Types of ladders

Fixed ladders have specific requirements based on OSHA regulation 1910.27. Among the basic recommendations in this standard are the following  

Portable ladder injuries usually result from faulty care or improper use of ladders and not from manufacturers deficiencies. Some of the most frequent causes of ladder incidents include using a broken ladder, improper climbing procedure, improperly securing the ladder, and selecting the wrong ladder for the task at hand. 

All wood parts must be free of splinters and sharp edges. Portable wood ladders are identified in OSHA 1910.25. 

Only heavy-duty industrial ladders should be used. 

Always place the ladder in such a way that reaching or extending the body is not required. 

---

Figure 2.4.3 Various types of ladder structures (I1-I9) found in [(R2Sn02CR )20]2 (see Table 2.4.1 for specific examples)...

A nonprofit association founded in 1947, dedicated to promoting safe ladder use. It is comprised of members from the United States and Canada who are ladder manufacturers and manufacturers of ladder components. The ALI is the American National Standards Institute (ANSI)-approved developer of ladder safety standards, which govern the construction, design, testing, care, and use of the various types of ladders. See also Ladder Safety. 

Types There are many types of ladders. They are classified by material of construction (wood, metal), load capacity, function and design. Some ladders are classified as type I, II, or in, depending on the standard loads (200,225, and 250 lb) used for certain tests. Most ladders are manufactured and sold for use. However, some ladders are job-made ladders, assembled at job sites. Ladders can be portable or fixed in place. Common types of portable ladders are step, platform, straight and extension ladders. Multipurpose ladders adjust to serve as several single-purpose ladders. Some ladders, such as those on truck trailers, have custom designs to fit around other design elements. There are many standards for ladder construction. 

Regardless of the type of ladder you use, you risk a fall if the ladder is not safely positioned. It needs to be set on stable, level ground to keep it from slipping or moving. You can lose your balance by simply getting on or off an unsteady ladder. 

There is no means of designing or operating to a calculated level of risk. Even if it could be shown that the use of a different type of ladder is of very low risk, for example, the OSHA rule has to be followed. 

Knowing the types of ladders is the first step for proper selection. There are basically three types of ladders slepladders, single ladders, and extension ladders. 

Another type of ladder polymer consists of a combination of poly(perinaphthalene) and polyacene (Fig. 40). The resulting structure is reminiscent of the open-chain analog of the belt region of Cgo [687]. More soluble oligomers have also been prepared for these materials [688,689]. 

See v hether an alternative means of access is more suitable. Take into account the nature of v/ork and duration, the height to be worked at, what reaching movements may be required, what equipment and materials may be required at height, the angle of placement and the foot room behind rungs, and the construction and type of ladder. 

Surprisingly, if a solution of the polyalcohol was treated with boron trifluoride etherate in, e.g., dichloro-methane or chloroform, the ring closure to give the ladder polymer took place within seconds and was quantitative. The resulting new type of ladder polymer, a planar methylene-bridged poly(p-phenylene), is deep yellow, and solutions thereof display an extremely intense blue photoluminescence. 

Recently, the synthesis of a similar type of ladder polysilox-anes described in Reference 102 was reported, but hydroquinone groups were changed to 9,10-diphenylanthryl groups. 

The product from acrylonitrile will withstand a bunsen flame in the open air and is the basis of one type of carbon fibre. None of the polymers produced by this route have a high degree of perfection in their ladder structure. 

In Figure 9-5 the worker is ascending a caged ladder. Notice that the worker s air pack, airline or apparatus could become entangled with the ladder protection. The worker in Figure 9-6 who is using absorbent to soak up a mock spill has no encumbrances pictured near the work area. So, besides the proper level of protection, the type of work being performed and the work area can be important. 

The airflow rate does not interfere with the building or the building materials, and usually not with the process. The air distribution may vary a lot, however, if the building and process layout and sometimes the building materials are not chosen with great care. Lamps, ladders, window shutters, cabins, process equipment, etc. are often placed where the ventilation designer did not expect any obstructions. Thus continuous cooperation between the different designers is necessary to prevent mistakes and to facilitate common solutions to this type of problem (see Chapter 8). 

Figure 9-2. Based on ihe conjugated backbone of a /H/ra-phenylcne the most common principle structures of conjugated molecules am described (a) the pure backbone (b) a backbone with attached side-groups R and R (e) a ladder type-eonjugaled backbone (d) and (c) represent different types of copolymers. where (d) represents a side cliain-gnill copolymer and (c) a single eliain-bloek copolymer.

Fig. 4.7 Five different types of PNA-dsDNA complexes. DNA is shown schematically as a ladder, and the PNA oligomers are shown in bold...

The "unfolded-drum" or "ladder" compound 2 has crystallographic symmetry. This corresponds to the idealized molecular symmetry and, therefore, there are three chemically inequivalent types of Sn atoms in the molecule, although all are hexacoordinated. The oxygen atoms in the open form can be subdivided into two types, as in the case of the drum molecule tricoordinate framework oxygen atoms and the dicoordinate oxygen atoms of the bridging carboxylate ligands. 

A similar investigation of the base adducts of K(PBu Ph) shows that [ KfPBuTh fTHF)], (34), [ K(PButPh) 2(AT-MeIm)]I (35), and I K(PBu Ph ) 2(py) lx (36) also adopt extended polymeric ladder structures in the solid state (74). These adducts resemble the Rb and Cs complexes 28—33 however, the base coligands in 34—36 do not bridge the potassium atoms but are bound in a terminal fashion. In each case there are two types of potassium atom in alternate positions... 

---