M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Calculation documentation &
technical information >>
In this chapter we have accumulated both general
and specific technical information for Backer's tubular
elements. Here you will find tables, formulas,
diagrams and check-lists for the design work.
Guide................................................................. 88
Thermology/science of electricity............. 90
Charts................................................................ 94
Base for calculation....................................... 98
Tables............................................................... 100
Design check list........................................... 104
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M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Guide
Guide
Operating temperature?
Backer tubular elements can
be
used
upBHV
to 900°C.
Backer
AB AB
Backer
BHV
Working
temperature?
Working
temperature?
Backer Backer
tubular tubular
elements
can
elements
can
be usedbe
atused
sheath
at sheath
temperatures
up
temperatures
up
to 900 to
degrees
C.
900 degrees
C.
Tube mantle material?
Surface load?
Bases
for
calculation/technical
information
10:12 10:12
Copper, steel, stainless steel andBases for calculation/technical
(W/cm² heated
area.)
information
Incoloy are standard materials
For recommended surface
that fulfill the demands in most
loads for different gases,
applications. See table on page
liquids and solid substances,
106. Special mantle materials
see page 105.
GUIDEGUIDE
can be acquired.
See corrosion
guide on page 102.
Surface
load? load?
SheathSheath
material?
material?
Surface
2
(W/cm
Copper,Copper,
steel, stainless
steel
and
heated
surface.)
steel, stainless steel and
surface.)
(W/cm2 heated
IncoloyIncoloy
are the are
standard
materials
surface
load load
the standard
materials For recommended
For recommended surface
which cover
requirements
in
whichthe
cover
the requirements
in
for different
gases,
liquid
and
for different gases, liquid and
most applications.
See table
most applications.
Seeontable on
solid substances,
solid substances,
page 10:30.
sheath materials
Thereafter:
pageSpecial
10:30. Special
sheath materials
see page
10:29.
see
page 10:29.
can be supplied.
See corrosion
guide
be supplied.
See corrosion
• can
Determine
required
power guide
on pageon
10:26.
page 10:26.
• Determine type of element,
standard or special
Next steps:
Next steps:
• Determine
required
power power
• Determine
required
• Determine
type of type
element,
• Determine
of element,
standard
or special
standard
or special
To determine the power demand use
To determine
the required
To determine
the required
one of the
formulas:
powerfollowing
use
one
of the
power use
one of the
following
formulas:
following
formulas:
Fluids:
Gases:
Gases:Gases:
P
qV
ρ
CP
∆ϑ
P
88
=
=
=
=
=
PPower
= [W]
Power [W]
3
flow
[mflow
/h] [m3/h]
qGas
=
Gas
V
[kg/m3][kg/m3]
ρDensity
= Density
Isobaric
specific heat [J/kg x K]
C
P = Isobaric specific heat [J/kg x K]
Increase
in temperature
[K]
∆ϑ
= Increase
in temperature
[K]
qV x ρ xqCV Pxxρ∆ϑ
x CP x ∆ϑ
_____________
= P_____________
=3600
3600
P =
m =
CP =
∆ϑ =
t =
Liquids:
Liquids:
Power
P = [W]
Power [W]
Mass
m
= [kg]
Mass [kg]
Specific
heat [J/kg
x K]
CP = Specific
heat
[J/kg x K]
Increase
in
temperature
[K]
∆ϑ = Increase in temperature
[K]
Heat
up
time
[h]
t = Heat up time [h]
m x CP m
x ∆ϑ
x CP x ∆ϑ
P = P__________
= __________
t x 3600t x 3600
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M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
For highest efficiency and quickest heating-up time,
use heaters immersed into the medium or process.
Gases in ducts, furnaces, or
pipes:
• Tubular elements without
surface enlargement
• Fin strip elements
• Finned elements
• Duct heaters
Liquids in tanks, other vessles
• Immersion heating elements
with flange
• Immersion heating elements
with screw plug
• Over the side immersion
heaters
Solid bodies:
• Tool elements
• Cast-in elements
Where the conditions do not
allow any of the above:
• Outside flat-positioned element
• Radiant heating element
• Heat transfer system for
instance with oil
Criterias and considerations at dimensioning
Provide adequate power
Design for long life:
• Low temperature
• Low surface load
• Correct material
The design must prevent:
• Corrosion
• Risk of damage to material
and surroundings
Provide sufficient safety for:
• Heating device (with suitable
control device such as thermal
cut-off )
• People (design according to
safety precautions and standards in force)
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Bases for calculation/technical information 10:14
Therminology
Backer BHV AB
Thermology
In nature, energy is found in many different forms that
can be transformed between each other. One of these is
mechanical work. Heat is another, which can come up from
chemical energy at combustion, from mechanical work or
from electrical energy. The transformation from electrical
energy to heat is the objective of electroheat technology.
In other segments of electro technology, when electrical
energy is transformed into mechanical work, heat is normally
produced in a greater or smaller extent. This heat dissipates
to the surroundings and is mostly regarded as an energy loss.
All forms of energy is normally measured in J or Ws, which
is the unit for energy.
Thermal parameters.
Specific heat: cp. The cp for a body is the number of J
per kilogram of the body that is required to raise its
temperature 1K.
∆ϑ = temperature rise
Q = m x cp x ∆ϑ
Melting heat: The melting heat of a substance is the energy
required to transform it from solid to liquid state. The unit
for melting heat is J/kg.
Vaporization heat: The vaporization heat of a liquid is the
energy required to transform it from liquid to vapour
state at constant pressure and temperature. The unit for
vaporization heat is J/kg.
Heat transfer
Heat can be transferred mainly in three different ways: by
convection, conduction or radiation.
Convection most commonly applies where liquids are in
circulation or gases are flowing, transferring heat from one
place to another.
The heat flow P (W) transferred by convection to a liquid or
a gas from a heat source such as a radiator can be calculated
by
The heat transfer coefficient depends on wether the gas
or the liquid is flowing freely, i.e. it flows as a result of the
difference in temperature between different places in the
medium, or as a result of applied mechanical force such as a
pump or a fan.
