POWER ENGINEERING TECHNOLOGY
(PET YR 1): 4B POWER BOILERS EXAM
A6boiler6with6a6single6safety6valve6has6a6MAWP6or610006kPa.6What6is6the6maximum6boil
er6pressure6permissible6when6the6safety6valve6is6blowing?
a.610606kPa
b.610006kPa
c.610306kPa
d.611006kPa6-6ans--a
If6a6high6pressure6boiler6is6on6high6fire6with6the6main6steam6stop6valve6closed,6the6safety6
valves6must6ensure6that6the:
a.6boiler6pressure6does6not6exceed6the6maximum6allowable6working6pressure6of6the6boil
er6by6more6than66%
b.6boiler6pressure6does6not6exceed6the6set6point6of6the6safety6valve
c.6steam6pressure6does6not6exceed6the6MAWP6of6the6boiler
d.6boiler6pressure6does6not6exceed6the6hydrostatic6test6pressure6-6ans--a
If6a6boilers6safety6valves6have6insufficient6relief6capacity,6the6boiler6pressure6may:
a.6not6rude6more6than615%6of6the6MAWP
b.6remain6at6the6MAWP
c.6force6water6from6the6boiler6causing6a6low6water6condition
d.6rise6more6than66%6of6the6MAWP6-6ans--d
The6blowdown6on6a6safety6valve6is6adjusted6by6turning6the:
a.6valve6disc
b.6adjusting6nut
c.6adjusting6ring
d.6valve6seat6-6ans--c
The6popping6pressure6of6a6safety6valve6____________6without6replacing6its6spring.
a.6cannot6be6changed
b.6can6only6be6increased6by65%
c.6can6only6be6decreased6by65%
d.6can6be6changed6by6plus6or6minus65%6-6ans--d
The6safety6valves6on6a6boiler6are6set6to6open6at613806kPa.6The6boiler6MAWP6is613806kP
a.6How6much6higher6can6the6boiler6pressure6rise6above613806kPa6if6it6is6fired6at6full6capa
city6with6the6steam6outlet6valve6closed?
a.637.56kPa
b.641.46kPa
c.606kPa
,d.682.86kPa6-6ans--d
What6is6responsible6for6the6popping6action6of6a6safety6valve?
a.6amount6of6spring6compression
b.6blow6down6ring6adjustment
c.6a6lip6on6the6valve6disc
d.6temperature6of6the6steam6-6ans--c
To6increase6the6opening6pressure6of6a6safety6valve:
a.6raise6the6blowdown6ring
b.6increase6spring6compression
c.6reduce6spring6compression
d.6lower6the6blowdown6ring6-6ans--b
A6safety6relief6valve6is6similar6to6a6safety6valve6except6that6it:
a.6does6not6have6a6blowdown6ring6or6bottom6guides
b.6must6have6greater6blowdown
c.6may6have6an6isolation6valve6placed6between6it6and6the6pressure6vessel
d.6must6discharge6directly6to6the6atmosphere6-6ans--a
When6is6a6stop6valve6allowed6between6a6heating6boilers6safety6valve6and6the6boiler6dru
m?
a.6only6if6the6stop6valve6is6locked6open
b.6if6there6is6more6than6one6safety6valve
c.6never
d.6if6the6stop6valve6is6the6quick6opening6design6-6ans--c
If6a6safety6valve6leaks6after6a6try6lever6test,6the6operator6should:6
a.6reduce6the6boiler6pressure
b.6operate6the6try6lever6several6times6to6blow6away6foreign6material
c.6for6a6gag6to6the6safety6valve
d.6reduce6boiler6pressure6and6call6the6chief6engineer6-6ans--b
Temperature6relief6devices6can6open6on6a6rise6in6temperature6by6the6expansion6of6a6wax
6filled6rod6or6by6the:
a.6melting6of6the6alloy6in6a6fusible6plug
b.6melting6of6a6fusible6link
c.6action6of6a6bi6metal6strip
d.6action6of6a6bellows6-6ans--a
A6high6gas6pressure6fuel6cut6off6switch:
a.6closes6when6gas6pressure6is6too6high
b.6automatically6resets6itself6when6the6gas6pressure6is6restored
c.6is6located6upstream6of6the6automatic6fuel6valve
d.6prevents6excessive6fuel6pressure6from6creating6an6unstable6flame6condition6-6ans--d
, A6flame6failure6device6is6unresponsive6to:6
a)6ultraviolet6light6
b)6infra-red6light6
c)6visible6light6
