When is duct cleaning appropriate?

When is duct cleaning appropriate? Although the value of regular duct cleaning remains questionable, the U.S. Environmental Protection Agency (EPA) and indoor air specialists agree that duct cleaning (or, in some cases, duct replacement) is appropriate in the following circumstances: • Permanent or persistent water damage in ducts   • Slime or microbial growth observed in ducts   • Debris build‐up in ducts that restricts airflow • Dust discharging from supply diffusers   • Offensive odors originating in ductwork or HVAC component. BEFORE hiring a duct cleaning contractor, make sure you can answer “YES” to all of these questions: 9 Are there known or observed contaminants in the ductwork? 9 Have you confirmed the type and quantity of contaminants based on testing or observation? 9 Are the contaminants (or their by‐ products) capable of entering occupied spaces? 9 Have you identified and controlled the source of the contaminant?   9 Will the duct cleaning effectively remove, inactivate, or neutralize the contaminant? 9 Have you considered other options, such as removal of affected ductwork? 9 Is duct cleaning the only (or most effective) solution? In all cases, duct cleaning should be undertaken only after the source of the contaminant has been identified and controlled. Otherwise, the problem will not go away. For instance, the water source

Operatives to board

Operatives to board over any open kitchen equipment e.g. hobs or ranges. Ensure equipment has cooled down sufficiently and cover all solid surfaces with appropriate sheeting.
5  Operatives to set up access equipment e.g. trestle, step ladders, etc.
6  Operatives to ascend access equipment and carry out sealing procedure of all holes and apertures.
7  Operatives to descend to floor level and prepare cleaning solution as per the manufacturer’s instructions. Note: refer to COSHH assessment supplied.
8  Operatives to check work equipment to be used as per cleaning specification. Where steam cleaners are to be used check that all connections are properly tightened, electric cabling is sound and equipment has current PAT test label or certificate.
9  Operatives to transfer cleaning equipment on to the access equipment taking care to ensure that no spillages occur and that safe manual handling techniques are observed.

Operatives will clean

Operatives will clean all necessary surfaces ensuring that where necessary care is taken not to cause damage to any fragile surfaces. Operatives to use cloths or  ‘Greenies’ as required.
7  On completion of cleaning operatives will descend the ladder using both hands, operatives must not slide down ladders at any time.
8  Operatives will check floor area for any sign of drips or spillage and clean up any that are found.
9  On completion of cleaning, operatives to dispose of all waste chemicals and materials on site and remove all cleaning equipment, chemicals and signage to company vehicle.
10  Operatives are not to leave the site until authorised by Supervisor.

Air compressors were introduced

 Air compressors were introduced as a more effective alternative to portable blowers. The use of skippers or snakes, which moved through systems with compressed air to assist in air washing air ducts. • Compressed air-washing and vacuuming are now sometimes augmented by manual scrubbing with brushes and flexible rods and whips and can assist in cleaning hard to reach dirt buildups in air handling systems. Where ducts are lined with fiberglass insulation, this treatment could damage the insulation and release fiberglass fibers to further contaminate air. • The use of HEPA filtration can be used to trap very small particles. This might be important for commercial duct cleaning where equipment exhaust stays inside a building, but offers little for residential duct cleaning where filtration equipment is placed outside. • For truly contaminated duct systems professionals can cut into the duct work to insert the vacuum line to remove localized dirt build-up. Some commercial air duct cleaners are equipped with tiny fiber-optic cameras to assist in locating dirt build-up and to confirm cleaning effectiveness.

