strops and not with wire chains or wire cables. 
5.4.3 All tanks shall be fitted with the lifting rigs, to enabl e lifting straps and shackles to be used and if the 
spread angle exceeds 600 at the apex, a spreader bar shall be used.  All lifting equipments shall comply with 
the regulations and procedures of the Occupational and Health Safety Act. 5.4.4 When a tank is offloaded, it shall be lifted clear off the transport courage and lowered either directly to 
the exaction pit or onto saddles, old tyres or other acc eptable supporting materials of sufficient surface area to 
prevent damage to the coating of the tank. 5.4.5 The tank shall be lowered gently into the exaction. Rolling of the tank shall not permitted at a time 
during transport, offloading and installation 
5.5 Transportation and offloading of fibre reinforced tanks 
5.5.1 During transportation the tank shall rest on s and bags or other suitable padding and shall be held 
down with webbing strops and not with chains or wire cables. 5.5.2 During offloading, the tan ks shall be prevented from rolling over or  dropping. Chains or wire cable 
shall not be used in handling of tanks unless in conjunc tion with the lifting lugs. Chain or cable shall not be 
used around fibre reinforced tanks or fibre-lined tanks. 
5.6 Back filling 
5.6.1 Stability  
The stability of underground tanks depends on backfill support, and is therefore es sential that the correct 
backfill be used. The backfiller shall be spread in layers of  150mm each layer being compacted to the 
requirement of standard Ministry of Works and Tran sport Building Control Regulation amended August 2010 
Underground tanks are designed to be used with adequate backfill support, and they shall be installed using 
acceptable construction practices a nd acceptable fill materials. Improper  installation can cause tank damage.  
5.6.2 Observation of wells  An engineering professional may do a risk assessment at  each new site to determine if future observation 
wells are necessary.  
If no risk assessment is done, observation wells (two for a single tank and four for a multi tank installation) 
shall be installed in the following manner before backfilling takes place: 
a) a non-metallic sloted/perfolated pipe of internal diameter of at least 100 mm, wrapped in a porous 
geotextile, or 
b) acrylonnitrile-but adiene-styrene(ABS) single walled wedge-slot tubular screens, FDUS : 2011 
© UNBS 2011 – All rights reserved  13
  947-1
shall be placed in each corner of excavation. The bottom ends shall be plugged and top end finished off with a 
suitable cover. 
NOTE Non metallic piping for this observation should  be rigid enough to withstand the compaction loads. 
If the soil at the bottom of excavation is of sandy natu re the observation well shall be taken 500 mm below the 
floor of excavation 
5.6.3 Backfill material  
The method to be adopted for backfilling of excavation s for all types of undergrou nd tanks shall depend on the 
type of backfill used, as well as on t he approval of the site engineer for the type of back fill material to be used. 
One of the following materials shall be used as backfill: 
a) sand: clean, inert, granular, well graded sand, free  from any organic matter material, and of grading 
0.02 mm to 2 mm. Appropriate sand includes 
• plaster sand, 
• building sand, and 
• river sand 
b) stone crushing: Clean and free-flowing crusher du st, obtainable from commercial sources and that 
complies with the following requirements: 
• 100 % passing a 19 mm sieve; 
• 98 % passing a 13.2 mm sieve; 
• 90 % passing a 4.75 mm sieve; 
• not more than 20 % passing a 75 μm sieve; and 
• maximum pH of 6.0. 
c) gravel: clean and free flowing naturally rounded co hesionless gravel of nominal diameter 6mm and 
particle size diameter in the range 3mm to 10mm.  A washed river sand would also fall under this 
classification 
Clay, silts, slags and ci nders shall never be used 
5.7 Installation of tanks and method of backfilling with cohesive backfill materials 
5.7.1 General   
Holiday test of 35 000 V, certified by the owner of the equipment shall be carried out on the tank before 
instalment. 
5.7.2 Water level    
The water level shall be maintained lower than excavation by de-watering from a sump.  
5.7.3 Excavation of floor  To ensure that the bottom of the hole is flat, level and free from rocks and other foreign objects, and that the 
highest point of excavation is covered with at least 150 mm of backfill material compacted to the specification  
14 © UNBS 2011 – All rights reserved
 of engineering professional. If so required by the pu rchaser’s engineer and as added precaution against 
products leaks (in pipes or tanks), a suitable non-metallic  sheet (see Figure 6)  shall be placed on a bed of a 
river sand of thickness at least 150 mm. the sheeting shall be so placed that it has a fall of at least 150 mm to 
one corner in which an observation well shall be installed.   
5.7.4 Tank installation  
Place the tank into excavation (in their correct position) and level them to ensure that the fitting apertures are 
in their correct positions. Install the necessary fi ttings and check to ensure that they are vertical. 
 
