Ac and Mech Ventillations Specs NBK

7/28/2019 Ac and Mech Ventillations Specs NBK

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PROPOSED NATIONAL BANK OF KENYA LTD, MOMBASA

POLYTECHNIC UNIVERSITY COLLEGE BRANCH-MOMBASA.

FOR

NATIONAL BANK OF KENYA LTDP.O. BOX 72866-00200

NAIROBI.

MECHANICAL ENGINEERING SERVICES SUB – CONTRACT

CONDITIONS, SPECIFICATIONS AND BILLS OF QUANTITIES

FOR AIR CONDITIONING AND MECHANICAL VENTILATION

NAME OF TENDERER: .....................................................................….

…………………………………………………………………………

ELECTRICAL/MECHANICAL ENGINEERS’ ARCHITECTS

SYNCHROCONSULT ASSOCIATES LTD BOUNDLESS ARCHTECTS

P. O. BOX 79626 00200 P.O. BOX 9668-00100

NAIROBI NAIROBI

QUANTITY SURVEYORS

NDERITU CONSULTANTS

P.O.BOX 62405-00200

NAIROBI

STRUCTUENGINEERS

XENOCON CONSLTINGNGI P.O00200



MAY 2012

INSTRUCTIONS TO TENDERERS

1. Tenders shall be submitted on the form of tender attached and all blanks in this space are to

be filled.

2. The tenderer and all other recipients of this document are to treat it as private andconfidential.

3. The employer does not bind himself to accept the lowest or any tender and will not be

responsible for paying any expenses of losses which may be incurred by any tenderer in the

preparation of his tender.

4. The tender and all accompanying documents shall be enclosed in a plain sealed envelope

marked:

“ Proposed National Bank of Kenya Ltd Mombasa Polytechnic University

College Branch-Mombasa

The sub-contract will deem to have been awarded when formal notice is given to thetenderer that the employer has accepted the tenderers proposals.

5. The tender must be received at the address given below not later than 12.00 noon on the

day stated in the covering letter :-

NATIONAL BANK OF KENYA LTD

P.O. BOX 72866-00200

NAIROBI.

2



FORM OF TENDER

MECHANICAL SERVICES

TO: NATIONAL BANK OF KENYA LTD

P. O. BOX 72866-00200NAIROBI

1. I/We understand that works, the subject of this tender, are covered by a prime cost of

provisional sum in the main contract entered into by the main contractor.

I/We shall become a Nominated sub-Contractor, that is to say, a sub-contractor nominated

by the Architects under the terms and conditions of the current form of agreement and

schedule of conditions, of Building Contract published by the Architects Association of

Kenya (latest edition with quantities).

2. It is confirmed that I/we have notice of all the provisions of the main contract including the

detailed prices of the contract in the schedule and Bill of Quantities.I/We undertake in accordance with the particulars set out in the preliminaries and to the

satisfaction of the Architects, to execute and complete the sub-contract works as described

in the specification and drawings for the sum of KENYA SHILLINGS

.................................................................................................................................

..................................................................................................................................only

(KSH............................................/=)

3. I/We confirm that this Tender is subject to adjustments by any variation ordered by theArchitects in accordance with the terms of the main contract.

4. I/We undertake to commence the works within 7 days from the date of official confirmation

of the acceptance of the Tender.

5. I/We further undertake to complete the work in accordance with the Main Contractors

programme.

6. I/We agree that this Tender shall be open for acceptance by the Architects within 90 days

from the date given below.

6. I/We understand that you are not bound to accept the lowest or any tender

7. Completion period ……………Days……………………………Weeks.

For and on behalf of:

..........................................................................................................................……………..

................................................................................................................................................

......................................................................................................................................……..

Signature/Official Stamp: …….............................................................................……....

3



Date:................................................

CONTENTS PAGE:

CONTENTS PAGE

FURTHER INSTRUCTIONS TO TENDERERS 5

DEFINITIONS 5- 6

ABREVIATIONS 7

PART A- PRELIMINARIES 8-13

PART B –GENERAL SPECIFICATIONS 14-23

PART C – PARTICULAR SPECIFICATION 24-29

PART D – BILLS OF QUANTITIES 30

SUMMARY OF PRICES D/5

4



FURTHER INSTRUCTIONS TO TENDERERS:

1. The tenderer shall make sure that he has received all pages of the specification and thedrawings on which this tender is based. Should the tenderer be in doubt on the precise meaning

of any item, word or figures, or observe any apparent omission of words or figures, he must

inform the Engineer in order that the correct meaning may be decided upon before the date for

the submission of the tender.

2. The tenderer shall complete in full such pages where he is required to do so.

3. Any alternative tenders for portions or the whole of the works will be considered as far as the

alternatives are clearly separated from the original tender. All alternative tenders must be

accompanied by a full and comprehensive specification of the alternative materials and design.

4. The tenderer shall be deemed to have made allowance in his prices generally to cover items of

preliminaries or additions to prime cost sums or other items, if those have not been priced

against the respective items.5. The subcontractor shall comply with the main contractor’s working programme.

6. The copyright of this specification is vested with the Engineer and no part thereof may be

reproduced without his express permission given in writing.

7. The subcontractor shall be solely responsible for the accurate ordering of materials in

accordance with the drawings and specification.