YOUR DUCT SYSTEM

YOUR DUCT SYSTEM In most residential and small commercial central heating and cooling systems, the conditioned (heated or cooled) air is delivered to each room through supply ducts and returned through the return duct to the furnace or air conditioner. The condition of both sections of this ductwork is vital to the overall efficiency of your heating and cooling system. What can go wrong? In some buildings, air escapes through poorly connected, disconnected, or deteriorated ducts, which can result in little conditioned air actually reaching your living or work space, leaving the area too warm or too cold. If the return duct system is leaky, it could be drawing in outside, stale, or polluted air and distributing it throughout the building; this air could come

Opening

Opening
Professor Wu Yuanwei of the China Academy of Building Research (CABR) and Mr John Ryan of the United States Department of Energy (DOE), chairman of the National and International Organising Committee respectively, opened the conference. Secretary General Mr Shi Dinghuan of the China Ministry of Science and Technology and Mr Chen Yiuing of the China Ministry of Construction welcomed the more than 330 participants.
The IEA representative at the conference, Mr Hanns-Joachim Neef, underlined the IEA members’ primary goals: energy security, economic growth and environmental protection for a sustainable (energy consuming) society. He recalled China’s challenging goal of ongoing zero growth in energy consumption by 2040, with energy
efficiency being one of the main building blocks in China’s energy policy. High-efficiency heat pumps can play an important role in achieving this goal.
ASHRAE president Mr Bill Coad used a lesson in thermodynamic history to underline his statement that ‘There is no turning back’ and that ‘Change is a fact of life that has resulted in a higher quality of life for mankind’. The greatest challenge to the human race will be to maintain and advance its quality of life in the face of dwindling energy reserves and an environment that is continually being degraded. It is the engineering community that faces the challenge of designing equipment and systems that use less energy to accomplish the same goals. There is also considerable scope for reduction of consumption. The opportunities for a sustainable future are there, and heat pumps can play a

Even though ground-source

Even though ground-source technology is reliable and cost-effective, continued research is needed to further lower the variable cost and broaden the applicability of ground-source heat pump systems. Research areas include: • computationally efficient simulation methods for ground loop heat exchangers, especially horizontal designs with above ground interaction; • more cost-effective vertical heat exchangers; •lower cost methods for estimating soil thermal properties; • design methodologies that incorporate system simulation, allowing interactions between the building system and the heat rejecter/exchanger system; • optimised fluid pumping system configurations and controls for reduced variable costs.
Several organisations have been active in transferring the technology to the market, which has significantly improved awareness by architects and engineers. However, more is needed to make ground-source heat pump systems a widely accepted technology.

Technological

Technological and related market developments Two of the conference sessions were devoted to components and systems. Almost 30 technology posters had been prepared, underlining the amount of research effort aimed at advancing the technology.
Technology topic areas included:
• CO 2 heat pumps and compressors; • heat pump system control; •advanced plate-type heat exchangers; •residential gas engine and absorption heat pumps; • ice thermal storage multi-split air conditioners; • ground-coupled heat pumps; •cycles; • thermal-physical properties; • frost formation, coil defrost and defrost control; •variable speed and variable discharge volume compressors; • chemical and liquid desiccant heat pumps; • solar-assisted heat pumps; • etc.

The 7th

The 7th International Energy Agency Heat Pump Conference, held at Beijing International Convention Center, Beijing, China, from May 19 to 22, 2002, was a great success. There were more than 330 formal participants from 19 countries, of which 129 from abroad and more than 200 from China. The conference included 8 sessions, 2 technical excursions and 4 social programmes. This was the first time that the IEA Heat Pump Conference was held in a developing country. The conference offered a good opportunity for people in China to learn about heat pump technology and application experience in the world, and made it easy for international friends to appreciate China and Beijing. Many Chinese officials from the Ministry of Science and Technology, the State Development and Planning Commission, the State Economic and Trade Commission and the Ministry of Construction were invited to attend the conference. Executives from the electric power industry, the manufacturing industry and organizations charged with the application of heat pump technology, i.e. the Architectural Society of China (ASC), the Chinese Association of Refrigeration (CAR) and the China Refrigeration and Air Conditioning Industry Association (CRAA), also participated in the conference. The Chinese government and people have gradually realised the great challenges that go hand in hand with economic development and social progress. Therefore, a strategy of sustainable development has been put forward to improve the utilization ratio of resources, to adjust the energy infrastructure, to expand the use of electric power and to promote constructionrelated energy conservation