Figure 6 — Cross section through underground tank 
5.7.5 Ballast fill  
Ballast fill the tanks with sufficient wa ter (or product as previo usly agreed upon and s ubject to the approval of 
local authority) to steady the tank and hold it in position. 
NOTE 1 While holding the ballast, use the lifting lug (or webb ing strop, as relevant) to keep the tank in position. 
NOTE 2 Ballast is not necessary in a dry excavation 
5.7.6 Distribution of backfill   Distribute the backfill material evenly around the tank(s) in uniform horizontal layers, ensuring that no part of 
backfill is more than 300 mm above any other part. The layers shall have a compacted thickness of 150 mm 
and the backfill shall be compacted to a suitable compacted level as indicated on the approved plan. 
5.7.7 Other materials   
Shall the construction programme warrant it, the backfill indicated on the plan may be stabilized with Ordinary 
Portland Cement. FDUS : 2011 
© UNBS 2011 – All rights reserved  15
  947-1
5.8 Installation of tanks and methods of backfilling with cohesionless backfill material 
Cohesionless back fill material is regarded as free-f lowing and can be poured into the excavation, ensuring 
that no part of backfill is more than 300mm above any other part at any given time . The installation procedures 
shall include the following: 
a) maintain the water table below that of the excavation by de watering from a sump;  
b) spread a layer of back fill of thickness of at least 150 mm evenly at the bottom of the excavation; 
c) lower the tank into excavation, position and level them; 
d) fill the tank as in 5.7.5; and 
e) backfill in accordance as  5.7.7. No stabilization with cement is deemed ne cessary when using this 
type of backfill, but water can assist in consolidation of this type of material. 
The backfilling around fibre-reinforced resin tanks shall be cohesionless gravel (pea gravel) 
5.9 Holding down 
5.9.1 General   
When local conditions dictate the likelihood of the water table rising above the level of installed tank, 
precautions shall be taken to counter the buoyancy force on the tank by installing either saddles and concrete 
slab or a single suitable concrete slab. 
5.9.2 Saddles   
If the concrete slab is so constructed at ground level that  load is transferred to the tank via the soil, there can 
be sufficient mass in the slab itself and thus concrete saddles must be installed directly on top of the tank 
shell. Saddles transmit the load of the slab to the tank  shell as a concentrated load, and cognizance shall be 
taken of the fact when the tank is being designed. 
It is recommended that saddles are placed a length equating to one quarter of the tank diameter from the tank 
ends, but placing shall be as indicated on the plan. 
If a reinforced concrete slab is to be used to hold the tank down, a leak test shall be carried out on the tank 
preferably before the slab is cast, in case the tank has to be removed for repairs. 
The concrete slab can be constructed directly on top of the tank shell( separated by melthoid or equivalent 
material) to take advantage of the mass of superimpos ed soil and permit access to pipe runs without having to 
break up the concrete. 
5.10 Concrete slab  
A concrete slab shall be so designed that 
a) its length and with exceed the length and widt h of the tank(s) by at least 600 mm on all sides 
b) its thickness is at least 150 mm, but may be increased if so specified by the purchaser, and 
c) the top and bottom reinforcement consist of mild steel bars of diameter at least 6 mm, at centres of 
not more than 150 mm in both directions, and double gland type fitting for plain end pipe  
16 © UNBS 2011 – All rights reserved
 5.11 Pipe connections and manholes on fibre-reinforced resin tanks  
5.11.1 Pipe connections 
Piping shall be free to move with the tank. Connections into the tank shall be made with short lengths of 
acceptable flexible hose, using compression fittings, or double gland type fittings for plain end pipe. 
5.11.2 Manhole construction 
Do not place bricks or other manhole materials directly  onto the tank surface. The tank shall be separated 
from the manhole itself by either backfilling material , melthoid or similar materials. Manholes may be 
constructed from but are not limited to the following  materials: load-bearing brickwork (fully bedded and 
jointed), high density poly-ethylene, precast or in-situ co ncrete and fibre-reinforced resin. Manholes shall be of 
diameter at least 1 m and minimum length 1 m, and shall be so designed as to prevent the ingress of surface 
water.  
5.11.3 Pipes 
Piping for tanks other than fibre-reinforced resin tanks may be of steel black piping, protected against 
corrosion by a petrolatum gauze wrapping, together with  a PVC outer wrap, or of a suitable non-metallic 
material. However, the pipe work on the upstream (tank) side of the dispensing delivery pump and the 
dispenser bottom connecting union, or of the shear co upler, shall be installed in accordance with the 
dispenser manufacturer's requirements.  
When steel piping is used it shall be protected against corrosion by petrolatum gauze wrapping, together with 
a PVC outer wrap, with at least 50% overlaps. All steel piping shall comply with the requirements of US159 for 
medium pressure rating (for cathodic protection, see also 5.3). 
5.12 In-situ leak test  
A full system pressure leak test at 40 kPa in accordanc e with an approved test method shall be carried out on 
the tank after installation.  
5.13 Manufacturing and Installation 
The purchaser or his appointed agent shall be permitted to inspect the materials or the work of the tank 
manufacturer at any time 
The installer shall provide the approv ing authority with a certificate stat ing that a competent person has  
a) examined the excavation and witnessed the placing of the tank in the excavation,  
b) witnessed an in-situ leak test being performed on the tank,  
c) witnessed a leak test being performed on the pipework, and  
d) witnessed a 35 000 V holiday test on the t ank before it was placed into the excavation. FDUS : 2011 
© UNBS 2011 – All rights reserved  17
  947-1
6 Pipe works and fittings 
6.1 Steel pipe and fittings for welding  
6.1.1 General 
Piping for welding shall be suitable for working pressu res of up to 1 000 kPa and shall comply with the 
requirements of at least US 159. The piping shall be plain end, bevelled for welding, electric-resistance 
welded, submerged arc welded or seamless. 
6.1.2 Fittings   
Fittings for welding shall comply with the requirements of an DUS 955-2. 
6.1.3 Flanges  
Flanges for welding shall be of class 150 pressure-temperature rating, slip-on or weld neck flanges that 
comply with the requirements of DUS 956.  
6.1.4 Gaskets  
Gaskets shall be non-asbestos, compatible with the liquid being handled, of thickness at least 1.5 mm and 
shall comply with an approved standard.  
6.2 Threaded steel pipe and fittings  
6.2.1 General 
Threaded steel piping shall comply with the requirements of US 159. No galvanized pipes and fittings shall be 
used. 
6.2.2 Fittings 
Only threaded mild steel fittings sha ll be used. Unions shall be cone-faced . 
6.2.3 Flanges  
Threaded flanges shall be of steel, and shall comply wi th the requirements for class 150 pressure-temperature 
rating of DUS 956or another approved standard.  
6.2.4 Pipe threads  
Pipe threads shall comply with the requiremen ts of ISO 7-1 or another approved standard. 
6.3 Non-metallic piping  
6.3.1 Material  All components of an installation shall be capable of oper ating in the prevailing soil conditions. If the material 
is susceptible to degradation from exposure to al kalis, acids, aqueous salts and hydrocarbons, acceptable 
adequate protection shall be applied.  
18 © UNBS 2011 – All rights reserved
 6.3.2 Fuel compatibility  
No significant degradation of the propert ies of the material shall occur over  the life of the installation. The 
various additives and blends in fuels shall be noted and considered.  
6.3.3 Fuel permeability  
Where non-metallic permeable materials are used for piping, the rate of permeation shall not exceed 2 
g/m2.day at a temperature of 23 °C. 
6.3.4 Ultraviolet exposure  All non-metallic components shall be able to withstand six months continual weathering before installation 
without significant property degradation.  
6.3.5 Primary delivery pipes  
Both positive pressure and vacuum suction lines w here the pipes continually contain liquid fuel shall be 
capable of withstanding 4 bar positive pressure and a 10 bar peak pressure pulse. 
Suction lines shall be capable of withstanding 0.6 bar vacuum and a 0.7 bar peak vacuum pulse, and a 1 bar 
positive pressure. 
6.3.6 Vents  
Vent lines that contain petroleum vapours but that are not normally exposed to liquid fuel shall be capable of 
withstanding 1 bar pressure and 0.1 bar vacuum pulse.  
6.3.7 Fill pipes  
