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THERMAL INSULATION AND LAGGING HVAC

Discussion in 'المنتدى التعليمي' started by mannan, 3/10/17.

  1. mannan

    mannan Administrator Staff Member


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    الحمد لله والصلاة والسلام على رسول الله وعلى آله وصحبه أجمعين

    THERMAL INSULATION AND LAGGING HVAC

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    General Requirements

    Thermal insulation shall be of approved material with thermal conductivity
    not higher than 0.29 Btu/Hr/Ft2/F inch thickness measured at an average
    temperature of 100 F. Thermal insulation shall be non-corrosive to the metal
    water repellent, sustenance to vermin and easily cut and fitted to shape during application
    The insulation should be resilient and retain its original shape
    The insulation shall be provided with approved fire retardant vapour barrier
    jacket to prevent the moisture penetration to the insulation
    Vapour barrier shall also be applied to all joints and edges

    The insulation shall be fixed on to the metal surface by means of an
    approved adhesive compound that has no corrosive effect on the metal
    and thoroughly applied to the metal surface and insulation
    The insulation shall be carried out by skilled labourers and before thermal
    insulation is applied, all metal surfaces shall be thoroughly cleaned and treated
    with approved corrosion inhibitors

    Piping Insulation

    The insulation shall be secured to the piping by adequate number of
    non-corrodable straps ¾” width at a center distance not more than one foot

    The straps shall not in any case cut the insulation or the vapour seal
    Wires shall not be acceptable

    Insulation Material Thickness

    Insulation material shall be Fiberglass 6 lb/Ft³ & shall have the following thickness

    Pipe Size Up to 2” dia 2½” – 6” dia 8” dia & above

    Chilled / Hot Water Pipes exposed to Sun 1” 2” 3”

    Chilled/Hot Water Pipes in non-A/C areas 1” 1½” 2”

    Chilled / Hot water pipes in A/C areas 3/8” 1” 1½”

    Condenser Water (Cold) pipe from cooling tower to condenser exposed to sun 1”

    Condensate drain pipe 3/8” 5/8”

    All pipes running inside the A/C Plant room, A/H unit rooms and other
    machinery rooms also inside the piping shaft or were they are exposed
    to view shall be covered with heavy gauge “not less than 22” aluminium sheet
    and in any case the designation and direction of fluid flow shall be suitable
    marked on the surface at intervals. Weather and water proofing treatment to
    be carried out prior to cladding

    Duct Work Insulation

    The thermal insulation used shall confirm to BS 5422: 1977 - BS 5422: 2009

    The thermal insulation shall be made of fiberglass material with reinforced
    aluminium foil external coating, factory applied with resin bonded internal
    layer to give flat and resilient surface. The insulation of all duct works exposed
    to outside and those in plant rooms shall be rigid slab type and for remaining
    ducting flexible blanket type

    Thermal conductivity shall not be more than 0.29 Btu/Hr. Sq. Ft. per inch thickness
    measured at an average temperature at 100° F. The thermal insulation shall be non-corrosive

    The insulation shall be provided with fiber retardant
    vapour barrier jacket to prevent moisture and penetration
    Vapour barrier shall also be applied to all joints and edges

    The insulation shall be applied to metal surface by means of
    approved non-corrosive adhesive compound.
    The metal surface shall be treated with corrosion
    inhibitors before the application of insulation

    The density of insulation shall be minimum 1.5 lb./cu. ft. for flexible
    blanket type and 3 lb./cu. ft. for rigid slab type and thickness

    All duct works exposed outside and those in plant
    room shall be insulated with 2” outside insulation

    Duct works inside air-conditioned spaced shall be
    insulated with one inch thick outside insulation

    h. Insulation shall be secured to duct work with 2” x 2” G.I. sheet metal
    strips of 22 gauge fixed to corners and tightened with wire 6” intervals
    The strips may be suitably grooved to take the wire fasteners

    In addition, all duct works exposed to outside be cladded with 24 gauge GI sheeting
    and shall be treated for water proofing prior to cladding, i.e. wrap
    the insulation with 0.5mm thick polyethylene sheet and secure the adhesive
    All the duct works in plant room shall be finished with 8 Oz. Canvas
    with 2 coats of fire retardant and water proof paint.

    All external duct cladding shall be painted with one coat of primer suitable for
    galvanized surface and two coats of final paint suitable for external application
    Colour of paint should match the building and approved by the Engineer

    Acoustic Duct Lining

    Internal duct lining for acoustic insulation where applicable shall
    not be less than 25 mm. thick fiberglass mat faced, flexible blanket
    of fine fibers with securely bonded surface mat coated with black
    neoprene or approved equal. Lining shall be applied with 100% coverage
    of fire resistive approved adhesive compound and mechanical fastenings
    according to the manufacturer's instructions. Acoustic lining shall be
    cleared 20 cm. on each side of the duct heater where applicable
    Duct lining density shall be 24 kg/cubic meter


    في أمان الله

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