Encouraging the Purchase

Encouraging the Purchase of Energy Efficient Heat Pumps The energy right® Heat Pump Plan is designed to encourage the installation of electric heat pumps meeting program standards and requirements at residential dwellings and small commercial businesses. Under the plan, distributors of TVA power may be eligible to receive an MVP for installation of a heat pump meeting TVA’s installation standard

Pressure Testing

Pressure Testing and Start-Up ⇒ The earth coil shall be pressure tested before connecting it to the heat pump and prior to complete backfilling. The piping shall be filled with water and/or air and pressure tested to 80-100 psi for at least 30 minutes. A visual inspection shall be made for leaks. Vertical U-bend assemblies shall be pressure-tested before insertion into the borehole. ⇒ When pressure testing is complete and a leak-free system is ensured, the system shall be thoroughly purged to remove air and debris. The preferred purging method is to use a flush cart consisting of a 1-1/2 to 2 HP water pump, tank, filter, flow meter, and flexible hose with connections. A minimum fluid velocity of 2 feet per second is required to purge the system of trapped air. The system circulating pump(s) cannot provide enough flow to remove pockets of trapped air out of the system.  ⇒ After the system has been filled and purged, it shall be pressurized as recommended by the heat pump manufacturer. Suggested pressures are 60 psi if installed during the heating season and 40 psi if installed during the cooling season.
Variable Speed Heat Pumps (VSHP). This section pertains to the installation of variable speed (compressor and fans) heat pump systems. All other sections of these standards are applicable unless otherwise noted. 1. The variable speed heat pump at high speed shall meet the required sensible and latent load of the structure as stated in the Equipment Requirements section. However, when the high speed sensible capacity exceeds the sensible load by 125 percent, the unit having a high speed sensible capacity closest to the sensible load shall be installed

Free-Delivery Split Heat Pump

Free-Delivery Split Heat Pump, Packaged Terminal Heat Pump, Self-Contained Through-theWall Heat Pump, Window Heat Pump System Inspection Procedures
Inspector shall verify the free-delivery split heat pump, packaged terminal heat pump, self-contained through-the-wall heat pump, and window heat pump adhere to installation standards. (See Installation Standards for certain sections that do not apply.) In addition, inspector shall verify the following: • Air flow is as recommended by the manufacturer. • Integral auxiliary electric heat is provided by the manufacturer within the unit cabinet or fan coil section as part of the heat pump. • Integral auxiliary heaters are controlled by the heat pump indoor thermostat. • Installing QCN member has met manufacturer's instructions for the complete installation of the system, including any recommended parts and accessories and any necessary wall/window case. • The joint around the unit case (between the case and wall or window) to ensure weathertight seal with caulk, seals, or gaskets, as provided by the manufacturer. • Cabinets are checked for proper alignment and any unnecessary holes. Holes allowed are for the manufacturer's approved internal condensate drain system (condensate drain lines shall be sized in accordance with the manufacturer's recommendations and all instances at least as large as the heat pump's drain connection).