The flow of gases or liquids by force is found mainly in
pipe or duct systems. The heat transfer coefficient can be
calculated from empiric formulae. Flowing air that is heated
by heating elements obtains this heat by forced convection.
The sheath temperature of the element can be determined
using the graphs 1 and 2 for this kind of heat transfer.
For the elements closest to the duct walls, heat radiation
from these elements should also be considered. This radiated
heat can raise the wall temperature quite a lot and must
always be taken into consideration when dimensioning the
insulation etc. The inner elements only ”see” other elements
with the same temperature and therefore the net radiation
is zero.
The power required to heat a flow of air can be calculated
by
ρ x cp x qv x (ϑ2 – ϑ1)
P=
3600
where
ρ = air density in kg/m3
cp = isobaric specific heat for air in J/kgK
qv = air flow in m3/h
ϑ1 = initial temperature of the air in °C
ϑ2 = final temperature of the air in °C
The values for ρ and qv are at same temperature. The value
for cp is at mean temperature (ϑ1 + ϑ2)
2
As a general rule, ρ × cp can be put equal to 1200 to which
must be added heat losses. This general rule applies at 20°C.
At higher temperatures ρ × cp > 1200.
2004.05
P = α x A x (ϑ1–ϑ2)
where
α = heat transfer coefficient in W/m2K
A = area of the heat dissipating surface in m2
ϑ1 = temperature of the heat emitting medium in °C
ϑ2 = temperature of the heat absorbing medium in °C
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cont. therminology
Bases for calculation/technical information 10:15
Backer BHV AB
Heat is conducted in a solid medium by the vibration of
molecules. These vibrations are transferred from molecule
to molecule. The heat flow P transferred by conduction from
one side of a hotplate to another can be calculated by
λ x A x (ϑ1 – ϑ2)
P = ______________
δ
where
λ = thermal conductivity in W/mK
A = area of the hotplate in m2
δ = thickness of the hotplate in m
ϑ1 and ϑ2 = temperature of the hotplate on each side in °C
Heat radiation is a heat transfer process between bodies
without the aid of heat transfer by a surrounding medium.
According to Stefan Boltzmann´s law of radiation the
following expression for heat transfer between two
absolutely black parallell surfaces of equal size apply:
Q12 = CS x A x (Θ14 – Θ24)
where
Cs = black body radiation constant: 5,77×10-8 W/m2K4
A = area of the surfaces absorbing or emitting
the heat in m2
Θ1 and Θ2 = absolute temperatures of the bodies in K, i.e.
temperatures in °C + 273°C
Bodies that are not totally black emit and absorb less
radiated energy than black bodies, at the same temperature.
For such bodies with parallell surfaces of equal size and
at short distance from each other, the Cs value must be
replaced by
CS
C12 =
1 –1
1
+
ε1
ε2
When a larger surface A2 completely surrounds a surface A1,
e.g. a heating element in a room, Cs is replaced by
CS
C12 =
1
1

–1
ε1 +  ε2
A1
A2


2004.05
For element in free air, heat is transferred both by free
convection and by radiation.
The element temperature can be determined from graph 3
for elements at different ambient temperatures.
ε = absorption/emission coefficient.
Calculation of required electrical power
The amount of heat that must be transferred to a medium
which is to be heated can be calculated by
Q = m x cp x (ϑ1 – ϑ2)
where
m = weight of the medium in kg
cp = specific heat for the medium in J/kgK
ϑ1 = initial temperature in °C
ϑ2 = final temperatue in °C
If h = desired heating time in hours, the required power is
P=
m x cp x (ϑ2 – ϑ1)
h x 3600
To this must be added 5–20 % to compensate for heat losses
which depend on the heat insulation of the appliance.
Electrical parameters
U = voltage in V
R = resistance in Ω
I = current in A
P = power in W
Q = energy in J
A heating appliance with a resistance R Ω at a current I
A requires an amount of energy per s defined as the rated
power of the appliance:
U
P = R x I2 = __
R
2
During the time t (in sec) the energy consumption of the
appliance is
Q=Pxt
The resistance of a conductor wire is calculated by
R=ρx
4xL
π x D2
where
L = wire length in m
D = wire diameter in mm
ρ = specific resistance, resistivity, for the wire in Ωmm2/m
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Bases for calculation/technical information 10:16
cont. therminology
Backer BHV AB
Designation
Parameter
Symbol
Name
P
U
I
R
Power
Voltage
Current
Resistance
W
V
A
�
Watt
Volt
Ampere
Ohm
In a 3-phase system
U = Main voltage
I = Main ampere
UV = Phase voltage
IV = Current in phase
_
P = √3 UI = 3UVI = 3 UIV
(cos ϕ of resistance = 1)
1
1
R1×R2 (2 elements)
1
1
__
______
__
__
__
Rp = R1 + R2 ···+ Rn Rp = R1+R2
Rs=R1+R2+···Rn
Connection
in series
Resistance
Power
Relationship
Rs=n R1
Ps=
U2
n R1
1
Ps
Pp = n2
Connection of equal resistances
Example of 2 resistances 52.9� U=230 V
Connection
in parallel
Connection in series
Connection in parallel
52.9
R1
Rp =
= 26.45
Rs = 2 x 52.9 = 105.8
Rp= n
2
U2n
2302 x 2
2302
Pp =
Pp=
= 500 W
Ps =
=
500
W
R1
52.9
2x52.9
1000 W resistance
250 W resistance
Pr = n2Ps
Pp = 22 x Ps = 4 x Ps
Power at different voltages
2004.05
P1=
U12
R1
U12
U22
P
P2= R ; 1 =
P2
U22
1
E.g. 400 V instead of 230 V
U22
P2= U 2 x P1
1
P2=
4002
x P1 = 3 x P1
2302
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cont. therminology
Bases for calculation/technical information 10:17
Backer BHV AB
Star and delta connections with 3-phase systems. Phases equally loaded
Star connection Y 400/230 V
UV2
PR = PS = PT = –––
R
PY = PR + PS + PT
U2
PRS = PST = PTR = –––
R
PD = PRS + PST + PTR
3UV2 U2
PY = ––––
= –––
R
R
__
PY = UVI = √3 UI(cos ϕ=1)
3U2
PD = –––––
R
__
PD = 3UIV = √3 UI (cos ϕ = 1)
PD = 3 x PY
1
IY = ––– PY
3UV
1 P (cos ϕ = 1)
__
I = –––––
√3 U
1
IV = –––– PD
3U
IY (A) = 1,52 x PY (kW)
I (A) = 1,52 P (kW)
IV (A) = 0,88 x PD (kW)
Effekt
100
133
167
200
250
333
350
500
667
750
1000
1250
1330
1500
1667
2000
2500
3000
3333
4000
4500
5000
2004.05
Delta connection D 400 V
230 V
Motstånd Ω
400 V
500 V
529,0
397,7
316,8
264,5
211,6
158,9
151,1
105,8
79,3
70,5
52,9
42,3
39,8
35,3
31,7
26,5
21,2
17,6
15,9
13,2
11,8
10,6
1600,0
1203,0
958,1
800,0
640,0
480,5
457,1
320,0
239,9
213,3
160,0
128,0
120,3
106,7
96,0
80,0
64,0
53,3
48,0
40,0
35,6
32,0
2500,0
1879,7
1497,0
1250,0
1000,0
750,8
714,3
500,0
374,8
333,3
250,0
200,0
187,5
166,7
150,0
125,0
100,0
83,3
75,0
62,5
55,6
50,0
Power with different connections of two or three
identical resistances. The power for one resistance
at 230 equals 1. The figure in brackets is the
corresponding effect connected to 400 V.