8. The specification must be priced in Kenyan currency.

DEFINITIONS

EMPLOYER

The employer is NATIONAL BANK OF KENYA LTD of P.O Box 72866-00200 NAIROBI

ENGINEER

The term ‘the Engineer’ shall in the case of Mechanical and Electrical Engineering works mean;SYNCHROCONSULT ASSOCIATES of P.O BOX 79626 00200 NAIROBI

ARCHITECT

The term ‘The Architect’ shall be deemed to mean;BOUDLESS ARCHITECTS of P.O. BOX 9668-00100 NAIROBI

QUANTITY SURVEYOR

The term ‘Quantity Surveyor’ shall be deemed to mean;

NDERITU CONSULTANTS of P.O BOX 62405 NAIROBI

THE CONTRACTOR

The term ‘contractor’ shall be deemed to mean the firm appointed by the employer to carry out the

works.

WORKS

5



The expression ‘work’ or ‘works’ shall mean all or any portion of the work, material and plant to

be provided and the labour to be performed for the execution and in fulfillment of this contract,

and whether the same may be on site or not.

THE SITE

The site of the proposed works shall be situated MOMBASA POLYTECHNIC UNIVERSITY

COLLEGE-MOMBASA

The tenderer is advised to visit the site and will be deemed to have satisfied himself with regard to

the contours thereof, the means of access, the risk of injury or damage to existing property and

property adjacent to the site or to the occupiers of such property. No claim by the contractor will be

allowed on the ground of any misunderstanding or misapprehension in respect of any such matter

or otherwise.

The contractor must obtain the approval of the Engineer regarding the use of any materials found

on the site.

GENERAL DESCRIPTION OF THE WORKS

The works comprise Supply and installation of air conditioning/Mechanical ventilation

equipments.

SPECIFICATION

Shall mean the whole of the contract document including but not restricted to:-

a) This document comprising definitions and preliminaries, General specifications, particular

specifications and schedules as contained herein.

b) The contract drawings.

BILLS OF QUANTITIES

Where the term ‘Bills of Quantities’ bears any relation to subcontract, it shall mean the

‘specification’ and the prices or any other schedules contained therein.

CONTRACT DRAWINGS

Shall mean those drawings listed in the schedules or referred to herein, forming part of this

specification.

MANUFACTURER’S RECOMMENDATIONS

Shall mean the manufacturer’s recommendation or instructions, printed or in writing and current at

the time of execution of the works.

OR OTHER APPROVED

Shall mean that commodities of a manufacturer other than that specified by the proprietary name

may be substituted provided they meet the standards specified and that express approval has been

obtained from the Engineer. The rates of prices will be held to be of the commodity specified and

current at the time of tender.

PROPRIETARY NAME

6



The phrase ‘or other approved’ shall be deemed to be included in every case where commodities

are specified by proprietary name.

APPROVED, DIRECTED AND SELECTED

Shall mean approved, directed or selected by the Engineer and shall not be binding unless put in

writing and signed by the Engineer.

ABBREVIATIONS

No - shall mean number

m - shall mean metre

LM - shall mean linear metre

mm - shall mean millimetre

kg - shall mean kilogramme

Ltr. - shall mean litre

S.S - shall mean stainless steel

G.M.S - shall mean galvanized mild steelM.O.P.W- shall mean ministry of public works

B.S - shall mean the Current British standards specification published by

the British standard Institution

C.P - shall mean the current British standard code of practice published

together with the B.S

I.E.E - shall mean the Institute of Electrical Engineers, Savoy Place,

London.

I.S.O - shall mean the International organization for standardization

K.B.S - shall mean the Kenya Bureau of Standards.

Ditto - shall mean the whole of the preceding description except as qualified

in the description in which it occurs.

7



PART A

PRELIMINARIES

ITEM DESCRIPTION KSHS CTS

A

B

C

FORM OF CONTRACT

The successful tenderer will be appointed as a

nominated subcontractor to the main contractor.

He will be required to enter into a sub contract with

the main contractor indemnifying him against the

same liabilities in respect of the subcontract works as

those for which the main contractor is liable to

indemnify the client under the contract.

The sub-contract Agreement shall be the latest edition

of agreement and schedule of conditions of building

subcontract, published by the kenya association of

Building and civil Engineering Contractors.

The particular and General Preliminaries of the Bills

of quantities for the main contractor shall apply, whereappropriate to the subcontractor who is to examine

these sections and allow for all costs incurred.

The particular and General preliminaries of the Bills

of quantities for the main contract can be seen at the

offices of Synchroconsult Associates by

appointment.

BOND

The subcontractor shall find and submit the name of

an approved surety who will be willing to be bound tothe main contractor in an amount equal to 10 % of the

subcontract amount for the due performance of the

subcontract up to the date of completion as defined in

clause 31 of the main contract.

STAMP CHARGES

Allow for the payment of all stamp charges in

connection with the surety Bond and contract

Agreement

Sub total carried .forward to collection

8



PRELIMINARIES


D

E

F

G

TRAINING LEVY

The contractor’s attention is drawn to legal notice No. 237

of October 1971 which requires payment by the contractor

of Training levy on all Contracts of more than Kshs. 50,000

in value.Allow for all costs arising or resulting therefrom.

PAYMENTS

Payments will be made through certificates to the main

contractor, unless he specifically agrees to forgo this right,

in which case direct payment can be made to the

subcontractor. All payments will be less retention as

specified in the main contract.

No payment will become due until materials are delivered

to the site.

FIRM PRICE CONTRACT

Unless specifically stated in the particular specifications this

is a firm price contract and the contractor must allow in his

tender for any increase in the cost of labour and /or

materials during the contract period. No claim for increased

costs will be entertained excepting only increased costs

arising from fluctuations in duties and exchange rates as

defined in condition No. 32 of the main contract.

IMPORTED EQUIPMENT

The contractor will be required to pay full import duty and

any other government taxes on all items of equipment ,

fittings and plant , whether imported directly for this

contract or not. No advance payment will be made to the

contractor by the client for the purpose of opening a letter of

credit for the items to be imported or purchased locally. The

contractor will therefore be expected to make his own

arrangements for the opening of letters of credit and payments of taxes.

