A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire trucks. There are two general types: pneumatic and electronic.
Many fire sirens (used for calling the volunteer fire fighters) serve double duty as tornado or civil defense sirens, alerting an entire community of impending danger. Most fire
sirens are either mounted on the roof of a fire station or on a pole
next to the fire station. Fire sirens can also be mounted on or near
government buildings, on tall structures such as water towers,
as well as in systems where several sirens are distributed around a
town for better sound coverage. Most fire sirens are single tone and
mechanically driven by electric motors with a rotor attached to the
shaft. Some newer sirens are electronically driven speakers.
Fire sirens are often called "fire whistles", "fire alarms", or
"fire horns". Although there is no standard signaling of fire sirens,
some utilize codes to inform firefighters of the location of the fire.
Civil defense sirens also used as fire sirens often can produce an
alternating "hi-lo" signal (similar to emergency vehicles in many
European countries) as the fire signal, or a slow wail (typically 3x) as
to not confuse the public with the standard civil defense signals of
alert (steady tone) and attack (fast wavering tone). Fire sirens are
often tested once a day at noon and are also called "noon sirens" or
"noon whistles".
The first emergency vehicles relied on a bell. Then in the 70s,
they switched to a duotone airhorn. Then in the 80s, that was overtaken
by an electronic wail.
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This photo refers to our 1000KV 10GB-SZ1 DC tangent and EHV transmission tube tower, it is widely used in our Chinese market. Some of technical features of this tower as follow:
1 climate condition
Item
Temperature (ºC)
Wind speed (m/s)
Ice thickness (mm)
Max. temperature
40
0
0
Mini. temperature
-20
0
0
Ice thickness
-5
10
10
Basic wind speed
-5
30
0
Installation condition
-5
10
0
Annual temperature
15
0
0
Lightning overvoltage
15
10
0
Operation overvoltage
15
16
0
Item
Conductor
OPGW
JGJ-630/45
JLB20A-240
construction
AL
45×4.2
Â
Steel(Al wrap steel )
7×2.8
19×4.0
Cross-section
(mm2)
Al
666.55
238.76
Steel
33.60
20
Total
2.060
1.5955
Diameter
148700
260010
Length mass (kg/km)
0.04633
0.36.1
Elastic module (MPa)
63000
147200
coefficient of linear expansion (1/ºC)
20.9×10-6
13.0×10-6
Tower
type
Nominal
Height
Scope (mm)
Horizontal
span
(m)
Vertical
Span
(m)
Angle
º
Nominal height tower weight Kg
1000KV 10GB-SZ1
135.82-156.66
430
550
0
48-60
Power
voltage
1000KV 10GB-SZ1
Conductor
type
8×JGJ-630/45
Max. operation Tension force (KN/phase)
56503
Un-balance Stress value(%)
10
OPGW
Type
JLB20A-240
Max. operation
Tension force
(KN/pc)
92859
Un-balance Stress value(%)
25
Â
Item
Â
Horizontal
span
(m)
Vertical
Span
(m)
Representative
Span (m)
Angle
º
Height
(m)
KV
Â
data
690
480-780
400
0
69
0.8
Site condition
Normal operation condition
Non-uniform
Ice condition
Broken
Installation
condition
Basic wind speed
Ice
Mini.
temperature
Climate condition
(t/v/b)
-5/30/0
-5/10/10
-15/0/0
5/0/10
-5/0/10
-10/10/0
Horizontal loading
conductor
98422
24724
0
0
0
12096
Insulator
Power fitting
4435
493
0
0
0
493
Jump & string
---
---
---
---
---
---
OPGW
9481
4150
0
0
0
1170
Vertical loading
 conductor
127489
176459
127489
176459
176459
244544
Insulator
Power fitting
2500
3000
2500
2500
2500
2500
Jump & string
---
--
--
--
--
--
OPGW
13602
20299Siren and Alarm
Megatro 1000kv 10GB-Sz1 DC Tangent and Ehv Transmission Tube Tower
Model NO.: MGP-1000KV-10GB-SZ1
Structure: According to Client Requirements
Design Software: Pls
Accessories 1: Power Fitting
Accessories 2: Conductor and Cable
Accessories 3: Earth Wire and Opgw
Accessories 4: Tower Foundation and Design
Accessories 5: Tower Earthing Kits and Lightning Rod
Accessories 6: Aviation Light
Accessories 7: Insulator
Accessories 8: Anchor Bolts and Templates
Accessories: Opgw and Cable
Trademark: MEGATRO
Transport Package: Export Standard Package
Specification: As per client requirements
Origin: Shandong, China
HS Code: 73082000
Model NO.: MGP-1000KV-10GB-SZ1
Structure: According to Client Requirements
Design Software: Pls
Accessories 1: Power Fitting
Accessories 2: Conductor and Cable
Accessories 3: Earth Wire and Opgw
Accessories 4: Tower Foundation and Design
Accessories 5: Tower Earthing Kits and Lightning Rod
Accessories 6: Aviation Light
Accessories 7: Insulator
Accessories 8: Anchor Bolts and Templates
Accessories: Opgw and Cable
Trademark: MEGATRO
Transport Package: Export Standard Package
Specification: As per client requirements
Origin: Shandong, China
HS Code: 73082000
MEGATRO 1000KV 10GB-SZ1 DC tangent and EHV transmission tube tower