stream. Systems controlling fuel and air by line shafting and mechanical
connections will not be acceptable.]
a.
A master pressure transmitter shall be provided and connected to
the main steam header at a point where the steam pressure is to be
controlled. The master controller, which is located on the panel,
shall load the various individual boiler controllers according to
steam pressure changes. On multiple boiler installations, an
operator station shall be provided to base load or bias each
individual boiler while keeping its fuel and air controllers on
automatic. This boiler master station shall be mounted on the
control panel between the master controller and the remainder of
loading impulse from the master controller to the boiler master
station and each boiler master station output.
b.
A [fuel feed] [steam-flow] transmitter shall be provided for each
boiler and shall feed a signal to a fuel feed controller. Each
fuel feed controller shall be loaded by the master controller for
the rate of [fuel feed] [steam-flow] corresponding to the rating
of the respective boiler. The controller shall operate the fuel
device controlling the rate of fuel feed. The controller shall
incorporate proportional plus reset control features.
c.
Air-flow transmitter shall be provided for each boiler. The
air-flow controller shall control from this signal or in such
other manner as to maintain a predetermined ratio of air to fuel.
An indicator shall be provided showing the amount of any manual
adjustment to the air-to-fuel ratio. The controller shall have
proportional plus reset modes of control.
d.
Each automatic controller shall have a manual-to-automatic station
and indicator on the control panel that will provide for selecting
either automatic control or manual control and also will provide
controlled manually while the other functions remain on automatic
control. The manual control station shall be complete with all
necessary indicators and provide bumpless balanceless transfer
from automatic control to manual control and vice versa.
e.
be sized to operate the device to be positioned and shall be so
mounted that a rigid mechanical connection to the device being
operated can be used. The units shall remain in the last position
to which they moved in event of failure of the operating medium.
disconnecting the linkages during power failure or other
air-drive units for interlock with safety systems. Retransmitting
devices shall be placed on all power units for remote indication
on the boiler panel of the position of the operator at any time.
If electric operators are utilized, gear trains on the units shall
be oil-immersed.
f.
Furnace draft controller of the modulating type shall be provided
with each boiler. The draft controller shall be designed to
maintain automatically within 2.5 Pa 0.01 inch water column the
desired furnace draft for which it has been set manually. The
SECTION 15559A
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