Specifications

OPERATION MANUAL
“customer” – LSG60 Freeze Drier – “contract ref”
Oil collected in the mist filter is continuously returned into the gas ballast port of the
pump. The pump is operated on gas ballast to reduce the risk of water condensation
in the pump oil (refer also to manufacturers instructions).
The condenser temperature and pressure is monitored with a pirani gauge and a
PT100 respectively; data can be continuously displayed on the touch screen if
required.
The drying chamber is situated alongside the condenser unit (refer to figure 4). The chamber
is fitted with nine temperature controlled product shelves, a refrigeration / heater plant with
heat transfer fluid circuit and a shelf stoppering mechanism. A aluminium door at the front
of the chamber provides access for loading and unloading and is fitted with two toughened
glass view ports (refer to figure 2) which allows the operator to inspect the product during
the freeze drying process.
Each shelf contains an internal network of channels through which the heat transfer fluid can
flow freely and continuously. Heat is extracted or introduced into the fluid via the
refrigeration / heater plant and is then distributed to each shelf in parallel through a common
manifold and liquid re circulating pump. Sensors in the fluid circuit provide feedback for
closed loop temperature control. Temperature control is achieved by modulating the
open/closed state of a valve within the refrigeration system between –100% and 0%. Where
–100% is always open, 0% is always closed.
In order to prevent the cooling compressor from free running, when there is no cooling
demand for sustained periods of time (cooling valve closed), which could result in oil
starvation, a timer control is used. When the Cooling valve has not been called to open by
the PID control for 2 minutes, the Auxiliary compressor is turned off. When the Cooling
valve is next called to open the compressor restarts.
A PT100 sensor mounted in the fluid circuit provides temperature feedback for the loop.
.
The shelves are mechanically linked to a hydraulically actuated ram with variable pressure
settings. The ram moves the shelves up and down allowing automatic stoppering of vials
under vacuum and other controlled atmospheres. Operation of the ram is interlocked with a
safety switch on the front door ensuring that the actuating mechanism is disabled when the
door is opened.
Note: the switch should never be removed or tampered with.
Up to nine (9) product probe sensors (Type T) can be connected and attached to the shelves
or the product to enable continuous monitoring of the process.
The operation of the freeze dryer is controlled from the Eurotherm Visual Supervisor (T800)
and the Eurotherm 2500 modular process controller.
The Visual Supervisor combines process control, data acquisition, data logging, and setpoint
programming and operator functionality. Features include comprehensive event and alarm
management and local data logging facilities. The front-end colour touch screen provides the
Section 3 Issue: 1 Page 13 of 42