Screen Sizing Information

ISI screens can be designed and fabricated in a variety of shapes and sizes to meet project requirements.  Each project screen is customized for the site and its environmental needs.  Design criteria to assist in sizing a screen can be found here.

Cylinder Screens are typically used on submerged intakes when there is adequate depth available.  Cone screens are typically used when the intake is at or near the river or lake bottom.  Consider multiple screen units for large intake volumes.

Please contact us to help you determine the appropriate screening options and sizing requirements.

Brushed Cylinder Screen

 

Model Unit Dimensions
A - B - C - D
Unit Weight Screen Surface Area Slot Velocity @
0.5 ft/sec
(0.08 m/s)
Approach Velocity @
0.2 ft/sec
(0.06 m/s)
Approach Velocity @
0.33 ft/sec
(0.10 m/s)
Approach Velocity
@ 0.4 ft/sec
(0.12 m/s)
ISI T30-42 30” - 42” - 36” - 128” 1,400 lbs. 55.0 ft2
(5.11 m2)
13.7 cfs
(388 l/s)
9.4 cfs
(266 l/s)
18.1 cfs
(513 l/s)
22.0 cfs
(623 l/s)
ISI T36-54 36” - 54” - 48” - 164” 1,900 lbs. 84.8 ft2
(7.88 m2)
21.2 cfs
(600 l/s)
17.0 cfs
(481 l/s)
28.0 cfs
(793 l/s)
33.9 cfs
(960 l/s)
ISI T42-66 42” - 66” - 60” - 200” 2,200 lbs. 119.5 ft2
(11.10 m2)
29.9 cfs
(847 l/s)
23.9 cfs
(676 l/s)
39.4 cfs
(1116 l/s)
47.8 cfs
(1354 l/s)
ISI T48-72 48” - 72” - 60” - 212” 2,900 lbs. 150.8 ft2
(14.01 m2)
37.5 cfs
(1062 l/s)
30.2 cfs
(885 l/s)
48.8 cfs
(1382 l/s)
60.3 cfs
(1708 l/s)
ISI T60-90 60” - 90” - 60” - 248” 4,500 lbs. 235.6 ft2
(21.89 m2)
58.9 cfs
(1668 l/s)
47.1 cfs
(1334 l/s)
77.8 cfs
(2203 l/s)
94.2 cfs
(2667 l/s)
ISI T72-96 72” - 96” - 72” - 276” 7,200 lbs. 301.6 ft2
(28.00 m2)
75.4 cfs
(2135 l/s)
60.3 cfs
(1707 l/s)
99.5 cfs
(2817 l/s)
120.6 cfs
(3415 l/s)

 

Units up to 8 feet in diameter available - Call for more information

  1. Allowable flow rates above are based on using wedgewire screens with 50% open area.  ISI typically uses #69 wedgewire (screen width 1.75mm), but other options are available.
  2. Maximum recommended slot velocity is 0.5 fps for sites subject to heavy debris or poor hydraulic conditions.
  3. Cylinder lengths are typically limited to 1.5 times the diameter as shown in the table above. Shorter cylinder lengths are available.
  4. Manifold (and overall) length is dependant on retrieval track width and opening requirements.
  5. Many fisheries agencies use a maximum approach velocity criteria instead of slot velocity. Approach Velocity is the component of velocity perpendicular to the screen surface and measured 3 inches away. A minimum open area is generally specified.
  6. Single cylinder units (i.e. “drums” or half of a “T”) are also available
  7. Regulatory design criteria varies and typically depends on fish protection needs. Call for information on slot sizes below 1mm

 

Brushed Cone Screen

NOTE: Cone screens are often positioned with the screen surface less than fully submerged. Please contact us for flow rating curves in these conditions.

Model Unit Dimensions 
A - B - C
Unit Weight Screen Surface Area Slot Velocity
@ 0.5 ft/sec
Approach Velocity
@ 0.2 ft/sec
Approach Velocity
@ 0.33 ft/sec
ISI C66-18

18 - 66 - 35

430 lbs. 26.8 ft2 6.7 cfs (3,000 gpm) 5.4 cfs (2,400 gpm) 8.8 cfs (4,000 gpm)
ISI C78-21

21 - 78 - 35

540 lbs. 38.3 ft2 9.6 cfs (4,300 gpm) 7.7 cfs (3,400 gpm) 12.7 cfs (5,700 gpm)
ISI C96-24

24 - 96 - 35

980 lbs. 54.8 ft2 13.7 cfs (6,100 gpm) 11.0 cfs (4,900 gpm) 18.1 cfs (8,100 gpm)
ISI C120-32

32 - 120 - 35

1,170 lbs. 89.0 ft2 22.3 cfs (10,000 gpm) 17.1 cfs (8,000 gpm) 29.4 cfs (13,200 gpm)
ISI C144-41

41 - 144 - 35

1,500 lbs. 131.9 ft2 32.7 cfs (14,700 gpm) 26.2 cfs (11,700 gpm) 43.2 cfs (19,400 gpm)
ISI C168-48

48 - 168 - 35

1,900 lbs. 181.5 ft2 45.4 cfs (20,400 gpm) 36.3 cfs (16,300 gpm) 59.9 cfs (27,000 gpm)

Custom Units Available Call for more information

  1. Allowable flow rates above are based on using wedgewire screens with 50% open area.  ISI typically uses #69 wedgewire (screen width 1.75mm), but other options are available.
  2. Maximum recommended slot velocity is 0.5 fps for sites subject to heavy debris or poor hydraulic conditions.
  3. If cone screen is not fully submerged, allowable flow rates will be reduced based on the available screen area.  Call ISI for a rating table.
  4. Many fisheries agencies use a maximum approach velocity criteria instead of slot velocity. Approach Velocity is measured 3 inches from screen surface.
  5. Large diameter cone screens may be fabricated and shipped in two halves and assembled at the site.
  6. Regulatory design criteria varies and typically depends on fish protection needs