Alfa Laval Copenhagen A/S
ALF – Installation, Operating and Safety Manual
ALF Instruction Manual UM_Filter_100B03
Page 21 of 67
6. Operating instructions
6.1 Field of Application
The Alfa Laval Filters, type ALF-R, ALF-S and ALF-P are designed to provide filtration of natural
water sources, such as sea, river or lake water. The filters are designed to remove residuals
contained in the water. Filtration rate depends on the selection of filter basket. Filters can be put
into operation in both indoor and outdoor areas. The filter is designed for either horizontal or
vertical installation and always on the pressure side of a pump.
6.2 Operating Principle
The liquid enters the inlet section of the filter and is filtered through the basket prior to leaving
through the main outlet.
The filter comprises a cylindrical filter basket inside the filter body. The filter basket is divided into
an inlet section and a debris collector after the flow diverter valve. At the end of the filter body there
is a debris collection chamber with a flushing outlet.
The flow diverter and flushing valves are operated by pneumatic or electrical actuators. The
operation of the actuators for automatic or manual flushing action is provided by timing or by
manual selection. The flushing sequence can optionally be controlled by a differential pressure
system.
The internal filter basket can be serviced or replaced without disconnecting the filter body from the
system pipe work.
The filter incorporates an automatic flushing system for removing collected debris without
disrupting the main liquid flow.
Filtration size depends on the selected basket. As a rule of thumb, Alfa Laval recommends a
filtration rate equal to half the channel depth of the heat exchanger.
6.3 Operating precautions
• Pressure shocks may damage the filter basket during the flushing if the flushing outlet is
connected to open air and the flushing differential pressure is higher than 3.0 bar (ALF10-
30) or 2.5 bar (ALF 40-80) between P1-P3. Make sure there is sufficient “back pressure”
available at P3 prior to opening the flushing valve.
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