Important! Check to ensure that none of
the resistances is overloaded when
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making these different connections.
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Charts
Bases for calculation/technical information 10:18
Backer BHV AB
AirAir Heating
heating
Example:
Calculate the surface temperature of the element for air
input at 100ºC and air output at 300°C.
The rate of air flow is 10 m/s.
The surface load of the tubular element is 2.6 W/cm2.
300 + 100 = 200°C.
The mean temperature will be
2
From graph no. 1 we obtain = 129 W/m2 K for a mean
temperature of 200°C and a rate of air flow of 10 m/s.
Then turn to the axis for surface load on graph no. 2. The
surface load was 2.6 W/cm2. Trace the graph upwards to
α = 129 W/m2 K. Then go horizontally towards the graph for
the increase in air temperature 200°C.
Now go to the graph for a mean air temperature of 200°C
and then horizontally to the axis for element temperature.
From this you will be able to read the surface temperature
of the element, 420°C
2004.05
Heat transfer coefficient α as
function of air speed at different
mean air temperatures
94
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M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
cont. charts
Bases for calculation/technical information 10:19
Backer BHV AB
2004.05
Temperature of element
at different surface loads,
heat transfer coefficient and
temperatures of input and
output air.
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M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
cont. charts
Bases for calculation/technical information 10:20
Backer BHV AB
2004.05
Surface temperature of
element at different ambient
temperatures and with different
surface loads in free air
ε = 0.75 for Element type 085.
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Beräkningsunderlag, teknisk information 10:21
Backer BHV AB
cont.
charts
2004.05
Loss of power from oven wall in an ambient
temperature of 20°C.
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Bases for calculation/technical information 10:22
Backer BHV AB
cont. base for calculation
Heating
water in a tank
Heating water in a tank
An open tank filled with water is to be heated to a
temperature of 70°C in one hour and after that be kept at
this temperature.
The tank is made of 5 mm stainless steel and the dimensions
are (L x B x H) 2 m x 1 m x 1 m. The tank is insulated with
50 mm mineral wool.
The tank is not fitted with a lid. The ambient temperature is
20°C and the relative humidity is 40 %.
A. Power required for heating
Density of steel: ρ = 7840 kg/m3
Weight of tank: (3 · 2 · 1+2 · 1 · 1) · 5 · 10–3 · 7840 = 314 kg
Weight of water: 2 · 103 kg
Specific heat of steel: cP, st = 0.46 kJ/kg K
Specific heat of water: cP, W = 4.18 kJ/kg K
(314 · 0.46 + 2 · 103 · 4.18) · (70 – 20)
PA = ––––––––––––––––––––––––––––––– = 118.1 kW
3600
B. Heat losses from vertical wall of tank
A = 2 (2 · 1 + 1 · 1) = 6 m2
PB = 1 kW
(see diagram page 10:28)
C. Heat loss from surface of water
A = 1 · 2 = 2 m2
F = 4.5 kW/m2
Pc = 2 · 4.5 = 9 kW
2004.05
During heating one should allow for a loss of 2/3 of the
losses of B and C above, i.e. 2/3 x 10 = 6.7 kW.
98
The total power required, inclusive of an additional 10 % as a
safety margin, will be:
P = 1.1 · (118.1 + 6.7) = 137.3 = 140 kW
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cont. base for calculation
Bases for calculation/technical information 10:23
Backer BHV AB
Pressure Pascal, Pa
1 Pa = 1 N/m
Pa
kp/cm
1
98.07 · 103
6.89 · 103
133
9.807
10.2 · 10
1
70.3 · 103
1.36 · 10–3
1 · 10–2
0.145 · 10
14.22
1
19.3 · 10–3
1.43 · 10–3
W, Nm/s
kpm/s
1
9.81
1.16
735.5
1.356
0.102
1
0.119
75
0.138
mmHg
lbf/in2
–6
mmvp
7.5 · 10
735.6
51.7
1
74.3 · 10–3
1.0120 · 10
1.10
697.3
13.46
1
kcal/h
hk
ft · ibf/s
0.86
8.43
1
632
1.166
1.36 · 10–3
13.,3 · 10–3
1.58 · 10–3
1
1.84 · 10–3
0.738
7.233
0.858
542.5
1
cal
ft · Ibf
3
–3
Power Watt, W
Energy Joule, J
J, Ws, Nm
Wh
1
3.6 · 10–3
4.19
1.356
0.278 · 10
1
1.16 · 10–3
0.377 · 10–3
0.239
860
1
0.324
0.738
2.66 · 10–3
3.088
1
Magnitude
Kelvin scale K
Centigrade scale C
Fahrenheit scale F
Related
temperatures
0
255.37
273.15
373.15
–273.15
–17.78
0
100
–459.67
0
32
212
Related
temperaturedifferences
1
0.55556
=5/9
1
0.5556
=5/9
1.8
1
–3
Temperature Kelvin, K
The electrochemical chain of potential
The electrochemical chain of potential showa in the table gives
the electrochemical potentials of the principle metals with their
relevant chemical symbols and also according to the magnitude
of their normal potentials which arise when each of the metals is
immersed in a normal aqueous solution (1n) of its salt.
