PMA 17504 



Figure 10. — Tin-covered fire door sealed with plastic. Note application of coating 

 to fittings and fire-door track. 



are relatively higher than the costs of paper and mineral asphalt similarly used. 

 The application of a thinner coating and the limiting of the coating to only a few 

 large areas tend to effect economies as compared with estimates established for 

 Navy application and for specialized packaging. However, economical operation 

 should be stressed. 



In any application, therefore, it is not advisable to extend the coverage of plastic 

 beyond that point where it furnishes adequate sealing and is supported by a 

 sufficiently wide adhesive margin. Where the material is applied to the edge 

 of a fire door, for example, an effort should be made to seal only the crack between 

 the door and the surrounding door jamb. In some instances, it is desirable and 

 economical to extend the material beyond this area in order to cover hinges and 

 fastenings or where bolt holes require sealing. Figure 10 gives an example of 

 this type of application. 



The sealing of fire doors presents a safety problem. Adequate access to the 

 building that is being sealed must be maintained in accordance with regulations 

 of the local fire department. It is recognized that in many instances the doors 

 that are sealed are already blocked by the stored hogsheads. In such cases, no 

 complication will exist. 



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