Attic Insulation

Attic Insulation - Measuring The Depth Of Insulation - Checklist • Measure the depth of insulation in each section using a nonmetallic ruler. Record the depth of each section. • If batt or blanket insulation with a vapor barrier was used, ensure that the vapor barrier is turned toward the attic floor if there was no existing insulation or removed if there was existing insulation. • Verify that batt or blanket insulation fits tightly against the sides of joists and against the ends of each batt or blanket. • Ensure that insulation does not contact chimneys, flues, or other energy-dissipating objects and that such insulations are properly blocked. • Ensure that cavities or voids which drop to a lower level have been insulated properly. • Verify that there is at least 1 inch of air space between the insulation and roof sheathing. • Ensure that permanent stairway ceilings and walls have been insulated properly. • Verify that the insulation installed does not cover or block any attic ventilation. (Check the eave vents without light in the attic--light can be seen coming through the eave vents from the outside.) • Ensure that the attic access door is insulated and weatherstripped if it is located in a conditioned area. NOTE any deficiencies detected during the inspection on the Heat Pump Installation Inspection Checklist TVA 6254T. • Ensure that the QCN member has removed any unused materials and debris from the premises. NOTE: All attics insulated with loose-fill insulation should be measured in at least three different points in the attic (preferably in the middle and at both ends) in order to verify that the insulation has been installed with a consistent depth throughout the attic area and at the minimum depth specified on the coverage chart.
Attic Insulation - Floored Attics - Checklist Inspect insulation installed in floored attics using the same procedures outlined for inspecting attic insulation in unfinished attics, with the following exceptions: • If insulation has been installed beneath the flooring material, verify that each joist cavity has been completely filled with insulation by looking through the cracks between the boards or under the area where the flooring material ends. Do not remove any flooring material secured to ceiling joists to inspect the installation. • If insulation has been installed above the flooring material, ensure that the proper R-value has been installed by checking the density (number of bags installed) and the minimum thickness of the installed material

Outdoor temperature (ODT)

Outdoor temperature (ODT) is below 75°F, check the following:
i) Perform compressor heating capacity check
ii) If an outdoor thermostat is utilized, check to assure that the setting is at the structure balance point and: If ODT is above the setting of the outdoor thermostat: First stage of indoor thermostat - heat pump only operates. Second stage of indoor thermostat - furnace only operates until second stage is satisfied (this could occur upon heat pump compressor failure) If ODT is below the setting of the outdoor thermostat: First stage of indoor thermostat - furnace only operates (no second stage)
iii) If an outdoor thermostat is not utilized: First stage of indoor thermostat - heat pump only operates. Second stage of indoor thermostat - furnace only operates until second stage is satisfied.

METHOD 1

METHOD 1: Us this method if the existing outdoor unit is not equipped with shut−off valves, or if the unit is not operational and you plan to use the existing HCFC−22 to flush the system. Remove all HCFC−22 refrigerant from the existing system. Check gauges after shutdown to confirm that the entire system is completely void of refrigerant. METHOD 2: Use this method if the existing outdoor unit is equipped with manual shut−off valves, and you plan to use new HCFC−22 refrigerant to flush the system. The following devices could prevent full system charge recovery into the outdoor unit: Outdoor unit’s high or low−pressure switches (if applicable) when tripped can cycle the compressor OFF. Compressor can stop pumping due to tripped internal pressure relief valve. Compressor has internal vacuum protection that is designed to unload the scrolls (compressor stops pumping) when the pressure ratio meets a certain value or when the suction pressure is as high as 20 psig. (Compressor suction pressures should never be allowed to go into a vacuum. Prolonged operation at low suction pressures will result in overheating of the scrolls and permanent damage to the scroll tips, drive bearings and internal seals.) Once the compressor can not pump down to a lower pressure due to one of the above system conditions, shut off the vapor valve. Turn OFF the main power to unit and use a recovery machine to recover any refrigerant left in the indoor coil and line set. Perform the following task: A Start the existing HCFC−22 system in the cooling mode and close the liquid line valve. B Use the compressor to pump as much of the existing HCFC−22 refrigerant into the outdoor unit until the outdoor system is full (high pressure switch will trip and shut the compressor off). Turn the outdoor unit main power OFF and use a recovery machine to remove the remaining refrigerant from the system. NOTE It may be necessary to bypass the low pressure switch (if equipped) to ensure complete refrigerant evacuation. C When the low side system pressures reach 0 psig, close the vapor line valve. D Check gauges after shutdown to confirm that the valves are not allowing refrigerant to flow back into the low side of the system.

