Refrigerant volumes in rooms regs'

[r.bartlett]

Hi

One of our customers is looking to reduce the fresh air volumes for their bedrooms during unoccupied times. AS it stands they use 100% fresh air and the running costs are high as it is conditioned before entering the building. They are wanting to reduce the motors via inverters.

I have already suggested this could lead to potential problems with both the burners and DX a/c but they wish to proceed none the less.

Each room has a room detector for the refrigerant but we are wondering if ventilation rates affect the volume regs.

I have searched but as yet not found any confirmation

Advice most welcome

Richard

[frank]

From all of the information we have, BS EN 378 refers to public buildings, not domestic properties, so if your customer is talking about his own home, the regs do not apply.......unless someone knows differently,,,,,,

Here's a summary of the document

EN 378 "Refrigerating systems and heat pumps - Safety and environmental requirements"

The EN 378 European Standard "Refrigerating systems and heat pumps - Safety and environmental requirements" was prepared by European Committee for Standardization/Technical Committee CEN/TC 182 (Refrigerating systems, safety and environmental requirements). It comprises 4 parts:

• Part1: basic requirements, definitions, classification and selection criteria, adopted by CEN on November 11, 1999 (52 pages);

• Part 2: design, construction, testing, making and documentation, adopted by CEN on October 10, 1999 (39 pages);

• Part 3: installation site and personal protection, adopted by CEN on October 10, 1999 (18 pages);

• Part 4: operation, maintenance, repair and recovery, adopted by CEN on October 14, 1999 (21 pages)

and is available in three official languages: English, French and German.
The aim of this standard is to "reduce the number of hazards to persons, property and the environment, caused by refrigerating systems and refrigerants".

Part 1, "basic requirements, definitions, classification and selection criteria" provides definitions of certain terms used in the standard. It also provides a classification system according to:
• the type of existing refrigerating systems (direct or indirect systems);
• usage of the premises:

Category A:
rooms, parts of building or buildings in which persons may sleep or may not have total freedom of movement and where persons are not aware of the safety measures to be applied. Such premises include hospitals, courthouses and prisons, supermarkets, schools, railway stations, etc. and thus are public buildings;

Category B:
rooms, parts of building or buildings in which certain persons may be aware of the general safety measures to be applied. Such premises include production plants, commercial premises, etc;

Category C:
rooms, parts of building or buildings in which all persons present are trained in the general and specific safety measures to be applied. Such premises include specific production plants, cold stores, etc.

• refrigerants Refrigerants are classified according to their flammability and toxicity.

Group L1 (non-toxic, non-flammable refrigerants) forming category A1;

Group L2 (slightly flammable refrigerants) comprising the categories A2, B1 and B2;

Group L3 (toxic, flammable refrigerants) comprising the categories A3 and B3.

Annex E contains information on refrigerants and indicates their characteristics (molecular mass, flammability limits, GWP, ODP, etc.).

Part 2, "design, construction, testing, marking and documentation",
applies to the design and manufacturing of refrigerating systems.
It defines the various pressure levels that must be applied (maximum allowable pressure), design pressure, etc.), the layout of the refrigerating system piping, the type of valves and pressure-regulating devices to be used. It also defines the testing procedures (tightness testing and testing of safety equipment, testing before commissioning) and acceptance procedures (marking of the refrigerating system and piping, supplying of test certificates, operating manual and plant plans, availability and location of maintenance records).

Part 3, "installation site and personal protection",
applies to staff and plant safety. It defines the principles governing the design and construction of machine rooms (dimensions, types of walls, ventilation) along with specific requirements for refrigerants in groups L1, L2 or L3. Requirements include detectors and alarm systems; protective equipment and the first aid procedures that must be made available to staff.

Part 4, "operation, maintenance, repair and recovery",
specifies safety and environmental requirements during plant operation, maintenance and repairs; it places particular emphasis on the training and skills of all persons working on the refrigerating plant (personnel involved in plant operation or monitoring). The standard emphasizes the need to recover and/or reuse refrigerants.