9



Sub total c.f to collection

PRELIMINARIES


A

B

C

D

E

F

TRADE NAMES

Where trade names and / or manufacturer’s catalogue

numbers are mentioned in the specification, the

reference is intended as a guide to the type of article or

quality of material required. Alternative brands of

equal and approved quality will be acceptable.

WATER AND ELECTRICITY FOR THE WORKS

These will be made available by the main contractor

The subcontractor shall be liable for the cost of any

water or electrical power used and for any installation

provided especially for their own use by the main

contractor.

STORAGE

Space for storage will be provided on the site by the

main contractor but the subcontractor will be

responsible for the provision of any lockup sheds or

stores required.

SAMPLES

The subcontractor shall furnish at his own cost,

samples, materials or workmanship that may be called

for by the Architect for his approval, and any further

samples in the case of rejection until such samples are

approved by the Architect, and the Architect may

reject any materials or workmanship not in his opinion

up to the approved samples.

FOREMEN

The subcontractor shall keep constantly on the works

a competent English speaking foreman and any

directions or explanations given by the contractor or

the Architect to such foremen shall be deemed t have

been given to the subcontractor .

MATERIALS AND WORKMANSHIP

10



All materials shall be new and in all cases where the

quality of goods or materials is not described or

otherwise specified ,is to be the best quality obtainable

in the ordinary meaning of the word ‘best’ and not

merely a trade signification of that word.


PRELIMINARIES


A

B

All materials and workmanship shall, unless otherwise

specified or described conform to the appropriate

British standards specification current at the date of

tender.

The subcontractor shall order all materials to be

obtained from overseas immediately after the contract

is signed and shall also order materials to be obtained

from local sources as early as necessary to ensure that

such materials are on the site when required to be used

in the works.

The contractor shall be responsible for and shall

replace or make good at his own expense any

materials lost or damaged. The works throughout shall

be executed by skilled workmen well versed in their

respective trades.

REJECTED WORKMANSHIP OR MATERIALS

Any workmanship or materials not complying with the

specific requirements or approved samples or which

have been damaged , contaminated or have been

deteriorated , must immediately be removed from the

site and replaced at the subcontractor’s expense, as

required.

CO-OPERATION BETWEEN CONTRACTORS

Other services will be installed in the premises under

separate contracts. This subcontractor will be expectedto acquaint himself with the general arrangement and

layout of these other services so that the

accommodation , scaffolding and plant is most

effectively used jointly by all contractors and

further , that the building work requirements are

properly indicated in good time to the main contractor.

The subcontractor shall also cooperate with other

contractors to ensure that ducts, chases, wall spaces

and plant rooms are most economically used to

accommodate the services which are to be installed.

11




PRELIMINARIES


A

B

C

D

If as a result of failure to comply with this clause , it

becomes necessary to remove , modify or re- install

any services, to avoid impeding installation of any

other services ,the installation of which the

subcontractor may, in the opinion of the Architect

,reasonably have been expected to foresee, the

subcontractor shall carry out such removal ,

modification or reinstallation at his own expense.

PROTECTION

The subcontractor shall adequately cover up and

protect his own work to prevent injury and also to

cover up and protect from damage all parts of the

building or premises where work is being performed

by him under the contract.

HANDING OVER

The subcontract works shall be considered complete

and the defects liability period shall commence only

when the subcontract works and supporting services

have been tested commissioned and operated to the

satisfaction of the Architect and officially approved

and accepted by the employer, provided always that

that the handing over of the subcontract works shall be

coincident with the handing over of the main contract

works.

DEFECTS AFTER COMPLETION

The defects liability period will be six months from

date of completion of main contract as certified by the

Architect.

DAMAGE FOR DELAY

Liquidated and ascertained damages as stated in the

main contract Agreement will be claimed against the

main contractor for any unauthorized delay in

completion. The subcontractor will be held liable for

the whole or a portion of these damages should he

12



cause delay in completion.


PRELIMINARIES


A

B

C

WORKING DRAWINGS

The subcontractor shall prepare detailed working

drawings for execution of the works. These drawings

will be submitted to the Engineer for approval of the

subcontractor’s proposals and designs. If not so

submitted the subcontractor shall accept at his owncost the risk that any work commenced at the site may

be rejected.AS ‘BUILT DRAWINGS’ AND MANUAL

The subcontractor shall within one month after

handing over of the works , submit to the Engineer 3

sets of ‘As Built drawings’ as well as 3 copies of

maintenance manuals and user’s instructions for all

equipment installed. This shall be properly bound in 3

separate files each with an index of the contents.

CLEAR AWAY ON COMPLETION

The subcontractor shall, upon completion of the

works, at his own expense remove and clear away all

plant, equipment, rubbish and unused materials and

shall leave the whole of the works in a clean and tidy

state, to the satisfaction of the Architect. On

completion, all the works shall be delivered clean,

complete and perfect in every respect to the

satisfaction of the Architect.

