Calculations
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Calculations : Paint
Abbreviations
WFT = Wet Film Thickness
DFT = Dry Film Thickness
% VS = Percent Volume Solids
LF = Loss Factor
DV = Dead Volume
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Formula for determining the DFT
Formula: DFT = WFT x % VS
100
Example:
WFT = 250 m
% VS = 50 %
250 x 50
DFT = = 125 m
100
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Formula for determining the WFT
DFT x 100 %
Formula : WFT =
% VS
Example:
DFT = 100 m
% VS = 65 %
WFT = 100 x 100 % = 154 m
65 %
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Formula for determining the
WFT after thinning (Method 1)
Formula: WFT = DFT x (100 % + % thinner)
% VS
Example:
DFT = 100 m
% VS = 65 %
Added thinner = 20 %
WFT = 100 x (100 % + 20 %) =185 m
65 %
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Formula for determining the
WFT after thinning (Method 2).
DFT = 100 microns
% VS = 65 %
Added thinner = 20 %
Volume of paint = 1 litre New % VS:
65 = 54 %
Volume of thinner = 0,2 litre
1,2
New volume = 1,2 litre
WFT = 100 % x 100 microns = 185 m
54 %
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Theoretical spreading rate
% VS x 10
Formula: = m2/litre
DFT
DFT = 100 microns
% VS = 65
10 = Factor
Spreading rate: 65 x 10
100
= 6,5m2/litre
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Consumption of paint, no loss (1 of 2)
To be painted: Tank, area of 500 m2
Paint DFT % VS
Epoxy mastic 200 microns 85 %
Polyurethane topcoat 50 50 %
Area (m2) x DFT
Consumption = = litre
10 x % VS
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Consumption of paint, no loss (1 of 2)
To be painted: Tank, area of 500 m2
Formula: Area, m2 x DFT
10 x % VS
Epoxy mastic 500 x 200 = 117,7 litre
10 x 85
Polyurethane topcoat 500 x 50 = 50,0 litre
10 x 50
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Consumption of Paint with loss
To be painted: Tank, area of 500 m2 , 40 % loss
40 % loss implies that only 60 % will remain on the surface.
The correction factor, Loss factor, will be 0.6
Formula: Area, m2 x DFT
10 x % VS x Efficiency
Epoxy mastic 500 x 200 = 196 litre
10 x 85 x 0,6
Polyurethane topcoat 500 x 50 = 83 litre
10 x 50 x 0,6
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Consumption of paint with loss
including Dead Volume (1 of 2)
A certain roughness will give a certain dead volume
Roughness, microns Dead volume, l/ m2
30 0.02
45 0.03
60 0.04
75 0.05
90 0.06
105 0.07
Total Dead volume, litre = Area (m2) x DV x 100
% VS x Eff
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Consumption of paint with loss
including Dead Volume (2 of 2)
Tank area 500 m2, 40 % loss, surface roughness 60 microns
DFT % VS
Epoxy mastic 200 85
Polyurethane topcoat 50 50
500 x 0,04 x 100
Litre dead volume = = 39 litre (EM)
85 x 0,6
Epoxy mastic (EM) 500 x 200 = 196 litre (EM)
10 x 85 x 0,6
Polyurethane topcoat 500 x 50 = 83 litre (PU)
10 x 50 x 0,6
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Dead volume increases the
volume of paint required
Smooth (polished) steel surface
Even film thickness
Steel
Specified thickness
Uneven steel surface
Paint will fill the valleys Dead volume
Steel
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How much paint should we order ?
calculation of paint consumption with
loss
A loss of 40 % means that only 60 %
will be applied on the surface
Example: 100 litre is needed, loss is 40 %
We have to order
100 x 100 100
60 = 0,6 (Efficiency) = 167 litre
Not 100 litre + 40 % extra = 140 litre
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Consumption of Paint with loss
To be painted: Tank, area of 1500 m2 , 30 % loss
Dicat dengan:
Jotamastic 87 Dft :200 Mic Volume solid 87%
Hardtop As Dft : 50 Mic Volume solid 50%
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Consumption of Paint with loss
To be painted: Tank, area of 1500 m2 , 30 % loss
Cari quantity
Jotamastic 87 = litre
Hardtop AS = litre
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Consumption of Paint with loss
To be painted: Tank, area of 1500 m2 , 30 % loss
Formula: Area, m2 x DFT
10 x % VS x Efficiency
Jotamastic 87 1500 x 200 = 492.61 litre
10 x 87 x 0,7
Hardtop AS 1500 x 50 =214.29 litre
10 x 50 x 0,7
CALCULATION
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