
LAUDA Ultra-Thermostats
UB 20(-D), UB 25, UB 50, UB 30, UB 40
UB 20 F, UB 20 J, UB 30 J, UB 40 J, UB 65 J
UB 20 JL, UB 30 JL, UB 40 JL
YATE0013 /10.04.02
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Note: When loosening or tightening the screw caps (19 mm a/f), hold the threaded
nipple on the tubing connections with a spanner (14 mm a/f)!
7
Connection of external systems
7.1 Circulation
pumps
In principle there are two different pump types:
SIMPLEX pumps, e.g. at UB 20, US 12 and
DUPLEX pumps, e.g. at UB 20-D, US 12-D.
SIMPLEX pumps are used for operation with closed external systems. They require a
pressure-tight external system.
DUPLEX pumps are used mainly with open external systems, such as bath vessels. In
contrast to SIMPLEX pumps they have a pressure and a suction stage as well as a float
for level control. DUPLEX pumps automatically maintain a constant level in the
thermostat irrespective of the level in the external bath. Liquid is poured into the external
bath until a level is achieved in the thermostat at which the pressure and suction stages
have exactly the same output.
7.2
Closed external circuits
If the thermostat is connected to closed external circuits, additional liquid must be
poured in after the thermostat has been switched on until the liquid in the bath remains
at the correct level (approx. 2 cm below the cover plate).
At higher operating temperatures the expansion in volume of approx. 8% per 100°C
during the filling has to be taken into account.
For suitable tubing materials see Section 5.
We recommend metal hoses for temperatures above 100°C.
With external systems at a higher level it may happen even in closed circuits that the
external volume drains down and the thermostat bath overflows if the pump is stopped
and air enters the thermostated system!
Always ensure the maximum possible flow area in the external system (nipples, tubing,
system). This results in a larger flow and therefore improved thermostatic control.
Note: Always protect the tubing with hose clips against slipping off, or use stainless steel
hoses (V2A) with screwed connections.