GESTRA UNA 38, Original Installation Instructions

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11
Task and function
Purpose
Type UNA 38 and UNA 39 units are used to remove
condensate from steam and other condensable
gases in steam-heated consumers in high-pressure
applications.
UNA 38 units with DUPLEX control unit are
especially suitable for saturated and hot steam.
Units with DUPLEX control unit are additionally used
for venting the system.
Units with SIMPLEX control unit are especially
suitable for cold condensate and superheated
steam.
A special MAX control unit is available for high
condensate flowrates.
Function
The float (33) opens the orifice (32) based on the fill
level. This regulates the drainage rate. With the
orifice opened to maximum, the drainage rate
depends on the diameter of the orifice (AO).
The DUPLEX control unit consists of the float and an
additional, temperature-dependent bimetallic vent
(6).
You can lift the float manually using the optional
manual lifting lever.
The optional manual vent valve allows you to vent
the pipe manually.
The diagram below shows a UNA 38 with DUPLEX
control unit. The DUPLEX control unit is only
supplied for the UNA 38.
A special MAX control unit is available for high
condensate flowrates.
If the float (33) is raised while the fill level is rising,
first of all the nozzle needle (34) is pulled out of the
pilot valve. This causes a small amount of medium
to flow through the pilot valve. The medium
squeezes the bellows (39) of the control unit, which
in turn fully opens the orifice (40).
A pressure relief line (36) connects the control
chamber (38) to the pressure relief orifice (35) on
the pilot valve. When the fill level falls, the float
causes the orifice to close. The pressure relief hole
(37) equalises the pressure between the control
chamber and the interior. The bellows expand and
close the orifice.
The diagram below shows a UNA 39 unit
with SIMPLEX AO 140 MAX control unit.
The special components of the UNA 38
units with SIMPLEX AO 80 MAX control
unit are identical in terms of design and
function.