To keep hydraulic components performing correctly, the hydraulic liquid must be kept as clean as possible. Foreign matter and tiny metal particles from normal wear of valves, pumps, and other components are going to enter a system. Strainers, filters, and magnetic plugs are used to remove foreign particles from a hydraulic liquid and are effective as safeguards against contamination.
Strainers
A strainer is the primary filtering system that removes large particles of foreign matter from a hydraulic liquid. Even though its screening action is not as good as a filter's, a strainer offers less resistance to flow. A strainer usually consists of a metal frame wrapped with a fine-mesh wire screen or a screening element made up of varying thicknesses of specially processed wire.
Filters
A filter removes small foreign particles from a hydraulic fluid and is most effective as a safeguard against contaminants. Filters are located in a reservoir, a pressure line, a return line, or in any other location where necessary.
What is the function of a Strainer?
Strainers are important components of piping systems to protect equipment from potential damage due to dirt and other particles that may be carried by the process fluid.
During system start-up and flushing, Strainers may be placed upstream of pumps to protect them from construction debris that may have been left in the pipe. The figures here below are start-up Strainers. Permanent Strainers may be installed upstream of control valves, traps, and instruments to protect them from corrosion products that may become dislodged and carried throughout the piping system.
Centrifugal and reciprocating pumps handling material containing solids should have permanent Strainers provided in the suction lines to the pump or in the vessel from which the pump takes suction. The free area of such Strainers should be not less than three times the cross-sectional area of the suction line.
What are the basic features to look for in a good strainer?
Some key features to look for in a good strainer are:
Adequate filtration area
Adequate mechanical strength of body & screen
Low rated pressure drop
Machined seating for NIL bypass
What is Basket/Bucket Type Strainer? What is the types of Basket type strainer?
Bucket Strainer is a closed vessel with cleanable or removable screen or element for removing particles from liquids or gases. Drain connection provided to remove accumulated particles or solids.
Basket Strainer designed for remove foreign matter from pipe lines and provides protection for pumps, meters, valves, and other similar mechanical equipment, which is called as Strainer. Basket Strainers feature top removal of the screen. The screen is in the form of a basket, with a lifting handle, so that all particulate captured and retained by the screen can be easily removed for disposal. The particulate matter is captured in the strainer basket. The line is then temporarily shut down and the basket removed for cleaning or replacement.
Baskets are fabricated from stainless perforated sheet. The strainer improves the clearance in the medium, and prolongs the life of valves; protect expensive pumps, meters and other equipments. It is suitable for water, Air, Gas, petroleum, steam and other fluids. Basket strainer is used where cleaning may occur frequently; it stands to reason that the basket should be able to be removed and replaced as simply as possible. The strainer cover is held down by a clamping yoke which is sturdy enough to hold full line pressure and yet, which can be quickly loosened or tightened by hand. Bolted covers are also furnished with basket strainers and they cost less than yoke covers.
Basket Strainers are generally used where high flow capacity is required. The basket Strainer is serviced by removing the cover, which yields access to the basket. Basket Strainers are also available in a duplex style which consists of two parallel basket Strainers and diverting valves, which permit diversion of the flow through one of the Strainer elements while the other element is being serviced-an essential feature where flow cannot be interrupted.
These strainers are widely demanded for straining foreign matter from the pipe line thus providing a cost-effective protection of pumps, meters, valves and similar mechanical equipment. Specifically used for drinking water, cooling water, hot water system sea water, these are used in various industries such as brine, paint heat exchanger, condensers, fuel oil, organic and inorganic chemicals. It is also effective for those applications, where non-standard construction materials are used.
Basket Type Strainers are of two types:
• Simplex Strainers
• Duplex Strainers
What is Y-Type Strainer?
Y-type strainer is used for remove foreign matter from pipe lines and provides protection for pumps, meters, valves, and other similar mechanical equipment, which is called as Strainer. "Y" Type Strainers are named after their shape and normally used for course filtration. But with large filtration area can be used with fine mesh also. The Strainer improves the clearance in the medium, and prolongs the life of valves; protect expensive pumps, meters and other equipments. It is suitable for water, Air, Gas, petroleum, steam and other fluids.
A Y-strainer can be installed in either a horizontal or vertical position (Downward flow) with the screen element pointing downward. This allows the strainer screen to collect material in the strainer at the lowest point of the screen.
