Strainer assembly for removing solid particulates from oil

A strainer assembly for removing solid particulates from a fluid has a housing shaped as an elbow-shaped conduit and a support member for supporting a screen adjacent a forwardly extending flange on an inlet conduit section of the housing, the housing also comprising an enlarged intermediate section, in which the support member is disposed, and an outlet conduit section. The support member is threadedly engaged in a wall of the enlarged intermediate section of the housing and preferably has a base and a plurality of posts extending from the base, with the screen seated on the distal ends of the posts. Fluid entering the housing through the inlet section passes through the screen and then through passageways between the posts of the support member and is then discharged from the housing through the outlet conduit section.

CROSS-REFERENCE TO RELATIVE APPLICATIONS 
This application is related to application Ser. No. 586,850, filed Sep. 24, 
1990 in the names of Paul G. Minard and Paul Toy, Jr., entitled "APATUS 
FOR REMOVING SOLID TICULATES FROM OIL" which is assigned to the 
assignee of the present invention. 
FIELD OF THE INVENTION 
The present invention relates to a strainer assembly for removing solid 
particulates from oil, such as an assembly used as a sampling device 
during turbine-generator lube oil flushes. 
BACKGROUND OF THE INVENTION 
As described in the above-referenced patent, U.S. Pat. No. 5,074,381, the 
contents of which are incorporated by reference herein, oil in components 
such as turbines is periodically checked to determine any presence of 
metallic or other solid particulates to determine the cleanliness of the 
turbine system. During shutdown for repair or maintenance, for example, 
oil is flushed through a turbine to oil handling equipment, such as 
piping, and circulated through a strainer assembly for a predetermined 
period of time. The strainer is then removed and any solid particulates 
collected by the strainer analyzed. 
When performing an oil flush on a turbine-generator, samples are taken at a 
plurality of locations in the system, with a strainer incorporated into 
the system at several locations, or sampling points. Such locations 
include each bearing, the main oil pump circuit, a point in the air side 
seal oil, a point on the hydrogen side seal oil, the high pressure 
operating oil, and the control oil. Only turbine-generators with 
mechanical hydraulic controls require sampling at the latter two sample 
points. In order to take a sample, oil is diverted through the strainer 
for about 30 minutes. This, typically, provides for the passage of between 
about 3000 to 5000 gallons (11,000 to 19,000 liters) of oil to pass 
through the screen of a sampling device. A particle count is measured on a 
150 mesh sampling screen and the measurement compared to an acceptable 
criterion. This method provides an accurate representation of pipe 
cleanliness, whereas, a grab sample, out of the oil reservoir, is a more 
representative test of oil cleanliness. 
Current procedures for taking an oil sample use a basket type strainer 
lined with a 150 mesh stainless steel screen through which the oil is 
passed. This basket-type strainer was originally designed for use as a 
filter and not for collection and analyzing of solid particles in the 
particle size range of 0.005 to 0.010 inch (0.0127 to 0.0254 cm) range. 
The original design of such a conventional strainer was meant to capture 
solid particles of a size above 0.125 inch (0.317 cm) in diameter. These 
strainers are conventionally lined with a 150 mesh screen to collect small 
diameter particles. 
For this reason, the strainer basket is difficult to wash down when taking 
a particle count. An oil flush of a three cylinder, nine bearing 
turbine-generator with mechanical hydraulic control system, for example, 
could require fourteen locations where basket strainers were inserted and 
approximately forty samples taken and analyzed. This number of samples 
requires a great deal of time just to clean the baskets to ensure that a 
"clean" strainer will not foil a particle count. 
SUMMARY OF THE INVENTION 
A strainer assembly for removing solid particulates from a fluid, such as 
oil from a turbine-generator, has a housing formed as an elbow-shaped 
conduit and a support member for supporting a screen in the housing 
adjacent a forwardly extending flange on an inlet conduit section of the 
housing. The elbow-shaped housing has the inlet conduit section, an 
enlarged intermediate section and an outlet conduit section. The inlet 
conduit section has the forwardly extending flange thereon, while the 
distant ends of the inlet and outlet conduit sections have threads for 
connection to lines for passage of fluid through the housing. Portions of 
the inlet and outlet conduit sections adjacent the enlarged intermediate 
section form an obtuse angle to each other, and the inlet conduit section 
has a vent valve connected thereto. 
