# Pipe Work Heat Loss – Watts/m

```Pipe Work Heat Loss – Watts/m
The guide table gives heat loss in Watts/m for frost protection with a Δt of 20&ordm;C and ke 0.034 W/m.
&ordm;C for glass/mineral fibre thermal insulation.
Insulation thickness (mm)
Pipe size
13
20
&frac12;
5.00
25
1
4.39
40
1&frac12;
3.51
50
2
3.04
75
3
100
4
150
6
-
-
-
25
6.73
5.87
4.56
3.88
3.15
-
-
38
8.83
7.42
5.64
4.71
3.75
-
-
50
10.41
8.74
6.54
5.41
4.23
3.62
-
65
12.18
10.11
7.47
6.13
4.73
4.01
-
75
14.36
11.81
8.63
7.00
5.35
4.49
-
100
17.79
14.52
10.46
8.40
6.31
5.23
-
150
24.82
20.25
14.30
11.31
8.28
6.74
-
200
-
25.61
17.88
14.03
10.10
8.13
6.12
250
-
31.30
21.70
16.88
12.04
9.60
7.12
300
-
36.65
25.27
19.58
13.85
10.96
8.05
350
-
39.99
27.51
21.25
14.96
11.82
8.63
400
-
45.35
31.08
23.94
16.77
13.18
9.52
450
-
50.86
34.65
26.61
18.56
14.52
10.46
500
-
56.03
38.22
29.29
20.36
15.87
11.36
600
-
66.72
45.35
34.65
23.94
18.56
13.17
750
-
82.76
56.03
42.67
29.41
22.59
15.81
Design factor of 1.1 not included
PROCESS TEMPERATURE MAINTENANCE
Heat losses in the table above may be adjusted for other temperatures as follows
Heat loss from table (W/m) x NEW Δt x NEW ke x factor
Factor =
1
x
0.034
Δt up to (&ordm;C)
30
40
60
80
100
120
140
160
1 = 1.47
20
ke
0.034
0.035
0.036
0.037
0.038
0.040
0.042
0.044
i.e. Heat loss to maintain 50mm NB pipe with 25mm insulation at Δt 100&ordm;C
= 8.74 x 100 x 0.038 x 1.47
= 48.82 Watts/metre
IMPORTANT NOTE: It is the responsibility of the design engineer and/or installer, to ensure that they
have calculated the correct heat loss required within the relevant and current standards.
IF IN DOUBT CONTACT US FOR TECHNICAL ASSISTANCE
The information provided in RS technical literature is believed to be accurate and reliable: however, RS Components assumes no responsibility for inaccuracies or omissions, or for the use of this information, and
all use of such information shall be entirely at the user’s own risk.
No responsibility is assumed by RS Components for any infringements of patents or other rights of third parties which may result from its use.
Specifications shown in RS Components technical literature are subject to change without notice
RS Components, PO Box 99, Corby, Northants, NN179RS
An Electrocomponents Company
Telephone: 01536 201234
Heat Loss Calculation to BS EN 60079
Where;
q
K
Tp
Ta
D2
D1
=
=
=
=
=
=
Heat Loss
Thermal Conductivity of Insulation at Mean Temperature
Maintain Temperature
Minimum Ambient Temperature
Outside Diameter of the Insulation
Inside Diameter of the Insulation
A Safety Factor of 10-25% may be added
The information provided in RS technical literature is believed to be accurate and reliable: however, RS Components assumes no responsibility for inaccuracies or omissions, or for the use of this information, and
all use of such information shall be entirely at the user’s own risk.
No responsibility is assumed by RS Components for any infringements of patents or other rights of third parties which may result from its use.
Specifications shown in RS Components technical literature are subject to change without notice
RS Components, PO Box 99, Corby, Northants, NN179RS
An Electrocomponents Company
Telephone: 01536 201234
```