Defrost cycle (timed)

Defrost cycle (timed) The ice which is produced on the outdoor coil during the heating cycle must be eliminated when it begins to block the coil. The defrost cycle begins after a period selected between 30, 60 & 90 minutes from the start-up or the last defrosting, and when the evaporation temperature drops to -5°C or less. The logic module activates the defrost relay, which: - Activates the 4-way valve to go into the cooling cycle. - Switches off the outdoor fan. The defrost cycle finishes when the liquid temperature is sufficiently high, measured by a thermistor 13°C, or when, if it does not heat up, it reaches a minimum of 7°C for a 5 minute period; also after 12 minutes from its beginning. When the defrost cycle finishes, the logic module disconnects the defrost relay, reestablishing normal operating conditions of the heating cycle. If the unit tries to go into another defrost cycle in less than 5 minutes, the logic module switches it off, leaving the system

COPON

COPON is a seasonal performance factor for the heat pump that includes electricity of the backup heater. COPON is calculated by the total electricity used by the heat pump and the backup heater over the total heat demand of the building. (LhpC_tp*COPC_tp+resC_tp)/LhsysC_tp  
SCOP is a seasonal performance factor which unlike COPON, also includes the electricity consumption of auxiliary energy for the heat pump operating in thermostat off mode, off mode and crankcase heater mode.  
The energy of the backup heater is included in all seasonal performance factors that results from the excel-calculation sheet.
The annual electricity consumption split up in supplementary heating, heat pump operation and auxiliary heating is given from the calculations.  
The annual carbon emission and label energy class is also result of the calculations

Description of evaluated

Description of evaluated field measurements 3.1.1 Fraunhofer The Fraunhofer-Institute for Solar Energy Systems ISE is running two large field monitoring project including approximately 200 heat pumps in total. The heat pump efficiency project includes approximately 110 installed heat pumps with a heating capacity of 5-10 kW. In the Replacement of Central Oil boilers with Heat Pumps in Existing Building Project 75 heat pumps are included. The heat pump types included are air to water, ground source and water to water heat pumps. In this study two heat pump producers, IVT and Nibe, have provided the project with data based on the field measurements in the Fraunhofer study. 3.1.1.1 Measured parameters Table 1 gives an overview of the parameters normally measured in the Fraunhofer field measurements. Exactly what parameters tested might differ from test site to test site. For some test sites additional equipment are measured as well. Examples of such equipment are circulation pumps or control equipment

Reference 1

Reference 1 gives cooling load temperature differences (CLTD) for several latitudes, months, time of day, and building wall orientations.  These CLTD values are based on 78F indoors and 95F maximum outdoor temperatures.
In the heating degree day (DD) method, a no load outside temperature (65F)  is used as a base at which no heating or cooling is required.  At any outside temperature below 65F, a building will need heating and the number of degree days is the difference between 65F and the outside temperature.  For example, in November, if the outside average temperature is 50F, there are 15 degree days for that day.  For 30 days at 50F, there 450 DD.  The DD for the entire heating season September through May are given for various cities in Reference 4. Course Summary
© Gary D. Beckfeld  Page 16 of 21
This course has presented the basic methods of evaluating building heat gains or losses for air conditioning or heating.  Heat conductivity and thermal resistance were reviewed. A numerical example of heat loads to a building was described including external and internal heat sources.  Both sensible heat and latent heat loads were discussed.  The air conditioning process including ventilation was presented in a diagram of a psychrometric chart.  Cooling load tonnage was found and air handler flow and pressures discussed.  An air distribution duct sizing method was detailed. Finally, the methods of cooling load temperature difference and heating degree days were reviewed.

