15 lights, 30 lights, and 60 lights refer to the number of LED components welded per meter length of the LED strip. Generally speaking, the 1210 specification strip has 60 LEDs per meter, and the 5050 specification strip has 30 LEDs per meter. Special There are 60 LEDs per meter. The price of LED strips with different LED quantities is different, which is also an important factor in distinguishing the price of LED strips. Concentrating Ball Head,Lamp Beads 2835,Hlight Warm White Glow,Light Emitting Diode 2835 Dongguan XINYUDA Technology Co., Ltd. , https://www.gdxige.com
Color temperature
It refers to heating a standard black body. When the temperature rises to a certain level, the color starts to change from dark red-light red-orange-white-blue. When the color of a certain light source is the same as that of the black body, we call the absolute temperature of the black body at that time Is the color temperature of the light source.
Generally speaking, color temperature is not used as an indicator for evaluating LED strips, but many foreign customers will make a special requirement due to the use environment.
The color temperature of the light source is different, and the light color is also different:
The color temperature is below 3300K, and the light color is reddish to give a warm feeling; it has a stable atmosphere and a warm feeling. It is commonly known as warm color temperature.
The color temperature is in the middle of 3000-6000K, and people have no obvious visual psychological effect under this color, and there is a refreshing feeling; therefore, it is called "neutral" color temperature
The color temperature exceeds 6000K, and the light color is bluish, giving people a cool feeling, commonly known as cool color temperature.
Explosion-proof knowledge
I. Division of hazardous areas
The meaning of a hazardous area is a measure of the possibility of actual danger in the area, thereby specifying the applicable explosion protection type. The explosion-proof zone divided by the International Electrotechnical Commission/European Electrotechnical Commission is:
Zone 0: There is an area of ​​continuous danger greater than 1000 hours/year;
Zone 1: Areas where there is an intermittent risk of 10 to 1000 hours/year;
Zone 2: The area where the risk exists in the state of accident 0.1 to 10 hours/year;
The effective area divided by China is the same as above.
Second, analysis of explosion-proof signs
1 gas group
typical
Dangerous
Gas European Electrician
Standardization Committee
EN50014EC North America
NEC500 clause
CLASS1 Gas China
GB-3836-1 Minimum ignition energy
(micro-focus)
Acetylene IIC A IIC 20
Hydrogen IIC A IIC 20
Ethylene IIB C IIB 60
Propane IIA D IIA 180
Note: The Chinese GB3836 standard stipulates that the minimum ignition energy of Class IIC is 19 microjoules and the minimum ignition energy of IIA is 200 microjoules.
The gas grouping and ignition temperature are related to the mixed concentration of flammable gas and air under certain ambient temperature and pressure.
2 temperature group (T group)
This is the highest surface temperature of the electrical equipment associated with the gas ignition temperature (assuming an ambient temperature of 40°C), regardless of the ignition temperature. All flammable gases and their groups are listed in Part 1 of Standard BS5345.
Maximum surface temperature (°C) Temperature group
IEC79-8 GB3836-1
450°C T1 T1
300°C T2 T2
200°C T3 T3
135°C T4 T4
100°C T5 T5
85°C T6 T6
3 explosion-proof signs
The following takes the CENELEC hydrogen explosion-proof mark as an example: E Ex ia IIC T4
E: approved by the CENELEC mark; Ex: explosion-proof public signs
Ia: Explosion-proof type (intrinsically safe); II: Equipment group
C: gas group; T4: temperature group
4 Glossary
Flameproof electrical equipment (d): An electrical device that encloses a component capable of igniting explosive mixtures in an enclosure that can withstand the explosion pressure of the internal explosive mixture and prevent the propagation of explosive mixtures with the surrounding explosive mixture.
Increased Safety Electrical Equipment (e): Under normal operating conditions, sparks or dangerous temperatures that ignite the explosive mixture will not be generated, and measures will be taken to improve the safety of the structure to avoid ignition under normal and specified overload conditions. Electrical equipment.
Intrinsically safe electrical equipment (i): Electrical equipment that does not ignite an explosive mixture under normal operating conditions or under standard test conditions.
Non-spark type electrical equipment (n): Under normal operating conditions no arcs or sparks are generated, no hot surfaces or burning hot spots capable of igniting the surrounding explosive mixture are generated, and electrical equipment with ignitable faults does not generally occur.
Explosion-proof special type (s): When electrical equipment or components use explosion-proof type not included in GB3836-83, the competent department shall formulate provisional regulations. Send it to the Ministry of Labor and Personnel for record, and after inspection by a designated appraisal unit, dispose of it according to the special electrical equipment "s" type.