An opening is provided in the wall of the enlarged intermediate section 
that is coaxially aligned with the forwardly extending flange on the inlet 
conduit section and a removable support member is disposed in the enlarged 
intermediate section, the base of which is sealed in the opening, and the 
base carries a screen support that disposes a screen between the support 
member and the flange of the inlet conduit section. Passageways are 
present in the support member such that fluid entering the enlarged 
intermediate section of the housing must pass through the screen and then 
through the passageways prior to exiting through the outlet conduit 
section. 
The support member for the screen has a plurality of posts extending from 
the base thereof towards the flange of the inlet conduit section and a 
ring member, having a central opening, is provided on the distal ends of 
the posts, with the screen extending completely across the central opening 
of the ring member. The ring member is provided with a recess in which the 
screen seats and has an inwardly directed ledge about the periphery to 
secure the screen on the ring member. 
A seal is provided between the base of the support member and the wall of 
the enlarged intermediate section and a seal is also provided between the 
flange of the inlet conduit section and the ring member for the screen.

DETAILED DESCRIPTION 
Referring now to the drawings, a strainer assembly 1 is shown which has a 
housing 3, the housing 3 formed as an elbow-shaped conduit with an inlet 
conduit section 5, enlarged intermediate section 7, and an outlet conduit 
section 9, and may be a metal casting formed from aluminum As illustrated 
in FIG. 1, the inlet conduit section 5 has as wall 11 which has connecting 
means, such as threads 13, on the end 15 of the wall 11 distant from the 
enlarged intermediate section 7, and the inlet conduit section terminates 
in a forward extending flange 17 in the enlarged intermediate section 7. 
The outlet conduit 9 has a wall 19 which has a connecting means, such as 
threads 21, on the end 23 distant from the enlarged intermediate section 
7. A portion 25 of the inlet conduit section 5 and a portion 27 outlet 
conduit section 9 adjacent the enlarged intermediate section 7 of the 
housing 3, as shown, form an obtuse angle therebetween. Also, as 
illustrated, the inlet conduit section, at the distant end 15, may be 
co-axial with the distant end 23 of the outlet conduit member. The outer 
shape of the wall 11 adjacent end 15 and the outer shape of the wall 19 
adjacent end 23 may be formed in an octagonal shape to accommodate a 
wrench for ready assembly into a system to be monitored. 
The enlarged intermediate section 7 has an opening 29 in the wall 31 
thereof, the opening 29 being spaced from and axially aligned with the 
forwardly extending flange 17 of the inlet conduit section 5. A portion 33 
of the wall 27 extends outwardly from the wall 11 of the inlet conduit 
section 5, spaced from flange 17. The wall of the inlet conduit 5 has a 
first bore 35 formed therethrough which is spaced from the forwardly 
extending flange, and a vent valve 37 in line 39 communicates with the 
bore 35 to provide venting of the inlet conduit 5 to the atmosphere. 
Likewise, the wall 27 of the enlarged intermediate section 7 has a second 
bore 41 formed therethrough, preferably adjacent opening 29, and a drain 
valve 43 in line 45 communicates with the bore 41 to provide for draining 
of the enlarged intermediate section 7. 
A support member 47 is disposed in the enlarged intermediate section 7, 
which support member 47 has a base 49 secured in and sealing the opening 
29 in the enlarged intermediate section 7. Preferably, sealing of the base 
49 to the wall 27 of the enlarged intermediate section 7 is effected by 
threadedly engaging threads 51 on the base 49 with threads 53 on the wall 
27 about the opening 29. A more complete seal is obtained by providing a 
groove 55 about the cylindrical base 49 in which a sealing member 57, such 
as an 0-ring, is secured which contacts the wall 27 about opening 29. The 
support member 47 has means 59 for supporting a screen 61, in the enlarged 
intermediate section 7 of the housing 3, adjacent the forwardly extending 
flange 17 of the inlet conduit section 5. The support means 59 has 
passageways 63 therethrough for the passage of fluid which flows through 
screen 61 to the outlet conduit section 9 of the housing 3. 
