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YARWAY COLOR-PORT
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
2 PRINCIPLE OF OPERATION
2.1 Operation - Water level gauges use the
principle of a liquid seeking a common level
between two connected vessels. The top of
the gauge glass is connected to the steam
space of the vessel. The bottom of the gauge
is connected below the normal water level
of the drum. This arrangement will allow
the liquid in the gauge glass to seek a level
indicative of the level in the vessel.
2.2 Accuracy - The water in the gauge glass is
cooler than the water in the vessel and is
therefore denser. This results in a gauge
water level which is lower than the true
water level in the vessel. The operator must
be cautioned to look for other conditions
which may also lead to variations in gauge
glass levels. Plugged connection lines will
cause abnormal level readings which can be
corrected by proper washdown. Steam leaks
will reduce the pressure in the steam space
of the gauge and will cause the water level
in the gauge to rise. Steam leaks should be
properly corrected to prevent damage to the
gauge gasket seating surface as well as to
prevent false readings.
2.3 Glass and Mica - At boiler pressures
above 300 psig, high temperature water
will corrode unprotected gauge glass.
Yarway protects the gauge glass from
corrosive attack by installing a thin sheet
of ruby mica on the inner face of each port;
however, this protection is not permanent.
Continual exposure to high temperature,
high pressure water will also corrode the
mica shield. The rate at which this corrosion
occurs is significantly less than that of
glass, and is dependent upon a number of
factors. Generally, the higher the operating
temperature, the higher the rate of attack.
Yarway recommends each customer establish
a preventative maintenance schedule which
insures the mica-gasket-glass assembly is
replaced prior to the dissolution of the mica
shield.
In service gauges that have glass which
appears white or is opaque should be isolated
immediately and the mica-gasket-glass
assembly should be replaced before returning
to service. Should any question develop on the
condition of the gauge glass, the procedure
given under the section on preparation for
washdown, auxiliary service or gauge inspection
should be used to evaluate port glass condition.
WATER LEVEL GAUGES & WELBLOC
®
WARNING
Failure to promptly replace the mica-gasket-glass
assembly that appears white or opaque can result
in catastrophic failure of the glass with violent
discharge of hazardous high velocity steam. The
discharge of high velocity steam can result in
severe personal injury and property damage.
3 INSTALLATION OF GAUGE SYSTEM
CAUTION
Gauge should not be subjected to acid wash
cleaning. Gauge must be isolated from this
process or replaced with a boil out gauge during
startup or cleaning.
3.1 If the gauge is furnished with an alarm
water column, water column, or gauge
isolation valves, they should be installed on
the proper connections prescribed for the
vessel. Any unused connections on some
models of valves furnished with multi-
connections should be sealed using the
plugs furnished.
3.2 Gauges furnished with Welbloc
valves (see Figure 3C) are installed as
follows:
3.2.1 Insert gaskets into groove of large
groove face flanges and mount gauge
(large tongue face flange) with studs
and nuts provided.
3.2.2 Mount the chain wheels (9) on valve
stems using nuts (16) and washers
(19) furnished. The lower chain wheel
should be mounted with the hub to the
outside, so that the upper chain hangs
to the outside and clear of the lower
chain wheel.
3.3 Gauges furnished with stuffing box (S/B)
isolating gaugecocks (refer to gauge cock
manual for the type of S/B gauge cocks
provided) are installed as follows:
3.3.1 Remove upper & lower nipple
stuffing box packing glands from the
gaugecocks.
3.3.2 Install packing gland and bottom ring
on top gauge nipple. Install packing
gland on lower gauge nipple.
3.3.3 Install the packing on the upper and
lower gauge nipples in the sequence
specified in the packing instructions
supplied with the packing.
3.3.4 Insert the gauge into the upper S/B
gaugecock first, and then the lower S/B
gaugecock.
3.3.5 Rotate the gauge to the desired
viewing angle, install and tighten the
upper and lower packing glands to the
gaugecocks.
GAUGE VALVES
®
FIGURE 1
Typical Gauge Assembly
3.3.6 Mount the chain wheels on gaugecock
stems using nuts and washers
furnished. The lower chain wheel
should be mounted with the hub to the
isolating
outside, so the upper chain hangs to
®
the outside and clear of the lower chain
wheel.
2
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