Sanitation of Buildings

Another type of grease trap operates by means of a syphon, the grease on the water surface being broken up by a flush, but it is generally found unsatisfactory. Traps are always placed under all sanitary fittings and are of the P or S type.

In American plumbing practice every plumbing fixture includ ing baths, shower receptors, water closets, urinals, lavatories, or wash basins, sinks, laundry tubs, floor-drains, area-drains, r o o f water-leaders and every fixture or fitting that discharges into a house drainage system must be properly and effectively trapped as close to the fixture or fitting as conditions will permit. These traps are of a variety of forms such as P. S. bottles, pot or drum, etc. All have water seals. Some are provided with check valves to prevent a back-flow of sewage through them. None, however, are permitted which depend upon mechanical contrivances as a substitute for a water seal. The water seal may, however, be augmented by a float, a check valve or other contrivance which will automatically close against back pressure. This protects the house against a backing-up of sewage as from a choked or flooded street sewer.

All fixture traps within a building must be protected against loss of seal by syphonage or air compression. The seal must re main intact to prevent sewer gas from entering the building through the traps. This trap protection is accomplished by the installation of special arrangements of vent piping which opens to the outer air and maintains the air pressure back of the trap seals practically at atmosphere.

Antisyphonage.—Since every sanitary fixture in a building must be trapped, possibilities might arise in which the seals of such traps would be broken by either increase or decrease of the air pressure unless provided against. Such cases would occur where a range of fixtures were connected to one soil or waste pipe and hence an antisyphonage or vent pipe is always provided. If no ventilating branches were provided it might be possible for a fitting on an upper floor to syphon out the water in the trap I of the fittings below by reducing the air pressure in the branch.

Unsealing could also happen through the discharge of the upper fitting compressing the air in a branch below and so forcing the seal of a trap below. While such

possibilities are not nowadays considered of such importance as formerly, the antisyphonage pipes are always fitted, as they form a convenient method of ventilating the branches. Each antisyphonage pipe connects the head of the trap to a ventilat ing stack which may be car ried up above the eaves of the house, or may be connected into the soil pipe above the high est branch. Such soil pipe has, in any case, to be continued full bore either well above the eaves, or to such a position that the gases let free cannot cause a nuisance or enter the house by means of chimneys, skylights, windows or other openings. The open ends of soil pipes, and any other pipes used as ventilators, are best covered by a wire cage to prevent their being used by birds for nesting purposes.

Water Closets.

Of the sanitary fittings or fixtures usually found in buildings, the water closet is of the most importance. The "wash-down" and syphon closets are now practically the standard types, being simple, self-cleansing, reasonably quiet and Companies insist that their discharge shall be limited to a speci fied amount at each use. Two gallons is usually allowed, but three would be better, and unfortunately as little as one and a half gallons is often found. The cistern should be placed not less than five feet above the fitting flushed and connected to the latter by a i inch diameter pipe, so as to give a good rush of water. An overflow must be placed below the inlet and should discharge direct into the open air, so as to give warning of irregular working of the valve. Similar cisterns are also made to discharge auto matically at chosen intervals and so flush such fittings as ranges• of urinals and closets. It is compulsory for such cisterns, whether automatic or otherwise, to be fitted to all apparatus receiving human excreta, so that there shall be no possibility of contamina tion of the rest of the water in the building. As regards the regu lations in force for house drainage, reference should be made to the local by-laws, as these vary in detail in the different towns.