Wye ('Y') and Tee ('T') strainers have many similarities, so how
does one decide which style is the best fit for an application?
Y and T strainers are both simplex style pipeline strainers designed for
batch applications with a light particle load; to clean the internal screen
requires interrupting the process flow.
Cast Y Strainer
Although commonly used for
liquid applications, Y strainers were initially designed for steam, air
and other inert gases to protect downstream equipment from a
"particulate upset condition" such as protecting steam condensers from
rogue pipe scale. Y strainers have a blow-down port for steam
applications and this flushing capability is a characteristic that T
strainers do not have. While blow-down may work for aqueous
applications, the efficiency of flushing depends upon the particles
retained not becoming embedded within the element.
Although it is
possible to fabricate Y strainers to satisfy specific applications, the
majority of Y strainers are cast items, thus non-customizable
It is common for Y strainers to be available in 1/4" through 10" sizes
and because they are a cast item manufactured in foundry-pour based
quantities, shipment is often made within just a day or two after
receipt of an order. The available pressure class ranges and breadth of
materials of construction (iron, steel, bronze, and 316SS) are also
advantages of Y strainers.
The open area ratio (OAR) for Y
strainers is typically a little better than T strainers; most of our Y
strainers have a 3:1 OAR wheras the larger size T strainers have an OAR
of ≤ 2.
Y strainers have a screwed or bolted chamber cover for
screen access and are installed such that when opened the process fluid
will fall/drain out.
|T strainer design
T strainers are mostly a custom fabricated product, often
manufactured from pipe. The advantage of a fabricated product is the
ability to provide customized features, such as a quick-opening style
cover, addition of a vent port or adding differential pressure taps. It
is also possible to off-set the inlet and outlet by 90 degrees, forming
an "elbow" shaped strainer which might be desirable when the
installation area is constrained.
T strainers usually begin at
larger sizes (2") and can be fabricated for 24" or larger pipelines. As
a fabricated product, the lead times range from 8-12+ weeks (inclusive
of generating approval drawings and manufacturing).
While the OAR for a T strainer is typically less than a
comparable size Y strainer,
its' flow capacity is higher.
This is attributable to the flow path within a T strainer having a
"straight-through" design as well as the convoluted element shape.
When installed horizontally, the chamber cover of a T strainer
can be opened without the process fluid draining from the chamber; this
might be a desirable feature with valuable or hazardous process fluids.
Y strainers typically offer the best
value in terms of initial cost, lead time and overall flexibility which
include materials of construction, pressure class, and inherent built-in
T strainers are used when transferring
fluids at higher velocities (equates to higher flow rates), for larger
pipelines, applications that require special features and for quicker
access to the straining element.
Chris Pasquali has been trained by Hayward Flow Control and Eaton Hydraulics
Filtration Division, having provided sales and engineering support for these
companies since 2001.