Separation efficiency
The capacity for separating the impurities in the medium
circulating in the system closed circuit basically depends
on three parameters:
1) It increases as the size and mass of the particle
increase. The larger and heavier particles drop before
the lighter ones.
2) It increases as the speed decreases. If the speed
decreases, there is a calm zone inside the dirt separator
and the particles separate more easily.
3) It increases as the number of recirculations increases.
The medium in the circuit, flowing through the dirt
separator a number of times during operation, is
subjected to a progressive action of separation, until the
impurities are completely removed.
The Caleffi DIRTCAL
®
and DIRTAMG
®
dirt separator, thanks
to the special design of its internal element, is able to
completely separate the impurities in the circuit down to a
minimum particle size of 5
µ
m.
The graph alongside, summarising the tests carried out in
a specialised laboratory (TNO - Science and Industry),
illustrates how the DIRTCAL
®
and DIRTAMG
®
dirt separator
(5462, 5463, 5465 and 5466 series) is able to quickly
separate nearly all the impurities. After only 50 recirculations,
approximately one day of operation, up to 100% is
effectively removed from the circuit for particles of diameter
greater than 100
µ
m and on average up to 80% taking
account of the smallest particles. The continual passing of
the medium during normal operation of the system
gradually leads to complete dirt removal.
Reduced head losses
A normal Y strainer performs its function via a metal mesh
selected for the size of the largest particle. The medium
therefore has a consequent initial head loss that increases
as the degree of clogging increases.
Whereas, the dirt separator carries out its action by the
particles striking the internal element and subsequently
dropping into the collection chamber as a result of gravity.
The consequent head losses are greatly reduced and are
not affected by the amount of impurities collected.
The graph alongside shows a comparison of the
differences in head loss between the two types of device.
Δ
p (kPa)
G (l/h)
Δ
p
(mm w.g.)
Efficiency
50 passages (0,5 m/s)
Efficiency (%)
Efficiency
50 passages (1 m/s)
Pa
rt
ic
le
d
im
en
si
o
ns
(
µ
µ
)
CARTRIDGE STRAINERS
SPECIAL
STRAINERS
WORKING ZONE
Y-
STRAINERS
Separated quantity
Initial quantity
Particle separation rating - Dirt separator efficiency
Comparison of head losses:
DIRT SEPARATOR - Y-STRAINERS
Y-strainer curve
3/4” - Kv=8
DIRTCAL
®
curve
3/4” - Kv=16,2
Tests in a specialised laboratory
TNO - Science and Industry (NL)
Installation
The dirt separator should preferably be installed on the return circuit
upstream of the boiler. This enables it to intercept any impurities already
present in the circuit, particularly when it is first started, before they
reach the boiler. The dirt separator should always be installed vertically
and ideally upstream of the pump. Use the specific versions designed
for installation on horizontal or vertical pipes. The flow direction of the
thermal medium is not important in dirt separators. For 5466 series a
space of at least 16 cm is needed underneath the dirt separator to allow
the magnet extraction.
CHILLER
01137-15_EN_01137/09 01/04/15 15:59 Pagina 5