Sub- total c.f to collection

COLLECTION ( PRELIMINARIES)

From page ----------------------------

From page ----------------------------

From page ----------------------------

From page ----------------------------

Total preliminaries c.f to summary of prices

13



PART B.1

GENERAL MECHANICAL SPECIFICATION

INDEX:

CLAUSE NO. DESCRIPTION PAGE NO

2.1 GENERAL 15

2.2 QUALITY OF MATERIALS 15

2.3 REGULATIONS & STANDARDS 15

2.4 ELECTRICAL REQUIREMENTS 15

2.5 TRANSPORT & STORAGE 16

2.6 SITE SUPERVISION 16

2.7 INSTALLATION 16

2.8 TESTING 16

2.8.1 GENERAL 16

2.8.2 MATERIAL TESTS 16

2.8.3 MANUFACTURED PLANT TESTS 17

2.8.4 EQUIPMENT WORKS TESTS 17

2.8.5 PRESSURE TESTING 17

2.9 COLOR CODING 17

3.0 WELDING 17

3.1 PREPARATION 17

3.2 METHOD 17

3.3 WELDING CODES AND CONSTRUCTION 17-18

3.4 WELDERS’ QUALIFICATIONS 18

14





Where control panels incorporating several starters are supplied, they shall be complete

with a main isolator.

The supply power upto and including local isolators will be provided and installed by the

Electrical subcontractor. All other wiring shall be as described in part C – the particular

specification.

The subcontractor shall supply three copies of all schematic, cabling and wiring diagrams

for the Engineer’s approval.

The starting current of all electric motors and equipment shall not exceed the maximum

permissible starting currents described in the Kenya power and Lighting Company’s by-

Laws.

All electrical plant and equipment supplied by the subcontractor shall be rated for the

supply voltage and frequency obtained in Kenya i.e. 415 volts, 50 Hz, 3-phase or 240

volts ,50hz , 1- phase as specified in part ‘C’ –the particular specification.

Any equipment that is not rated for the above voltage and frequencies may be rejected by

the Engineer.

2.5 TRANSPORT AND STORAGE

All plant and equipment shall, during transportation be suitably packed, crated to minimize

the possibility the possibility for damage, and to prevent corrosion or other deterioration.

On arrival at the site all plant and equipment shall be examined and any damage to parts

and protective priming coats made good before storage or installation.

Adequate measures shall be taken by the subcontractor to ensure that plant and equipment

do not suffer any deterioration during storage.

Prior to installation all piping, plant and equipment shall be thoroughly cleaned.

If in the opinion of the Engineer any equipment has deteriorated or been damaged to such

an extent that it is not suitable for installation, the subcontractor shall replace this

equipment at his own cost.

2.6 SITE SUPERVISION

The subcontractor shall ensure that there is an English speaking Supervisor on the site at all

times during normal working hours.

2.7 INSTALLATION

Installation of all special plant and equipment shall be carried out by the subcontractor

under adequate supervision from skilled staff provided by the plant and equipment

manufacturer or his appointed agent, in accordance with the best standards of modern

practice and to the relevant regulations and standards described under clause 2.3 of this

section.

2.8 TESTING

2.8.1 GENERAL

All testing shall be carried out to the entire satisfaction of the Engineer.

The following sub-clauses are intended to define the subcontractor’s responsibilities with

respect to testing and inspection.

2.8.2 MATERIAL TESTS

All materials for plant and equipment to be installed under this subcontract shall be tested,unless otherwise directed, in accordance with relevant B.S. specification concerned.

16



For materials where no B.S. specification exists, tests are to be made in accordance with the

best modern commercial methods to the approval of the Engineer having regard to the

particular type and application of the materials concerned.

The subcontractor shall prepare specimens and performance tests and analyses to

demonstrate conformance of the various materials with the applicable standards.

If stock material, which has not been specifically manufactured for the plant and equipment

specified is used, then the subcontractor shall submit satisfactory evidence to the Engineer

that such materials conform to the requirements stated herein in which case test of the

material may be partially or completely waived.

Certified mill test reports of plates, piping and other materials shall be deemed acceptable.

2.8.3 MANUFACTURED PLANT AND EQUIPMENT- WORK TESTS

The rights of the Engineer relating to the inspection, examination and testing of plant and

equipment during manufacture shall be applicable to the insurance companies or inspection

Authorities so nominated by the Engineer.

The subcontractor shall give two weeks notice to the Engineer of the manufacturer’s

intention to carry out work tests and inspection.

The Engineer or his representative shall be entitled to witness such tests and inspections.The costs of such tests and inspections shall be borne by the subcontractor.

Six copies of all test and inspection certificates and performance graphs shall be submitted

to the Engineer for his approval as soon as possible after the completion of such tests and

inspections.

Plant and equipment which is shipped before the relevant test certificate has been approved

by the Engineer shall be shipped at the contractor’s own risk and should the test and

inspection certificate not be approved, new tests may be ordered by the Engineer at the

subcontractor’s expense.

2.8.4 PRESSURE TESTING

All pipe work installation shall be pressure tested in accordance with the requirements of

the various sections of this specification. The installation may be tested in sections to suit

the progress of the works but all tests must be carried out before the work is buried or

concealed behind building finishes. All tests must be witnessed by the Engineer or his

representative and the subcontractor shall give 48 hours notice to the Engineer of his

intention to carry out such tests.

Any pipe work that is buried or concealed before witnessed pressure tests have been carried

out shall be exposed at the expense of the subcontractor and the specified tests shall then be

carried out.

The subcontractor shall prepare test certificates for signature by the Engineer and shall keepa progressive and up to date certificate of the sections of work that have been tested.

2.9 COLOUR CODING

Unless stated otherwise in the particular specification all pipe work shall be color coded in

accordance with in accordance with the latest edition of

B.S 1710.

3.10 WELDING

3.10.1 PREPARATION

17



Joints to be made by welding shall be accurately cut to size with edges sheared, flame cut

or machined to suit the required type of joint.

The prepared surfaces shall be free from all visible defects such as laminations, surface

imperfections due to shearing, flame cutting operation etc., and shall be free from rust,

scale, grease and other foreign matter.

3.10.2 METHOD

All welding shall be carried out by the electric arc process using covered electrodes inaccordance with B.S 639.