What is the Difference between Strainer & Filter?
A filter is a device that removes particles from a given liquid or gas. It includes a disposable medium for removing particles of specified micron sizes.
Simply stated, a Strainer is also a filter; however, it uses a perforated plate or screen mesh to remove larger particles from a process stream.
Strainers and filters are both products that filer solids from fluids. A strainer is, in reality, a coarse filter. Generally it is assumed that if the particle to be removed is not visible to the naked eye, the unit is filtering, and if the particle is visible, the unit is straining. The average human eye can detect a specific particle between 50 and 70 micros. Most people cannot see anything smaller than 325 mesh, or 44 microns. Since 200 mesh is equivalent to 74 microns, a general rule would be that if the screening device is coarser than 200 mesh, it is a strainer and if it is finer than 200 mesh it is a filter.
One of the best uses for a strainer is in conjunction with a filter. By installing a strainer directly ahead of a filter, the large heavy pieces which would quickly clog the filter are removed. The filter is then free to do its major job of fine particle removal and does not have to be cleaned so often. The major advantage of a Strainer is that it is reusable. There are three levels of straining a) coarse, b) medium, and c) fine
What are the maintenance requirements of strainers?
Depending on the type of the strainers, the maintenance requirements of strainers vary. Generally basket strainers are the easiest to maintain as the cleaning is from the top and they are designed to hold the dirt in a closed basket design. The easiest of all strainers to maintain are the quick open strainers, which do not require much effort to clean.
What is Strainer Open Area Ratio & Important?
Amount of free open area is the ratio of the open area through the strainer basket to the cross sectional area of the pipe. A common term used in strainer design is “Open Area Ratio” (OAR) equals the total open basket area divided by the internal cross-sectional area of the inlet pipe. It is a measure of relative debris-holding capacity and is usually between 1 to 4 times the inlet pipe area.
Open Area Ratio = Total Basket Element Open Area / Inlet Pipe Cross Sectional Area
To determine the anticipated maximum differential pressure (DP), it is common to request the DP at 75% blockage. At 75% blockage, there is a 75% reduction in flow area compared to clean, and a DP equal to approximately 4X that of the clean DP Value. This is based on a proportional analysis with open basket area being inversely proportion.
The open area ratio in strainer element refers to the amount of free open of the strainer and basket element. It is the ratio of the open area through the strainer basket to the cross sectional area of the pipeline. Anything less may cause excessive pressure drop. The ratio is calculated with a clean basket and as the basket begins to clog the ratio will drop. Unless there is a wide safety margin the area through the basket may quickly become smaller than the pipe area. This will reduce flow through the strainer and necessitate very frequent cleaning. A small open area ratio also means the holding capacity of the basket is small - an important consideration if the amount of solid matter to be removed is large.
How to select right Strainer Element?
The strainer element (it can be for y type strainer for basket type strainer) is the heart of a strainer since this is where the unwanted material is trapped. Strainer baskets elements are made of perforated sheet metal and a wide range of opening sizes is available. The size of the basket perforation should be slightly smaller than the minimum particle size to be removed. Using a smaller perforation opening than necessary only means the basket will fill and clog more quickly and have to be cleaned more often. By the using of fine element mesh sheet along with perforated sheet can achieve fine filtration up to 5 Micron.
When to Clean Basket Strainer Element?
Strainer basket element should be cleaned on a regular basis, not when they become clogged, to insure that they are not damaged by too high a differential pressure. One more reason for frequent cleaning is a phenomenon known as “runaway buildup”. As dirt in a strainer basket accumulates and as the mesh or perforations plug up, pressure drop increases. The curve of this pressure difference is not a straight line. It starts out as a low slope, but as the basket clogs more and more it turns upward faster and faster. As the dirt builds up the free open area in the basket gets smaller and smaller.
Basket type filter feature top removal of the screen. The screen is in the form of a basket, with a lifting handle, so that all particulate captured and retained by the screen can be easily removed for disposal. The particulate matter is captured in the strainer basket. The line is then temporarily shut down and the basket removed for cleaning or replacement.
Advanced dynamic flow path and large filtration area elements ensure low pressure drops and reduced maintenance periods. These strainers reduce downtime for cleaning due to their construction of bolted cover and easy removal of screen. They are ideal for very fine straining.
