EC

Question 1

What are the auto starts for the EC system?

Answer 1

SIAS
CSAS
CREFAS
CRIVIAS
LOP
AFAS 1/2

Question 2

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

Answer 2

38 degrees F

Question 3

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

Answer 3

45 degrees F

Question 4

What do we have to prevent surging?

Answer 4

Hot gas bypass

Question 5

What do we have to prevent stacking?

Answer 5

RHPVC

Question 6

What is the EC auto makeup?

Answer 6

DW

Question 7

What is the backup to EC makeup?

Answer 7

CST

Question 8

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

Answer 8

28 psig

Question 9

What will auto isolate makeup from the EC expansion tank?

Answer 9

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

Question 10

What are the power supplies to the Essential Chillers?

Answer 10

Compressors- PB

Circ pumps- PH

Question 11

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

Answer 11

Chiller will trip on high refrigerant pressure in condenser

Question 12

What is some OE associated with EC system valves?

Answer 12

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

Question 13

How are chemicals driven into the EC system?

Answer 13

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

Question 14

What are the ways you can check EC oil?

Answer 14

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

Question 15

Where does the refrigerant cool the EC water?

Answer 15

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

Question 16

Where does the EW system cool the EC refrigerant?

Answer 16

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

Question 17

What does the compressor do in the EC system?

Answer 17

Raises pressure and temperature

Question 18

What flows through condenser of the EC package?

Answer 18

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

Question 19

What flows through the cooler of the EC package?

Answer 19

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

Question 20

What is surging in the EC system?

Answer 20

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

Question 21

What does the hot air bypass line do for us?

Answer 21

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.

Question 22

Where is the thermal economizer located in the EC condenser?

Answer 22

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

Question 23

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

Answer 23

• Chiller start
• Cold EW
• Low loads

Question 24

When is stacking most likely to occur?

Answer 24

Low load and low EW temperature

Winter months

Question 25

Where does stacking occur in the refrigerant process?

Answer 25

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

Question 26

When will the RHPCV be open or closed?

Answer 26

open > 23 psig | closed

Question 27

How does the RHPCV prevent stacking?

Answer 27

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

Question 28

What does the flash economizer do?

Answer 28

- additional sub cooling of the liquid refrigerant | - differential pressure between the condenser and cooler

Question 29

Where can we start the EC circ water pumps?

Answer 29

- 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).

Question 30

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

Answer 30

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