high temperature limit setting. A safety shutdown due to high temperature
shall require manual reset before operation can resume and shall prevent
recycling of the burner equipment.
2.3.12
Low Water Pressure Control
Provide mercury switch type. Control shall have a main scale, adjusting
screws at the top of the case, and have an internal or external bellows.
Control shall be of the type which will open an electric circuit on a drop
in pressure below a set minimum. Control shall be set and installed to
cause a safety shutdown by closing fuel valves, shutting down burner
equipment, activating a red indicating light, and sounding an alarm in the
event that water pressure in the system drops below [83 kPa (gage)] [12
psig] [_____]. A safety shutdown due to low water pressure shall require
manual reset before operation can resume and prevent recycling of burner
equipment.
2.3.13
Low Water Level Cutoff Switch
Provide float actuated type. Low water level cutoff shall cause a safety
shutdown by closing fuel valves, shutting down burner equipment, activating
a red indicating light, and sounding an alarm in the event that water level
drops below the lowest safe permissible water level established by the
boiler manufacturer and ASME BPVC SEC IV. A safety shutdown due to low
water level shall require manual reset before operation can resume and
prevent recycling of burner equipment.
2.3.14
Low Water Flow Interlock
Low water flow interlock required by MIL-B-17452 is not required.
2.3.15
Boiler Safety Control Circuits
Provide boiler safety control circuits, including control circuits for
burner and draft fan, shall be single-phase, two-wire one-side grounded,
and not over 120 volts. Provide safety control switching in ungrounded
conductors. Provide overcurrent protection. In addition to circuit
grounds, ground metal parts which do not carry current to a grounding
conductor.
2.3.16
Indicating Lights
**************************************************************************
NOTE: Include indicating lights for low gas
pressure and high gas pressure on all but size 1
burners.
**************************************************************************
Provide indicating lights as follows. Each safety interlock requiring a
manual reset shall have an individually-labeled indicating light.
Non-recycling controls/interlocks shall have the reset located on
control/interlock itself. Indicating lights shall have colors as follows
in lieu of the colors required by MIL-B-18796:
a.
Amber: Ignition on
b.
Blue: Draft
c.
Green: Main fuel safety shut-off valves open
SECTION 15515N
Page 11
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