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Self regulating trace heating systems
Step 8: Determine the required allowance for pumps, valves, flanges and pipe supports:
Determine the required allowances for pumps, valves, flanges and pipe supports using the following table:
Pipe diameter
DN8
in DN / inch
1/4"
Allowance for pumps
1.5
in m
Allowance for valves
0.5
in m
Allowance for flanges
0.2
in m
Allowance for pipe supports
0.2
in m
Typical pipe support interval
1
in m
→ Example
▪ Pipe diameter: DN25
▪ 1 pump
▪ 2 valves
▪ 6 flanges
▪ 24 pipe supports
The total required allowance is calculated as follows:
total required allowance = no. of pumps × pump allowance value +
Step 9: Add all lengths / allowances together:
Add the lengths for piping (as determined in step 6) and allowances (as determined in step 7 and step 8) together to obtain total required trace
heater length.
→ Example
▪ required trace heater length for piping (step 6): 50 m
▪ required allowances for connection kits (step 7): 1.0 m
▪ required allowances for pumps, valves, flanges and pipe supports (step 8): 12.3 m
total required trace heater length = required trace heater length for piping + required allowances
Determination of the required number of heating circuits
Step 10: Confirm the number of electrical circuits required for the application:
Using Table J on page 17, compare the required heater length and start up temperature to the available circuit breaker allowances to determine
the number of electrical circuits that will be required.
→ Example
▪ total required trace heater length: 63.3 m
▪ circuit breaker voltage: 230 Vac
▪ selected trace heater: 10 PSB
▪ circuit breaker amperage: 20 A
▪ required start-up temperature: -15 °C
allowable trace heater length from table below = maximum of 64 m at -15 °C on 20 A circuit breaker at 230 Vac
01-5800-7N0012/-
05/2019-EHT-432712
Design Guide for Hazloc / Industrial
DN15
DN20
DN25
1/2"
3/4"
1"
2
2
2.1
0.5
0.5
0.6
0.2
0.3
0.3
0.2
0.3
0.3
1.5
1.5
2
no. of valves
valve allowance value +
×
no. of flanges × flange allowance value +
no. of pipe supports × pipe support allowance value
= 1 × 2.1 m + 2 × 0.6 m + 6 × 0.3 m + 24 × 0.3 m
= 12.3 m
= 50 m + 1.0 m + 12.3 m
= 63.3 m
= 63.3 m calculated < 64 m maximum allowable for 20 A
= 1 circuit
Notice Technical data subject to change without notice.
No claims for damage arising from alternations, errors or misprints shall be allowed.
Table I: Allowance values and pipe support intervals
DN32
DN40
DN50
DN65
11/4"
11/2"
2"
21/2"
2.3
2.3
2.4
2.4
0.6
0.7
0.7
1
0.3
0.3
0.4
0.4
0.3
0.3
0.4
0.4
2
2.5
3.1
4
DN80
DN100
DN150
DN200
3"
4"
6"
8"
2.4
2.6
3
3.5
1
1.3
1.5
1.6
0.5
0.7
0.9
1
0.5
0.7
0.9
1
4
5
6
7
DN250
DN300
10"
12"
4
4
1.8
2
1.2
1.2
1.2
1.2
8
8
Page 16 / 46
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