Provisioning Plant

Question 1

State the components (and their qty) of the provisioning plant system. State what type of cooling system the provisioning plant system is.

Answer 1

2x Cool Rooms (PORT and STBD)
1x Cold Room
2x Provisional Plant Compressors
Direct Cooling System

Question 2

What should personnel do should they be stuck in the cold room?

Answer 2

Press the red safety button in the cold room to activate alarms outside the galley

Question 3

State the standard defrosting time setting, and describe the defrosting cycle.

Answer 3

6h cycle (5.5h normal operation, 0.5h defrosting)
The compressor stops and and the heaters in the cold room turn on. This will cause an alarm to sound at the SCMMS due to increasing cold room temperature.

Question 4

State the 2 purposes of the defrosting cycle.

Answer 4

Prevents icing from forming on the cooling fins of evaporator and blocking the flow of cold air, causing food to spoil faster.

Prevents ice from forming on the coaming of the cold room door, jamming it and trapping operators in the room.

Question 5

State the 4 heaters installed in the cold room.

Answer 5

Door Heater: Melts ice on the door frame to prevent the door from jamming when excessive amounts of ice form

Defrost Heater: Melts ice on evaporator tubing to prevent restricted air flow

Pan heater: Due to the low temperatures in the cold room, condensation occurs very easily and water is collected in a pan. This heater prevents the water in the pan from freezing so it can flow off

Pipe heater: The pipe extends from the pan to outside the cold room. This heater prevents the water in the pipe from freezing so it can flow off.

Question 6

State the 8 important valves for the provisional plant.

Answer 6

1. Oil return v/v
2. Oil p. Switch v/v
3. Compressor inlet v/v
4. Compressor outlet v/v
5. Receiver inlet v/v
6. Receiver outlet v/v
7. Filter drier inlet v/v
8. Filter drier outlet v/v

Question 7

State the 7 side components of the provisional plant.

Answer 7

• Mufflers: Reduces the noise produced by the plant
• Oil Separator: Separates compressor L/O from Freon
• Receiver: A large space that can store Freon during pump down
• Filter Drier: Filters out contaminants and moisture from Freon
• Sight Glass: A window which allows operators to observe whether Freon is sufficient and/or contaminated
• Solenoid v/v: Controlled by the “Pump Down” switch. When the v/v is closed, pump down is initiated
• Accumulator: Stores any liquid Freon that may exist after the evaporator until it becomes gas, so that the compressor does not take in unwanted liquid Freon

Question 8

State the changeover procedure from Provisional Plant 1 to Provisional Plant 2.

Answer 8

1. Make sure the compressor is running. If it isn’t, open the cool/cold room door to force compressor to run.
2. Switch Provisional 1 pump switch to “PUMP DOWN” In “Auto”, will cut out via the Low p.Switch after awhile
3. Once Provisional 1 compressor stops, switch it to “MANU” and STOP”
4. Open S/W inlet/outlet of condenser of Provisional Plant 2
5. Close S/W inlet/outlet of condenser of Provisional Plant 1
6. Close 8 v/vs of Provisional Plant 1
7. Open 8 v/vs of Provisional Plant 2
8. Check oil level and Freon level and ensure that both are > ¾
9. Switch Provi 2 pump switch to “AUTO” and “RUN”

Question 9

State the procedure to shutdown the entire provisional plant system in local mode.

Answer 9

1. Pump down both units
2. Close condenser suction and discharge valves
3. Switch off cool and cold room fans
4. STOP S/W cooling pump and OFF door heater
5. Switch supply to OFF

Question 10

State the 4 essential components to turn on/off to start/shutdown the provisioning refrigeration system completely

Answer 10

1. Normal/Alternate (Power) Supply
2. Door Heater
3. S/W Cooling p/p
4. Cool & Cold Room Fans

Question 11

State the optimum operating parameters of the provisioning plant for Low Pressure, High Pressure, Oil Pressure, and S/W pump discharge pressure.

Answer 11

LP range: -20 ~ 15psig
HP range: 100 ~ 170psig
OP range: 4 ~ 11psig
S/W p: 1 ~ 2.5 bar

Question 12

State the standard cut-in and cut-out parameters for LP range, HP trip and OP trip

Answer 12

• LP range: -20psig (cut-out), 15psig (cut-in)
• HP trip: >180psig
• OP trip <10psig

Question 13

State the room temperatures of the cold room and cool room and their cooling medium.

Answer 13

Cold room: -14 – -18°C
Cool room: 2 – 6°C
Cooling medium: Seawater

Question 14

State the 2 methods to perform emergency cooling for the condenser in case the S/W pump is down.

Answer 14

1. Connect fire hose to provisional plant emergency cooling connection and spray water on provisional plant (found in AHU 20, next to provi plant)
2. Open connecting v/v between the firemain and the provisional plant S/W cooling line (found in sewage compartment, below greywater panel, to provide S/W cooling from firemain line.)

Question 15

State how the SCMMS alarm can activate when the condenser is on NORMAL. State how the compressor starts and stops when it is on AUTO.

Answer 15

On NORMAL, SCMMS alarm will activate when S/W p/p is down.
On AUTO, the compressor starts and stops based on the LPS.

