reducing valves are used for reducing the steam pressure to the deaerating
heater, the valves shall be the single seated type. The sensing lines
shall be connected to the steam space in the deaerator or at least 3 m 10
feet downstream of the pressure reducing valve.
2.26.7.5
Thermostatic Regulating Valves
**************************************************************************
NOTE: If a hot water generator is not installed,
this subparagraph will be deleted.
**************************************************************************
Valves of the self-contained type to control water temperature within the
domestic hot water generator by regulating the steam supplied to the
Thermostatic regulating valves shall be designed for a steam working
pressure of 1.4 MPa 200 psig and shall operate at the pressure shown. The
valves shall be adjustable within an operating range of approximately 38 to
71 degrees C 100 to 160 degrees F and shall maintain the desired water
temperature within plus or minus 3 degrees C 5 degrees F.
2.26.7.6
Valves shall have cast-iron or steel bodies and shall be equipped with
corrosion-resistant trim and valve seats. The valves shall be properly
guided and shall be positive closing to prevent leakage. Adjustment of the
desired back pressure shall cover a range between 34 to 103 kPa 5 to 15 psig.
The adjustment shall be effected externally, and any shafts extending
through the valve body shall be provided with adjustable stuffing boxes
having renewable packing.
2.26.7.7
Boiler Automatic Feedwater Recirculating Control Valve
**************************************************************************
NOTE: If automatic recirculation valve is not
utilized, delete this paragraph.
**************************************************************************
Valve shall be the self-contained self-powered type. The unit shall
automatically program the recirculation flow when required and assume all
functions for prevention of the backflow of the main feedwater flow, for
detection of low flow, for cycling of the control valve, and for the
pressure reduction for liquid delivery to the low-pressure feedwater
heater. The valve assembly shall be flanged type with flanged spools
provided in both the main line and recirculation line for ease of
disassembly.
2.26.8
Exhaust Heads
Exhaust heads for the discharge of steam to atmosphere shall be one-piece
plate steel, semisteel, or cast-iron construction with internal baffle
arrangement for the removal of entrained condensate and oil, and with
provision for drain connection. Flow area through unit shall be larger
than connecting pipe.
2.26.9
Strainers
The strainer body connections shall be of the same size as the pipelines in
which the connections are installed. The strainer bodies shall be heavy
SECTION 15559A
Page 77
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