Fill lines experience regular, but short periods of exposure to liquid fuels and continual exposure to petroleum 
vapours. The lines shall be capable of withstanding 1 bar positive pressure and a 0.6 bar vacuum pulse. 
6.3.8 Compressibility  
Pipes shall not deform more than 5 % when subjected to normal road wheel loads at a cover of 300 mm. 
Stabilized material or concrete may be used as ba ckfill to reduce any deformation of the pipe.  
6.3.9 Transition  
When non-metallic piping is used, the tr ansition from steel tank fittings to no n-metallic fittings s hall be made in 
the manhole nearest to the tank.   
6.3.10 Shear-off valve 
The vertical riser beneath any remote dispenser shall be so  firmly fixed as to ensure the correct functioning of 
the shear-off valve of the dispenser and shall comply with the manufacturing requirements. 
6.4 Installation  
6.4.1 Pipework  
Steel pipework shall be laid out in a geometrical pattern  and shall be indicated on the plan of the site. All non-
metallic piping shall be laid out in accordance with the manufacturer's recommendations. FDUS : 2011 
© UNBS 2011 – All rights reserved  19
  947-1
6.4.2 Joint fittings  
Only standard fittings shall be used on joints.  
6.4.3 Incline on pipe work  
Pipe work shall be designed by a competent person to hav e an adequate fall to the tank from the dispenser(s) 
or suction pump(s), vent(s) or  breather(s), and fill point(s).  
6.4.4 Jointing tape  Jointing tape or compound used on screwed th reads shall be of an acceptable quality. 
6.4.5 Buried pipe work  
All buried pipe work shall be covered by backfill of thickness at least 300 mm. A shallower backfill may be 
permitted if it is of a reasonable engineering design. 
6.4.6 Welding   
All welds shall be visually inspected for compliance with  DUS 955-2. All welding fo r non-metallic type piping 
(where applicable) shall comply with an approved standard.  6.4.7 Pipework leak test  
Before the pipe work system is backfilled, it sha ll be isolated from the tank (s) and pump/dispenser and 
subjected to a pneumatic pressure of at least 600 kPa or  to a nitrogen gas and soap solution test for at least 1 
hour. A hydraulic test can be performed, with the pressu re being maintained for 15 min at 1 000 kPa, or an 
ultrasonic leak detector can be used to search for leaks within the system.  
6.4.8 Corrosion protection  
All steel pipes and fittings shall be corrosion protected by means of wrapping. Cathodic protection of the pipe 
work may be the same as for the tank if so specified by the competent person in charge. 
6.5 Dip pipes or gauging pipes  
Each tank shall have a connection through which the cont ents of the tank can be manually or automatically 
gauged. The connection shall be of nominal diameter at least 40 mm and shall be fitted with a lockable cap 
capable of sealing against a hydrostatic pressure at leas t equal to the pressure of the tank or that of the 
delivery head (whichever is the greatest). 
NOTE In order to avoid spillage in case  of an overfill, this dip cap should be  in the closed, sealed position whilst 
deliveries are taking place.  
6.6 Suction pipes  
Where suction pipes are installed to each pump, a non- return valve shall be fitted at the base of and under the 
pump and not in the manhole chamber.  
6.7 Delivery pipes  
Delivery pipes are installed where submersible pump s are used. A single header for each product or a 
designed header that is site specific shall be run along  or underneath the line of the dispenser island(s).  
NOTE  For maintenance purposes an isolating valve may be fitted to the branches of the dispensers.   
20 © UNBS 2011 – All rights reserved
 6.8 Breather pipes or vent pipes  
Breather pipes or vent pipes shall be of internal diamet er at least 50 mm and shall terminate at a distance of 
at least 1.5 m away from any opening to a building, the distance being measured horizontally. The vent pipes 
shall so terminate that the fumes are exhausted vertically upwards or horizonta lly. Discharge shall not be 
vertically downwards. The termination sh all be protected by means of a screen.  
The fact that petroleum vapours are heavier than air shall be taken into account, and free rapid dispersion 
shall be allowed for at the termination of the vent. No  brick or other architectural screening of the vent 
termination shall be permitted. One vent per tank is required and these shall not be manifolded since overfills 
can lead to cross-contaminati on. The vent outlets shall be so located that they  
a) are not situated beyond the ex isting building line boundary on a stand excluding the street boundary, 
b) allow unrestricted v enting to the open air,  
c) are at least  
i. 600 mm above roof level,  
ii. 3.5 m above ground level,  
iii. 1.5 m from any door, window, or other opening in a building, and  
iv.  3 m from any chimney opening, any hot  surface, or any source of ignition,  
d) are, if possible, within  sight of the filling point (under certain circum stances, where the vent outlet is 
not within sight of the filling point, the approving au thority may require that an alternative warning 
system/procedure be employed to guard agains t the possibility of overfilling), and  
e) are not installed within 1.5 m of any  electrical and electronic equipment.  
All breather/vent pipes shall be cross bonded using 25 mm copper cable and connected to a copper earth 
spike of length at least 1.2 m and of diameter 10 mm, dr iven into the ground as near as possible to the pipe(s) 
and connected to the pipe(s) using 25 mm green-plastic-i nsulated copper conductor. This copper conductor 
shall then be connected to the earth cont inuity of the site by an acceptable  means, for example with a copper 
U-bolt. 
7 Fillers, pumps and drainage 
7.1 Fillers 
7.1.1 General  
Underground tanks shall be filled by gravity filli ng. No direct connection pump deliveries shall be permitted 
unless there is an engineered system/adaptor fitted wh ich will prevent excess pressure being placed on the 
tank.  
Fillers shall be so sited that surface water and soil are prevented  from entering the filler box. Each of the fillers 
shall be so sited that the tanker is able to leave the premises without having to reverse, and can park safely 
when bulk deliveries are being made. Where limited acce ss prevents tankers from parking or entering the 
premises, filler sites shall be designed by the engineering professional to accommodate them. 
7.1.2 Filler box  
The filler box shall be leak proof, shall be able to cont ain the contents of a bulk delivery vehicle discharge 
hose, and shall be of capacity not less than 35 R.  FDUS : 2011 
© UNBS 2011 – All rights reserved  21
  947-1
7.1.2.1 Metal filler box  
Each metal filler box shall have a frame bolt that can be used as an earth connection point, and the filler box 
shall be connected to the electrical earth continuity condu ctor of the installation. A metal tag shall be provided 
onto which the operator can connect the bonding cable from the bulk vehicle while delivering product.  
7.1.2.2 Non-conductive filler boxes  
In a non-conductive filler box, the conductive parts inside the box shall be connected to the electrical earth 
continuity conductor, and a connection point shall be provided onto which the operator can connect the 
bonding cable of the bulk vehicle.  
7.2 Pumps and dispensers  
7.2.1 General  
Submersible pumps, dispensers and suction pumps shall comply with a specification approved in terms of the 
Occupational Health and Safety Act of 2006. (Approv ed electrical specifications are listed in DUS 975, 
Dispensers and dispensing pumps).  
Resetting dispensers and dispensing pumps shall comply with the requirements of the Weights and Measures 
Act 1963, Cap 93. 
7.2.3 Specific requirements  
7.2.3.1 Leak detector  
Each submersible pump shall have a leak detector that automatically checks the integrity of the pipe work on 
the pressure side of the pump.  
7.2.3.2 Shut-off valve  
Each dispenser shall be fitted with an emergency shut-off valve that incorporates a shear section and has its 
body anchored rigidly below the dispenser in acco rdance with the manufacturer's specification.   
7.2.3.3 Plinth  
Each dispensing pump and dispenser shall be protected by a concrete or brick plinth projecting at least 300 
mm from the base and of height at least 150 mm above fini shed floor level (see Figure 2). Alternatively, the 
plinth can be widened at the ends only, as illustrated in Figure 7  
7.2.3.4 Steel bollards/crash barriers  Where a plinth cannot be installed steel bollards or cr ash barriers may be installed, provided that they are 
acceptably fixed onto a concrete base.  
7.2.3.5 Dispensing hose  
Each dispensing pump or dispenser shall be so located that  when the hose is fully extended in the direction of 
any ramp leading down to a basement, no fuel can flow from the nozzle down the ramp.  
22 © UNBS 2011 – All rights reserved
 
