1、 Explosion proof special type's'
It refers to the use of special designs, evaluations, and tests to achieve the required level of protection for explosion-proof types when equipment cannot be fully evaluated according to existing explosion-proof types or combinations of explosion-proof types due to functional or usage limitations.
Specially designed explosion-proof type for explosive gas and dust environments.
2、 Design of explosion-proof special type's'
When designing products, special type "s" is allowed when it cannot fully comply with existing explosion-proof types, or when the following operating conditions are not included in the existing explosion-proof type standards:
1. Exceeding the normal atmospheric pressure given in GB/T 3836;
2. Exceeding normal oxygen content;
3. Exceeding the environmental temperature range specified in GB/T 3836;
4. Mixed substances (gases and dust).
3、 The protection level of explosion-proof special type "s" electrical equipment is divided into:
Sa "protection level (EPL" Ma, Ga, Da "); or
SB "protection level CEPL" Mb, Gb, Db "); or
SC "protection level (EPL" Gc, Dc ").
4、 Independent inspection agency
Due to the characteristics of the special type "s" itself, the testing and evaluation of the special type "s" are not determined as they are for other explosion-proof types. A lot of communication is needed between manufacturers and independent inspection agencies. To ensure that the corresponding protection level is achieved, independent inspection agencies may require additional tests.
An independent inspection agency refers to an organization that has the ability to apply explosion-proof technology, is responsible for verifying design calculations, evaluations, and tests, and is independent in terms of management, finance, and other resources. It is different from organizations engaged in all related activities such as equipment design, manufacturing, or sales.
5、 Explosion proof special type "s" may be used in the following situations
1. The equipment basically meets the requirements of one or more existing explosion-proof type standards, but does not meet the existing explosion-proof type standards in one aspect, but can be handled in other ways;
For example, the type of explosion-proof joint surface shall not exceed the existing standard range;
For example, the qualification requirements or testing requirements for the high voltage standard of the sealed type.
2. The equipment meets the requirements of existing explosion-proof type standards, but the parameters exceed the existing standard range;
For example, The increased safety motor of 15 kV exceeds the voltage range specified by Zhongnuo's testing standards;
For example, gas detectors that need to be used in oxygen rich environments.
3. The method (technology) used by the equipment does not meet the requirements of existing GB/T 3836;
The equipment meets one or more explosion-proof type standards, but typically requires a higher EPL protection level.
6、 Explosion proof special type's' inspection standard
GB-T 3836.24-2017 Explosive atmospheres Part 24: Equipment protected by special type "s"
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