An integral component in the construction of an explosive facility or structure is lightning protection. But what if a taller building is located nearby such an object?
In this case, this building is used as a natural lightning rod. A request was received by ZANDZ Technical Center for the calculation of lightning protection systems for a warehouse for diesel fuel storage in the city of Samara.
The measures were performed in accordance with:
- EIC 7-th ed.;
- IS 153-34.21.122-2003 «Instruction to lightning protection of buildings, structures and industrial communications» (hereinafter IS);
- AD 34.21.122-87 «Instruction on arrangement of lightning protection for buildings and structures» (hereinafter AD).
Warehouse refers to the “special, representing a danger to the immediate environment”, in accordance with the IS and to the 2nd category, according to AD.
Source data:
- object: diesel fuel storage warehouse;
- location region: city of Samara;
- measures of the protected object: 1,05х2,05х2,5 m;
- tank material – profiled sheet not less than 1 mm thick;
- there is a garage 5,3 m from the object, it is 7,87 m high;
- soil resistivity – 150 Ohm*m.
The set of measures to ensure the necessary requirements for a lightning protection system for a warehouse for diesel fuel storage is presented by the following solutions:
- installation of a vertical air terminal mast with a height of 1.5 m (GL-21134) to the facade of the container on one side, on the opposite side a garage building is used as an air terminal (natural) (see Fig. 1);
- installation of a grounding device, according to AD, p.2.2g., consisting of 3 vertical electrodes 3 m long, united by a horizontal electrode (copper-bonded tape 30x4 mm) along the contour of the warehouse. The distance from the horizontal electrode to the object is at least 1 m, burial depth is 0.5 - 0.7 meters.
Calculation of the resistance of the grounding device:
Vertical electrode resistance:
where ρэкв – equivalent soil resistivity - 150 Ohm·m;
L – vertical electrode length - 3 m;
d – vertical electrode diameter - 0,014 m;
T – deepening – distance from the ground surface to the ground electrode – 2 m;
where t – deepening of the electrode top - 0,5 m
Horizontal electrode resistance:
where ρ – soil resistivity - 150 Ohm·m;
b – horizontal electrode width - 0,03 m;
h – horizontal electrode laying depth - 0,5 m;
Lгор – horizontal electrode length - 14 m.
Grounding device impedance:
where n – number of kits, vertical ground electrodes - 3 pc, horizontal electrode – 1 pc. ;
Kисп – utilization ratio, 0,65;
The rated resistance of the grounding device is 13.26 ohms.
The results of the calculation of the protection zone in accordance with IS:
Air-terminal mast №1 (GL-21134):
h = 3,7 m;
Height of the cone according to IS table 3.4:
Radius of the cone according to IS table 3.4:
Air-terminal mast №2 (Garage):
h = 7,87 м;
The height of the cone according to IS table 3.4:
The radius of the cone according to IS table 3.4:
The distance between the lightning rods:
L = 7,35 м;
Ultimate distance between the lightning rods, according to IS, table.3.6 (we take the height of the lowest lightning rod):
There is no dip height.
The equipment location and protection zone are shown in Figure 1.
The list of equipment and necessary materials is given in table 1.
- Молниеприемник-мачта высотой 1, 5 м – Air-terminal mast 1,5 m high
- Проволока омедненная стальная диаметров 8 мм – Copper-bonded steel tape 8 mm in diameter
- Полоса омедненная стальная сечением 30*4 мм – Copper-bonded steel tape with the cross-section of 30*4 mm
- Электрод - Electrode
Figure 1 – Equipment location.
Table 1 – List of material needs.
|
№ |
Picture |
Product item |
Name |
Quantity, pieces |
|
1. |
|
GL-21134 |
GALMAR Air-terminal mast (1,5 meters: for vertical surfaces: galvanized steel) |
1 |
|
2. |
|
GL-11149-10 |
GALMAR Copper-bonded tape (D 8 мм / S 50 мм²; coil of 10 meters) |
1 |
|
3. |
|
GL-11704A |
GALMAR Clamp to the façade for down conductor (painted galvanized steel) |
3 |
|
4. |
|
ZZ-001-065 |
6 |
|
|
5. |
|
ZZ-002-061 |
4 |
|
|
6. |
|
ZZ-003-061 |
3 |
|
|
7. |
|
ZZ-004-060 |
2 |
|
|
8. |
|
ZZ-006-000 |
1 |
|
|
9. |
|
ZZ-008-000 |
1 |
|
|
10. |
|
ZZ-005-064 |
5 |
|
|
11. |
|
ZZ-007-030 |
2 |
|
|
12. |
|
GL-11075-20 |
GALMAR Copper-bonded tape (30*4 mm / S 120 mm²; coil of 20 meters) |
1 |
Do you have questions on grounding and lightning protection of a warehouse for storing diesel fuel? Contact ZANDZ Technical Center!
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