Unit 9 - Chapter 6-Refrigeration Plant Safety Exam Questions and Answers
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Module
Refrigeration machine operator
Institution
Refrigeration Machine Operator
What concentration is R-717 refrigerant toxic at? - Answer-0.03% by volume in air.
What is the toxic level of refrigerant R0123? - Answer-In concentrations over 0.1% by volume in air.
What is R-290 (Propane) explosive range - Answer-Between 2.1% and 9.5%
What is the explosive range for R-7...
Unit 9 - Chapter 6-Refrigeration Plant
Safety Exam Questions and Answers
What concentration is R-717 refrigerant toxic at? - Answer-0.03% by volume in air.
What is the toxic level of refrigerant R0123? - Answer-In concentrations over 0.1% by
volume in air.
What is R-290 (Propane) explosive range - Answer-Between 2.1% and 9.5%
What is the explosive range for R-717? - Answer-Between 15-28%. Propane is more
flammable and explosive than ammonia.
Why is it best to measure ammonia at different heights? - Answer-Because it is lighter
than air.
When is a refrigerant harmful? - Answer-At certain concentrations in air. Depending on
refrigerant used designers consider amount of refrigerant in system and volume of
enclosed that refrigerant could leak into. Make sure if a leak happens, it will not be
hazardous.
Buildings are categorized according to their use, including: - Answer-Residential,
Institutional, Public Assembly, Commercial, Industrial.
Probability of a leak have either _____________________ according to CSA B52 -
Answer-Low or high leak
High-probability System - Answer-Located in such a manner that refrigerant could leak
into the occupied space. Example is a direct expansion system. If component should
fail, could enter the occupied space through HVAC ducting or other means.
Low-probability System - Answer-Includes indirect closed and double indirect systems.
Anything that can leak is effectively isolated from the area. Leaks won't enter space
where people are.
Direct systems that use ammonia are only permitted in ___________________. -
Answer-Industrial occupancies.
Safety considerations for direct system that uses ammonia - Answer-Area containing
the refrigeration system machinery must be separate from res of the building by tight
construction and tight fitting doors.
Access restricted to authorized personal
Ammonia detectors installed
No flame producing device or surface about 425C in vicinity where leak can occur
, All refrigerant containing parts must be installed in a special machinery room.
Indirect systems safety considerations - Answer-All refrigerant containing parts except
piping, low side components, condensers, and parts outside the building must be
installed in a Class T machinery room.
Class T Machinery room requires - Answer-Access Restriction and doors that open
outward and are self closing. Doors can't open to a public corridor or any room for
assembly. Must have at least one door that exits to outside
Openings and Penetrations regarding Class T machinery room - Answer-Must not have
openings that permit passage of escaping refrigerant to other parts of the building. Any
pipes passing through must be tightly sealed.
Class T machinery room can not have flame producing device or hot surfaces over
___________. - Answer-427C permanently installed in the room.
Where must Class T rooms be vented to? - Answer-Outdoors. Readily accessible fan
switches must be installed inside and outside the machinery room. Fan outside room
must be capable of starting the ventilation system but not stopping it.
When must a vapour detector start a ventilation fan for ammonia? - Answer-At
concentrations of 300ppm or less.
Machinery Shutdown switch - Answer-Must be provided directly outside the machinery
room, solely for shutting down machine in an emergency.
All ammonia compression refrigeration systems must have _______________. -
Answer-Pressure limiting devices. Set to not more that 90% of the system high-side
design pressure. Must be connected to the compressor discharge pipe before
compressor discharge valve.
Every positive displacement compressor with a discharge stop valve must be equipped
with a _____________________. - Answer-Pressure-relief valve.
What kind of specialty safety valve must be used on the high side of the refrigeration
system? - Answer-Ones that are not affected by back pressure.
(low side has to be able to contain entire capacity of refrigeration system because high
side will discharge into low side before venting to atmosphere)
Where must Stop valves be placed on a refrigeration system? - Answer-On each
suction inlet of each compressor, liquid pump or condensing unit
On each discharge.
On each inlet of each liquid receiver
On each outlet of each liquid receiver
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