How to Read a Sight Glass

Sight glasses have many industrial applications.

A sight glass is a device attached along a pipe. Essentially, it is a glass window that is looked through in order to inspect the fluid or air flowing through the pipelines below. Reading a sight glass is important during manufacturing processes, because it indicates whether fluids are discolored or contaminated. It can also be used to detect blockages or debris along a pipeline. Normally, individuals are trained to read sight glasses in professional or industrial environments.

Instructions

1. Read the manufacturer's instructions on operating and using the sight glass. This will give you a clear indication of how to use it, as each device is different.

2. Clear the glass window on the sight glass. Use a clean, dry cloth to wipe it so that it provides a clear view to the pipe below.

3. Look directly at the sight glass. Try and stand so that your eye line is in front of the window. If the sight glass is in a shadow, use a torch or switch on a light so the fluid or air is clearly illuminated for viewing.

4. Observe the flow indicator on the sight glass. Checks are performed manually and visually, so look for at least a minute to make sure you obtain the correct information. Make a note of the level and speed of flow, and then check that it is correct by looking once more at the indicator.

5. Assess the transparency of the fluid or air in the pipes by looking at the clarity of the fluid itself. Compare the color and clarity you can see against the specification it should have, and spot any debris floating through the pipe.

6. Collect your information gathered from your inspection and observation of the sight glass. Write it down in one place so that you can change the pipe's flow, if necessary, or locate blockages if the flow was slow.

References

• Filter: Sight Glasses for Fluid Indication and Inspection
• Flow Meter Directory: Sight Glass /Sight Flow Indicator