Third, explosion-proof standards and selection
1 Corresponding standard of various explosion-proof types
Explosion-proof type allowed in the UK
Place of Use China Standard
GB3836 explosion-proof type
Symbol IEC standard
79-CENELEC Standard
EN50
Increased Safety 1 or 2 3 e 7 019
Intrinsically safe 0,1 or 2 4 ia or ib 11 020 (equipment)
Flameproof d 2 d 1 018
Special type s No s No No
2 Types of Explosion Protection Types for Electrical Equipment Used in Gas Explosion Hazardous Locations
Protection type applicable to explosion hazardous areas
Electrical equipment type symbol
Zone 0, intrinsically safe (ia) ia
2. Other electrical equipment specially designed for zone 0 (special type) s
1, suitable for type 0 protection
2, explosion-proof type d
3, increased safety e
Zone 1, intrinsically safe ib
5, oil-filled o
6, positive pressure type p
7, sand filling q
Zone 2 1 Type of protection applicable to zone 0 or zone 1
2, no spark type n
Fourth, the shell protection class (IP) code
(BS EN60529;1992)
The first characteristic number prevents foreign matter from entering the fixed conductor
0 No protection
1 Fixed foreign body diameter greater than 50mm
2 Fixed foreign body diameter greater than 12mm
3 Fixed foreign body diameter greater than 2.5mm
4 fixed foreign body diameter greater than 1.0mm
5 Dust prevention
6 dust-tight
Second feature number prevents harmful effects of water ingress
0 No protection
1 Vertical drip
2 Dip 75-90°
3 watering
4 Splashing water
5 Water Spray
6 Violent water spray
7 Invasion of water for a short time
8 continuous influx
Example: IP 65 requires dust and water protection
V. Flammable gas
The lower explosion limit of a flammable gas is the lowest concentration that can cause an explosion in the air, that is, the LOW EXPLOSION-LEVEL (LEL). The upper explosion limit is the highest concentration (UEL) that can cause an explosion in the air. The flammable gas detection range is usually 0-100% LEL or 0-100% VOL, which means the threshold or percent volume before reaching its lower explosive limit. The following table lists the explosion limit parameters of some common flammable gases.
Six, poison gas / oxygen
Toxic gases in the atmosphere at concentrations of one part per million can cause vomiting, coma, or even death in humans. The unit for detecting toxic gases is in parts per million, that is, ppm, lppm = 1 x 10-6 m3. Conversion formula for ppm and mg/m3 (mg/m3): ppm = 22.4 x mg/m3/molecular weight The following table lists some common toxic gas detection parameters:
VII. Ensure that the oxygen content is at a safe level
In the atmosphere, the oxygen content is usually 20.9%. Without ventilation equipment, the oxygen content will be drastically reduced by the breathing and burning of personnel. Some gases will also replace oxygen, such as carbon dioxide and nitrogen. When the oxygen content dropped to 17%, humans began to feel difficulty in moving. If they were reduced by 2-3% or more, they would soon lead to suffocation. Hypoxia causes more damage than other types of dangerous gases. Because people often overlook its harmfulness. When the oxygen content rises, the possibility of burning of some flammable substances will increase sharply. If the oxygen concentration reaches 24%, even a material like cloth, a little dark flame can cause a great deal of trouble. So be sure to check the oxygen in the air to a safe level.
Note: The alarm point of all testing instruments is generally set to (take the international low line):
Gas-fired primary alarm: 20%-25% LEL of full scale
Fuel gas secondary alarm: 40%-60% LEL of full scale
Gas three-level alarm: 80%-100% LEL of full scale
Toxic gas alarm: 20%-25% ppm of full scale
Poison gas secondary alarm: 40%-60% ppm of full scale
Low oxygen level alarm: 19.5% of the air content
Secondary oxygen alarm: 17% of air content
Oxygen high alarm: 23.5% of the air content
Eight, CROWCON toxic and harmful gas range
Gas Type Molecular Formula Standard Range
(ppm) Special Range
(ppm) *Intrinsically safe
Probe model
O2 0-25%VOL - Txgard-IS/OX
Hydrogen (low) H2 0-2000 - Txgard-IS/H/Lo
Hydrogen (High) H2 0-50%LEL - Txgard-IS/H/Hi
Carbon Monoxide CO 0-250 0-2000 Txgard-IS/CO
Hydrogen Sulfide H2S 0-25 0-1000 Txgard-IS/HS
Sulfur dioxide SO2 0-10 0-500 Txgard-IS/SO
Chlorine CL2 0-5 0-20 Txgard-IS/CL
Nitric Oxide NO 0-100 0-500 Txgard-IS/NO
Nitric Oxide NO2 0-10 0-100 Txgard-IS/ND
Acid CH2CHC 0-10 0-100 Txgard-IS/NX
HCN 0-25 0-100 Txgard-IS/HCN
Ammonia NH3 0-100 0-500 Txgard-IS/AM
HCL 0-10 0-100 Txgard-IS/HCL
Ozone O3 0-1 - Txgard-IS/OZ
Organic Volatile - 0-100 - Txgard-IS/VP
Ethylene Oxide (CH2) 2O 0-10 - Txgard-IS/ETO
Phosphine PH3 0-1 - Txgard-IS/HP
Hydrogen fluoride HF 0-10 - Txgard-IS/HF
Fluorine F 0-3 - Txgard-IS/F
Benzene C6H6 0-100 - Txgard-IS/VO
COCL2 0-5 - Txgard-IS/COCL
* The range of explosion-proof and field-displayed poison gas detection probes and so on.
Industrially, a series of proven methods have been developed for installation of gas detection probes through installation experiments at different locations. CROWCON can provide users with help to ensure that the fixed gas detection device works after installation.
Nine, the basic principles of installing a fixed gas detection device:
1. The installation location can monitor various locations on the site or where there are hidden dangers.
2. The monitoring system can issue an early on-site alarm and indicate the location of the gas leak in order to start the following work:
1 Evacuation of personnel in hazardous locations
2 Seek and eliminate leak sources
3 Power failure of production line or factory equipment
4 Turn on ventilation equipment
The gas detection probe should be installed as close to the original hazard as possible. Since wind and wind direction affect the detection effect, gas signals should be collected comprehensively and extensively.
The installation position of the gas detection probe must take into account the mounting height.
In general, the gas density is less than air, and the position of the probe should be above the area where leakage may occur; for example, if the gas density is greater than air
Gas, probes should be installed in the ground, tunnels or trenches; and gas with a similar density of air, easy to flow with the air due to airflow and ventilation equipment and other factors. In this case, the probe placement height should be as close as possible to the on-site personnel's work space (breathing area).
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