For Sales & Service Call 1+201.419.6111 or sales@nciweb.com 

Clark Reliance Flat Glass Gages

Clark Reliance Level GagePressures from 450 to 2000 psi - Steam generating boilers are equipped with at least one gage glass. It indicates the level of water in the boiler so the operator can be assured that the level is within safe limits. The level must be high enough to completely cover all parts of the heating surface to prevent overheating and low enough so that water is not carried over with the steam. All such boiler installations must comply with ASME and CSA regulations.

Note the drain valve which permits all the connections to be blown through daily to be sure that they are not plugged with sludge or sediment. The valves can be slow or quick opening. This method of attachment is commonly used only on boilers that provide a straight vertical surface, unobstructed by reversing chamber or smoke box, such as the cast-iron heating boiler or some types of vertical boilers.

A more usual construction is to have the gage glass connected to a water column which in turn is connected to the boiler. The water column acts as a reservoir to dampen agitation in the water. In addition, the column traps any sludge or sediment and prevents it from collecting in the glass connections. The column also provides a place for installation of high and low level alarms and controls. Trycocks are installed on the column to provide a means of point level detection when the gage glass is being replaced.

Note that the bottom of the gage glass must be 76 mm above the top row of firetubes, flue or crownsheet, to prevent overheating. This will ensure that the tubes are covered even when the gage glass shows zero level. Heating boilers have a lowest permissible water level marked by the manufacturer. The lowest visible level in the gage glass should be 50 mm or more above this marker.

When a water column houses an alarm, a water level control, or a low-water fuel cutoff device, isolating valves are not permitted in the piping between the column and the boiler.

Click to openFEATURING MICA PROTECTION & HEAVY DUTY CONSTRUCTION

The precision manufacturing of these time tested designs assures outstanding performance and service life.  Choose from single, double, or triple windows for ultimate visibility. Clark Reliance Flat Glass Gages FG Series feature four function designs. Larger View Of CutaWay

FG Series Gages provide wide body construction for added strength and rigidity.  Tempered flat glass composition of premium quality to resist thermal shock.   All glass is tested for surface trueness prior to assembly and is protected with a high quality mica shield for steam applications.

All models feature finger-clamps which impart a uniform, perpendicular load across the glass surface, assuring gasket tightness.  This design allows easy dismantling for cleaning and servicing.  A window slot, 5/8" wide, provides high visibility gage reading.  For many Prismatic Gages installations,  Water gage illuminators are recommended to improve gage readability. 

Single Window Gages - MINIMUM WATER GAGE CENTERS
  VISIBILITY 404RS SG854
MODEL NO. IN. MM IN. MM IN. MM.
FG404 6-5/8 168 14 356 17 432
FG405 7-3/4 197 16 406 18 457
FG406 9 229 17 432 20 508
FG407 10-1/8 257 18 457 21 533
FG408 11-3/4 298 20 508 22 559
FG409 12-1/2 318 20 508 23 584
DOUBLE WINDOW - MINIMUM WATER GAGE CENTERS
  VISIBILITY 404RS SG854
FG466 15 381 24 610 26 660
FG477 17-1/2 444 26 660 29 737
FG488 20 508 29 737 31 787
FG499 21-1/2 546 30 762 33 838
Three or more window models are available upon request.
Single Window Gages
  Visibility Minimum Water Gage Centers
Model Number Inches MM Inches MM
FG904 6-5/8 168 17 432
FG905 7-3/4 197 18 457
FG906 9 229 20 508
FG907 10-1/8 257 21 533
FG908 11-3/4 298 22 559
FG909 12-1/2 318 23 584
Double Window Gages
FG966 15 381 26 666
FG977 17-1/2 444 29 737
FG988 20 508 31 787
FG999 21-1/2 546 33 838
Minimum centers based on using Clark Reliance Valve Series SG854 & SG860
SINGLE WINDOW GAGES
MODEL NO. VISIBILITY Minimum Water Gage Centers
  IN. MM IN. MM
FG1504 6-5/8 168 20 508
FG1505 7-3/4 197 21 533
FG1506 9 229 23 584
FG1507 10-1/8 257 24 609
FG1508 11-3/4 298 25 635
FG1509 12-1/2 318 26 660
DOUBLE WINDOW GAGES
FG1566 15 381 29 737
FG1577 17 432 31 787
FG1588 19 495 33 838
FG1599 21 533 35 889
SINGLE WINDOW GAGES
MODEL NO VISIBILITY Minimum Centers
  IN. MM IN. MM
FG2004 6-5/8 168 15 381
FG2005 7-3/4 197 16 406
FG2006 9 229 17 432
FG2007 10-1/8 257 19 483
DOUBLE WINDOW GAGES
FG2055 12 305 20 508
FG2066 15 381 23 584
FG2077 17 432 25 635