The valency of the metai ions of each solution is indicated by
a corresponding number of dots after the chemical symbol.
the metals listed above hydrogen (H) in the table are termed
electropositive, those listed below H are termed electronegative.
If two metals are placed together in a galvanic element the further
the two metals are from each other in the chain of potential the
greater will be their electromotive force. Electromotive forces can
be calculated using the formula e.g. Cu/Ni gives + 0.34 – (–0.23)
= 0.57 V.
Conversion
ºC ↔ ºF
tC = 5/9 (tF–32)
tF = 9/5 tC+32
Metals
Process that
detemines
potential
(oxidation)
Normal
potential
Megnesium
Aluminium
Beryllium
Manganese
Zinc
Chrome
Iron
Cadmium
Nickel
Tin
Lead
Hydrogen
Copper
Silver
Mercury
Gold
Mg → Mg··
Al → Al···
Be → Be··
Mn → Mn··
Zn → Zn··
Cr → Cr··
Fe → Fe··
Cd → Cd··
Ni → Ni··
Sn → Sn··
Pb → Pb··
H → H·
Cu → Cu··
Ag → Ag·
Hg2 → 2Hg··
Au → Au·
–2.34
–1.70
–1.69
–1.10
–0.76
–0.60
–0.44
–0.44
–0.23
–0.14
–0.13
0
+0.34
+0.80
+0.80
+1.5
04.05
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M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Tables
Bases for calculation/technical information 10:24
Backer BHV AB
2004.05
Physical properties
100
Temperature
ºC
Density
kg/m3
Specific heat
kJ/kg K
Thermal conductivity
W/m K
Gases
Ammonia
Carbon dioxide
Carbon monoxide
Nitrogen
Air
Oxygen
Sulphur dioxide
Hydrogen
0/100
0/200
0/200
0/200
0/200
0/200
0/200
0/200
0.771
1.951
1.234
1.234
1.276
1.410
2.888
0.089
2.056/2.219
0.816/1.001
1.038/1.055
1.038/1.047
1.005/1.022
0.909/0.963
0.586/0.712
14.05/14.41
0.022/0.033
0.015/0.030
0.023/0.037
0.024/0.037
0.024/0.039
0.024/0.039
0.0086/0.019
0.171/0.249
Liquids
Ethanol
Fuel oil class 1
Paraffin
Glycerine
Glycol
Hydraulic oil
Methanol
Olive oil
Paraffin
Lubricating oil
Coal tar
Turpentine
Trichlorethylene
Water
18
15
20
20
20
XX
20
20
20
30
15–90
18
20
18
791
860
800
1260
1120
XX
790
920
710
900–930
1100–1260
840
1480
999
2.39
2.36
0.50
2.36
2.4
XX
2.50
1.65
0.71
2.09
1.42
1.75
0.96
4.18
0.17
0.285
0.145
0.285
Metals
Babits
Lead
Bronze
Cast iron
Incoloy 800
Copper
Brass
Stainless steel
Silumin
Steel
20
20
20
20
20
20
20
20
20
20
10000
11340
8670
7000–7800
8030
8950
8100–8600
7840
2700
7850
0.16
0.13
0.34
0.54
0.50
0.42
0.38
0.46
0.90
0.50
Other solid
substances
ABS
Acryllic
Asbetos
Asphalt
Bakelite
Cement/concrete
Beeswax
Oak (air dried)
Fat
Glass
Graphite (pure)
Pine (air dried)
Gravel (dry)
Rubber (pure)
Resin
Ice
Marble
Nylon
Paper
Paraffin wax
Polyethylene
Polyimide
Polycarbonate
Polyprobylene
Polystyrene
Polyester
Porcelain
Sand (dry)
Steatit
Brick
20
20
0
20
20
20
20
20
20
20
20
20
20
20
20
0
20
20
20
20
20
20
20
20
20
20
20
20
20
20
1100–1220
1100–1180
470–700
1100–1500
1400
1800–2500
965
690–1030
920–940
2400–2900
1800–2350
350–600
1800–2100
900–1000
1030–1340
920
2500–2800
1070–1150
700–1200
900
910–960
1440
1180-1250
880-910
1060
1060–1470
2150–2360
1410–1600
2590
1400–2000
1.46
1.42
0.81
2.09
1.60
0.88
65
2.38
2.09
0.71–0.83
0.75–1.25
2.72
3.34
1,42–2,1
0.19
0.14
0.15–0.23
0.7
0.23
0.8–1.4
1.92
0.83
1.26–2.09
1.88
2.88
2.26
1.31–1.30
1.26
1.93
1.34
0.84–1.46
1.09
0.80
0.84
0.83–1.09
2.25
2.1–3.5
0.24
0.19 (0.13)
0.28 (0.24)
0.33
0.36–0.98
0.20
0.25
0.05–0.14
0.57–0.72
1.05 (1.52)
0.32
2.94
0.41
www.backer.se
Melting point
°C
–115
–18
0.21
0.17
0.242
0.13–0.14
0.15
0.15
0.60
10
34.6
26.0
55–64
14.0
388.0
110–150
15.0
160.0
65.8
327
1000
1200
1357
1083
925
1440
570
1516
120
0,1-0,46
0.9
1.46
0.1–0.46
0.34
0.23
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
3000
125
70200
0
54
1550
1580–2200
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
cont. tables
Bases for calculation/technical information 10:25
Backer BHV AB
General physical constants for elements in solid form
m
bo
l
p
d
ro
u
Sy
G
Pe
rio
At
o
no mic
M = Atomic weight; ρ = Density at 18ºC, kg/m3; λ = Thermal conductivity at 18ºC, W/mK
cp = Specific heat at 20–100°C, J/kgK; ϑSM = Melting point in ºC; ϑKP = Boiling point at 1 bar, ºC
QKP = Vaporization heat at ϑKP kJ/kg; QSM = Melting point, kJ/kg; ρe = Resistivity at 20ºC, Ωm
ρ – ρO
e0 = Volta-effect at 0°C, µV; e100 = Volta-effect at 100°C, µV
β = ––––––––
= Temperature coefficient of the resistivity
ϑ (e – e ) µV
eϑ = Volta-effect at ϑ°C = e0 + –––––
(ϑ – ϑO)ρO
100
0
100
Resistivity
Volta-effect
No Name
cP
M
Qkp
ϑsm Qsm
ϑkp
λ
ρ
e0
e100
108 e 103β
1
2
Aluminium .................
