Special type of protection

In principle technical development and standardization go side by side, the latter, however, shows a certain time delay of months or even some years. So it is quite common that regulations (directives drawn up by national or international authorities, standardization) open a bypass for technical solutions which do not comply (in full or in part) with established standards. 

The marking of such s -apparatus has been (Sch)s for mining equipment and (Ex)s G... for explosion protected apparatus (suitable for zone 1 applications). In many cases, protection techniques, which are covered by their own standards today, e.g. encapsulation - m - or static pressurization (as a part of pressurization - p - ), have entered the field of explosion protection as s -apparatus [17]. 

As a next step, the directives covering the field of explosion protection within the European Community have overtaken this T)ypass regardless of Harmonized European Norms (HN), see Table 3.7. Articles 4 and 9 of Directive 82/130/EEC (for mines endangered by firedamp and/or combustible dusts) and of Directive 76/117/EEC (for areas hazardous due to combustible gases, vapours and mists) have opened the way for a control 

The ATEX 100a Directive, Directive 94/9/EC, specifies Essential Safety Requirements (ESRs) in its Annex II (see Section 3.3). 

As a general rule, explosion protected apparatus (in this book restricted to electrical apparatus) shall comply with these ESRs. 

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Cyclic vinyl ethers have been deprotonated using f-butyllithium in THF (77TL4187). The carbanions formed, which react readily with a variety of electrophiles, constitute a special type of protected acyl anion. Compound (658), available from the metallated pyran (657) and methallyl bromide, gave the /8-vinyl enone (659) on hydrolysis and cyclization (Scheme 152). 

The most widely used and best known resistance furnaces are iadirect-heat resistance furnaces or electric resistor furnaces. They are categorized by a combination of four factors batch or continuous protective atmosphere or air atmosphere method of heat transfer and operating temperature. The primary method of heat transfer ia an electric furnace is usually a function of the operating temperature range. The three methods of heat transfer are radiation, convection, and conduction. Radiation and convection apply to all of the furnaces described. Conductive heat transfer is limited to special types of furnaces. 

This special type of laboratory fume cupboard is used for the same work as a normal laboratory fume cupboard (Section 10.2.3.3). There is some evidence to suggest that auxiliary air systems are better for walk-in fume cupboards and generally result in better protection than normal fume cupboards.However, several articles have been published which point out the inherent problems with an auxiliary cupboard. ... 

In general, interior steelwork is exposed to less severe conditions than exterior, but in some chemical factories the reverse is true and here special types of paint are needed. Much structural steel is encased in concrete it is therefore hidden from view and is given some protection while the concrete remains alkaline. Where the concrete is thick, corrosion may be delayed, but as the concrete becomes carbonated and particularly if it is penetrated by acidic rain water, the metal will corrode. In general it is advisable that steel which is to be encased in concrete, especially for industrial plants, should... 

Records are considered as a special type of documents and shall therefore be identifiable and properly controlled. The system for their storage, protection, retrieval, and for their retention time and disposition is documented in written procedures. The laboratory records provide objective evidence of conformity to requirements and of the effective operation of the QMS. 

To determine product protection requirements. Forced degradation studies provide valuable information related to the type of protection (i.e., container-closure system and storage conditions) that will be necessary, not just for the API, but also for the drug product. These studies also help to determine whether or not special precautions are required during shipping. 

Only in the field of data transmission, communications, remote controlling and monitoring, has the very small energy amount, when switching electric circuits, formed a very useful basis for a special type of explosion protection, the so-called intrinsic safety as given in IEC 60079-11 and EN 50020. 

The marking of Ml equipment goes along with the principles laid down in Chapter 5, with the special marking in the case of using two independent types of protection. The outer protection is indicated first, followed by the internal protection, e.g. ... 

Type of protection (Sch)dz indicates that this flameproof enclosure has passed successfully a special type test to avoid the propagation of an explosion inside the enclosure initiated by high current fault arcs to the surrounding atmosphere. This test has been prescribed by a decree of the Supreme Authority in Mines. 

Special protection comprises all protection techniques such as powder filling, static pressurization and encapsulation (by plastics materials). At that time, these techniques started their career in the field of explosion protection and advanced to autonomous types of protection described by IEC or European Standards individually. VDE 0170/0171/1969-01 does not contain any specific requirements for these techniques. It has been the decision of the certifying body that an s -apparatus will operate at the same level of safety compared with other well-defined types of protection, e.g. flameproof enclosure d ... 

As a general rule, the access to uninsulated live parts within an apparatus shall be possible only with the aid of a tool. Some types of protection, e.g. flameproof enclosure - d and increased safety - e - require special fasteners complying with the following ... 

Where it is intended that electrical components (other than the lampholder) shall remain energized after opening of the luminaire, special precautions shall be taken, e.g. the component shall comply with a type of protection, or an internal supplementary enclosure which prevents access to the components remaining energized with an IP degree of at least IP 30 according to IEC 60529 shall be installed. 

Rated power 150 W Ballast special type Frequency of lamp current 250 kcps Marking Ex II 2G EEx ed NO T4 Type of protection EEx ed IIC T4 Certificate PTB 99 ATEX 2065 Rated voltage AC/DC 220-240 V Ingress protection code IP 54 Rated luminous flux 120001m Luminous efficiency 80lm/W Dimensions (L x W x H) 652 x 400 x 205 mm (b) Induction lamp. 

Figure 6.69 gives an example for an optical current sensor. The light path is wound around a current-carrying conductor equidirectionally with the azimuthal magnetic field of the current. The rotation of the plane of the electric vector is not detectable on its own and is converted to light intensity variations by a polarizer/analyser combination. A photo diode is used as a light intensity detector. The optical sensor itself is installed in the - e - compartment, the electronics shall be protected in an adequate type of protection, e.g. in a small flameproof - d - enclosure or in encapsulation - m -. In the special case of an energy distribution system with combined - e - and - d - compartments, the optical fibres may enter the d-compartment to the electronics inside via bushings complying with d -standards EN 50018 or IEC 60079-1 respectively (Fig. 6.70). The evacuation of the sensors into the e-compart-ment results in additional available space in the more expensive d-compart-ment, compared with increased safety - e -. ...

Requirements are given in EN 50014 as well as in IEC 60079-0 General requirements, covering all types of protection. Plugs and sockets shall be mechanically or electrically (or otherwise) interlocked to avoid disconnection when energized, or shall be fixed together by special fasteners and additionally be marked with a warning label DO NOT SEPARATE WHEN... 

Classification and marking of intrinsically safe apparatus concerning explosion groups (I, IIA, IIB, IIC) and temperature classes (T1-T6) are organized in the same way as for, e.g., flameproof enclosure - d (see Tables 4.1 and 4.2, Chapter 4, and Chapter 5 for marking). Some special features, however, which are of importance for type of protection intrinsic safety - i only, will be explained in the following. 

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