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Item Number 691S-AB-2 1/2, Duplex Basket Strainer

Duplex Basket Strainer

Colton series 690 duplex basket strainers are designed for use in fluid handling systems where flow cannot be shut down for cleaning of screen.

Available in sizes from 3/4" to 8" with cast iron, cast bronze, cast steel or cast stainless steel body with threaded or ANSI flanged end connections for maximum operating pressures up to 740 psi.

3/64" perforated 304 stainless steel supplied as standard on sizes up to 1-1/2". 1/8" perforated 304 stainless steel supplied as standard on sizes 2" and larger. Other perforations, meshes and materials are available upon request.

Optional Accessories:
  • Differential Pressure Indicator for visual indication that screen is dirty or clean
  • Manual Blowdown facility
  • Automatic Blowdown facility
  • Steam Jacket
  • Magnetic Screen Inserts
  • 100% Shut-off on changeover

Unit of Measure: Imperial Metric Both

Specifications  · Accessories


Basic Model Number

691 (ANSI 125#)


2 1/2 in

Connection Type


Body Material 

Cast Iron

Plug Material 



7 1/4 in


16 3/4 in


8 3/4 in


13 13/16 in


4.50 in


6 1/8 in


4 13/16 in


8 1/4 in


6 1/2 in


5 1/8 in


11 in


1/2 in

Weight (Cast Iron)

108 lb

Body Bolt Material

Cast Iron BS1452 grade 220 min

Sleeve Material

Bronze BS1400 LG2C

Changeover Plugs Material

Bronze BS1400 LG2C

Internal Machine Parts Material

Stainless Steel BS970 303 S31

Baskets Material

304 Stainless Steel

Drain Plugs Material


Seals Material

Viton -30 ºF to 390 ºF

Maximum Working Pressure at 100 ºF

250 psi

Body Color


ANSI Class



Differential Pressure Indicator
Colton’s own purpose-designed product, which indicates when the baskets require cleaning, takes the guesswork out of maintenance. Indicator body has anodized aluminum body as standard. (Stainless steel body and internals also available).

Heating Jacket
To aid the flow of viscous liquids, etc…

100% Shut-Off On Changeover
This can be achieved by the use of a special seal within the changeover plug mechanism and eliminates leakage between chambers during cleaning

Automatic Air Eliminators
To vent air from filter, eg. after element cleaning

Magnetic Inserts
Suspended from the cover to capture metallic particles. Magnets can be nylon coated if required

Mounting Studs or Brackets
To allow the filter to be independently supported.

Pressure Equalizing Valves
Are fitted to sizes 5", 6" and 8" as standard but can be fitted to other sizes on request.


Duplex Basket Strainers - Product Data Bulletin
(PDF, 397KB)

Duplex Basket Strainers - Installation, Operating & Maintenance Instructions
(PDF, 219KB)