d)6fuel6flow6-6ans--d
A6photoelectric6flame6scanner:
a.6uses6a6pilot6stat
b.6conducts6current6through6the6flame
c.6requires6a6clear6line6of6sight6to6the6flame
d.6produces6a6steady6voltage6signal6-6ans--c
All6flame6safeguard6devices6have6the6following6in6common:
a.6close6the6safety6shut6off6valves6in6case6of6pilot6flame6failure6or6main6burner6failure
b.6are6limited6to6temperature6comfortable6to6the6hand
c.6monitor6the6pilot6flame6and6main6burner6simultaneously
d.6activate6an6alarm6system6if6flame6failure6is6detected6-6ans--a
If6a6shutdown6occurs6during6normal6firing6of6a6boiler6and6the6steam6pressure6is6below6th
e6normal6cut6off6value,6the6problem6could6be:6
a.6an6interlock6such6as6the6combustion6air6proving6switch6has6failed
b.6main6flame6trial6failure
c.6pilot6flame6trial6failure
d.6igniter6transformer6failure6-6ans--a
A6low6fire6start6switch
a.6is6a6type6of6manual6over6ride
b.6ensures6the6purge6takes6place6with6the6damper6in6the6low6fire6position
c.6acts6as6a6pre6ignition6interlock6to6ensure6minimum6damper6setting6during6ignition6
d.6is6closed6when6the6damper6is6at6high6fire6-6ans--c
The6primary6function6of6a6burner6management6system6is6to:
a.6alert6the6operator6of6adverse6operating6conditions
b.6maintain6the6air-fuel6ratio6of6the6burner
c.6start6of6stop6a6burner6following6a6safe6sequence
d.6regulate6the6air6flow6and6the6fuel6flow6in6accordance6with6steam6demand6-6ans--c
When6an6automatic6unattended6boiler6starts6up,6the6programming6control6will6first:
a.6energize6the6ignition6transformer6and6pilot6gas6solenoid6valve
b.6start6the6post6purge6period
c.6start6the6forced6draft6fan
d.6energize6the6main6gas6valve6-6ans--c
At6the6end6of6the6pre6purge6period,6the6programming6control:
a.6opens6the6main6fuel6valve
(PET YR 1): 4B POWER BOILERS EXAM
A6boiler6with6a6single6safety6valve6has6a6MAWP6or610006kPa.6What6is6the6maximum6boil
er6pressure6permissible6when6the6safety6valve6is6blowing?
a.610606kPa
b.610006kPa
c.610306kPa
d.611006kPa6-6ans--a
If6a6high6pressure6boiler6is6on6high6fire6with6the6main6steam6stop6valve6closed,6the6safety6
valves6must6ensure6that6the:
a.6boiler6pressure6does6not6exceed6the6maximum6allowable6working6pressure6of6the6boil
er6by6more6than66%
b.6boiler6pressure6does6not6exceed6the6set6point6of6the6safety6valve
c.6steam6pressure6does6not6exceed6the6MAWP6of6the6boiler
d.6boiler6pressure6does6not6exceed6the6hydrostatic6test6pressure6-6ans--a
If6a6boilers6safety6valves6have6insufficient6relief6capacity,6the6boiler6pressure6may:
a.6not6rude6more6than615%6of6the6MAWP
b.6remain6at6the6MAWP
c.6force6water6from6the6boiler6causing6a6low6water6condition
d.6rise6more6than66%6of6the6MAWP6-6ans--d
The6blowdown6on6a6safety6valve6is6adjusted6by6turning6the:
a.6valve6disc
b.6adjusting6nut
c.6adjusting6ring
d.6valve6seat6-6ans--c
The6popping6pressure6of6a6safety6valve6____________6without6replacing6its6spring.
a.6cannot6be6changed
b.6can6only6be6increased6by65%
c.6can6only6be6decreased6by65%
d.6can6be6changed6by6plus6or6minus65%6-6ans--d
The6safety6valves6on6a6boiler6are6set6to6open6at613806kPa.6The6boiler6MAWP6is613806kP
a.6How6much6higher6can6the6boiler6pressure6rise6above613806kPa6if6it6is6fired6at6full6capa
city6with6the6steam6outlet6valve6closed?
a.637.56kPa
b.641.46kPa
c.606kPa
,d.682.86kPa6-6ans--d
What6is6responsible6for6the6popping6action6of6a6safety6valve?
