Waterside Care and Requirements
3-12
750-211 (revised 2009)
Promethean Boilers, Model 4WI Manual
Equipment generally consists of two quick opening valves and one slow opening valve. The valves and necessary
piping are not normally furnished with the boiler. but supplied by others. All piping must be routed to a safe point
of discharge. Piping must be properly supported and fee to expand.
3.7.1.2 — Continuous Blowdown (Controlling TDS)
Continuous blowdown is used in conjunction with a surface blowoff tapping (furnished on units 60” in diameter
and larger) and is the continuous removal of totally dissolved solids in the water.
The surface blowoff opening, when furnished, is on the top center line of the pressure vessel. It is provided with an
internal collecting pipe terminating slightly below the working water level for the purpose of skimming TDS, oil, or
other impurities from the surface of the pressure vessel water.
A controlled orifice valve or an auto-sensing/metering valve is used to allow a continual, yet controlled flow of
concentrated water to drain or a place of recovery.
The flow control valve and piping are generally provided by others. All piping must be routed to a safe point of dis-
charge.
3.7.2 — Frequency of Manual Blowdown
When continuous blowdown is utilized, manual blowdown is primarily used to remove suspended solids or sludge.
The continuous blowdown removes sediment and oil from the surface of the water along with a prescribed amount
of dissolved solids.
When surface or continuous blowdown is not utilized manual blowdown is used to control the dissolved or sus-
pended solids in addition to the sludge. This will involve chemical treatment to sequester the TDS.
In practice, the valve(s) of the bottom blowdown are opened periodically in accordance with an operating schedule
and/or chemical control test. From the standpoint of control, economy and results, frequent short blows are pre-
ferred to infrequent lengthy blows. The length and frequency of the blowdown is particularly important when the
suspended solids content of the water is high. With the use of frequent short blows a more uniform concentration
of the pressure vessel water is maintained.
In cases where the feedwater is exceptionally pure, or where there is a high percentage of return condensate, Blow-
down may be employed less frequently since less sludge accumulates in the pressure vessel. When dissolved and/or
suspended solids approach or exceed predetermined limits, manual blowdown to lower the concentrations is
required.
It is generally recommended that a steam boiler be blown down at least once in every eight-hour period, but fre-
quency may vary depending upon water and operating conditions. The blowdown amounts and schedule should be
recommended by your local Cleaver-Brooks authorized representative.
A hot water boiler does not normally include openings for surface blowdown and bottom blowdown since blow-
downs are not practiced. The need remains to be alert to system water losses and corresponding amount of raw
water make-up. A water meter is recommended for water make-up lines.
Summary of Contents for 4WI
Page 46: ...Burner Operation and Control 2 22 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
Page 62: ...Waterside Care and Requirements 3 16 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
Page 70: ...Sequence of Operation 4 8 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
Page 114: ...Adjustment Procedures 6 28 750 211 revised 2009 Promethean Boilers Model 4WI Manual...