Gas welding may be employed in certain circumstances providing that prior approval is

obtained from the Engineer.

3.10.3 WELDING CODES AND CONSTRUCTION

All welded joints shall be carried out in accordance with the following specification:-

a) Pipe welding

All pipe welds shall be carried out in accordance with the requirements of B.S 806.

b) General welding

All welding of mild steel components other than pipe work shall comply with the generalrequirements of B.S 5135: 1974.

3.10.4 WELDER’S QUALIFICATIONS

Any welder employed on this subcontract shall have passed the trade tests as laid down by

the government of Kenya.

The Engineer may require seeing the appropriate certificate obtained by any welder and

should it be proved that the welder does not have the necessary qualifications, the Engineer

may instruct the subcontractor to replace him/her by a qualified welder.

18



PART B 2

GENERAL MECHANICAL VENTILATION AND AIRCONDITIONING SPECIFICATIONS

CLAUSE DESCRIPTION PAGE NO .

1.0 General 20

2.0 Installation 20

3.0 Ductwork 20

5.0 Testing and inspection 21

5.1 Site tests 21

5.2 Site tests – fans 22

5.3 Completion of works – Balancing 22

5.4 Completion of works –Commissioning 22

6.0 Finish painting. 23

19



1.0 GENERAL

This section specifies the general requirements for mechanical ventilation and air

conditioning plant, equipment and materials forming part of the subcontract works and

shall apply except where specifically stated elsewhere in the specification or on the

contract drawings.

2.0 INSTALLATION

Installation of all ductwork, plant and equipment shall be carried out under adequate

supervision from skilled staff to the relevant Codes and Standards specified herein.

The subcontractor shall be responsible for ensuring that sufficient provisions are made to

prevent the transmission of vibration from the equipment to the supporting structure. In the

case of fans, this shall be done by rot and vermin- proof flexible connections and

antivibration mountings of an approved type.

The subcontractor shall ensure that all ducting systems are provided with sufficient access

hatches complete with covers, for maintenance purposes.

Dampers and other user equipment shall be installed with adequate access for operation and

maintenance. Where dampers and other operational equipment are unavoidably installed

beyond normal reach, and in such a position as to be difficult to reach from a short step

ladder, extension spindles shall be provided.

The variety and type of supports for ducts and fans shall be kept to a minimum and their

design shall be such as to facilitate quick and secure fixing to metal, concrete, brickwork

and wood.

Where the design of the structure is in reinforced concrete, supports shall be secured to the

structure by means of redheads, raw bolts or other approved means.

Where the subcontractor proposes to secure his supports by other means than to the main

structural concrete, he shall consult with the Engineer before proceeding.

3.0 DUCTWORK

The subcontractor shall supply, deliver and erect all ductwork as shown on the contract

drawings.

All ductwork shall be manufactured in accordance with the Heating and ventilation

contractors Association 9H.V.C.A.0 specification DW/142. 1982 except where stated

otherwise.

Ductwork shall be manufactured from galvanized mild steel sheet unless specified

otherwise. All external ductwork shall be manufactured from black mild steel sheet which

shall be galvanized after manufacture.

All seams shall be lock form type. All ductwork systems shall be complete with all

necessary dampers, bends, tees, tapers, transformation and special pieces.Where removal is required for access or maintenance, ducting shall be provided with steel

angle flanged joints suitably painted and protected against rust.

20



Only bends type 1-7 inclusive detailed in the H.V.C.A specification will be permitted.

Only duct connections type 42-44 inclusive, 53 and 54 as detailed in the H.V.C.A

specification will be permitted. All joints shall be fixed as to be suitable for the direction of

air flow.

All proposed positions for the plant and ductwork shall be confirmed on site prior to

development of shop drawings and manufacture of ducts.

Transformation and Taper pieces shall , wherever possible, be constructed so that the

included angle does not exceed 30 degrees.

All flanged joints shall be sealed by the use of asbestos string or equivalent material

compressed between the flanges , and where slip joints occur, these shall be sealed by

‘prestik’ or other similar jointing compound and adhesive tape 40mm wide.

Dampers shall be of aerofoil section and manufactured from galvanized mild steel sheet.

Damper plates shall not exceed 150 mm in width and the edges of the blades shall be sealed

with a 3 mm thick felt or rubber seal to minimize leakage.

Operating quadrants shall be provided with locknuts and the quadrants shall be clearly

marked with ‘open’ and closed’ positions.Multileaf damper blades shall be operated by one

arm through a linkage external to the duct.

The subcontractor shall provide sufficient access doors and handholds in the ductwork for

the purpose of maintenance and inspection. Access doors shall be of the hinged type anddoor openings shall be adequately stiffened and made airtight with purpose made rubber

gaskets around the door perimeter.

All supports and brackets shall be wire brushed and painted one coat of red oxide paint

prior to and after erection. Fastening of cables to ductwork shall not be permitted.

Where ductwork has insulation incorporating an external vapour seal, the ductwork shall be

insulated from the support by rot-proof softwood, hardwood or other suitable closed cell

insulator of not less than 25mm greater thickness than the insulation to be applied. This is

to ensure that the vapour seal may be bonded to the face of the timber, all as detailed in

clause 6.4 of the H.V.C.A specification DW/142. 1982.

Where ductwork passes through floors and walls, galvanized sheet sleeves or timber

frames ( builders work ) shall be provided. The space between duct and sleeve or frameshall be packed with asbestos rope or mastic to prevent air movement or noise transmission

from one controlled space to another. Ducts must not come into direct contact with the

building fabric.

Hangers and brackets shall be manufactured from rolled mild steel angle or channel

sections and shall generally be of the drop rod hanger or cantilever type. The hangers

shall be spaced to ensure adequate support. And where practicable shall be fitted at each

ductwork joint .