a.6amount6of6spring6compression
b.6blow6down6ring6adjustment
c.6a6lip6on6the6valve6disc
d.6temperature6of6the6steam6-6ans--c
To6increase6the6opening6pressure6of6a6safety6valve:
a.6raise6the6blowdown6ring
b.6increase6spring6compression
c.6reduce6spring6compression
d.6lower6the6blowdown6ring6-6ans--b
A6safety6relief6valve6is6similar6to6a6safety6valve6except6that6it:
a.6does6not6have6a6blowdown6ring6or6bottom6guides
b.6must6have6greater6blowdown
c.6may6have6an6isolation6valve6placed6between6it6and6the6pressure6vessel
d.6must6discharge6directly6to6the6atmosphere6-6ans--a
When6is6a6stop6valve6allowed6between6a6heating6boilers6safety6valve6and6the6boiler6dru
m?
a.6only6if6the6stop6valve6is6locked6open
b.6if6there6is6more6than6one6safety6valve
c.6never
d.6if6the6stop6valve6is6the6quick6opening6design6-6ans--c
If6a6safety6valve6leaks6after6a6try6lever6test,6the6operator6should:6
a.6reduce6the6boiler6pressure
b.6operate6the6try6lever6several6times6to6blow6away6foreign6material
c.6for6a6gag6to6the6safety6valve
d.6reduce6boiler6pressure6and6call6the6chief6engineer6-6ans--b
Temperature6relief6devices6can6open6on6a6rise6in6temperature6by6the6expansion6of6a6wax
6filled6rod6or6by6the:
a.6melting6of6the6alloy6in6a6fusible6plug
b.6melting6of6a6fusible6link
c.6action6of6a6bi6metal6strip
d.6action6of6a6bellows6-6ans--a
A6high6gas6pressure6fuel6cut6off6switch:
a.6closes6when6gas6pressure6is6too6high
b.6automatically6resets6itself6when6the6gas6pressure6is6restored
c.6is6located6upstream6of6the6automatic6fuel6valve
d.6prevents6excessive6fuel6pressure6from6creating6an6unstable6flame6condition6-6ans--d
, A6flame6failure6device6is6unresponsive6to:6
a)6ultraviolet6light6
b)6infra-red6light6
c)6visible6light6
d)6fuel6flow6-6ans--d
A6photoelectric6flame6scanner:
a.6uses6a6pilot6stat
b.6conducts6current6through6the6flame
c.6requires6a6clear6line6of6sight6to6the6flame
d.6produces6a6steady6voltage6signal6-6ans--c
All6flame6safeguard6devices6have6the6following6in6common:
a.6close6the6safety6shut6off6valves6in6case6of6pilot6flame6failure6or6main6burner6failure
b.6are6limited6to6temperature6comfortable6to6the6hand
c.6monitor6the6pilot6flame6and6main6burner6simultaneously
d.6activate6an6alarm6system6if6flame6failure6is6detected6-6ans--a
If6a6shutdown6occurs6during6normal6firing6of6a6boiler6and6the6steam6pressure6is6below6th
e6normal6cut6off6value,6the6problem6could6be:6
a.6an6interlock6such6as6the6combustion6air6proving6switch6has6failed
b.6main6flame6trial6failure
c.6pilot6flame6trial6failure
d.6igniter6transformer6failure6-6ans--a
A6low6fire6start6switch
a.6is6a6type6of6manual6over6ride
b.6ensures6the6purge6takes6place6with6the6damper6in6the6low6fire6position
c.6acts6as6a6pre6ignition6interlock6to6ensure6minimum6damper6setting6during6ignition6
d.6is6closed6when6the6damper6is6at6high6fire6-6ans--c
The6primary6function6of6a6burner6management6system6is6to:
a.6alert6the6operator6of6adverse6operating6conditions
b.6maintain6the6air-fuel6ratio6of6the6burner
c.6start6of6stop6a6burner6following6a6safe6sequence
d.6regulate6the6air6flow6and6the6fuel6flow6in6accordance6with6steam6demand6-6ans--c
When6an6automatic6unattended6boiler6starts6up,6the6programming6control6will6first:
a.6energize6the6ignition6transformer6and6pilot6gas6solenoid6valve
b.6start6the6post6purge6period
c.6start6the6forced6draft6fan
d.6energize6the6main6gas6valve6-6ans--c
At6the6end6of6the6pre6purge6period,6the6programming6control:
a.6opens6the6main6fuel6valve
