Despite its small size, a boiler’s sight glass has great importance. In this post, we’ll show you how to replace a faulty sight glass. This will help keep your boilers running smoothly and your workplace safe.
Note that different types and lengths of glass will give you different readings. Always ensure that you use a glass rated for your boiler. Now let’s get started!
NO PRESSURE
Ensure the shut-off valves are tightly closed. Also, check that your boiler is completely empty of pressure and water. Make sure there is no pressure in the line before you replace the sight glass. This helps prevent serious injury. In our sight glass replacement demonstration video, we use a boiler that is not firing or hooked in.
DOWN THE DRAIN
Make sure the line has no pressure. Then, close the valve to the water column. Drain the water from the gauge using the valve at the bottom. Remove the protective rods, crack the nuts on the top and bottom of the sight, and spin them off.
Some sight glass enclosures have a “seat” or “stop” at the bottom. Make sure to include that seat when you measure your new glass. Slide the glass up and out of the enclosure, then you’re ready to measure for your new glass.
AS EASY AS 1-2-3
Measure from valve face to valve face, and be sure to factor in the depth of the seat. This measurement is how tall you should cut your replacement glass. You should now have a new piece of glass, new brass and rubber washers, and the nuts you removed earlier. To each end of the glass, slide your parts on in this order:
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Nut
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Brass washer
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Rubber washer
The brass washer keeps the nut from damaging the rubber washer. So, be sure to install these three pieces in the right order on both ends of the glass to prevent any damage.
SNUG AND SECURE
Slide the top of the glass through the bottom entrance of the top valve. You can’t push it through the top because the nuts and washers attach. Then, place the bottom of the glass into its seat or stopper. Hand-thread the nuts to start, and maneuver the washers into position. If your glass has a line in it, be sure to face it toward the back.
Now that your sight glass is in place, use a wrench to finish tightening the nuts. When tightening, aim for “slightly more than snug.” It should be secure, but not so tight that it risks breaking the glass.
FULL STEAM AHEAD
You’re now set to replace the protective rods. Your sight glass is the window to your boiler once again.
You can find sight glasses and valves here, and if you want to learn more or need help, contact us.
