QJ- Freeze Protection Flashcards
What is the purpose of the QJ system?
To prevent the freezing of water in selected station instrument lines, piping, pumps, tanks, nozzles, and valves which are exposed to cold weather
What powers the QJ heater control panels?
NH
Which freeze protection panel is powered by the QA system?
WRF panel
What systems utilize QJ?
CH, NC, WC, CM, CW, PW, SC, CT, TB, DS, and DW
In the QJ system, to what voltage do the step down transformers supply to the panels? Where are the transformers located?
120 VAC
next to their associated control panel
What does a white light on the QJ panels indicate?
That the circuit is energized
In the QJ system, what controls the freeze protection heaters when the switch is in AUTO?
Ambient and/or line thermostats
Regarding the QJ heaters, what does self-regulating mean and what does it protect against?
Self-regulating means they respond to temperature variations anywhere along the heater length
Protects against overheating even when the heater is overlapped
How many ambient thermostats are provided for each freeze protection panel? What is their fixed setpoint?
Two
40F
Turn on at 40 and decreasing, turnoff at 40 increasing
Since the CST is safety related, what else is installed to measure the temperature?
Four line-sensing thermostats are provided to monitor pipe line temperatures and serve as a backup to the two ambient thermostats
(sends an alarm to the main control room upon line temp. drop)
Where can the QJ system get powered from upon a loss of offsite power?
DGs
When is the QJ system required to be in operation?
Whenever ambient temperature is equal to or less than 40F
What is the purpose of the QJ control panels?
through main and branch circuit breakers, the panels distribute and control heater power
monitor heater power and neutral continuity
white light indicating the circuit is energized
control handswitch of the system
In the QJ system, what does the safety related control panel have that the others don’t?
reset pushbutton for clearing alarm in the main control room
also monitors line temperatures and sends alarms to the main control room
The QJ heaters are strips of 120VAC Chemelex heat tracing insulated parallel wires. Where are they located in regards to the subsystem they are protecting? How long are these strands?
either spiraled or straight under the insulation
to whatever length the system is