The subcontractor shall supply and install where called for , louvered inlets and outlets

with insect-proof screens. The louvers shall be constructed throughout from extruded

aluminum sections and shall have a lacquered or anodized finish to prevent corrosion. The

louvers shall be weather-proof and have a free area of not less than 50 %.The subcontractor shall ensure that wherever fans or similar equipment are connected to

the ductwork system , the connections are made with a heavy duty rod and vermin-proof

neoprene , or similar material, flexible connection to prevent vibration transmission to the

ductwork or building fabric. Flexible connections shall be secured by a pre-drilled mating

flange, or when fixing to a spigot , the spigot should be beaded and a jubilee clip or split

flat iron ring should be used.

5.0 TESTING AND INSPECTIONS

5.1 SITE TESTS:

The subcontractor shall provide all labour, materials, apparatus and properly calibratedand certified instruments and equipment necessary to carry out site tests and shall arrange

with other sub-contractors for the testing of associated equipment which may affect the

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Performance of the plant installed under these subcontract works.

The tests on air flow and pumped water circulation systems shall be carried out in

accordance with the appropriate British standard specification and appropriate codes of

practice, the relevant CIBSE commissioning codes and regulations for the Electrical

Equipment of buildings issued by the institution of Electrical Engineers.

5.2 SITE TESTS – FANS:

All fans shall be charged with a suitable lubricant and shall be tested upon completion of

the ancillary system erection to ascertain that the performance of each fan complies with

the requirements of the specification.

5.3 COMPLETION OF WORKS AND TESTING:

Following the site test and prior to hand-over, mechanical ventilation or air-conditioningsystems shall be balanced by means of grilles, dampers and other special controls

installed, so as to give the required air flow rates and where applicable the desired

temperatures, pressures and humidity conditions in all areas served by the said systems.

The complete system shall be balanced and commissioned as a whole. Sectional balancing

and commissioning on any one part of the system where this excludes final complete

system balancing and commissioning, shall not be accepted.

Test volumes within ducts shall be within +/- 5% of the design volumes and volumes at the

grilles and diffusers shall be within +/- 10 % of the design volumes.

When the system has been balanced to the satisfaction of the Engineer, it shall be run under

automatic control for 72 hours continuous operation to ascertain any faults in operation

before acceptance and hand-over. Any faults discovered during this time shall be correctedand a further test or tests of 72 hours duration shall be carried out to ensure satisfactory

operation, all at the expense of the subcontractor.

5.4 COMPLETION OF WORKS - COMMISSIONING

For the purpose of this specification ‘commissioning shall mean the advancement of an

installation from the stage of static completion to full working order to specified

requirements. The object of commissioning procedures shall be to ensure that theinstallation operates in conformity with the requirements of the design specification.

Commissioning shall be carried out in accordance with the procedures as laid down in the

CIBSE commissioning codes : Series A- Air distribution, Series C- Automatic controls,

Series R- Refrigeration systems and series W- Water distribution systems. If the

subcontractor wishes to use alternative techniques these may be adopted subject to prior

discussion and agreement with the Engineer. The commissioning procedures shall include

demonstrations of the operation and function of all items of plant and their ability to

perform and maintain the full design requirements as described.

Specialist plant items such as water chillers and air handling units shall be started up and

set to work by the subcontractor according to the recommendations of the equipment

manufacturer or his approved representative. On composite or built up plant items such as

air handling plant , the contractor shall start up and set to work all constituent components.

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Prior to running any item of electrical equipment, the subcontractor shall ensure that the

item of equipment has been correctly connected and that all fuses , overload etc. have been

set in accordance with the manufacturers recommendations . The subcontractor shall

ensure that the correct voltage is available on all supply phases, that the correct number of

phases are available to the equipment and that the power and control wiring to the

equipment has been connected in accordance with the manufacturer’s external wiring

diagrams.

It is essential that the results of checks and measurements are recorded in writing and no

commissioning procedure shall be deemed to be satisfactorily completed until the

regulation of the system has been demonstrated to the Engineer’s satisfaction. It is the

subcontractor’s responsibility to ensure that when a check or commissioning procedure has

been satisfactorily carried out , it is witnessed and the commissioning sheets are signed by

the Engineer.

On completion, the commissioning sheets shall be signed by the subcontractor and

countersigned by the Engineer. Acceptance of the commissioning sheets shall not imply

acceptance of the complete installation. All documentation proposed for hand-over shall

be submitted to the Engineer for checking and comment.

6.0 FINISH PAINTING :

Upon completion of the installation and after all tests have been carried out to the satisfaction of the

Engineer, the plant, equipment, supports etc, shall be examined and all priming coats damaged

during erection made good.

Any plant or equipment, ductwork etc, which is to be insulated, shall have had the priming

coat made good before application of the insulation.

After the above procedures have been carried out to the satisfaction of the Engineer, the

various surfaces shall be given the necessary preparation as recommended by the paint and

insulation manufacturers and finish painted in colors to be agreed between thesubcontractor and the Architect at a later date.

For the purpose of the specification, however, it shall be deemed that the subcontractor’s

tender price was based on the identification requirements for the various services detailed

in code of practice DW/161 Identification of ductwork as published by the H.V.C.A.

Adequate notice in writing shall be given to the Engineer by the subcontractor stating his

intention to carry out any of the commissioning procedures and this period shall not be less

than 7 working days. The subcontractor shall complete detailed ‘commissioning sheets’

and shall submit to the Engineer for review copies of the proposed schedules to be used for

the commissioning checks prior to the commencement of commissioning. The Engineer

shall not attend the site for the purpose of witnessing acceptance tests and commissioningdemonstrations until the commissioning sheets are submitted to the Engineer for his

review and comment.

