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→Vented Loops (Siphon Breaks)
The valve is one-way, drawing air into the line but preventing water or sewage from escaping. Larger valves are less susceptible to clogging. Siphon breaks are typically made of cast bronze or glass-reinforced plastic, which is not affected by corrosion.
== Deck Fittings ==
The USA federal standard for a deck fitting for pump out is 1.5-in (38mm) inside diameter pipe thread. The plug should be clearly and permanently labelled "Waste". Consider a black plug for waste, a white plug for water and an orange plug for diesel.
== Through Hulls ==
Toilet intake and overboard discharge lines should be equipped with sea cocks (valves) to stop the inflow of seawater in the event of a hose failure. Sea cocks have a lever-type handle that clearly shows whether it is open or closed. All sea cocks should be located with easy access, and oriented so that the open position is vertical.
Sea cocks and through-hulls are made of bronze or glass reinforced plastic. Both can be used successfully for toilet intake or overboard discharge lines. Bronze sea cocks and both bronze and glass reinforced plastic ball valves may be used for toilet intake or overboard discharge lines. It’s generally a good idea, however, to fit plastic valves on reinforced plastic through-hulls. Either glass reinforced plastic or bronze valves may be fitted to a bronze through-hull.
The use of gate valves, which are made of brass, should be avoided because they corrode rapidly and their stems tend to break.
== Piping/Hoses ==
There is some disagreement about the type of conduit to use for plumbing. Many government marine web sites recommend rigid plastic PVC pipe. It is highly impermeable and will not corrode. It is easy to cut and install. Chief disadvantage is that it is rigid and susceptible to damage from flexing. If you use rigid pipe, use Schedule 80 PVC or ABS, together with flexible hose connections to prevent stress on the pipe. Don’t use Schedule 70 PVC.
A preferred solution is flexible sanitation hose, compounded to minimize permeation. This is typically made of flexible PVC or rubber and labelled sanitation hose. Thicker walls increase the resistance to odour permeation. Disadvantages are a shorter life, susceptibility to permeation and sagging.
Sanitation hose should be flexible smooth-walled PVC with an inner diameter of 1.5-in (38mm) or 1.875-in. Be aware that standard fittings are 1.5-in. Use two 100% stainless-steel clamps at every connection. Typical hose vendors are Dometic [13], Raritan [3], HoseXPress [16], Tek-Tanks [15] and Trident Marine [17].
== "Y" Valves ==
"Y" valves are used to mechanically direct waste overboard, into the holding tank or to a deck pump-out fitting. Regulations require that "Y" valves are padlocked in no-discharge areas, so make sure you can easily access it, readily identify the closed position, and that it is lockable. Most "Y" valves used in sewage systems are made of plastic; however, bronze may also be used. Key attributes of a good "Y" valve include corrosion resistance, fully operating ports for minimal resistance to flow, ease of disassembly for maintenance, and a sturdy handle for positive stops
[[Category:SewageSystems]]