General Concepts

General Concepts
Energy provided by the fan creates a motive force,or pressure,divided into two components: static pressure and dynamic pressure as defined below. a) Static pressure, Ps, is the result of compressing fluid (air) within a duct. It is measured with reference to atmospheric pressure.Static pressure reaches a peak atthe fan unitand decreases throughoutthe ductdue to frictional pressure losses and declines to almostzero atthe exit.The same occurs in the exhaust duct, although in this case the value is negative. It is ‘positive’ during suction and ‘negative’during ‘discharge’.
b)Dynamic pressure, Pd, is the energy component due to fluid velocity and is calculated using following formula:
Where: r=airflow density (kg/m2) v=airflow velocity (m/s)
Dynamic pressure is always positive.The velocity varies with changes in duct geometry, size etc along the ductlength,as the air mass atany pointin time is the same throughoutthe duct.This is the case until its exitpointor when air is distributed into various branches of the ductnetwork.
c) Total pressure, Pt, is the algebraic sum of Ps + Pd.P t is positive in supply duct and negative in the discharge duct.
Units and measuring equipments
The international unitof pressure is the Pascal (1Pa = 1N/m2). However,calculations relating to pressure in HVAC systems is conventionally expressed in mm of manometer hydrostatic head.The conversion factor is 1 mmwg= 9.81 Pa (‘mmwg’,or sometimes expressed ‘mmca’,is the measurementin millimetres of water measured in the manometer).
The instrument for such measurements is the Pitot-Static Tube,illustrated in the adjacentfigure.
6.2Pressure losses
The movementof the air (akin to the movementof a fluid) inside ducts causes two types of pressure loss:friction losses and dynamic losses.
a) Pressure losses by friction
Frictional losses are influenced by the viscosity of a fluid (in this case,air),changes in the direction of the air and the behaviour of air molecules as part of the turbulent effect;‘normal’operating conditions in HVAC systems.
Losses take place along the length of the ductand are expressed in Pa/m or mmwg/m (total pressure by the length of the duct).
The formulaic calculation ofthe pressurelosses is complex,since itdepends on a considerable number of factors including exponential equations,established by Darcy-Weisbach and Colebrook.These formulae can be calculated with computing tools and the appropriate software.
If no software is available,a more convenient method is to use friction graphs already created to describe a duct’s geometry. Material type (using only the friction coefficient), air conditions of density and temperature,as well as the atmospheric pressure are also taken into account.
If considering another type of installation,corrective factors have to be applied to the data from the graph,which provide values for the real pressure losses of the system.
Pressurelosses in ISOVER’sglass wool ductboards
Laboratory investigations and practical experience of duct assemblies with diverse cross-section sizes and types haveestablished the following: •Real pressure losses are practically equal to the theoretical values predicted by ASHRAE’s friction graphs for cylindrical galvanized metal ducts,for air speeds from 0to15m/s. •Elbows with two 135º-angles,thatis to say,those made from straightductsections,have similar or slightly inferior pressure losses compared to curved elbows made of glass wool ductboards

Avoid extremes of temperature

Avoid extremes of temperature. Do not place in
direct sunlight or near air conditioning vents.
Make sure the scale is located on a strong table and
free from vibration.
Avoid unstable power sources. Do not use near large
users of electricity such as welding equipment or
large motors. Do not mix batteries and use only the
factory approved power adapter supplied with the
machine. Do not use batteries and the AC adapter at
the same time.
Keep free from vibration. Do not place near heavy or
vibrating machinery.
Avoid high humidity that might cause condensation.
Keep away from direct contact with water. Do not
spray or immerse the scales in water.

Integrated Design

Integrated Design
The HVAC system must be considered in the early schematic design phase to achieve optimal
performance in an energy efficient house. During the schematic phase, the design team needs to
allocate adequate space for the equipment and ducts while identifying principal potential
conflicts between the building’s structure and the HVAC system. Decisions made during the
early design phase will be critical to the successful performance of the HVAC system.
Locating the HVAC equipment centrally within the house is an early design consideration with
many benefits for the performance of the system and implications for the space planning in the
house. Locating the equipment centrally will allow for shorter duct runs with similar lengths,
which can lead to a better balanced system and improved performance. Centrally located
equipment with shorter duct runs also facilitates running ducts to interior walls with the high
performance strategy of more efficient high sidewall diffusers aimed at the exterior walls.
An energy efficient house utilizes strategies to keep all ductwork inside the thermal boundaries
of the house. Keeping all ductwork inside thermal boundaries will eliminate losses to the outside
of the building enclosure but may require the use of soffits that reduce ceiling heights or chases
that must be designed with the floor plan flow.
A preliminary layout of the duct system can be made on the floor plan, taking into consideration
the performance criteria. By considering a preliminary duct layout, early accommodations can be
made in the framing plan as needed.
Floor systems are a commonly used element to run duct systems within the thermal boundary,
particularly in multistory houses. Creating chases deliberately when designing the floor plan
layout will allow the HVAC system to perform as designed. Considering the location of
horizontal and vertical chases early in the design can decrease the level of complexity in the duct

