ARI Armaturen CONA TD PN63 EN - Manual (Page 4)

Page 4 Rev. 0040806000 2404
Operating and installation instructions
CONA
®
TD - Thermodynamic steam traps
4.2 Operating principles
Series 640/641:
(refer to Fig. 1-Fig. 2 page 5, Fig. 7-Fig. 8 page 6)
For control the steam trap uses the condensate temperature as well as the available
upstream pressure and back pressure.
In the controller (Pos. 24) the valve plate (Pos. 25) is enclosed by the cap and the seat.
When the boiling temperature of the medium is reached, a cushion of steam forms over the
valve plate (Pos. 25) and presses the valve plate (Pos. 25) onto the seal faces of the seat.
To a very great extent the external sealing cap (Pos. 6) frees the steam trap (in PN40) from
environmental influences. The steam cushion collapses as a result of condensate formation
and the associated temperature drop.
The system pressure lifts the valve plate (Pos. 25) from the seat face. The steam trap
opens and removes condensate.
The steam trap vents air automatically during system start-up and operation, but with a time
lag. The steam trap acts as a non-return valve.
The built-in controller is marked on the type plate.
Series 642/643:
(refer to Fig. 3-Fig. 4 page 5, Fig. 5-Fig. 6 page 6 )
The thermodynamic steam trap has an axially movable, flat valve plate (Pos. 25), which is
enclosed within a sealed cap (Pos. 6) and in its closed position simultaneously seals on the
inner and outer annular seat. For control this steam trap makes use of the differing pressure
and temperature conditions of steam and condensate flow during gradual expansion.
The annular clearance areas between valve plate (Pos. 25) and seat (incorporated in body
(Pos. 1)) or toroidal chamber, as well as the flow channels in the supply and discharge
area, are selected so that hot water flow in the valve area already produces intensive
evaporation, and at the same time the pressure chamber above the valve plate (Pos. 25) is
laden with this flash steam.
This presses the valve plate (Pos. 25) onto the seat opposite (incorporated in the body
(Pos. 1)).
If cooling/condensation causes the pressure of the steam enclosed in the pressure
chamber to drop, as the inner annular valve seat (inflow) falls below the opposing surface
force the valve plate (Pos. 25) is lifted and the steam trap opens.
If no evaporation occurs in the annular clearance area (e.g. cold water inflow), the steam
trap stays open. The valve system is dimensioned so that the valve is shut shortly before
the boiling temperature of the inflowing condensate is reached.