Question 16

State the functions of the LPS, HPS, and OPS.

Answer 16

LPS is an operational switch which will cut out the compressor when the temperature in the cool/cold rooms are cold enough.

HPS and OPS are safety switches which will cut out the compressor when Freon pressure is too high and oil pressure is too low respectively. The compressor can only be restarted after resetting the switch.

Question 17

State the purpose/ function of the Provisioning Refrigeration System.

Answer 17

Allow the ship to do out to area of operations longer while keeping the morale of the crew high with hot meals.
Allows the storage and preservation of vegetable and meat.

Question 18

Explain the working principles of the system and the main components as follows (mention the state, pressure and temp of Freon):
Compressor
Condenser
Thermal Expansion Valve
Evaporator

Answer 18

Compressor: Pressurise the Freon via compression to increase the enthalpy values (Gas, high pressure, high temp)
Condenser: Heat is released from the Freon, maintaining the pressure of the freon, change state from vapour to liquid (Liquid, high pressure, Low temp)
Thermal Expansion Valve: The freon expands and reduces its pressure while maintaining it’s Enthalpy values and ready for heat exchange in the next phase. (Semi liquid, Low pressure, Low temp)
Evaporator: Heat from the surrounding air is absorbed from the Freon through direct or indirect contact with the evaporator coil, lowering the temperature of the surrounding air and causing all the Freon to evaporate into gasesous state. (Gas, Low pressure, Low Temp)

Question 19

State the 3 pre-sea checks of the Provisioning Refrigeration System.

Answer 19

1. Check correct function of S/W cooling pump
2. Check correct function of refrigeration system
3. Check cool and cold room temperatures within range

Question 20

State the pre-start checks of the provisioning system.

Answer 20

1. Ensure crankcase heater has been turned on for at least 24 hours
2. Ensure compressor oil level is about ½ of sight glass level
   3.Open:
   - S/C valves
   - S/W cooling pump suction and discharge valves, O/B valves
   - Condenser inlet and outlet valves
   - Pressure gauge valves
   - Compressor suction and discharge valves
   - Condenser refrigerant inlet and outlet valves
   - Filter Drier inlet and outlet valves
   - Cool and cold room valves (from control valve panel)
3. CLOSE:
   - Charging valve
   - Filter drier & TEV bypass valve
   - all valves on the standby unit/provisioning plant not in use

Question 21

Describe how to perform the daily PMS tasks for the Provi Plant:
1. Function check of Refrigeration Compressor
2. Inspect Compressor for Refrigeration Provisioning Plant

Answer 21

1. Function check of Refrigeration Compressor
   Check for vibration, unusual noise, check compressor seal for leaks
2. Inspect Compressor for Refrigeration Provisioning Plant
   a. Turn “ON” the power supply on the Provisional Refrigeration Panel and leave unit “ON” for 24hours
   b. Inspect and ensure compressor oil level is 1/3 to 2/3 of sight glass before starting up the compressor. Top up as required.

Question 22

Describe how to perform the weekly PMS tasks for the Provi Plant:
1. CHECK FOR LEAKS (REFRIGERATION [REF] SYSTEM)
2. CHECK FOR REFRIGERANT LEAKS (CONDENSING UNIT)
3. CHECK FILTER DRYER (CONDENSING UNIT)
4. INSPECT COMPRESSOR (REFRIGERATING PROVISION PLANT NO 1*)

Answer 22

1. CHECK FOR LEAKS (REFRIGERATION [REF] SYSTEM)
   a. Check system for leaks during operation, rectify any leaks found without delay.
2. CHECK FOR REFRIGERANT LEAKS (CONDENSING UNIT)
   a. Check all refrigerant piping & compressor gasketed joints for refrigerant leaks
   b. Use an electronic halogen leak detector for checking refrigerant leaks.
3. CHECK FILTER DRYER (CONDENSING UNIT)
   a. Check the liquid refrigerant moisture indicator.
   b. If the indicator is pink, replace the filter core of the filter dryer.
4. INSPECT COMPRESSOR (REFRIGERATING PROVISION PLANT NO 1*)
   a. Inspect compressor and motor for unusual noises, excessive vibration and compressor seal for excessive leakage during operation

Question 23

Describe how to perform the monthly PMS tasks for the Provi Plant:
1. Check shut-off valve (Refrigeration System)
2. Inspect Compressor for Refrigeration Provisioning Plant
3. Inspect Compressor head cooling fan assembly

Answer 23

M: Check Shut-Off valves (REF SYS)
a. Operate all shut-off valves and check them for easy movement. Shut-off valves that do not have easy movement must be overhauled or renewed as soon as possible
b. Retighten leaky stuffing boxes, repack if required
c. Clean and grease spindles of shut-off valves

M: INSPECT COMPRESSOR (REFRIGERATING PROVISION PLANT NO 1*)
a. Inspect and ensure compressor oil level is ⅓ to ⅔ of sight glass before operating the system. Top up if necessary

M: INSPECT COMPRESSOR HEAD COOLING FAN ASSEMBLY* (REFRIGERATING PROVISION PLANT NO 1*)
a. Inspect and clean dirt accumulated on the compressor head cooling fan cage.