Control Oil

Question 0

Describe the basic flow path of CO.

Answer 0

Hydraulic fluid reservoirs => hydraulic fluid pump => hydraulic fluid filters => common header => accumulators! operating devices, servo valves, & trip devices => through one of 2 hydraulic fluid coolers
Some fluid goes over to the fuller earth filters and through the transfer pump filter before going straight back to the reservoir

Question 1

What components are supplied by control oil?

Answer 1

Main steam stop & control valves
Main steam combined intermediate valves
EHC system

Question 2

When is the transfer filtering pump used?

Answer 2

When filling the reservoir, draining the reservoir, for bypass filtering of the reservoir when the hydraulic pumps are shut down.

Question 3

What cools the control oil hydraulic coolers?

Answer 3

TC

Question 4

What are the power supplies to the main hydraulic pumps? The filter pump?

Answer 4

Filter pump - NH

Main hydraulic pumps - NG

Question 5

What is the capacity of the fluid reservoir?

Answer 5

800 gallons

Question 6

What temperature is the reservoir kept at or above?

Answer 6

85F

Question 7

How is temperature controlled on the fluid coolers?

Answer 7

TC inlet valve is throttled to maintain 115F through the coolers.

Question 8

What happens when the hydraulic fluid reservoir heater and fan control is placed in start?

Answer 8

Fans start, but heaters will not energize at all

Question 9

What happens if the fans and heaters are in auto and hydraulic fluid temp goes above 85F?

Answer 9

Heaters de-energize and fans run for 10 more minutes to cool the heaters then shut off.

Question 10

What is the purpose of the aux pump that is attached to the main hydraulic pump?

Answer 10

Take a suction on the hydraulic reservoir and supply cooling and lubrication to the main pump.

Question 11

What will cause the standby control oil pump to auto start?

Answer 11

Low control oil pressure of 1300psig

Question 12

What are the accumulators charged to?

Answer 12

1000 psig nitrogen to immediately provide a 200% reserve of fluid for transient flow requirements

Question 13

Where does the high or low control oil temperature alarm sound?

Answer 13

In the control room

Question 14

What color is good desiccant?

Answer 14

Blue

Question 15

Where can you start the hydraulic fluid filtering pump from?

Answer 15

Locally at the pump

Question 16

What do the Fullers Earth filters do?

Answer 16

Maintain close to neutral pH by neutralizing acids and absorbing water.

Question 17

What does the Stealth EHC system do?

Answer 17

It’s a dry gas blanketing system.
It blankets the control oil reservoir headspace with super dry clean air. It simultaneously extracts moisture from the air while excluding contaminants from getting in.

Question 18

How does the Stealth EHC work?

Answer 18

It uses a hollow fiber membrane to pass air through. It uses 5-20% of the rated air flow to transport the moisture from the module.

Question 19

Where does the moisture laden air come out of the Stealth EHC?

Answer 19

Special ports located in the modules inlet end cap.

Question 20

How is the membrane in the stealth EHC protected?

Answer 20

By incorporating a high efficiency coalescing pre filter into the system.

Question 21

When is the transfer filter in service?

Answer 21

During reservoir filling and draining

Question 22

What is the recirculating tank used for?

Answer 22

Used as a vessel for batch mode purification independent of the rest of the system.

Question 23

What are the possible positions for the transfer and filtering system selector valve? (204)

Answer 23

Closed
Discharge (to oily waste)
Recirc to fluid reservoir
Discharge to recirc tank

Question 24

How is the test function of the main hydraulic pumps performed?

Answer 24

The actuation of HV-29 manually relieves system pressure on an isolated supply header to test start the stby pump.
Test is performed locally at the skid.

Question 25

What is the logic for the control oil pressure low alarms in the control room?

Answer 25

2/3 at 1100 psig

Question 26

What happens to CO on a loss of IA?

Answer 26

Temperature control valves fail open and the stealth air dryer loses it’s air supply

Question 27

What is the name of the EHC fluid and what are the handling precautions?

Answer 27

Fyrequel EHC

Causes illness if swallowed, skin and eye irritant.