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Area 4 > EC > Flashcards

EC Flashcards

1
Q

What are the auto starts for the EC system?

A 
SIAS
CSAS
CREFAS
CRIVIAS
LOP
AFAS 1/2
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2
Q

At what water temperature in the chiller will it trip on auto load recycle?

A

38 degrees F

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3
Q

When will a chiller auto restart after it tripped on auto load recycle?

A

45 degrees F

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4
Q

What do we have to prevent surging?

A

Hot gas bypass

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5
Q

What do we have to prevent stacking?

A

RHPVC

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6
Q

What is the EC auto makeup?

A

DW

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7
Q

What is the backup to EC makeup?

A

CST

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8
Q

What is the N2 over-pressure in the EC surge tank?

A

28 psig

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9
Q

What will auto isolate makeup from the EC expansion tank?

A

Lo lo level in the EC expansion tank. (prevent feeding a leak)

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10
Q

What are the power supplies to the Essential Chillers?

A

Compressors- PB

Circ pumps- PH

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11
Q

What happens to the EC if we lose spray pond or EW?

A

Chiller will trip on high refrigerant pressure in condenser

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12
Q

What is some OE associated with EC system valves?

A

The RHPCV was left locked ‘open’ for a long time. It is suppose to be locked “closed”

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13
Q

How are chemicals driven into the EC system?

A

The delta-P across the Circulating pump drives the chemicals through the system.

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14
Q

What are the ways you can check EC oil?

A
  • Black light
  • Refraction
  • Temperature difference
  • Request LO pump start to see level
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15
Q

Where does the refrigerant cool the EC water?

A

In the Cooler. The refrigerant gives up its latent heat of vaporation and goes from a liquid to a gas.

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16
Q

Where does the EW system cool the EC refrigerant?

A

In the condenser. This is where the refrigerant goes from a gas to a liquid.

17
Q

What does the compressor do in the EC system?

A

Raises pressure and temperature

18
Q

What flows through condenser of the EC package?

A

EW flows through the Condenser and provides the cooling mechanism for the EC refrigerant

19
Q

What flows through the cooler of the EC package?

A

EC flows through the cooler and is cooled by the EC refrigerant

20
Q

What is surging in the EC system?

A

Momentary flow reversal thru the compressor. It is caused by not enough heat load to evaporate a sufficient volume of refrigerant in the cooler.

21
Q

What does the hot air bypass line do for us?

A

Helps prevent surging. Directs a portion of the compressor discharge gas to the bottom of the cooler. In which case high pressure, high temperature gas causes more refrigerant to flash and result in more flow which should eliminate surging.

22
Q

Where is the thermal economizer located in the EC condenser?

A

In the bottom of the condenser. It is exposed to the coldest EW flow in order to increase overall refrigeration cycle efficiency.

23
Q

What are some conditions that the RHPCV may close during normal operations?

A
  • Chiller start
  • Cold EW
  • Low loads
24
Q

When is stacking most likely to occur?

A

Low load and low EW temperature

Winter months

25
Q

Where does stacking occur in the refrigerant process?

A

The liquid refrigerant remains in the condenser since there is not enough pressure to drive the liquid through the flash economizer to the cooler

26
Q

When will the RHPCV be open or closed?

A

open > 23 psig

closed

27
Q

How does the RHPCV prevent stacking?

A

By reducing condenser cooling flow rate (EW), when EW temperatures are low, stacking will be prevented.

28
Q

What does the flash economizer do?

A
  • additional sub cooling of the liquid refrigerant

- differential pressure between the condenser and cooler

29
Q

Where can we start the EC circ water pumps?

A
  • Local start pushbutton at MCC

- Disc. Switch by the chillers, then start from control room. (This INOP’s the EC so this is not the preferred method).

30
Q

Where is flow adjusted for the EC system ACU’s?

A
  • All adjust manually at each ACU except the CR essential ACU. Which is controlled by air temperature.

Area 4 (5 decks)

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