Antimony ...................
13
51
3
5
3
15
26.97
121.76
2700
6680
Al
Sb
218
19
890
210
658
630.5
388
164
2500
1635
11500
1250
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Arsenic .......................
Barium ........................
Beryllium....................
Lead ............................
Boron..........................
Cerium .......................
Cesium .......................
Phosphor, yellow ......
Gallium .......................
Germanium ...............
Gold ...................... ....
Hafnium......................
Indium.........................
Irdium .........................
Iodine ..........................
Iron (amorph) ...........
Cadmium ...................
33
56
4
82
5
58
55
15
31
32
79
72
49
77
53
26
48
4
6
2
6
2
6
6
3
4
4
6
6
5
6
5
4
5
15
2
2
14
13
3
1
15
13
13
11
4
13
9
17
8
12
74.91
137.36
9.01
207.21
10.82
140.13
132.91
30.98
69.72
72.60
197.2
178.6
114.76
193.1
126.92
55.85
112.41
5720
3780
1840
11340
2500
6800
1873
1830
5903
5460
19300
13300
7250
22420
4950
7860
8640
As
Ba
Be
Pb
B
Ce
Cs
P
Ga
Ge
Au
Hf
In
Ir
J
Fe
Cd
–
–
168
35
–
–
–
–
128
–
300
–
–
59
–
84
100
325
300
1800
125
1300
170
210
790
330
290
130
–
210
135
220
460
330
–500
–710
1280
327
2300
775
28.5
44
30
958
1063
2230
155
2454
113.5
1530
320.9
–
–
1400
24.8
–
–
16.3
22
79
–
84
–
–
120
120
270
54
615
1640
3000
1750
2550
1400
690
280.5
2064
–
2960
>3200
1450
>4800
184.35
2500
765
1700
1350
24800
920
–
–
500
1650
540
–
2280
–
–
3900
100
6400
1000
20
21
22
23
24
20
19
14
27
6
6
6
29
24
80
57
3
12
25
42
11
28
41
76
46
78
75
45
37
44
34
47
38
47
48
49
50
Calcium ......................
Potassium...................
Cilikon ........................
Cobalt.........................
Carbon, diamond .....
Carbon, graphite ......
Carbon, amorphous
Copper .......................
Chrome ......................
Mercury .....................
Lanthanum .................
Lithium .......................
Magnesium.................
Manganese .................
Molybdenum .............
Sodium .......................
Nickel .........................
Niobium .....................
Osmium .....................
Palladium ....................
Platinum .....................
Renium .......................
Rhodium ....................
Rubidium ....................
Ruthenium .................
Selenium (amorph) ..
Silver ...........................
Strontium ...................
Sulphur, amorph .......
Sulphur, monocloride
Sulphur, rhombic ......
Thallium .....................
Tantalum ....................
Tellurium ....................
Tin ...............................
81
73
52
50
4
4
3
4
2
2
2
4
4
6
6
2
3
4
5
3
4
5
6
5
6
6
5
5
5
4
5
5
3
3
3
6
5
5
5
2
1
14
9
14
14
14
11
6
12
3
1
2
7
6
1
10
5
8
10
10
7
9
1
8
16
11
2
16
16
16
13
5
16
14
40.08
39.096
28.06
58.94
12.01
12.01
12.01
63.54
52.01
200.61
138.92
6.94
24.32
54.93
95.95
23.00
58.69
92.91
190.2
106.7
195.23
186.31
102.91
85.48
101.7
78.96
107.88
87.63
32.07
32.07
32.07
204.39
180.88
127.61
118.70
1540
870
2330
8800
3510
2220
1900
8918
7100
13550
6150
534
1734
7200
10200
970
8900
8550
22480
12160
21450
20530
12100
1520
12200
4800
10500
2500
–
1960
2070
11850
16600
6250
7300
Ca
K
Si
Co
C
C
C
Cu
Cr
Hg
La
Li
Mg
Mn
Mo
Na
Ni
Nb
Os
Pd
Pt
Re
Rh
Rb
Ru
Se
Ag
Sr
S
S
S
Tl
Ta
Te
Sn
600
134
–
70
165
160
2
395
43
10.3
–
70
171
–
138
140
88
–
–
67
71
–
89
–
–
–
420
–
0.19
–
0.29
51
55
–
65
630
750
750
420
490
690
840
385
440
140
170
3400
1000
500
260
1250
450
270
130
250
130
135
240
350
250
375
230
670
–
735
720
125
140
210
210
850
63.5
1420
1492
3500
3500
3500
1083
1920
38.9
885
179
650
1260
2620
97.5
1452
1950
2500
1555
1773
3170
1966
38.5
2500
217.4
960.5
577
–120
119.0
112.8
303
3027
452
231.9
328
60
–
260
17000
17000
17000
205
315
11.5
–
140
200
260
290
115
300
–
145
160
100
–
215
25.5
–
64.5
105
–
–
46
39
17
–
30
59
1487
776
2600
3185
4200
4200
4200
2595
2327
357
1800
1372
1097
2152
4800
877
3075
–
5300
2200
4300
–
>2500
713
>2700
690
2170
1360
–
–
444.6
1457
5300
1300
2430
4200
2050
14000
6500
–
50000
–
4650
6150
287
–
21300
5650
4200
7100
4200
6200
–
–
3950
2500
–
–
8400
–
1100
2150
–
–
–
290
800
–
670
2600
51
52
53
54
55
Titanium .....................
