Ventilation and air conditioning

Question 1

what does air conditioning control ?

Answer 1

• temperature
• humidity
• air purity
• air movement
  With in a space or group of spaces

Question 2

why do we use AC?

Answer 2

To ensure that ships staff continue to operate at high levels of effectiveness and efficiency for long periods of time

It ensures that the environment for weapons and other essential equipment is always satisfactory for reliable operation

Question 3

what do vents provide?

Answer 3

Supply
- cool electrical equipment
- provide fresh air
- tolerable working conditions
- tolerable living conditions

exhaust is used to remove:
- wild heat
- noxious fumes
- odours
- stale air

Question 4

what is the purpose of heaters ?

Answer 4

To prevent discomfort or chilling, heaters provide heat to occupied spaces.
If the air supplied is too cold the occupants of the compartment will find means to reduce or stop the air flow with potential dangers to health

Question 5

what spaces do heaters provide to?

Answer 5

accommodation spaces, offices, and other compartments occupied for prolonged periods are to be capable of maintaining a compartment of 22 degrees

unmanned compartments requiring heating should be maintained at 13 degrees

Question 6

why do be have system arrangement’s ?

Answer 6

to ensure that correct conditions are maintained in each compartment, properly designed air conditioned or mechanically ventilated or natural supply exhaust system arrangements are essential

Question 7

when should fan exhaust be fitted in a compartment?

Answer 7

• remove air directly from the vicinity of the heat producing equipment
• prevent the accumulation of explosive or noxious gases
• remove odours and vapours

Question 8

give some examples where an individual compartment is supplied by individual supply and exhaust fans?

Answer 8

• fan supply/fan exhaust systems, fitted to remove large quantities of wild heat, moisture or noxious fumes. And provide fresh air to personnel. Galleys, laundries, heads machinery spaces
• natural supply/ fan exhaust is used to remove noxious gases or flammable vapours. Paint store or inflame

Question 9

what is TACS?

Answer 9

• When the ship is divided vertically into sections, vents and AC within each section are completely self contained
• TACS smoke clearance is achieved by installing dedicated smoke clearance fans, axial flow fans with auto interlocked butterfly valves which are operated from the SCC
• fresh air make up (10%) i supplied at all times via by-pass valves fitted to AFUs
• Excess air from AC is exhausted to atmosphere by the mechanical vent systems in heads and bathrooms

Question 10

where are centrifugal fans used and how do they work?

Answer 10

• Fans are generally used as supply or exhaust in trunked systems
• air is drawn into the centre and expelled outwards to the tops of the blades by centrifugal forces and into a delivery trunk

Question 11

where are axial fans used and how do they work?

Answer 11

• fitted in machinery spaces and large centralised ventilation supply and exhaust systems
• Air is drawn past a rotor or impeller
• they are best for large movements of air against low resistance
• the body of the fan being in line with the trunking takes up less space

Question 12

Why do we not use circular trunking?

Answer 12

• even though circular trunking offers the least resistance to air flow and is less susceptible to drumming
• rectangular section trunks are easier to manufacture and make better use of available space
• the ratio max to min side should be as near to 1:1 as possible, and not more than 1:4

Question 13

why do we insulate trunking?

Answer 13

• prevent condensation the internal and external of the trunk
• restrict heat pick up from cool air passing through a warm compartment
• restrict heat loss by carrying heated air through a cold compartment

Question 14

what materials are used for trunking and where do we use them?

Answer 14

• Aluminium alloy, NWT and gas tight trunking, not subject to heavy treatment
• Mild steel galvanised, WT and NWT trunking subject to rough usages. `vertical trunks in passage ways

Question 15

why do we use filters?

Answer 15

Air which is supplied will contain impurities
- Dust
- oily soot funnels
- salt
- sand
- bacteria
Impurities will clog inlets, heaters and coolers and reduce overall efficiency and performance of the system, equipment and personnel

Question 16

where do we used odours filters, when do they need changing?

Answer 16

• fitted in recirculation trunks for heads, bathrooms and galleys
• The filter medium can be Carbon granules, carbon cloth or a combo of chemicals
• under normal conditions the life of the filter cartridge should be at lest 6 months
• it’s essential to ensure that the relieve humidity in the compartment does not exceed 90%
• this will impair the filter’s efficiency

Question 17

How is ventilation provided for Sewage treatment spaces ?

Answer 17

• require 15 air changes an hour
• Separate exhaust system and slight excess of exhaust capacity from that of supply
• must have a limited air supply under closed down conditions for the air compressors
• exhaust trunking is to be led to a low level to prevent the build up of hydrogen sulphide which can be lethal

Question 18

Access is required into trunking, to carry out what activities ?

Answer 18

• inspections to assess the state of cleanliness of fittings or any section of trunking
• cleaning of all trunking, especially in way of fittings, bends and other obstructions of air flow
• access for inspection by rapid opening inspection holes that to don’t required unbolting

Question 19

explain what testing requirements Local exhaust ventilation systems (LEVS) require ?

Answer 19

• this is a legal requirement for ventilation system and LEVs to be visually inspected and tested against parameters by a competent person
• Maintance requirement is an annual mandatory, carried out every 12 months BUT NOT EXCEEDING 14 MONTHS
• object of the test will be to establish if the performance of the systems concerned is with in the nominated parameters
• 60% of design output

Question 20

what aspects of CBRNDC have been considered in design of ventilation ?

Answer 20

• in the event of fire, smoke migration is restricted to defunded zones
• post fire contamination can be cleared with minimal loss of operational effectiveness
• a positive pressure relative to external atmosphere can be achieved and maintained within the the citadel and machinery spaces when required
• wt and got is not impaired

Question 21

what are the set of three CBRNDC filters?

Answer 21

• pre-particulate filter, removes coarse particulate matter, including radioactive fallout from airstream
• particulate filter, this removes fine particulate matter, including bactria
• gas filter, removes all known chemical ware fare agents in the form of gases or vapours

Question 22

what do we do CITADEL tests and when are they done?

Answer 22

To ensure the correct function of a Citadel and gas tight integrity
Citadel tests are carried out on the rolling occasions and the results recorded in the SEF

• annually
• prior to DED to locate leaks and ensure that those beyond the capacity of ships staff are included in the defect list
• during harbour acceptance trails (HATS)
• during sea acceptance trials (SATS)
• all ships will be required to carry out a Citadel test during FOST work-up