Huber 705 - Degassing Externally Closed Applications

Setup mode
OPERATION MANUAL Chapter 4
Unistat® V2.0.0en/09.06.16//15.09
66
4.3.1.2 Degassing externally closed applications
With a fluid mix, rapid heating can cause thermal fluid to suddenly escape from the >Expansion
vessel< [18]
COMBUSTION/PROPERTY DAMAGE
 Due to the rapid heating of the low-boiling component contained in the mixture, a sudden
overflow from the >Expansion vessel< [18] is to be expected.
Hot surface on the >Expansion vessel< [18] in “degassing” setup mode
BURNS TO LIMBS
 Do not touch the >Expansion vessel< [18] during “degassing” setup mode!
 Wear your personnel protective equipment (e.g. temperature-resistant safety gloves, safety
goggles).
Inert gas blanket over the >Expansion vessel< [18] over 0.1 bar (g)
MATERIAL DAMAGE CAUSED BY MECHANICAL DAMAGE TO THE >EXPANSION VESSEL< [18]
 When using the optional sealing sets for Unistate in connection with a static inert gas overlay, a
pressure limit of 0.1 bar (g) must be used.
When changing from a low-boiling thermal fluid (low-boiling components) to a higher boiling
thermal fluid, remains of the low-boiling component may remain in the temperature control unit.
Depending on the working temperature, the low-boiling component begins to boil, gas bubbles
form and cause the pump pressure to momentarily collapse. This may cause a safety shutdown.
The gas bubbles reach the >Expansion vessel< [18] and can escape via the >Expansion vessel cap<
[22] and the >Filling port< [17]. Degassing removes the remains of the low-boiling component
from the thermal fluid.
For your temperature control unit, we recommend the inert gas overlay. For this purpose we offer
the sealing set for Unistats (Order No. 9402) in the Huber catalog.
A Unistat protects the thermal fluid from environmental influences. Thus an accumulation of mois-
ture or an increased oxidative degradation of the thermal fluid is prevented. A static overlay by an
inert gas significantly further extends the useful life of the thermal fluids. This is especially true if
you want to work long-term near the operating temperature limits of the thermal fluids. (hygro-
scopy, oxidation).
The temperature in the >Expansion vessel< [18] is measured by a temperature sensor. The expan-
sion of the hot thermal fluid during degassing may increase the temperature in the >Expansion
vessel< [18]. A passive cooling device prevents too high temperatures in the >Expansion vessel<
[18], thereby protecting the thermal fluid from oxidation too. The factory setting for this is 45 °C.
However, brief temperatures of > 70 °C may be caused in the >Expansion vessel< [18] by rising gas
bubbles during degassing. This happens due to aging and the nature and amount of the low-boiling
thermal fluid contained in the temperature control circuit.
Under the category “Safety” in the section “Overtemperature”, the cut-out value of the installed
temperature sensor can be set up to 100 °C in the degassing mode. In normal mode, only max. 70 °C
can be set for the >Expansion vessel< [18].
Thermal fluids are more or less hygroscopic (water-attracting). This effect increases, the lower the
working temperature. The de-gassing mode described below, which must be permanently moni-
tored, also helps to remove any water residues from the temperature control circuit. Using the
optional sealing set (order no. 9402) further reduces the influence of oxidation and hygroscopy in
the >Expansion vessel< [18].
PROCEDURE
 Activate the menu item “Degassing” after completing the venting operation.
Prerequisite: You have filled the temperature control unit according to the instructions on page
64 in Section »Filling and venting externally closed application« and/or cleaned it as per page
88 in Section »Rinsing the thermal fluid circuit«.
 Go to the “Categories Menu”.
 Tap on the category “Temperature Control”.
 Tap on the category “Start/Stop”.
 Tap on the dialog entry “Start degassing”.