50 CONSTRUCTION AND MANAGEMENT OF SMALL GASWORKS. 



not too heavy a tax on the energies of the man in charge, 

 who has a considerable amount of idle time on hand. 

 The quantity of gas required to drive the engine will not 

 exceed i to 2 per cent, on the make, and the additional 

 yield of gas secured by it will be 5 to 10 per cent., so 

 there is ample margin for earning a good interest on the 

 outlay. The engine will also drive a small pump for the 

 scrubber. 



The connecting pipes throughout, from retorts to gas- 

 holder, should be ample, but not necessarily excessive in 

 size. Large pipes leave more room for accumulation of 

 pitch before a stoppage takes place, but they do not secure 

 immunity from such trouble. In fact, pipes, and especially 

 seal traps, that are too large for the work are more apt to 

 choke, because the liquids move more slowly through them. 

 The pipes should be in straight runs, with cleaning doors at 

 each end, and should be readily accessible at all parts. 

 Every bend or curve that is avoided is not only an 

 assistance towards the comfort of the man in charge, but 

 improves the efficiency of the plant. The importance of 

 easy access to all cleaning doors is evident when we 

 remember that there is only one man in charge, and in the 

 event of stoppage he does not want to lose an hour or more 

 in excavating to strip the pipes. If the pipes must of neces- 

 sity be underground, pits with flap covers can be provided 

 where necessary. And these remarks also apply to the 

 pipes leading from the seal traps to the tar well. It is 

 possible to so arrange the seal traps that they can be cleared 

 out without interfering with the make of gas. 



A thorough wash-out every summer is a great help towards 

 getting through the winter without trouble ; and sometimes 

 the design is blamed for negligence in this respect. In 

 the course of a few years' working, pitchy matters are bound 



