Danfoss Filter solutions Data sheet
Data sheet
Filter solutions for
Danfoss high-pressure pumps and
energy recovery devices
hpp.danfoss.com
Data sheet | Filter solutions for Danfoss high-pressure pumps
1. Introduction
1.1 Cartridge filters
Cartridge filters are widely used in industrial and
domestic applications for removal of suspended
solids in water. The variety of cartridges available
and the confusing methods of ratings, however,
make selection of cartridges difficult for consumers. It becomes important for users,
therefore, to understand cartridge filters, how
they work, and how manufacturers rate them.
1.2 Filtration
Filtration is a process of removing unwanted
solids from fluids by passing the fluid through a
form of sieving material that retains the solids,
but allows the fluid to pass through. Filtration
efficiency is, therefore, the percentage of solid
retention by the sieve. It is this “sieve” that we
refer to as the filter medium, or simply the filter.
A contaminant is generally referred to as the
material that is to be removed from the fluid, and
the clean fluid is called the
filtrate. In today’s market, manufacturers use
three types of ratings to evaluate filters: nominal
rating, absolute rating and beta ratio.
1.3 Nominal filter rating
A nominal filter rating is an arbitrary value
determined by the filter manufacturer, based
upon removal of some percentage of all particles
of a given size or larger.
- The rating is typical based on a weight percent
(etc. 60 -95%)
- The 5-40% that pass through are NOT defined
by the manufacturer (normally much larger
particles pass through).
- The rating is based on a weight analysis test.
- There is a high risk of channelling when a filter
medium has some oversized pores or a wide
pore-sized distribution.
- There is a high risk of bypass when
cartridge-to-housing seal is ineffective.
1.4 Absolute filter rating
The absolute rating or cut-off point of a filter
refers to the diameter of the largest hard
spherical particle, normally expressed in
micrometres (µm), which will pass through the
filter under specified test conditions.
- The filter is tested under a specific
international well known test method (modified OSU-F2 single-pass filter test system).
- The rating is based on a particle measuring
test.
- The filter is reproducible.
- Higher ∆P does not result in particle
unloading.
- The filter can withstand flow pulsations as well
as viscosity and temperature changes.
- There is no risk of channelling due to the high
quality of the filter media.
- Absolute filtration means that the fluid is
filtered both horizontally and vertically. In
comparison, an inferior nominal type of filter
will allow particles which are more than 10
µ in length to pass the filter, as it only filters
the fluid according to the diameter of the
particles.
- It is NOT possible to reproduce the filter.
- Particle unloading is rising when the ∆P across
the filter increases
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Data sheet | Filter solutions for Danfoss high-pressure pumps
2. Requirements
2.1 Filtration requirement
To achive warrenty and assure the service intervals stated from Danfoss, the PAH, PAHT, APP
pumps require water with no particles larger than
10 micron (10 µ). Thus a 10 µ absolute filter with a
Beta value > 5000 must be used.
- 10 µ means that particles of 10 µ or larger in
size will be caught by the filter.
β-value of filter Filter efficiency
2 50.00% 50,000
4 75.00% 25,000
10 90.00% 10,000
20 95.00% 5,000
40 97. 50 % 2,500
100 99.00% 1,000
200 99.50% 500
-
The Beta value > 5000 refers to the efficiency
of the filter. A filter with a Beta value of > 5000
catches 99.98% of the particles being 10 µ or
larger. This means if there are 100,000 particles
in the fluid (10 µ or larger), only 20 of them
would pass through that filter. Other types of
filters on the market have a Beta value > 10
(90% efficiency), and these filters would allow
10,000 of the 100,000 particles to pass through
the filter.
Number of particles downstream for each
100,000 particles upstream
500 99.80% 200
1,000 99.90% 100
2,000 99.95% 50
5,000 99.98% 20
10,000 99.99% 10
2.2 Filter types
Pleated polypropylene filter elements use the
very latest gradient density micro-fibre media
technology to provide a combination of excellent
absolute micron ratings, high flow rates, and high
dirt-holding capacity.
2.3 Features
- The absolute particle retention provides
excellent protection of the pump and the rest
of the system.
- Compatibility with a broad range of process
chemicals allows use in most applications.
- High flow rate and long service life ensure
minimum downtime of the system.
- High dirt-holding capacity.
- Filter element is easily exchanged.
2.4 Applications
The Danfoss filters can be used in a wide range of
demanding applications such as:
- General water filtration
- RO/DI water filtration
- We recommend CIP cycles in the range of 3-10
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Data sheet | Filter solutions for Danfoss high-pressure pumps
0
0,5
1
1,5
2
2,5
0 10 20 30 40 50 60 70 80 90 100 110
Pressure drop Bar
Time [%]
Typically filter life
Cartridge Pressure Drop
2.5 Right filter choice
There are 2 factors to consider in order to choose
the right filter:
a) The flow through the filter
b) Amount of dirt in the fluid (E.g. SDI).
If the fluid is relatively clean (low SDI), the filter
choice can be based on the pump size as this will
indicate the flow through the filter.
If the fluid is relatively dirty with small particles, a
larger filter size should be chosen to increase the
dirt-holding capacity. For instance, for a flow of
60 l/min fluid containing many small particles a
filter for a flow up to 170 l/min should be chosen.
If the fluid is relatively dirty with larger particles,
a cheaper and less efficient pre-filter should be
placed in front of the main filter. This will ensure
a long life of the more expensive main filter, as
most of the larger dirt particles will be caught in
the cheaper pre-filter.
The prefilter may be of the type ”Nominal filter”.
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