In the present preferred embodiment of the strainer assembly 1, the means 
59, for supporting the screen 61 in the enlarged intermediate section 7 of 
the housing 3, adjacent the forwardly extending flange 17 of the inlet 
conduit section 5, comprises a plurality of posts 65 which extend towards 
the flange 17 from the base 49, with the passageways 63 being the open 
areas between adjacent posts 65. Three such posts 65 are shown in the 
drawings, although the particular number of such posts may vary. The posts 
65 preferably carry a ring member 67 at the distal ends 69 thereof to aid 
in supporting the screen 61, the ring member 67 having a central opening 
71, with the screen 61 extending completely across the central opening 71. 
Most preferably, the ring member 67 has a recess 73 in the upper surface 
75 and an inwardly directed ledge 77 about the periphery of the surface 75 
facing the forwardly extending flange 17 when the strainer assembly is 
assembled. The screen 61 may thus be snap-fitted under the ledge 77 to 
secure the screen. 
The screen 61, as illustrated in FIGS. 5-7, has a circular support band 79 
with a screen-like mesh 81 attached to the support band 79 extending 
across and filing an open area of the support band. As shown in FIG. 6, 
the screen 61 may comprise a circular support band 79 having two 
disc-shaped bands 83 and 85, with the screen-like mesh 81 sandwiched 
therebetween and secured thereby. Or, as shown in FIG. 7, the screen 61 
may comprise a circular support band 79 having a single disc-shaped band 
87, with an inwardly and downwardly extending inner shoulder 89, with the 
screen-like mesh 81 secured at the edge 91 thereof to the shoulder 89. The 
ledge created by the bands 83, 85 or 87 will help to keep particles from 
falling off the screen-like mesh 81 during disassembly. The screen-like 
mesh 81 of screen 61 may be formed from any suitable material, such as 
stainless steel or a polyester material, the latter preferred due to cost 
and formability. A polyester screen-like mesh 81 would be disposable, and, 
in the event of rupture, only a few soft fibers of polyester would be 
introduced into the oil system of a turbine-generator. During operation of 
the strainer assembly 1 to determine the presence of solid particulates in 
a fluid, such as the oil of a turbine generator system, the strainer 
assembly is inserted into the desired section of the system. The assembled 
strainer assembly is engaged with the desired section of the system by 
engaging the threads 13 of the inlet conduit section 5 and the threads 21 
of the outlet conduit section 9 engaged with threads on portions of the 
desired section of the turbine generator system. The flow of oil is then 
effected, with the oil flowing through inlet conduit section 5 and through 
the screen 61 which will collect any solid particulates carried by the 
oil. The oil, after passage through screen 61, then passes around the 
posts 65 and through passageways 63 to the outlet conduit section and is 
returned to the turbine generator system. After a predetermined period of 
time, the flow of oil is stopped. With vent valve 37 and drain valve 43, 
which are closed during passage of oil through the strainer assembly 1, 
opened, residual oil contained in the strainer assembly is removed. The 
support member 47 is then removed from the remainder of the strainer 
assembly 1, by unthreading the threads 51 on base 49 from threads 53 on 
wall 27 using the hand grip 99. The screen 61 is then readily removed from 
the support member 47 and a new screen 61 engaged therewith for subsequent 
use. The removed strainer 61, being disc-shaped is easy to clean and 
simple to manufacture as a disposable part. The present strainer assembly 
can be disassembled for sampling without the need of tools and the bottom 
accessibility feature lessens the chance of contamination of the screen 
from any air born dust particles. Using the elbow-shaped conduit, the 
present strainer assembly is less restrictive to flow than most 
basket-type strainers. 
If desired, in order to perfect a seal between the forwardly extending 
flange 17 of the inlet conduit section 5 and the screen 61, a groove 93 
may be formed in the end face 95 of the flange 17 and a sealing member 97, 
such as an 0-ring, secured in the groove and placed in contact with the 
circular support band 79 of a screen 61 when the strainer assembly is 
assembled. When the support member 47 is formed from a metal casting, 
sealing member 97 is desired. However, the circular support band 79 may be 
formed from a hard but flexible material, such as a hard rubber, and 
adequate sealing may be then achieved without the use of sealing member 
97. 
Manual placement and removal of the support means 59 is readily achieved by 
use of a handgrip 99, that is provided on the exposed surface 101 of the 
base 49 of the support member 47. The inner surface 103 of the base 49 may 
have a concave recess 105 formed therein to provide a beneficial flow 
pattern to fluid striking the same, so as to divert the fluid outwardly 
through the passageways 63 between the posts 65.