Special category s

I.2.1.1.2 Special category spaces are to be equipped with forced ventilation capable of effecting at least
10 air changes per hour. Special category spaces are closed vehicle decks on passenger ships to which
the passengers have access.
I.2.1.1.3 During loading and unloading periods an increased air change rate of 20 air changes per hour
is to be provided 8.
I.2.1.2 Performance and design of ventilation systems
I.2.1.2.1 In passenger ships, the power ventilation system of the space shall be separate from other
ventilation systems and shall be in operation at all times when vehicles are in such spaces. Ventilation
ducts serving such cargo spaces capable of being effectively sealed shall be separated for each such
space. The system shall be capable of being controlled from a position outside such spaces.
I.2.1.2.2 On passenger ships, a fan failure (monitoring of motor fan switching devices is sufficient) or
failure related to the number of air changes specified for vehicle decks and holds shall be alarmed on the
bridge.
I.2.1.3 Closing appliances and ducts
Ventilation ducts, including dampers shall be made of steel. In passenger ships, ventilation ducts that
pass through other horizontal zones or machinery spaces shall be "A-60" class steel ducts constructed in
accordance with D.5.3.

Additional Rules for Passenger Vessels

Additional Rules for Passenger Vessels
I.1 General
I.1.1 Application
These Rules are applied in additional to the Rules of D. to E.
I.1.2 Means of control
All controls indicated in D.7.2 as well as means of control for permitting release of smoke from machinery spaces
are to be located at one control position or grouped in as few positions as possible. Such positions are to
have a safe access from the open deck.
I.1.3 Ventilation ducts
Where in a passenger ship it is necessary that a ventilation duct passes through a main vertical zone
division, a fail-safe automatic closing fire damper shall be fitted adjacent to the division. The damper shall
also be capable of being manually closed from each side of the division. The operating position shall be
readily accessible and be marked in red light-reflecting colour. The duct between the division and the
damper shall be of steel or other equivalent material and, if necessary, insulated to the same standard as
the penetrated division. The damper shall be fitted on at least one side of the division with a visible indicator
showing whether the damper is in the open position.

The design of mechanical

The design of mechanical exhaust ventilators has to comply with D.6
H.2.6 A fan failure (monitoring of motor fan switching devices is sufficient) shall be alarmed on the
bridge.
H.2.7 Inlets for exhaust ducts are to be located within 450 mm above the vehicle deck. Outlets are to
be located in a safe position, having regard to sources of ignition near the outlets.
H.3 Closing appliances and ducts
H.3.1 Arrangements shall be provided to permit a rapid shutdown and effective closure of the ventilation
system from outside of the space in case of fire, taking into account the weather and sea conditions.

Access routes to the controls for closure of the ventilation system “permit a rapid shutdown” and adequately
“take into account the weather and sea conditions” if the routes:
 are clearly marked and at least 600 mm clear width;
 are provided with a single handrail or wire rope lifeline not less than 10 mm in diameter, supported
by stanchions not more than 10 m apart in way of any route which involves traversing a deck exposed
to weather; and
 are fitted with appropriate means of access (such as ladders or steps) to the closing devices of
ventilators located in high positions (i.e. 1.8 m and above).
Alternatively, remote closing and position indicator arrangements from the bridge or a fire control station
for those ventilator closures are acceptable.