 
Figure 7 — Plinth 
 
Figure 8 — Alternative plinth 
7.3 Drainage and interceptors  
7.3.1 Surface water  
Drainage shall be planned in accordance with statutor y regulations. Every advantage of natural seepage for 
disposal of surface water shall be utilized. Existing storm-water drains, rivers and streams shall be used to 
cope with the outflow, though it might be necessary to provide special catchment basins or seepage areas in 
large settings  where heavy precipitation rates (that might temporarily be beyond the capacity of the local 
system) can be expected. FDUS : 2011 
© UNBS 2011 – All rights reserved  23
  947-1
7.3.2 Containment separation  
Where it is necessary to use interceptors to separate contaminants from water, consult the relevant 
regulations as contained in the National Environmental Act 1995.  
The collecting system shall be so designed as to mi nimize the amount of surface water (that results from 
precipitation and normal drainage channels) passing through the interceptors (thus avoiding the need for 
inordinately large interceptors). This is best achieved  by providing separate systems for surface water and for 
water from contaminated sources such as dispensi ng and tank filling areas (for design details of an 
interceptor, see Annex C).  
The driveway area around the dispensers/dispensing pumps where spillage might oc cur during the refuelling 
operation, shall be so graded t hat any effluent run-off will not flow to t he street, or into watercourses or into 
storm water systems without first passing through an in terceptor. Contrary sufficient  channels and slopes shall 
be shall be constructed and maintained to stop outside e ffluent run-off from entering the service station 
forecourt. 
Slopes of 1:50 to1:20 shall be maintained throughout the forecourt directing water and spillage towards the 
corresponding drainage channels. 
In cases where effluent is mixed with detergents, thus breaking down the petroleum product and rendering the 
gravity separator ineffective, the effluent shall pass thr ough an interceptor and from there to a foul sewer (see 
Figure 9 .) 
Precautions shall be taken to ensure that rain water wi th spills do not flow into a foul sewer or storm water 
system without first passing through a gravity separator 
7.3.3 Sewage 
Where a local system for the disposal of sewage exists, it is obviously desirable that the drainage system be 
connected to it, but where this is impracticable, septic tanks or other suitable disposal units shall be installed. 
Consult the regulations of the local authority and investi gate the suitability of the ground with a view to the 
installation of disposal beds. Contamination with product in such systems s hall be avoided. Conversely, 
sewage systems shall not be connected to interceptors.  
7.3.4 Washing of vehicles  
All wash-bays shall be so designed that effluent, detergents and contaminated water are contained. Run-off 
water that contains effluent shall be of such quality that  it complies with the relevant regulations of national 
environmental authority and with the by -laws of the local authority before the water passes into the relevant 
drains. Specially designed wetlands can al so be considered for this purpose.   
24 © UNBS 2011 – All rights reserved
 