Thorium .....................
Uranium .....................
Vanadium ...................
Bismuth ......................
22
90
92
23
83
4
7
7
4
6
4
4
6
5
15
47.90
232.12
238.07
50.95
209.00
4500
11200
18700
5866
9800
Ti
Th
U
V
Bi
–
–
–
–
10
460
125
125
500
120
1727
1840
1690
1715
271.3
–
–
–
–
59
3000
>3000
–
3000
1560
–
–
–
–
840
55 Wolfram .....................
57 Zinc .............................
74
30
6
4
6
12
183.92
65.38
19300
7140
W
Zn
170
113
135
390
3370
419.5
250
112
5900
907
4800
1800
58 Zirconium ..................
40
5
4
91.22
6400
Zr
–
275
1857
–
2900
–
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
16
–1.6
+21
+47
–
–
–
–1.2
–
–
–
–
–
+301.3
+1.7
–
+1.2
+1.2
–
+15.0
±0.0
+3.2
–9.4
–12.5
–
–18.6
–
–
–
+1.7
–
–3.2
–
+13.2
–1.3
–
+4.7
–5.4
–17.8
–
–
–6.7
-4.4
–
+1.0
–1.5
–
–
+1.3
–
–
–
–
+0.5
–5.0
+330
–0.7
–1.5
–
–
–
–
–110
–54
+0.4
+0.4
+2.2
–
–2.1
+25
+53
–
–
–
–1.4
–
–
–
–
–
+373.6
+2.2
–
+1.2
0.9
–
+10.3
+2.0
+7.2
–12.5
–16.5
–
–26.6
–
–
–
+2.2
–
–4.9
–
+21.8
–1.5
–
+8.0
–4.4
–21.6
–
–
–9.5
-7.3
–
+0.8
–7.7
–
–
+2.0
–
–
–
–
±0
–6.7
+330
–1.1
–1.5
–
–
–
–
–95
–59
+3.6
+0.8
+3.6
–
2.72
39.8
4
5.4
37.6
57.5
6.3
20.7
–
74.0
20.8
–
43.9
–
2.21
32
9.1
5.3
–
9.9
7.25
3.89
–
0.42
4.2
–
–
4.4
–
4.0
–
4.0
–
4.7
4.1
–
6.6
4.2
4.5
6.9
–
6.8
–
–
–3500
1.7241
2.8
95.4
59.8
9.1
4.3
5.0
4.72
4.6
7.35
–
9.45
10.75
10.5
–
5.0
12.6
14.5
–
1.58
32.4
–
–
–
17.5
14.7
200000
11.3
3.3
5.8
–
6.6
–
–
-0.5
3.93
–
0.99
–
4.4
4.1
–
4.7
5.5
6.7
–
4
3.8
3.92
–
4.4
5.2
–
–
4.1
3.83
–
–
–
5.2
3.5
–
4.6
90.2
40.1
–
–
118
–
2.1
–
–
4.5
5.32
5.95
4.8
4.2
45
–
2004.05
Reproduced from Ingenjörshandboken (The Engineer’s handbook).
The Basic Technical Sciences, Nordisk Rotogravyrs Förlag/Norstedts
1965. Reproduced with necessary permission.
www.backer.se
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
101
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
cont. tables
Bases for calculation/technical information 10:26
Backer BHV AB
Corrosion guide
Corrosion
Guide
The effects of corrosion have been graded in the table as
follows:
0:
Rate of corrosion <0.1 mm per year
Material used is resistant to corrosion.
1:
Rate of corrosion 0.1–1.0 mm per year.
Material not resistant to corrosion but usable
in certain cases.
2:
Rate of corrosion >1.0 mm per year.
Excessive corrosion. Material not usable.
Substance
2004.05
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
102
Conc.%
Acetone .....................................................
Aluminium chloride.................................
Aluminium sulphate neutr. low Fe .......
Ammonium hydrate solution ................
Ammonium bicarbonate ........................
Ammonium chloride ...............................
Ammonium nitrate ..................................
Ammonium persulphate ........................
Ammonium sulphate ...............................
Benzene .....................................................
Blood (meat juices) .................................
Lead acetate ..............................................
Borax ..........................................................
Boric acid ..................................................
Citric acid ..................................................
Ether ...........................................................
Ethyl alcohol .............................................
Carbolic acid.............................................
Formaldehyde ...........................................
Phosphoric acid........................................
Photographic developer .........................
Fruit juices .................................................
Furfurol, vapour .......................................
Gallic acid ..................................................
Tannic acid .................................................
Glycerine ...................................................
Iron chloride (111) ..................................
Iron nitrate (111) .....................................
Iron sulphate (11, 111) ...........................
Coffee.........................................................
Calcium chloride......................................
Potassium chromate ...............................
Potassium cyanide ...................................
Potassium chloride ..................................
Potassium nitrate .....................................
Potassium permanganate .......................
Potassium sulphate ..................................
Chlorine (hydrous) ..................................
Chloroform ...............................................
5
10
5
saturated
10
all concentrations
20
saturated
saturated
5
all concentrations
all concentrations
all concentrations
<35, 50
saturated
50
all concentrations
5
5
5
5
25
saturated
saturated
5
5
P:
Risk for pitting and crevice corrosion.
S:
Risk for stress corrosion.
Please note that the figures in the corrosion table can change
considerably in if concentrations and temperatures are
increased. The mixing of different substances can result in the
resistance to corrosion being reduced. This applies above all
to solutions ccntaining chlorides.
