Boilers and hydronics Flashcards
a pressuretrol operates due to
an increase in steam pressure AND a decrease in steam pressure
pressuretrols that operate the main burner are manual reset.
false
to set an additive operating pressurtrol that shuts the main burner ‘off’ at 130 psig and turns the main burner “on” at 120 psig, you the technician would set the adjustment screws as follows:
main scale setting 120 psig/ differential scale setting to 10 psig
the maximum setting for a high limit pressurtrol on a low pressure steam boiler would be:
15 psig
why do high input gas appliances with power burners require gas pressure switches?
because proper combustion would be affected if the manifold pressure varies too much
the maximum setting on a high-pressure gas switch is:
25% in excess of the manifold pressure stated on the rating plate
the minimum setting on a low pressure gas switch is:
50% less than the manifold pressure on the rating plate
A LWCO should be installed to maintain what level of water above the highest set of tube in a fire-tube boiler?
1 inch
referencing a float type LWCO what could happen if the blow down valve is opened too quickly?
the float could be damaged
how often does a relief valve on a steam boiler have to be recertified?
every year
the manual valve can be installed between the pressure vessel and the relief valve?
false
the aquastat utilises this control principal to operate:
hydraulic
the high limit aquastat utilised on a commercial hot water tank is known as:
ECO (energy cut off)
An aquastat used to control the main burner would be considered:
Normally closed
a flow switch on a hot water boiler system verifies operation of what device?
water flow through the boiler itself.
an “indoor/outdoor” control controls what
water temperature
a manual by-pass would be found on which of the controls listed below?
a NC zone valve
A flow switch is not adjustable:
false
a probe type LWCO uses this principle to operate:
conductivity of the boiler water
which section of the ASME code details construction regulations of a packaged steam boiler with a design pressure of 15 psig?
ASME IV
which section of the ASME code would you reference for operating and maintenance regulations for a section IV boiler
Section VI
a packaged Low temperature hot water (LTHW) boiler operating at 150 psig with a temp of 230 deg F constructed under which section of the ASME code?
ASME IV
which section of the ASME code would you reference for operating and maintenance regulations for a packed LTHW boiler?
ASME VI
according to ASME code an unsupervised LP steam boiler requires ______ LWCOs:
2
What agency is responsible for inspection and approval of LP steam and LTHW boilers in alberta?
ABSA
what assembly is utilised to prevent a LP steam boiler from complete drainage on the event of a broken wet return line?
Hartford loop
what is required when connecting a potable water make-up supply piping to a LP steam system?
reverse pressure back-flow preventor (RPBP)
when installing a cast iron sectional steam boiler, if all the steam nozzles are not required, could the installer plug the nozzle outlets that are not needed?
false
what is the grade required for a LP steam header
1/4”/ft
what part of the LP steam boiler trim protects the burner controls from exposure to live steam?
syphon pigtail
with regards to an additive DOPS, if the required system operating pressure is 10 psig and a differential set point is 2 psig, what should the main scale set point be?
8 psig
which of the boiler/s listed below are considered low-mass?
copper fin tube
cast iron sectional
scotch marine
firetube
Copper fin tube
all high-mass boilers over 400 MBH require what additional control?
LWCO
An indoor/outdoor controller typically is a/an __________ control with a 1:1 ratio.
inverse
if an indoor/outdoor controller is set for 65 deg F with the boiler water supply temperature operating at 160 deg F and the temperature outside drops to 20 deg F, what will be the new operating temperature set point of the boiler supply?
205
65 + 160 = 225 - 20 = 205 deg F
a probe type LWCO operates due to the principle of?
Conductivity
what is the maximum set point for a safety relief valve installed on a LTHW boiler?
30 psig or 160 psig depending on the maximum design pressure of the boiler
Boiler safety controls and the pop safety revive devices are recommended to be checked:
monthly
who is responsible for supplying your worksite with any necessary personal protective equipment specified by OH&S?
the employer
which portion of the light spectrum can cause “welding flash” to a worker without the proper eye protection?
ultraviolet
which type of a clothing material has a tendency to melt when in contact with a flame?
polyester AND nylon