 
Figure 9 — Sampling chamber and interceptor 
7.4 Overfill protection  
7.4.1 Care shall be taken to ensure that the basic indication that an overfill has occurred or is imminent, is 
not the spilling off the product out of the dip pipe but a slowing down or stoppage of the delivery meter. To 
achieve this, a backpressure has to develop in the storage tank. 
7.4.2 The dip cap shall be able to seal against a hydrostatic pressure of at least the pressure of the tank or 
that of the delivery head (whichever is the greatest), a nd shall be securely closed before delivery takes place.  
7.4.3 The tank shall be fitted with an overfill protector. The critical level shall be such that a space remains 
in the tank to accommodate the delivery hose volume (the standard 2 % ullage will suffice).  
8 Electrical installation 
8.1 General 
All electrical and electronic installation shall comply with the requirements of the Occupational Health and 
Safety Act 2006, and Electrical Installation Regulations, 
Uncertified electrical equipment or systems s hall not be installed in hazardous locations.  FDUS : 2011 
© UNBS 2011 – All rights reserved  25
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8.2 Electric cables  
Electric cables and wiring shall be so installed that they do not come into extended contact with substances 
that might be harmful to their insulation. All cables with in a service station shall be encased in suitable sleeve 
piping and buried either underground or within walls.. No bare cables shall run along surfaces on either 
ground or walls of building within a service station.  
8.3 Buried cables  
All power and electronic cables passing under paving and driveways shall be encased in suitable sleeve 
piping. Marks shall be erected where buried cables pass to guide future maintenance and development 
activities  
8.4 Sleeve pipes 
All sleeve pipes that pass through a hazardous area,  whether or not for electrical purposes, shall be 
acceptably sealed to prevent hazardous vapours fr om seeping into unsafe unprotected locations.  
8.5 Non-explosion-protected equipment  
Only certified explosion-pr otected electrical equipment shall be used in zones 1 and 2 as defined in figures1- 
5. This provision refers mainly to refrigerators, automatic vending machines and any non-explosion protected equipment that the user might install on a pump island or driveway.  
8.6 Accredited electricians and certification of electrical work  
8.6.1 Electricians  
All electricians who work on installations that fall within the scope of this standard shall either be an electrical 
contractor who is registered according to Electricity (Installation Permits) Regulations 2003 or be employed by 
a registered contractor.  
8.6.2 Electrical installations   
All electrical work on installations that fall within the scope of this standard shall be done by an accredited 
electrician or under the general control of an accredited electrician.  
8.6.3 Certification  
Electricians shall provide a prescribed "Certificate of Co mpliance" for the work that they carry out. Electrical 
work in hazardous locations shall be certified as per Electricity Regulatory  Authority’s regulations.   
8.7 Emergency  
There shall be an "emergency stop" station so demarcated as to be easily visible in the forecourt and easily 
accessible for operation in case of an emergency. When the "emergency stop" is activated, it shall cut all 
power to the forecourt.  
Each pump shall have an individual circuit with overload and thermal protection.  
8.8 Hazardous installations  
Electrical work in hazardous locations requires specialized knowledge and experience, so this type of 
installation shall only be designed and installed by persons competent in this field.   
26 © UNBS 2011 – All rights reserved
 9 Operation and maintenance of filling stations 
9.1 Marking of equipment  
To provide easy identification, Dispenser and dispen ser pumps shall be clearly marked to indicate the 
product(s) dispensed as per DUS 976. 
Calibrated metering device displays, shall be visible to consumers and indicates the price in local currency 
and the volume of the products dispensed in metric units. 
9.2 Notice and labels 
A service station shall have notices well displayed in appropriate and visible areas to indicate: 
a) entrances and exits shall be made of artificially illuminated retro reflective material and read from a 
distance of 50 m; 
b) warning notices and signs such as, “Switch o ff engine”, “No smoking”, “Danger inflammable” and any 
other as authorities may deem nece ssary. These signs will be of such  type and sizes that they can be 
read from a distance of 7.5 m; and 
c) price tag(s) shall be laid  on raised metallic billboard. 
9.3 Fire-fighting equipment 
All fire equipment and hydrant points shall be clearly identified by the appropriate colours and signs in 
accordance with DUS 962 or an approved international standard. It is recommended that retro- reflective 
materials be used for this purpose.  
9.3.1 Portable and mobile fire extinguishers  
9.3.1.1 Each service station shall have portable fire exti nguisher of not less than 9kgs per each dispenser 
of not more than two dispensing hoses. Portable fire extinguishers shall be inspected at least once every 
calendar year by a designated person and those found to be defective on inspection shall be replaced. 
Portable and mobile fire-exti nguishers shall comply with US ISO 7165. 
9.3.1.2 Chemical powders shall be of a type that complies with US ISO 5923 and is compatible with the 
intended application. 
9.3.1.3 All fire-extinguishers shall be protected from the weather. 
9.3.2 Fire hoses 
9.3.2.1 Fire fighting hoses shall comply with an  approved standard. 
9.3.2.2  Hoses shall be inspected at least once every calendar year by a designated person. Hoses found 
to be defective on inspection shall be replaced or repaired immediately . 
NOTE A record should be kept that shows the date of each inspection and is signed by an appointed 
responsible person.  
9.3.2.3 Fighting hoses shall be housed or stored in weatherproof containers when not in use. 
9.3.3 Couplings  
9.3.3.1 Couplings for hoses, branch pipes, nozzles and connectors shall comply with an  approved standard. FDUS : 2011 
© UNBS 2011 – All rights reserved  27
  947-1
9.3.3.2 All couplings shall be compatible with the local authority's fire-fighting equipment . 
9.3.4 Fire alarms 
9.3.4.1 All stations shall be equipped with fire alarms. Fire  alarms shall be of such volume and tone that 
they are clearly distinguishable from background no ise and are audible, under prevailing wind conditions, 
anywhere along the perimeter of the site. 
9.3.4.2 Where an alarm is electrically powered, an independent source of power shall also be 
available. 
NOTE Hand-cranked or compressed gas units may also be used. 
9.3.4.3 An approved means of direct emergency communication with local emergency services shall be 
available  
9.3.5 Colour identification of fire-fighting equipment 
All fire-fighting equipment shall be painted a distinctive red (A11 signal red or A14 poppy red), and Notices 
shall be displayed in accordance with the requirements of DUS 962 and the location of equipment that is not 
visible shall be clearly indicated.  
9.3.6 Employees for fire-fighting  
All selected key employees shall be trained and remain competent to deal with all possible emergencies and 
shall be conversant with the principles of fire-fighting and the operation of the fire- fighting equipment provided 
in their work environment. 
An adequate number of employees shall be trained to stand in for absent trained key employees during 
periods of leave (including absences due to sickness) and on public holidays. 
Records shall be kept of all training, as  required by the US 534 and OHS Act, 2006.  
9.4 Protection and welfare of personnel  
It is assumed that, the type of plant and equipment installed, and the methods of operation are fully in 
accordance with the relevant recommendations given in this standard,  and  that  familiarity  and  general  
compliance  with  ordinances,  the  applicable regulations framed under the OHS Act, 2006, and any other 
applicable regulations are ensured. 
All accidents and dangerous occurrences shall be reported  to the designated person or safety representative, 
who shall arrange for medical attention for the injured and for the elimination of unsafe conditions or unsafe 
actions, or both. 
9.4.1 Safety and protection measures   
The following specific safety and protection measures shall be provided for in accordance with the OHS 
Act, 2006: 
• first-aid treatment; 
• medical assistance; 
• emergency treatment; 
• prevention of inhalation of fumes;  
28 © UNBS 2011 – All rights reserved
 • protective clothing; 
• protective footwear; 
• protective equipment; 
• breathing apparatus; and 
• safety goggles or eye shields. 
9.4.2 Contact with petroleum products   
Contact with petroleum products and the associated dangers require that the following points be attended to: 
• prevention and treatment of contamination; 
• prevention and treatment of occupational diseases; 
• prevention of contamination by leaded petrol; 
• correct handling of materials and packages by hand; 
• accident reports; 
• good housekeeping; 
• welfare facilities; and 
• material safety data sheet.  
9.5 Repairs and alterations 
9.5.1 Permits  Any major maintenance of or extensions or major repair work to a petroleum filling station shall be carried out 
after an appropriate permit has been issued as according Petroleum Supply Act 2003. 
To  ensure  safety,  construction  and  repair  work  shall  only  be  performed if written permission has been 
granted by the manager or his authorized representative. This will follow but not be limited to the following 
procedure: 
a) lay down clearly defined responsibilities; 
b) adopt specific and explicit rules and regulations; 
c) ensure that instructions and orders given are simple and clear; and 
d) ensure that the cathodic protecti on system is turned off before the start of any work on pipelines, 
pumps, valves, etc. 
9.5.2 Equipment  
Repairs  or  alterations  shall  not  be  permitted  on  any  plant  or  equipment  while  such  plant  or 
equipment is in use. 
When repairs or alterations necessitate the dismantling of  essential items of system such as valves, pumps 
and pipelines, a specific notice shall be issued to all concerned.  FDUS : 2011 
© UNBS 2011 – All rights reserved  29
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9.5.3 Pipelines, pumps and valves  
In the event of a broken connection, no reliance shall be placed on closed valves. Complete drainage 
shall be effected and openings shall be closed proper ly by means of blank fl anges or line blinds. Any 
spillage of product shall be co llected and disposed of in an acceptabl e way. When continuity in a pipeline is 
broken, the work area shall be bridged with a heavy electr ical jumper cable to reduce the risk of sparks from 
stray or induced currents. 
9.5.4 Hot work  
When any hot work is to be carried out in a hazardous area that contains a petroleum product, a high 
degree of control and supervision shall be maintained.  
NOTE All petroleum products become flammable when heated to their Flash points. 
9.5.5 Electrical equipment  
An accredited person shall certify that  the electrical equipment has been isolated and locked out safely before 
any repair, adjustment or test is commenced. Warning notices (symbolic signs) shall be hung onto or 
affixed to main switches or circuit-breakers, to prevent accidental switching on while repairs are in 
progress. After repairs have been completed, an accredit ed person shall certify that the apparatus is in order, 
both mechanically and electrically, bef ore it is brought back into use 
9.5.6 Plant 
When a mobile plant is temporarily stationed in a hazardous area for maintenance, repair or other purposes, 
care shall be taken to ensure that the plant is of such construction that it is not likely to cause a fire by the 
emission of sparks or flames, or by any other source of ignition . 
No plant belonging to a contractor shall be used on t he premises without the written permission of the 
manager or his authorized representative . 
9.6 Personnel safety  
All staff engaged in f illing station operati onal and maintenance duties shall be fully acquainted with the 
requirements of the safety regulati ons in terms of the OHS Act, 2006. 
9.6.1 Supervision  
Maintenance and inspection work shall be planned and supervis ed by responsible member s of staff, who shall 
ensure that all relevant precautions are observed. 
9.6.2 Use of casual and contractors' labour  
When  casual  and  contractors'  labourers  are  employed,  they  shall  be  familiarized  with  all  the relevant 
precautions adopted by the filling station. The necess ary precautions to be taken shall have been thoroughly 
explained to them before any work is commenced.  
When such labourers are employed in or adjacent to a hazardous area, strict supervision shall be arranged to 
ensure that all relevant precautions are observed. 
9.7 Removal or abandonment of tanks and pipe work  
9.7.1 Removal  
A tank or pipe work which is leaking or which is to be taken out of service permanently, shall be removed from 
the site, except in cases where there are well justified structural or practical reasons against removal. In such  
30 © UNBS 2011 – All rights reserved
 cases the tank or pipe work may be abandoned on site subject to approval by the local authority, and in 
compliance with the relevant requirements of National Environmental Management Authority 
Before any tank or pipe work is removed, it sha ll be inspected and certified as free from all liquid 
hydrocarbons. All safety precautions shall be strictly adhered to at all times. 
When a tank or pipe work is being removed, due prec autions shall be taken against risks associated with the 
following:  
a. The likely presence of hydrocarbons in the surrounding soil; and b. The possible presence of explosive vapour s in the tank or pipe work (or both).  
Once a leaking tank or leaking pipe work has been re moved, it is necessary to rehabilitate the surrounding 
area to the satisfaction of National Environmental management Authority or its duly authorized agent.  
9.7.2 Abandonment 
9.7.2.1 General requirements  
When the abandonment of a tank or pipe work has been duly approved, the tank or pipes shall be filled with 
an acceptable filler material, for ex ample polyurethane foam, slush conc rete, etc. (see also DUS 974). 
9.7.2.2 Requirements for polyurethane (PUR) foam used as filling material for abandoned tanks and 
piping  
9.7.2.2.1 General  
Any PUR foam used as a filling material shall:  
a. be generally compatible with the tanks or pipe work which it f ills and, in particular, shall not be 
aggressive or corrosive towards such pipe work;  
b. evolve no noxious or toxic gases or fumes in  the course of its formation or in subsequent 
service;and  
c. retain its structural integrity in normal conditions throughout its service life.  
9.7.2.2.2 Foam-forming system  
9.7.2.2.2.1 General suitability and application procedure  
A foam-forming system (isocyanate and polyol with any app ropriate additives) to be used for filling a tank or 
pipe work shall be recommended by the system's supplier as suitable for the particular application, and the 
supplier's instructions shall be followed when the system is being applied on site.  
9.7.2.2.2.2 Properties relevant to cavity filling  
When each of the properties of a f oam-forming system listed in column 1 of Table 1 is determined by the 
corresponding test method indicated in column 4, the result of the determination shall comply with the relevant 
requirement given in column 3 of the table.  FDUS : 2011 
© UNBS 2011 – All rights reserved  31
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Table 1 — Properties of foam-forming systems [determined at (25 ± 1) °C] 
1 2 3 4 
Foam- forming system Requireme nt Test method, clause 
Property and units Foam application 
Viscosity, mPa.s Tank filling: polyol and 
isocynate 150 to 2501) B.1.1 
Pipework filling: polyol 150 to 3002) 
isocyanate 150 to 2501) 
Cream time, s Tank filling 30 to 90 B.1.2 
Pipework filling 20 to 90 
String time, s Tank filling 180 to 360 B.1.2 
Pipework filling 120 to 360 
Rise time, s Tank filling 300 to 600 B.1.2 
Pipework filling 240 to 600 
1)150 cP to 250 cP 
2)150 cP to 300 cP 
 