H.2 Performance and design of ventilation systems

H.2 Performance and design of ventilation systems
H.2.1 In cargo ships, ventilation fans shall normally be run continuously whenever vehicles are on
board. Where this is impracticable, they are to be operated for a limited period daily as weather permits
and in any case for a reasonable period prior to discharge, after which period the ro-ro or vehicle space
shall be proved gas-free. One or more portable combustible gas detecting instruments are to be carried
on board for this purpose.
H.2.2 The system shall be entirely separate from other ventilating systems. Ventilation ducts serving
ro-ro or vehicle spaces shall be capable of being effectively sealed for each cargo space. The system
shall be capable of being controlled from a position outside such spaces.
H.2.3 The ventilation system shall be such as to prevent air stratification and the formation of air
pockets.
H.2.4 An independent power ventilation system is to be provided for the removal of gases and vapours
from the upper and lower part of the cargo space. This requirement is considered to be met if the
ducting is arranged such that approximately 1/3 of the air volume is removed from the upper part and 2/3
from the lower part. Supply ventilation may be natural and be introduced into the cargo spaces at the top
of these spaces.

This does not prohibit

Note
This does not prohibit ventilators from being fitted with a means of closure as required for fire protection
purposes under SOLAS, Chapter II-2, Regulation 5.2.1.1.
F.5.5 If fans of electrical explosion protection type are required, the fan openings on deck are to be
fitted with fixed protective screens with mesh size not exceeding 13 mm.
F.5.6 The fans of electrical explosion protection type must be of non-sparking design, see D.6.2 and
D.6.3
F.5.7 For the area around ventilation openings requiring explosion protection see F.1 and F.2.
F.5.8 For cargoes emitting toxic gases or vapours the ventilation outlets shall be arranged away
from living quarters on or under deck.
F.5.9 If adjacent spaces are not separated from cargo spaces by gastight bulkheads or decks, then
they should be considered as part of the enclosed cargo space and the ventilation requirements should
apply to the adjacent space as for the enclosed cargo space itself.

If fans of electrical

F.4.3 If fans of electrical explosion protection type are required, the fan openings on deck are to be
fitted with fixed protective screens with mesh size not exceeding 13 mm.
F.4.4 The fans of electrical explosion protection type must be of non-sparking design, see D.6.2 and
D.6.3.
F.4.5 For the area around ventilation openings requiring explosion protection, see F.1 and F.2.
F.4.6 If adjacent spaces are not separated from cargo spaces by gastight bulkheads or decks, then
they should be considered as part of the enclosed cargo space and the ventilation requirements should
apply to the adjacent space as for the enclosed cargo space itself.
F.4.7 For open top container holds the mechanical ventilation is interpreted to be required only for
the lower part of the cargo hold for which purpose ducting is required.
F.5 Solid dangerous goods in bulk and materials hazardous only in bulk
F.5.1 The requirements on the capacity of the ventilation system, the certified safe type of electrical
explosion protection, the electrical protection and mechanical design are summarised in the GL Rules for
Machinery Installations (I-1-2), Section 12, Q, Table 12.11 and are related to the requirements indicated

If mechanical

F.5.2 If mechanical or natural ventilation is required the ducting is to be arranged such that the
space above the cargo can be ventilated and that exchange of air from outside to inside the entire cargo
space is provided. The position of air inlets and air outlets shall be such as to prevent short circuiting of
the air. Interconnection of the hold atmosphere with other spaces is not permitted.
F.5.3 If mechanical ventilation required portable fans may be used instead of fixed ones. If so, suitable
arrangements for securing the fans safely are to be provided. Electrical connections are to be fixed
and expertly laid for the duration of the installation. Details are to be submitted for approval.
F.5.4 If continuous ventilation is required a ventilation system which incorporates at least two powered
fans with a capacity of at least three air changes per hour each based on the empty cargo hold is to
be provided. The ventilation openings shall comply with the requirements of the Load Line Convention, for
openings not fitted with means of closure. According to ICLL, Regulation 19(3) the openings shall be
arranged at least 4.50 m above deck in position 1 and at least 2.30 m above deck in position 2.