Anti-Siphonage Traps

Cast-lead traps of various kinds are now made for the express purpose of preventing siphonage in the case of single fittings. Smeaton’s “Eclipse” trap (Figure 2) has served as the model from which later designs have been produced. It has a round dip-pipe and the body is designed to give a considerable area of standing water on the outlet side of the trap and a volume of air in the angle above this water. The concealed dip-pipe is objectionable. In Hellyer’s “Anti-D” trap (Figure 3) the chief peculiarity is the square outgo. It has the same angular air-space above the standing water as the “Eclipse” t rap, but differs from the latter in having two thicknesses of lead between this air-space and the inlet-pipe. The size marked A has a 4 1/4-in. inlet and a 3-in. outlet, and is intended chiefly for valve-closets and slop sinks; B has a 3 1/2-in. inlet and 2 1/8-in. outlet, the depth below the dip being 2 in., and is intended for large sinks and baths; C is a lavatory trap and has a 1 1/4-in. inlet and outlet; D is similar to C, but with the inlet enlarged to 2 1/2 in. and is suitable for lavatories and small sinks and baths. A is of metal equal to 8-lb. lead, and B, C, and D, 9-lb.; the three latter are made with cleansing screws, if required. The depth of seal is in every case about 1 3/4 in., and even the largest trap holds only 2 1/2 pints of water, or less than one-sixth of the quantity generally allowed for flushing a water-closet.

Figure 1: Hand-made Trap.

 

Figure 2: Smeaton’s “Eclipse” Trap.

4 1/4-in. inlet and a 3-in. outlet, and is intended chiefly for valve-closets and slop sinks; B has a 3 1/2-in. inlet and 2 1/8-in. outlet, the depth below the dip being 2 in., and is intended for large sinks and baths; C is a lavatory trap and has a 1 1/4-in. inlet and outlet; D is similar to C, but with the inlet enlarged to 2 1/2 in. and is suitable for lavatories and small sinks and baths. A is of metal equal to 8-lb. lead, and B, C, and D, 9-lb.; the three latter are made with cleansing screws, if required. The depth of seal is in every case about 1 3/4 in., and even the largest trap holds only 2 1/2 pints of water, or less than one-sixth of the quantity generally allowed for flushing a water-closet.

Figure 3: Hellyer’s “Anti-D” Traps.

 

McAlphine trap – this has a reserve chamber into which water is retained as siphonage occurs. after siphonage the retained water descends to reseal trap.



 

Anti-Siphon trap – as siphonage commences, a valve on the outlet crown opens allowing air to enter. this maintains normal pressure during water discharge, preventing loss of water seal.

 

 


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s