9.7.2.2.3 Finished foam  
9.7.2.2.3.1 Origin 
The foam shall be produced on site from a system t hat complies with the relevant requirements given in 
9.7.2.2.2.1 and in accordance with the relevant inst ructions provided by the su pplier of the foam-forming 
system. Foam samples for the tests of physical and mech anical properties (see 9.7.2.2.3.2) shall be obtained 
as described in B.2.1.  
9.7.2.2.3.2 Physical and mechanical properties  
When each of the foam properties listed in column  1 of Table 2 is determined by the corresponding test 
method indicated in column 4, the result of the determi nation shall comply with the relevant requirement given 
in column 3 of the table.   
32 © UNBS 2011 – All rights reserved
 Table 2 — Physical and mechanical properties of foam 
1 2 3 4 
Foam 
Requirement Determination Property and units Function 
Density, kg/m3 Tank filling 30 to 401) B.2.2 
Pipework filling 15 to 202) 
Closed – cell content, % Tank filling > 80 B.2.3 
Pipework filling > 20 
Comprehensive 
strength, kPa Tank filling > 150 B.2.4 
Pipework filling > 20 
Bending Properties  
Deflection at break, mm Tank filling > 15 B.1.2 
Pipework filling > 20 
Force at Break, N, min1 Tank filling > 15 B.2.5 
 Pipework filling > 2 
If the test breaks before reaching deflection of 20 mm ( see US ISO 1209-1) 
1. 0.030 g/cm3 to 0.040 g/cm3 
2. 0.015 g/cm3 to 0.020 g/cm3 
 
9.7.2.2.3.3 Dimensional stability  
When tested in accordance with B.2.6, the foam shall  
a. exhibit no distortion, and  b. maintain its structural integrity.  
9.7.2.2.3.4 Absence of volatile emissions  
No chlorinated hydrocarbon vapours or formaldehyde, det ectable by smell, shall be emitted by the foam at 
any time after the completion of its production. 
9.8 Registration  
Each installation shall be registered with the aut hority before being commissioned and receiving product to 
operate as per Petroleum Supply Act 2003. FDUS : 2011 
© UNBS 2011 – All rights reserved  33
  947-1
Annex A 
(normative)  
 
