APPENDIX I 



NOISES IN WATER PIPES 



IT frequently happens that when all is complete and 

 a water system is put into operation that noises 

 appear in the pipes, which give rise to nuisance and 

 are sometimes difficult to locate. Sometimes they 

 take the form of loud cracking, which points to air 

 in the service pipes, which accumulates in any raised 

 parts in those underground, and which air is periodi- 

 cally driven through the cistern ball-valves. The 

 remedy is to arrange the underground pipes so that 

 no air can be pent up inside. Continuous noises 

 are caused by water accelerating to and fro in each 

 branch service pipe by which a vacuum is formed by 

 each reflux motion inside, usually at the highest end 

 or near to the cistern ball-valve. The water flows 

 into this vacuum with such force as to knock against 

 the inside of the pipe and cause a sound similar to 

 that made by the stroke of a hammer. To remedy it 

 a small air vessel should be placed on the service pipe 

 as near to the highest ball-valve as may be con- 

 venient. 



Humming noises are caused in a variety of ways : 



(a) By the valve washer not fitting true on the seat 

 round the orifice inside the valve. 



(b) By the edges of the washer being loose and 



(159) 