Temp.ºC
20-K
50
20-K
20-K
20-K
20-K
20-K
20
20-K
20-K
20
20-K
20-K
20-K
20-K
20
20
20-K
20
80, K
20
20-K
vapour
20-K
20-K
20
20
20
20-K
K
20-K
20-K
20
20-K
20-K
20-K
20-K
20
20-K
SS2337
SS2348
0
2
0
2
P S
0
2
0
1
0
2
0
P
P
0
1
www.backer.se
0
P S
2
0
0
0
0
0
0
P S
2
0
0
0
P S
0
0
0
P
0
0
0
0
P
2
0
0
0
P
2
P
1
0
0
0
0
0
0
0
P S
2
0
0
0
P S
0
0
0
P
0
0
0
0
0
0
P
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
P S
2
0
0
0
P S
0
0
0
P
0
0
0
0
P
2
P S
0
0
P S
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
I 800
0
0
0
0
0
P S
0
0
0
0
0
0
0
0
0
0
0
0
0
0
–
0
0
0
0
0
0
P S
2
0
0
0
P S
0
0
0
P
0
0
0
0
P
1
P S
0
0
P S
0
1
0
0
0
0
0
0
0
0
0
0
0
SS2562
0
P S
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
P
0
P S
0
P S
P
0
0
P S
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
cont. tables
Bases for calculation/technical information 10:27
Backer BHV AB
Substance
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
Carbone tetrachloride ...........................
Copper cyanide........................................
Copper nitrate .........................................
Copper sulphate ......................................
Chromic acid ............................................
Magnesium chloride ................................
Magnesium sulphate ................................
Manganese chloride ................................
Lactic acid ..................................................
Formic acid ...............................................
Sodium bisulphate ...................................
Sodium bisulphate ...................................
Sodium citrate ..........................................
Sodium hydroxide....................................
Sodium carbonate ...................................
Sodium nitrate ..........................................
Sodium nitrite...........................................
Sodium peroxide......................................
Sodium sulphate .......................................
Sodium sulphite........................................
Sodium thiosulphate ...............................
In presence of Cl .....................................
Nickel chloride .........................................
Nickel sulphate.........................................
Oxalic acid ................................................
Pyrogallic acid ...........................................
Nitric acid .................................................
Hydrochloric acid ....................................
Silvernitrate ...............................................
Butyric acid ...............................................
Stearic acid ................................................
Sulphuric acid ...........................................
.....................................................................
.....................................................................
Stanic chloride ..........................................
Trichlorethylene .......................................
Tartaric acid ..............................................
Hydrogen peroxide .................................
Zinc chloride ............................................
Zinc sulphate ............................................
Acetic acid .................................................
Malic acid ...................................................
Conc.%
Temp.ºC
SS2337
SS2348
SS2562
I 800
100
saturated
10
10
10
2.5
saturated
10
5
5
10
10
saturated
20
25
saturated
saturated
10
saturated
5
25
25
saturated
saturated
5
all concentrations
<40
1
5
20-K
20-K
20-K
20-K
20-K
20
20-K
20-K
20-K
20
20–50
20-K
20
20-K
20-K
20-K
20-K
20-K
20-K
20-K
20-K
20-K
20
20-K
20-K
20-K
20-K
60
20-K
20-K
130
20–100
20–100
20–70
20
20-K
20-K
20
20-K
20-K
20-K
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
20
60
5
10
30
5–20
saturated
80
10
0
2
0
0
0
P S
0
0
0
0
0
1
2
0
0
0
2
0
0
1
2
2
2
P
2
0
0
0
0
0
0
P
1
2
0
1
0
0
0
0
0
P S
1
2
2
0
0
0
0
1
0
0
0
P S
0
0
0
1
2
2
P
0
P
1
0
0
2
0
0
0
1
0
0
0
0
0
0
2
0
0
P S
0
0
0
0
0
0
0
0
0
0
0
0
0
0
P S
0
P
0
0
P
P
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
004.05
0
0
0
P
1
0
0
0
2
1
0
0
0
P S
0
0
P
1
1
1
P
1
0
0
2
0
0
P S
0
0
0
0
0
0
0
0
0
0
0
0
0
0
P S
0
P
0
0
P
0
0
2
0
0
0
0
0
0
P
0
0
0
0
0
0
0
0
0
P S
0
P
0
0
0
2
0
0
P S
0
0
0
0
0
0
0
0
0
0
0
0
0
0
P S
0
P
0
0
P
P
0
0
P S
0
0
0
103
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Design
check list
Read more on page:
· Calculate the power required
· Suitable surface load................................. 105
· Decide increase in heat dissipation surface
· Choice of type of element....................... 106
· Choice of mantle material....................... 106
· Choice of cold parts.................................. 107
· Calculation of total length of element.107
· Bending........................................................ 108
· Choice of fixing devices and
connections .................................................. 12
104
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Bases for calculation, technical information 10:29
Backer BHV AB
Maximum recommended surface loads when heating
Maximum
recommended
surface loads when
different substances and media
heating different substances and media
Surface effect in W/cm2
Substance
2004.05
Still air ................................................................
Still air ................................................................
Still air 3 m/s .....................................................
Still air 6 m/s .....................................................
Still air 10 m/s...................................................
Still air 10 m/s...................................................
Still air 10 m/s...................................................
Alkaline solutions ............................................
Thin oil ...............................................................
Thin oil solutions .............................................
Thin oil solutions .............................................
Vegetable oil......................................................
Heat transfer oil ..............................................
Heat transfer oil ..............................................
Tar .......................................................................
Still water ..........................................................
Flowing water ...................................................
Metallic surfaces for contact heating ...400
Metallic surfaces for contact heating ...600
Solid castings in aluminium ............................
