Insulate ducts
Objectlves : At the end of this exercise you shall be able to:
• select different insulating material based on their physical propertie s
• insulate ducts with glass wool
• insulate ducts with foam spray
• insulate ducts with foam sheet
• insulate ducts with expanded polystyrene (Thermocole).
Requirements
Tools/Instrument Materials
• Double ended spanner set 8 to 22 - 1 Set. • GI sheet 22 SWG size 5x4" - as reqd.
• Ring spanner set 5 to 22 - 1 Set. • Foil-faced fiber glass - as reqd.
• Wrench adjustable 150 mm -1 No. • Bitumen - as reqd. I
• Screw driver 6mm x 150mm -1 No. • Glass wool - as reqd. 11
• Snipper sheet metal -200mm • Chicken wire - mesh - as reqd. 11
• Scissor -1 No. • Foam sheet/ Foam tool kit - as reqd.·ll
11
• Knife folded -1 No. • Thermoco le 20mm thick - as reqd.
• Vapour retarder - as reqd.
Equipments
• Pre-fabricated ducts.
PROCEDURE
g m at er ia l ba se d on th ei r ph ys ic al pr op er tie s.
TASK 1 : Select different in su la
tin
rio us ty pe s of du ct in su lti ng m at er ia ls lik e SI . Va po ur ,
1 Id en tity va
ol, Co rk , Th er m oc ol e, PU F, Fi be r gl as s, Fo am No
Glass wo
ru ct or .
sheet etc, by ta kin g th e he lp of In st
do wn th e ph ys ic al pr op er tie s of th e be lo w 1 Bi tu m en co a
2 No te
ne d in su la tin g m at er ia ls in Ta bl e - 1 co ns ul tin g
mentio
2 Al um in iu m fc
with th e Instructor.
A dv an ce d b
1
d no te do w n th e ph ys ic al pr op er ty , 3
3 Id en tif y an
io n ra te s of va po ur
permanence or wa te r va po r tra ns m iss 4 C hl or in at ed
st ru ct or .
re ta rd er s/ ba rri er wi th th e he lp of In
5 at oi\ oai 1
TASK 2: Insulate ducts using glass wool as insulation
1 Cement the duct joints before insulating . 7 Apply a uniform coating of bitumen or a solvent tree
adhesive compound to the duct surface.
2 Check the ductwork for leaks, and repair any that found.
8 Stuck the glass wool to the coated surface.
3 Check for proper supply and return air temperatures.
9 Cover the insulation with a suitable vapor barrier, like
4 Check for proper air pressure.
aluminium fail.
5 Check if there is any chance of moisture condensation
10 Plaster the surface after spreading Ghicken -wire mesh
on the duct.
as reinforcement.
Take greater care if moisture condensation can
11 Cover the insulation with perforated sheet or fiber glass
occur incase of glass wool insulation.
cloth to prevent the flying of the fiber due to airvelocity.
6 Insulate the duct with glass wool, if there is no chance
of moisture condensation.
TASK 3: Insulate the ducts using spray foam
1 Make sure that a spray foam insulation kit with 5 Open the valves on the tanks by turning them counter
insulating chemical tanks, nose pipes and spray bottle, clockwise so that the insulation foam can flow through
with adequate instruction material are ready the spray nozzle
2 Check the temperature of the insulation kit tanks to 6 Hold the spray nozzle about 12 to 16 inches away
make sure that they are in proper temperature range. from the duct wall.
Normally the tanks should be between 65 to 85 degree 7 Spray the foam with a back-and-forth motion.
Fahrenheit.
8 Not apply to much insulation at one spot
3 Clean the duct area to be insulated . Remove any dust
and defines with a broom or a vacuum cleaner. Also 9 Apply a thin layer of about 2 inch of foam insulation for
wipe down the surface of the walls and studs with a it to be effective.
damp cloth to remove cob webs and dust. 10 Allow the foam insulation to dry for about 20 to 30
4 Space connect the spray hose to the tank (insulation). minutes.
11 Inspect the duct wall for missed spray spots.
TASK 4 : lnsolate the ducts using ready made foam Isheet
1 Thoroughly clean the surface to be insulated. 4 Apply contact adhesive to the insulation surface and
to the duct surface.
2 Mark the measurements of the surface to be insulated
on the sheet. 5 Insulate lower surface of the duct first, then the side
walls and lastly the top.
3 Cut the required site out of the foam sheet roll.
6 Use contact adhesive to join the edges of the foam
sheet together.
TASK 5 : lsulate the ducts using expanded polystyrene (Thermocole)
1 Coat the duct surface uniformly with bitumen. r-:C:-a-u-=_
t:-io_n_:- - - - - - - - - - - - - - - - .
2 Stuck the thermocole of 20mm thickness with the 1 Foam insulation is highly flammable and
coating. release toxic smoke, if catches fire.
3 Do not use separate vapour barrier, as bitumen coating 2 Always use goggles and gloves while laying
acts as one. glass wool as insulation.
4 Finish the insulating with cement and plaster or metal
cladding.