Design and construction of tanks 
A.1 General  
A.1.1 The minimum internal design pressure for a tank s hall be equal to the static head measured from the 
top of the bulk delivery vehicle to the bottom of the installed tank.  
A.1.2 A tank shall be capable of withstanding a working pressure (vacuum) of S20 kPa (that is,. 
atmospheric minus 20 kPa absolute).  
A.1.3 A tank shall be able to resist the upward thrust of  pressure generated by water surrounding the tank, 
taking due cognizance of any point l oading imposed by the holding-down system . 
A.1.4 A tank shall be able to withstand imposed loads ge nerated by a legal maximum loaded wheel and 
axle system. A limit on the tank diamet er might also be necessary if remote  suction pumps are used instead of 
submersible pumps. 
A.1.5 All tanks shall be internally free from loose dirt and foreign matter. All openings shall be sealed as 
soon as tests have been satisfactorily completed. Allowance shall be made for thermal breathing.  
A.1.6 The manufacturer shall provide a general calibration chart per tank size.  
A.1.7 The major dimensions of a tank shall be as specified by the purchaser.  
A.2 Interceptors and drainage  
A.2.1 Interceptors are different from gravity separators, in  that they take effluent containing emulsifiers and 
detergents.  A.2.2 The interceptor shall take the floor washings from  the lubricating bay and the workshop and effluent 
from the wash bay. The interceptor chamber shall be  covered with a suitable manhole and shall be vented by 
a pipe of diameter at least 50 mm to an elevation of at least 3.6 m. The depth of the interceptor chamber, measured from the in vert of the outlet to the level of the bottom of the 
chamber shall be at least 600 mm. Increased depth does not improve the efficiency of the interceptor and 
complicates cleaning. The minimum plan area of the chamber shall be 800 mm × 800 mm.  A.2.3 Interceptor chambers shall be oil proof and waterproof and for this reason prefabricated units shall be 
considered.  
A.2.4 A downstream sampling chamber of diameter 300 mm shall be provided for the purpose of sampling 
the effluent before it enters the f oul sewerage system. The minimum retention volume shall be 32 R. The 
effluent can be sampled for the testing of chemical o xygen demand and, as a field indicator, dissolved oxygen.  
A.2.5 In terms of the Petroleum Supply Act, 2003 used oil and paraffins may not be taken into this 
interceptor.   
34 © UNBS 2011 – All rights reserved
 A.3 Used oil and solvent washings (paraffins)  
In terms of the Petroleum Supply Act, 2003, all used oil and contaminated used hydrocarbons shall be sold as 
waste to a licensed oil refiner or recycling plant.  
At every installation, a system and fa cilities shall be provided for colle cting and storing the waste products 
without spillage or infringement of the Water Act of 1956, and for removing the waste. FDUS : 2011 
© UNBS 2011 – All rights reserved  35
  947-1
Annex B 
(normative) 
 
PUR foam-forming systems and foams for filling abandoned tanks and 
pipework — Test methods 
B.1 Tests for foam-forming systems  
B.1.1 Determination of viscosity at (25 ± 1) °C of the components (isocyanate and polyol) of 
a foam-forming system  
Use the method in ISO 3219.  
B.1.2 Determination of foaming characteristics at (25 ± 1) °C: cream time, string time and rise time  
B.1.2.1 Apparatus  
B.1.2.1.1 Laboratory apparatus  
For small-scale preparation of PUR f oam, comprising the following items:  
a. mixer, operating within the rotational frequency range 24 s-1 to 29 s-1 (1 440 rpm to 1 740 
rpm), equipped with an aluminium disc-type stirrer of diameter 65 mm;  
b. balance , accurate to 0.1 g or better;  
c. thermometer , reading accurately to within 0.5 °C or better, suitable for measuring 
temperature in a range encompassing 25 °C;  
d. mixing container, polyethylene beaker, or a non-waxed ca rdboard container, of capacity 500 
mR to 700 mR, and height of side wall preferabl y not greater than twice the diameter; and  
e. glass rod  or wooden spatula.  
B.1.2.1.2 Stopwatch, Reading accurately to 1 s or better  
B.1.2.2 Test specimen  
The components (isocyanate and polyol ) of a foam-forming system (incl uding any requisite minor additives) 
for the filling of a tank or  pipework, as appropriate 
B.1.2.3 Procedure  
NOTE Isocynates are highly reactive c hemicals, aggressive to the skin and eyes. It is essential to ensure that the 
person performing the foaming characteristi cs test is thoroughly familiar with the necessary safety precautions, and with 
procedures for dealing with accidental splashes and spills. T he relevant instructions are obtainable from any reputable 
mmanufacturer of the isocyanate comp onents of foam-forming systems. 
B.1.2.3.1 Thoroughly stir each of the two liquid components of the foam-forming system to ensure their 
homogeneity .   
36 © UNBS 2011 – All rights reserved
 B.1.2.3.2 Check the temperature of each component and, if  necessary, adjust it to a value between 24 °C 
and 26 °C by gentle warming or cooling with stirring.  
B.1.2.3.3 Set up the stirrer for operation in the mixing container.  
B.1.2.3.4 Weigh 25 g of the polyol into the mixing container.  
B.1.2.3.5  Weigh out 30 g of the isocyanate and add it to the polyol in the mixing container. Immediately 
after this addition, start the stirrer and the stopwatch simultaneously.  
B.1.2.3.6 Continue stirring the mixture in the mixing containe r for a total time of 15 s ± 1 s, then stop the 
stirrer (but not the stopwatch) and take it out of the container.  
B.1.2.3.7 At the end of the stirring the mixture will be ess entially clear. Watch it, and note the time at which 
it first turns cloudy ("creamy") and begins to expand. Record as the cream time  (in seconds), the length of the 
period between this time and the time of the start of mi xing (see B.1.2.3.5). Check the cream time so recorded 
for compliance with the relevant requirement given in table 1.  
B.1.2.3.8 Continue watching the expanding mixture, checking at frequent intervals whether "strings" of the 
tacky material can be pulled away from the surface w hen it is touched with the spatula or glass rod.  
NOTE The time of commencement of this  stringing effect and record, as the string time (in seconds), the length of 
the period between this time and the time of the start of stirring (s ee B.1.2.3.5). Check the string time so recorded for 
compliance with the relevant requirement given in Table 1.  
B.1.2.3.9 Continue watching the mixture in the container, and note the time at which the expansion in 
volume ceases, as indicated by the cessation of the upward movement of the top (the white-appearing "cap") 
of the rising foam. Record, as the rise time (in seconds), the length of the period between the start of stirring 
(see B.1.2.3.5) and the time at wh ich the expansion stopped. Check the ri se time so recorded for compliance 
with the relevant requirement given in Table 1.  
B.1.2.3.10 If, after completion of expansion, the foam is to be used for determinati on of properties (see 
B.2.1), leave it to stand for at least 72 h before such use.  
B.2 Determination of foam properties  
B.2.1 Foam samples  
Take foam samples from free-rise foam prepared as directed in B.1.2. Where so ne cessitated by the size and 
number of specimens required for a particular test, the size of container used and the amounts of foam-
forming system components may be increased appropriately  (in comparison with those given in B.1.2.1.1(d) 
and B.1.2.3.4 to B.1.2.3.5, respectively). cedure  
NOTE – Isocyanates are highly reactive  chemicals, aggressive to the skin a nd eyes. It is essential to ensure 
that the person performing the foaming characteristics test is thor oughly familiar with t he necessary safety 
precautions, and with procedures for dealing with accidental  splashes and spills. The relevant instructions are 
obtainable from any reputable manufacturer of t he isocyanate components of  foam-forming systems. 
B.2.2 Density of foam  
Determine the foam density using the method in ISO 845. Check the result for compliance with the relevant requirement given in Table 2.  
B.2.3 Closed-cell content  
Determine the closed-cell content of the foam using method 2 of ISO 4590. Check the result for compliance 
with the relevant requirement given in Table 2.  FDUS : 2011 
© UNBS 2011 – All rights reserved  37
  947-1
B.2.4 Compressive strength  
Determine the compressive strength of the foam, in the di rection parallel to the direction of foam rise, using 
the method in ISO 844. Check the result for compliance with the relevant requirement given in Table 2.  
B.2.5 Bending properties  
Determine the bending properties of the foam using the apparatus and method in ISO 1209-1. Note that the 
specimens comprising one of the two sets of specimens prescribed by ISO 1209-1 shall be cut from the foam 
sample so that their longitudinal axes are parallel to t he direction of rise of the foam, and the longitudinal axes 
of the specimens of the other set shall be normal to this direction.  
Check the results of the determination for compliance with the relevant requirements given in Table 2.  
B.2.6 Dimensional stability  
Determine the dimensional stability of the foam using t he method in DIN 53428, using the following reagents: 
water, gasoline and diesel oil, and expose the specimens for 28 d at 25 °C.  
  
