750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
8-5
8.4 — Water Gauge Glass
On a steam boiler, the head mechanism of the low-water cutoff device(s) should be removed from the bowl at least
semi-annually to check and clean the float ball, the internal moving parts, and the bowl or water column.
Remove the pipe plugs from the tees or crosses and make certain the cross-connecting piping is clean and free of
obstructions. Controls must be mounted in a plumb position for proper performance. Determine that piping is
vertically aligned after shipment and installation and throughout life of equipment.
FIGURE 8-5. Low Water Cutoff Piping
A blowdown of the water controls on a steam boiler should be performed daily. Open the drain valve slowly to pre-
vent float damage.
8.3.2 — Hot Water Boiler
It is impractical to blowdown the low-water cutoff devices on a hot water boiler since the entire boiler and system
is flooded. Many hot water systems are fully closed and any loss of water will require make-up and additional feed-
water treatment that might not otherwise be necessary. Since the boiler and system arrangement usually make it
impractical to perform daily and monthly maintenance of the low-water cutoff devices, it is essential to verify
proper operation. Remove the operating mechanism from the bowl annually or more frequently, if possible, to
check and clean float ball, internal moving parts, and the bowl housing. Also check the cross-connecting piping to
be certain that it is clean and free of obstruction.
8.4 — Water Gauge Glass
A broken or discolored glass should be replaced at once. Periodic replacement should be a part of the maintenance
program. Always use new gaskets when replacing a glass. Use a proper size rubber packing. Do not use loose pack-
ing which could be forced below the glass and possibly plug the valve opening.
Close the gauge glass valves when replacing the glass and open the drain valve to release any pressure. Slip a pack-
ing nut, a packing washer, and packing ring onto each end of the glass. Insert one end of the glass into the upper
gauge valve body far enough to allow the lower end to be dropped into the lower body. Slide the packing nuts onto
each valve and tighten.
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