Temp °C
Steel
Stainless steel
Copper
50
450
200
260
200
300
450
100
50
200
350
200
200
300
150
100
80
2
1.7
6
4
5
7
10
8
4
6
6
4
2
4
5
2
1
10
15
10
15
300
1.5
2.5
3.5
1.5
5
12
12
www.backer.se
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
105
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Bases for calculation, technical information 10:30
Backer BHV AB
The following types of tubular elements are produced
The following
types of tubular elements are produced
We can supply these different types of elements in the following sheath materials:
Swedish
standard
Material
Steel ........................................
Stainless steel ......................
Stainless steel ......................
Acid proof steel ...................
Copper...................................
Nickel/bronze .......................
SMO254.................................
Incoloy 800 ...........................
Incoloy 825 ...........................
R323 .......................................
Titan .......................................
SS2333
SS2337
SS2348
SS5015
SS5667
SS2378
AISI
WERK-stoff
Max. temp*
064
085
140
–
304
321
316L
C12200
C70600
UNS S31254
–
–
(302B)
–
–
1.4301
1.4541
1.4404
–
–
–
1.4876
2.4858
1.4828S
–
400
750
750
700
250
275
400
800
450
900
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
2004.05
* Max. temp refers to the sheath
temperature of the element.
106
www.backer.se
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
X
X
X
X
X
X
X
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Bases for calculation, technical information 10:31
Standard cold part - and max/min element lengths
Backer BHV AB
other cold part lengths on request
Standard inactive lengths and max/min. element lengths
Other inactive lengths can be made if required
All tubular elements must be produced with an inactive part in both ends.
Tubular ElementCold part length in mmElement length
Type
30 35 45 60 70
85 100110130145175190200205235245275325375425475 Min.
Max.
•
3400
Element length
064
TubularTerminal
element pin Ø 2,5 mm
•
•
45
60
70
064 085
TerminalTerminal
pin of 2.5pin
mmØdiam
•
••
2,5 mm
Qual. SSQual.
1914 SS 1914
••
••
• • • • • ••
••
••
•
•
085
TerminalAlt.pinMof4
2.5 mm diam
• •
•
Qual. SSQual.
1914 SS 1914
••
••
•
•
• •
•
•
••
• • • ••
Type
Qual. SS 1914
30
35
•
Alt. M 085-2
4
•
•
Qual. SSTerminal
1914 pin Ø 1,5 mm •
085-2 Qual. SS 1914
Terminal pin of 1.5 mm diam
•
•
Qual. SS140-1
1914
Terminal pin M 6
•
•
•
•
•
•
•
•
•
•
•
•
•
140-2 Terminal pin Ø 2,5 mm •
TerminalKval.
pin of
mm diam
•
•
SS2,5
1914
Qual. SS 1914
•
•
•
•
140-3 140-3
2,5 mm
TerminalTerminal
pin of 2,5pin
mmØdiam
•
••
Qual. SSQual.
1914 SS 1914
••
••
•
•
•
250
85 100 110 130 145 175 190 200 205 235 245 275 325 375 425 475
•
140-1
Qual. SS 1914
Terminal pin M 6
Qual. SS 1914
• Inactive
• •
•
length in mm
•
•
•
•
•
•
•
•
•
•
•
Max.
•
• • • • • ••
••
•
• 6400
155
210
4500
•
• • • • •
•
••
210
•
• 6400
170
6400
•
•
•
•
•
•
•
350
170
350
•
•
•
•
160
•
6400
3600
•
•
Min.
3900
6400
•
160
6400
140-2
•
•
•
•
•
•
•
• • • • • ••
•
•
•
•
•
•
••
••
•
•
•
•
•
•
•
•
•
•
•
• • • • • ••
160
4200
•
•
•
160
4200
••
220
•
• 4200
220
4200
Through other companies within the Backer group we can offer a wide range of other dimensions. Please contacts us for more info!
Surface load
Among other factors the functional life of an element
depends on the surface load of the element.You will find
recommendations for surface loads for different kind of
heating
onpage
page10:29.
105.
heating purposes
puposes on
Surface load is calculated as follows:
P
Y = –––––––
LXM
P
L = –––––––
MXY
Y = Surface load in W/cm2
L = Active length of the element in cm
P = Output in W
M = Element type 064: 2.01 cm2/cm
Element type 085: 2.67 cm2/cm
Element type 140: 4.40 cm2/cm
Total length of element
The total length of the element is obtained by adding L to
the total length of the inactive section.
Ohms/metre
In certain cases ohms/metre can be a limiting factor. The
following limits apply:
Min. 66�/mL
Ω/ mL
Max.
Ω/ mL
Type of element 064
min.
max.61300�/mL
085
3
1300
085-2
14
700
140-1
3
1300
140-2
8
1200
140-3
8
1000
P = Power in W
U = Voltage in V
L = Active length of element in m
U2
Ohms/metre = –––––––
PxL
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
107
M o r e t e c h n i c a l d e t a i l s a t w w w. b a c k e r. s e
Bases for calculation, technical information 10:32
Backer BHV AB
Bending instructions
Bending instructions
Inactive length
Smallest bending radius
In cold state Backer’s elements can easily
be bent to a small radius. This simplifies the
work of design. The requirement for space in
different electrical applinaces can be reduced
Inactive length Min. 10
Min. 10
Smallest bending radius
to a minimum. Terminal pins must always be
least 10 mm from the extremity of a bend (see
diagram).
Smallest bending radius of different sheath materials.
Type of
tubular
element
Copper
C12200
Steel
Grade D
Stainless
steel
304
ENAISI
1.4301
Stainless
steel
AISI
316L
EN
1.4404
Stainless
steel
323
EN R1.4828
Stainless
steel
Incoloy 800
Stainless
steel
Incoloy 825
Stainless
steel
UNS S31254
S/Titanium
20
064
085
140
10
12,5
25
–
12,5
25
10
12,5
25
10
12,5
25
10
11
25
11,5
15
30
17,5
18
30
12,5
15
30
–
2004.05
When figuring an element drawing, c-c measures apply.
108
Te l . + 4 6 4 5 1 6 6 1 0 0 · Fa x . + 4 6 4 5 1 6 6 1 9 5 · i n f o @ b a c k e r. s e
www.backer.se
35