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PART C

PARTICULAR SPECIFICATION FOR MECHANICAL VENTILATION & AIRCONDITIONING

INSTALLATION

CLAUSE DESCRIPTION PAGE NO.

3.1.0 PARTICULAR CONDITIONS 22

3.1.1 LOCATION OF SITE 22

3.1.2 DESCRIPTION OF PROJECT 22

3.1.3 COMMENCEMENT OF WORKS 22

3.1.4 CLIMATIC CONDITIONS 23

3.1.5 INTERNAL CONDITIONS 23

3.2.0 SCOPE OF SUBCONTRACT WORKS 23

3.3.0 SHEET METAL DUCTWORK 23-24

3.4.0 AIR CONDITIONERS 24

3.5.0 ELECTRICAL CONTROLS 25

3.6.0 AIR HANDLING SYSTEM 25

3.6.1 SUPPLY FANS 25

3.6.2 LOUVERS 25

3.6.3 INSULATION 25

3.6.4 ROOM OR SPACE THERMOSTATS 25

3.6.5 TEMPERATURE AND HUMIDITY CONTROL 25

3.6.6 EXTRACT FANS 26

3.5.0 GRILLES, SUPPLY AIR DIFUSSERS, RETURN

AIR REGISTERS, DAMPERS AND VALVES 26

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3.1.0 PARTICULAR CONDITIONS

3.1.1 Location of site:

The site of the proposed subcontract works is Mombasa Polytechnic University College

-Mombasa

3.1.2 Description of the Project:

The project involves the installation of a new mechanical ventilation system.

3.1.3 Commencement of Works:The subcontractor in submitting his tender shall be deemed to have included for

commencing any necessary work on site at such time as will comply with the main

contractor’s programme.

3.1.4 Climatic conditions:

The following climatic conditions apply at the site of the works and all plant, equipment,

materials and installations shall be suitable for these conditions.

Maximum temperature 32 °C

Minimum temperature 7 °C

Average temperature 13° C

Relative Humidity 48-95 %Altitude 5 m above sea level

Rainfall Can be extremely heavy at certain periods of the year.

The subcontractor shall be deemed to have taken into account all the above details in his

prices and planning for the execution of the works.

3.1.5 Internal Conditions:

Temperature 22+/- 2 ° C

Relative Humidity 30- 70 %

Noise level NC 35.

The cold rooms, freezer room and air-conditioning systems are designed to maintain the

following internal conditions with the ambient design conditions of 30 ° C DB.

3.2.0 SCOPE OF WORKS

The subcontract shall comprise the supply ,delivery, installation, setting to work, testing

and commissioning of all the materials and equipment called for in this specification or

shown on the drawings.

The subcontract shall include for all appurtenances(accessories) and appliances, notnecessarily called for in this specification or on the contract drawings but which are

necessary for the completion and satisfactory functioning of the works.

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No claims for extra payments will be accepted from the subcontractor because of his

noncompliance with the above requirements.

If in the opinion of the subcontractor, there is a difference between the requirements of the

specification and the contract drawings, he shall clarify this difference with the Engineer

before tendering.

All works shall be performed in a straight forward manner by competent workmen under

skilled supervision to the entire satisfaction of the Engineer.

It is deemed that the tenderer has based his tender on equipment which is similar in

design ,performance and manufacture to that stated in this specification. If the tenderer

wishes to offer suitable alternative equipment to that specified , he may do so under a

separate covering letter and justification of such alternative.

Submission of the above will be under the tenderers own initiative and in no case will any

expenses incurred in preparation and documentation of such alternative be reimbursed. The

employer reserves the right of accepting any alternative to the specification.

The alternative equipment shall not form part of the main tender which must be based on

the equipment specified.

The works to be installed under the subcontract shall comprise but not restricted to the

following installations:-

3.3.0 SHEET METAL DUCTWORK

The duct sizes shall be as shown on the contract drawings, fabricated from galvanized mild

steel sheets of thickness as specified below.

The ductwork shall be made from mild steel strip mill cold rolled continuously and hot

galvanized to BS 2989. The construction of ductwork shall comply with sheet ductwork as

specified by the Association of Heating and Ventilating contractors’ specification DW/142:

1982.

Ductwork material, gauge and stiffening shall be in compliance with the requirements set

out in table A.

TABLE A

Length Nominal Maximum spacing Minimum AngleSide sheet between joints/ section for

Thickness stiffeners intermediateStiffeners

(mm) (mm) (mm) (mm)

upto 400 0.6 unlimited unlimited none

400 to 600 0.6 1500 unlimited 25*25*3

601 to 800 0.8 1500 unlimited 25*25*3

801 to 1000 0.8 1200 1500 25*25*3

1001 to 1500 1.0 800 1200 40*40*4

Cross joints for ducts upto 500 mm narrow side shall be ‘C’ cleat type and sealed withliquid mastic sealant

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Cross joints for ducts with narrow side in excess of 500 mm shall be reinforced standing

seam.

Longitudinal seams shall be of the lock form type riveted spot/plug welded ap seams . The

subcontractor shall ensure that the joints are completely airtight.

All bends shall have a centerline radius of one and half times the width of the duct.

Transformation and Taper pieces shall where the cross sectional area is unchanged have a

minimum slope of 22.5 degrees and where the cross sectional area is reduced upto 20 % ,

the maximum slope shall be 15 degrees.

3.4.0 AIRCONDITIONERS:

The air conditioning units shall be completely factory assembled and tested, piped and

internally wired fully charged with R-22 and compressor oil. All units shall be suitable for

ground installation inside plant rooms with ducts fitted to run to the supply areas.