Strainer - What does mesh size mean?
The number of openings in one inch of screen. The number of openings is the mesh size. So a 4-mesh screen means there are four little squares across one linear inch of screen. A 100-mesh screen has 100 openings, and so on. As the number describing the mesh size increases, the size of the particles decreases. Higher numbers equal finer material. Mesh size is not a precise measurement of particle size.
What happens if the strainer not cleaned regularly?
They need to be cleaned before clogging to ensure smooth operation. Hence, one spare screen required on hand to reduce downtime to minimum.
Strainer - What do the minus (-) and plus (+) plus signs mean when describing mesh sizes?
Here’s a simple example of how they work. –200-mesh would mean that all particles smaller than 200-mesh would pass through. +200 mesh means that all the particles 200-mesh or larger are retained.
What is the timeline to clean the strainer screen?
The simple way to know when to clean a strainer screen is to install a differential pressure indicator (between inlet and outlet). When the differential pressure reaches a threshold point, it can be ascertained that it is time for cleaning. These differential pressure indicators can even have electronic control equipment fitted to them to enable remote access. Alternatively, one can also use independent inlet and outlet pressure gauges to denote inlet and outlet pressure. The difference between the two would give the differential pressure.
Strainer - How fine do screens get?
That depends on the wire thickness. If you think about it, the finer the weave, the closer the wires get together, eventually leaving no space between them at all. For this reason, beyond 325-mesh particle size is usually described in “microns.
Strainer - What is a micron?
A micron is another measurement of particle size. A micron is one-millionth of a meter or one twenty-five thousandth of an inch.
Material of Construction (MOC) for Fabricated Strainers and Filters?
Body & Cover
ASTM A 312 TP 304L/316L (Stainless Steel 304L/316L)
ASTM A 312 TP 304/316 (Stainless Steel 304/316),
IS 2062 GR. A, IS 3589,
ASTM A 516 GR. 60/70,
ASTM A 106 GR. B.
Gasket
SS 304/316 Spiral Wound with CAF/Graphite Filled
CAF - Compressed Asbestos Fibre,
Graphited Asbestos,
Mesh/Filter Element
S.S. 304 / 316,
S.S. 304L / 316L,
Brass
Bolts & Nuts
ASTM A 193 GR. B7 / A 194 GR. 2H,
S.S. 304/316/304L/316L
What is the timeline for change out a micron filter element?
The indication that it is time to change out a micron filter element is provided by either a visual or electrical differential pressure indicator mounted on the filter. Micron filters are strongly recommended to be fitted with differential pressure indicators. The pressure differential at which the indicator informs you to change out the filter is called terminal pressure drop – a key parameter in filter design.
What is the reasons to use strainer or filter?
There are two reasons to use a strainer or filter:
Safety requirement
A strainer is to be used before any expensive capital equipment like pump, valve, heat exchanger, flow meters, compressors, etc to protect them damage from foreign particles like dirt, scales, seeds, salt, un-dissolved resins, lumps of pulp, pigments, etc. This guarantees a long service life for the expensive equipment and reduced operational costs in the long run.
Process requirement
If the process requires that the fluid be free from particles above a certain size, then a strainer (or filter) can be used to meet that requirement. For example if an ethylene glycol process line requires that it be free from particles above 30 μm for further processing, then a strainer with a 30 μm opening filter media can be used to eliminate particles above that size.
What are the different fluids that can be filtered in strainers?
Strainers are designed to be used for practically any fluid be it liquid or gas. Most of our standard offerings would suit common applications like water, fuel/furnace oil, liquor, diesel, steam, air, nitrogen and the like.
In fluid have 50% impurities by volume. Can I use a strainer for this application?
As a thumb rule, strainers are best effective when impurities are, at most, less than 0.5% by volume. If the impurities are more than this, specially designed strainers are to be used mostly in a multi-stage set up.
What are the major factors in the selection of strainer design?
There are two aspects to strainer design:
Strainer sizing
This is done based on fluid characteristics. We optimally design the strainer for you based on your flow data utilizing our extensive filtration know-how.
Material selection
This is done based on the fluid and service conditions (atm. pressure/temperature/humidity). Based on chemical resistance charts we decide the recommended material for strainer. Cast steel is the most common material used. Stainless steel or other alloy materials are used where corrosion is a concern.