RB Vent Flashcards
What is the purpose of the RB Vent System?
TO provide protection to plant personnel and equipment from extreme thermal conditions
Max of 103 when outsed temp is 95
Min of 65F when outside temp is -6F
What are the control requirements for the RB Vent System?
Vent air flow shall be routed from areas of lesser to greater contamination prior to final exhaust. With reverse flow prevented by dampers.
AND
DP of ~0.25in H2O shall be maintained between clean areas and areas having gratest contamination, AND between RB and outside environment
What is the volume flow design for RB Vent?
Provides at least 1 free volume change of air per hour in the RB.
What are the physical actions required to put a RB fan in service?
Fan control switch must be held closed for a MINIMUM of 20 seconds for flow to develop.
What are the purpose of Rollomatic filters?
To remove airborne particles or dust that could damage supply fans or become contaminated.
What is the power supply for the RB Vent Chillers?
Power for pumps and chiller unit from 480V transformer via :
Line J661 via 34kV L1263
How many Supply and Exhaust Fans are in teh RB Vent System?
3 supply, 3 exhaust. 2 of each normally running
What are the power supply for the Supply and Exhaust Fans?
Supply: 2A & C - Bus 28; 2B - Bus 29
Exhaust: 2A - Bus 28; 2B & C - Bus 29
What are the trips for the RB Vent Fans?
Any butterfly damper NOT FULL OPEN - Trips ALL fans
Supply Fans trip on RB Press TOO HI (can’t take more air) - +2.2”WC
Exhaust Fan Trip on RB Press TOO LO (Exhaust faster than supply) - -2.7”WC
WHat is the purpose of the Isolation Dampers?
How do they fail?
They isolate the RB Vent under abnormal conditons:
Normally operated via IA. On loss of IA, each damper has a failsafe accumulator which provides a volume of air to close the isolation damper.
When air pressure drops to <67psig, mech versa valve repositions, allowing accumulator pressure on operating piston of damper to close damper
What is used to control the exhaust fan ? setpoint?
Variable Vane Controller to maintain -0.25”WC
What Isolation Signal feeds into ventilation system?
Group II
What does a Group II Isolation do to RB Vent, why?
Closes All dampers, which trips Fans. SBGT auto starts
Why must the Dampers be separately reset following a Group 2 Isoaltion?
If C/S were last placed to OPEN and reset p/b pressed after isolation, dampers will go OPEN as soon as button is pushed. Must take c/s to CLOSE prior to resetting or may lose -0.25”WC on secondary containment
Where do the Radiation Elements take indication off of for RB Vent?
Located on exhaust ductwork prior to isoaltion dampers (after SBGT tie in)