38 © UNBS 2011 – All rights reserved
 Annex C  
(normative) 
 
Design criteria for interceptors (gravity separators) 
C.1 General 
From the results of experiments and from plant operating data, it has been determined that the design of 
waste water separators shall be based on the rate of rise of oil globules that have an average diameter of 150 
µm. This globule size, although somewhat arbitrary, has been adopted for design  purposes  because  
satisfactory  oil  removals  are  achieved  when  a  pa rticle  of  150 µm diameter is used as a basis for design 
or investigation. 
C.2 Design procedure 
The vertical rate of rise, Vt, of an oil droplet in water is given by the formula 
Vt= 1962 × 10−9 × ∆δ ×  D2/η 
where 
Vt is the vertical rate of rise, in metres per hour; 
∆δ is the difference in densities between water and oil, in kilograms per cubic metre; 
D is the diameter of the oil droplet, in micrometres; and  
η is the dynamic viscosity of water, in pascal-seconds. 
The interceptor shall be so designed for a given water flow rate q that there is sufficient time for the oil 
globules to rise all the way from the botto m of the interceptor to the under-surface. 
The design of the retention system around the spill origin and outlets shall be able to  cope even with the worst 
rainfall conditions and shall therefore take into account the maximum rain intensity (this figure can be obtained from the Mean Annual Precipitation (MPA) m ap of the RSA), viz, 40 mm/h for both coastal and 
inland zones. Assuming that the rain water runs off as fast as it is deposited, the maximum runoff becomes 
q = C.I.A. /60000  
where 
q is the runoff flow capacity, in cubic metres per minute; 
C is the runoff coefficient (for example, 0.9 for concrete); 
I is the rain intensity, in millimetres per hour; and 
A is the catchment area, in square metres.  
The horizontal velocity, Vh, is given by 
Vh = q / Ac FDUS : 2011 
© UNBS 2011 – All rights reserved  39
  947-1
where 
Vh is the horizontal velocity, in metres per minute; 
q is the runoff flow capacity, in cubic metres per minute; and 
Ac is the cross-sectional area of the separator, in square metres. 
An acceptable maximum horizontal velocity Vh, for the flow through an interceptor would be less than 
0.91 m/min (3 ft/min or 55 m/h), or 15 Vt, whichever is the smaller. 
The length of the separator, L, in metres, is given by 
L = F (Vh/Vt ) × d 
where 
F is a design factor (dimensionless); and 
d is the depth of the separator, in metres. 
The design factor F is the product of the short-circuiting factor, Fsc, which can be taken as 1.2, and the 
turbulence factor, Ft, which is a function of the ratio of Vh to Vt: 
F = Fsc × Ft 
The American Petroleum Institute gives the following recommended values of turbulence factors:  
Vh/Vt Turbulence factor, Ft 
15 137 
10 127 
6 114 
3 107 
 
Furthermore, a separator shall be designed within the following limits: 
a) a depth d of between 1 m (3 ft) and 2,4 m (8 ft); 
b) a recommended depth-to-width ratio greater than 0.3 and less than 0.5 that is, d = 0.3 W to 0.5 W, 
where W is the width of the separator; and 
c) a width W of between 2 m (6 ft) and 20 m (6 m).  
C.3 Example 
A separator is to be designed to cater for runoff from a concrete area 50 m × 45 m = 2 250 m2
, assuming 
a maximum rain intensity of 40 mm/h. The design temperature is 10 °C, and waste water through the 
separator contains diesel with a density of 860 kg/m3 
at 10 °C. 
q = C.I.A. /60000 
= 0.9 × 40 × 2 250/60 000  
40 © UNBS 2011 – All rights reserved
 = 1.35 m3
/min 
Vt = 1,962 × 10−9 × ∆δ × D2
/η = 1,962 × 10−9 × (997-860) × 1502
/1,348 × 10−3
 
= 4,487 m/h 
= 0.0748 m/min 
Vh = 15 V t 
= 1,122 m/min 
which is greater than 0.91 m/min, therefore use Vh = 0.91 m/min as a maximum. 
To avoid excessively long separators, Vh shall, in practice, be kept to a minimum. This can be done by 
increasing (within reason) the cros s-sectional area of the separator. 
Therefore assume 
From Then d d W 
Ac = = = =1.3 m 0.5 × W 2.6 m 
d.W
  = 
 
=1.3 × 2.6 3.38 m2 
 and  V
h  =  q / A
c 
  = 1.35/3.38 
    
04/i Hence  V
h/Vt  =  0.4/0.0748 
  = 5.34 
By interpolation between the listed turbulence factors, 
Ft = 1.125 
so that 
F = Fsc × Ft 
  = 1.2 × 1.125 
  = 1.35 
This gives 
L = F (Vh/Vt ) × d 
  = 1.35 × 5.34 × 1.3   = 9.37 m 
Therefore, the final dimensions  of the separator would be: FDUS : 2011 
© UNBS 2011 – All rights reserved  41
  947-1
• length = 9.4 m; 
• width = 2.6 m; and  
• depth  = 1.3 m. 
 
  
42 © UNBS 2011 – All rights reserved
 Bibliography 
[1] ANSI/NFPA 329:1992, Underground leakage of flammable and combustible liquids  
[2] API 5L:1995, Specification for line pipe   
[3] BS 4994:1987, Specification for design and construction of vessels and tanks in reinforced plastics  
[4] SABS 533-2:1982, Black polyethylene pipes for the conveyance of liquids – Part 2: High density black 
polyethylene pressure pipes   
[5] SABS 763:1988, Hot dip (galvanized) zinc coatings (other  than on continuously zinc-coated sheet and 
wire)  
[6] SABS 1217:1984, The production of painted and powder-coated steel pipes 
[7] SABS 064:1979, The preparation of steel surfaces for coating  
[8] SABS 0129:1977, Plastics tape wrapping of steel pipelines  
[9] SABS 0140-1:1978, Identification colour marking – Part 1: General  
[10] SABS 0140-2:1978, Identification colour marking – Part 2: Identification of hazards and equipment in 
work situations  
[11] SABS 0140-3:1992, Identification colour marking – Part 3: Contents of pipelines  
[12] SABS 0214:198,The design, fabrication and inspection of articles for hot-dip galvanizing  FDUS : 2011 
© UNBS 2011 – All rights reserved  43
  947-1
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 gove rned by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licens ed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in co njunction 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 National  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.  
 
 FDUS 947-1: 2011 
 
ICS nn.nnn.nn 
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© UNBS 2011 – All rights reserved