Previously the wash-basins here, discharged into the stainless-steel
urinals. Importantly the urinals were 'open' ie they discharged
into a P trap. Now they are replacing the old urinals with ceramics
which have outlets which are air sealed to the old P trap.
My feeling is that such urinals should not be 'sealed' onto a
P trap outlet. Clearly there is the back-pressure of the P trap's
trap-height to over come. IMO if you had a series of P traps
in a sealed circuit, you could potentially have an air lock.
I think the P trap 'receiver' must be open to the air.
In one of the installations [opposite my office/cupboard]
the outlet from the basin, goes via a shower outlet; and now
the basin discharge starts bubbling in the shower floor
instead of flowing straight to the lower total outlet.
Ie. after the urinals.
Thanks for any opinions.
== Chris Glur.