The equipment shall be fully tropicalised. The external casing of the equipment shall be

phosphatised , Zinc coated steel with epoxy resin primer and baked enamel finish .The

screws shall be coated with Zinc plus Zinc chromate and with neoprene washers where

sealing is required.Hinged access doors shall provide access to control components, filters, outside and return

air dampers, evaporator coil and supply the exhaust fan sections. All access doors shall be

lined with gaskets and mat faced fiberglass insulation.

The condenser section shall be provided with drain points. Each unit shall have lifting lugs

to accept chains or cables for rigging.

The air conditioning unit (split type) shall be as Trane Model RAC 075 + BPH 0.75 with a

cooling capacity of 30.8 kw and an air flow rate of 0.817 m/ sec

3.5.0 ELECTRICAL CONTROLS

The units shall be suitable for use on 3 phase, 415 volts, and 50HZ power supply. It shall be

the responsibility of others to provide all electrical wiring upto the isolator. The

subcontractor shall be responsible for all electrical wiring between the isolator and all items

of equipment.

The subcontractor shall also provide all electrical control panels and shall be responsible

for their fixing and satisfactory operation.

The control and power cables shall be run in firmly fixed steel conduits where concrete

encased conduits are not provided.

The control shall include for oil safety, supply and exhaust fan overload protectors, fuses

for supply, exhaust air and condenser fans, compressor fuses and dead front panels. Eachcontrol item shall have an identifiable tag.

3.6.0 AIR HANDLING SYSTEM

3.6.1 SUPPLY FANS

All fans shall be statically and dynamically balanced in the Factory. Fan shaft shall be

capable of self alignment.

Air filters shall be provided within the unit. The filters shall fit in slide –in racks for ease of

change out.

3.6.2 LOUVRES

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Discharge and fresh air intake louvers shall be similar or equal to type WG/EF as

manufactured by Waterloo CO. Ltd.

They shall be manufactured from robust Aluminum alloy extrusions with lacquered finish.

An insect screen shall be fixed to the back of the louvers. All louvers shall have a minimum

of 50 % free area.

3.6.3 INSULATION

Any external ductwork shall be wrapped with roofing felt properly lapped to ensure a

waterproof covering. All cooled air ducts shall be insulated with either expanded

polystyrene sheet or sprayed polyurethane foam without gaps using suitable adhesive and

plastic impingement pines attached to ductwork.

3.6.4 ROOM OR SPACE THERMOSTATS

These shall be located in the extract duct immediately after the air-conditioned space andwired to the air conditioner control system. The thermometer shall have a range of 15 ° C to

35 °C. The thermostat shall be set at the required room temperature and should maintain the

temperature with a differential of 1°C.

3.6.5 TEMPERATURE AND HUMIDITY CONTROL

The temperature and humidity control, overriding on humidity shall be affected from

detectors mounted on the return air duct. The resultant signal from the control unit shall

cause the motorized step controller on A-C unit to step up or down accordingly.

3.6.6 EXTRACT FANSThe extract fans shall be duct-mounted continuously rated axial flow fans as ‘woods’

Aerofoil axial flow fans double stage or equal and approved.

The case work of both the bowler unit (BPH) and condenser (RAC) shall be galvanized

steel with polyester paint finish. The evaporator coil in BPH shall be manufactured from

copper tube mechanically bounded or expanded into aluminum fins.

The compressor shall be of robust construction and high reliability. It shall be suitable for

use with refrigerant R22.

The condenser shall be of steel / copper tube with aluminum fins.

3.6.8 SUPPLY AIR DIFFUSERSShall be aluminum extruded four way rectangular or circular complete with dampers and

adjusters. They should be suitable for ceiling mounting. The sizes shall be as shown in the

bill of quantities.

3.6.9 RETURN AIR REGISTERS

Shall be aluminum with enamel finish: 4 way with opposed blade dampers.

3.7.0 DOOR TRANSFER GRILLES

Shall be similar to return air registers with paint to architect’s approval.

3.7.1 FLAP VALVES (NON RETURN AIR REGISTERS)

This shall be self closing dampers with minimum resistance to air flow under runningconditions and maximum resistance under reverse air flow conditions. Resilient strips or

28



other purpose made devices shall be provided to prevent rattling and for air sealing under

reverse flow.

3.7.2 BALANCING DAMPERS

The balancing dampers shall be provided and fixed at appropriate positions indicated on the

contract drawings. Damper blades shall be of rigid construction without sharp edges and

shall be substantially airtight. The dampers shall be multi-leaf type and be constructed indemountable ductwork sections, which shall extend beyond the swing of the blades.

Provisions shall be made for linkages to connect the multiple extended spindles. The

‘open’ and ‘closed’ positions shall be clearly marked on all dampers.

3.7.3 FLOW MEASURING POINTS

There shall be adequate flow measuring points in the ductwork to enable the proportional

balancing of the systems to be done. These shall be incorporated with volume control

dampers .

3.7.4 FIRE DAMPERS

Fire dampers shall be provided where indicated on the contract drawings. They shall besingle plate top hinged type . Each damper plate shall be held in the open position by a

fusible device set to release at a temperature of 72 °C.

3.7.5 FLEXIBLE CONNECTIONS

Flexible connections shall be provided where indicated on contract drawings.

The connections shall be made of tough tear-resistant and fire-resistant materials.

29



4.00 CONTRACT DRAWINGS

SCA/NBK/MOM 2012/AC/01

SCA/NBK/MOM/2012/AC/02

30



PART D

BILLS OF QUANTITIES

Documents

Ac and Mech Ventillations Specs NBK