الحمد لله والصلاة والسلام على رسول الله وعلى آله وصحبه أجمعين THERMAL INSULATION AND LAGGING HVAC 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