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Oil Tank Sight Glasses

Often referred to as BS&W bowl (bottom sediment and water bowl), our Oil Sight Glass (OSG) can play a critical role in early detection of contamination and allow for constant monitoring of what’s in your oil that can decrease equipment life. Users have an immediate, crystal-clear visual inspection of the oil and a magnified view of the presence of sediment, thanks to an innovative white bottom design. The OSG has the versatility to be installed vertically or horizontally to a drain port depending on space needs for the application. With the addition of indication marks on the side of the bottle, you can quickly and easily monitor the rate of water accumulation. According to the latest API 610 standard (12th edition, January 2021) the use of a BS&W bowl is now recommended for wet sump oil lubricated pumps to detect the presence of water and other gross contamination.



Part Number Description Overall Length Outside Diameter
DC-OSG1X250 1 oz X 1/4″ 3.0 in / 7.62 cm 1.72 in / 4.37 cm
DC-OSG1X375 1 oz X 3/8″ 3.0 in / 7.62 cm 1.72 in / 4.37 cm
DC-OSG1X500 1 oz X 1/2″ 3.0 in / 7.62 cm 1.72 in / 4.37 cm
DC-OSG3X250 3 oz X 1/4″ 3.15 in / 6.35 cm 2.50 in / 6.35 cm
DC-OSG3X375 3 oz X 3/8″ 3.15 in / 6.35 cm 2.50 in / 6.35 cm
DC-OSG3X500 3 oz X 1/2″ 3.15 in / 6.35 cm 2.50 in / 6.35 cm

High Volume Vertical Acrylic Sizes

Part Number Description Overall Length Outside Diameter
DC-OSG16X500 16 oz X 1/2″ 5 in / 12.70 cm 3.5 in / 8.89 cm
DC-OSG32X500 32 oz X 1/2″ 5 in / 12.70 cm 4.5 in / 11.43 cm

Vertical and horizontal acrylic available in 1 oz and 3 oz sizes while supplies last.


By the Numbers

1. Oil Visibility
The view is crystal clear and now you can inspect your oil from the top of the sight glass.

2. Extremely Durable
The inherently strong polyamide material will withstand the toughest environments.

3. Chemical Compatibility
Polyamide is compatible with all gear and mineral oils, most synthetic oils, and diesel fuel.

4. UV Resistant
Excellent weathering allowing it to withstand exposure to sun, rain, and other extreme conditions.

5. Indication Marks
Visually inspect and monitor the rate of accumulation of water in the oil sight glass.

6. Sediment Drainage
A sloped floor for better evacuation and resetting of the oil sight glass.

7. White Bottom
Provides a highly visible canvas and virtually magnifies the presence of sediment.



  • Transparent polyamide
  • Brass Hex nipple
  • Brass drain valve

Recommended Temperature Range

  • -40˚F to 200˚F
  • -40˚C to 93˚C

Maximum Operating Pressure

  • 65 psi
  • 4.48 bar

Chemical Compatibility
All gear and mineral oils and most synthetic oils

Available Options

  • 1/4″, 3/8″, and 1/2″ Hex nipples
  • 1oz and 3oz
  • 16oz and 32oz sizes
  • Available in acrylic
  • Stainless steel fittings
  • Magnetic drain valve for collecting ferrous material


  • Pumps
  • Gearboxes
  • Storage Tanks
  • Fluid-Lubricated Machinery


  • Allows for the observation of free water within the wet sump
  • Spring loaded petcock allows free water to be drained off during normal operators rounds
  • A darkening of the oil can be indicative of degradation of the fluid and can be used in conjunction the ASTM D1500 color comparator chart
  • The presence of a hazy or cloudy oil/water emulsion can indicate a more serious issue such as severe fluid degradation of chemical contamination
  • The observation of “shiny” particles in the bottom of the BS&W bowl can indicate active bearing wear

Did You Know...

Additional Resources