[r.bartlett]

Sorry Frank for not making myself clear. It's a hotel.

We are trying to confirm if the fresh air + extract can be taken into account when applying the regs

[Tradewinds]

Hi RBartlett,

I don't have my copy of TM44 AC Inspections for commercial Buildings with me, but you might find something in there on this topic.

Also have a look in google for:
Non Domestic HCV Compliance Guide (free download)

http://www.cibse.org/index.cfm?go=publications.view&item=372

Im pretty sure there is something in there about minimum fresh air rates for commercial buildings.

I tried uploading it for you but it wouldnt attach for some reason.

Hope this helps

[install monkey]

isnt it 10ltr per second per person for an office type enviroment?

[frank]

Guys

Richard is asking about the ventilation rates when related to the refrigerant leakage detectors under BS EN 378 - Concentrations of Refrigerant in spaces occupied by humans

[install monkey]

Check of Density Limit

The room in which the air conditioner is to be

installed requires a design that in the event of refrigerant

gas leaking out, its density will not exceed a set

limit.

The refrigerant (R410A), which is used in the air conditioner,

is safe, without the toxicity or combustibility of

ammonia, and is not restricted by laws imposed to protect

the ozone layer. However, since it contains more than air,

it poses the risk of suffocation if its density should rise

excessively. Suffocation from leakage of refrigerant is

almost non-existent. With the recent increase in the number

of high density buildings, however, the installation of

multi air conditioner systems is on the increase because of

the need for effective use of floor space, individual control,

energy conservation by curtailing heat and carrying power,

etc.

Most importantly, the multi air conditioner system is able

to replenish a large amount of refrigerant compared to

conventional individual air conditioners. If a single unit

of the multi air conditioner system is to be installed in a

small room, select a suitable model and installation procedure

so that if the refrigerant accidentally leaks out,

its density does not reach the limit (and in the event of

an emergency, measures can be made before injury can

occur).

In a room where the density may exceed the limit, create

an opening with adjacent rooms, or install mechanical

ventilation combined with a gas leak detection device.

The density is as given below.

Total amount of refrigerant (lbs)

Min. volume of the indoor unit installed room (ft.

3)

< Density limit (oz/ft.

3)

The density limit of refrigerant which is used in multi air

conditioners is 0.3 oz/ft.

3 (ISO 5149).

NOTE

1.If there are 2 or more refrigerating systems in a single

refrigerating device, the amount of refrigerant should be

as charged in each independent device.

For the amount of charge in this example:

The possible amount of leaked refrigerant gas in

rooms A, B and C is 353 oz.

The possible amount of leaked refrigerant gas in

rooms D, E and F is 529 oz.

Outdoor unit

Refrigerant tubing

Indoor unit

e.g., charged

amount (353 oz)

Outdoor unit

Indoor unit

Room A Room B Room C Room D Room E Room F

e.g., charged

amount (529 oz)

Refrigerant tubing

Outdoor unit

Very

small

room Indoor unit

Small

room

Medium

room

Large room

Mechanical ventilation device – Gas leak detector

0 0

57

114

170

227

284

341

398

454

0

500

1000

1500

2000

2500

3000

3500

4000

200 400 600 800 1000 1200

Total amount of refrigerant

Min. indoor volume

Min. indoor floor area

(when the ceiling is 8.8 ft. high)

ft.

3 ft.2

oz

Range above

the density limit of

0.3 oz/ft.

3

(countermeasures

needed

[dannycool]

Richard

Found this section in EN378 Part 2, ive not really read it properly but it may shed some light.

Danny

6.2.14 Requirements for ventilated enclosures
In case the refrigeration circuit is isolated from the occupied space (see EN 378-1:2008, 3.2.3, Annex E) by a
ventilated enclosure, the appliance enclosure shall have a ventilation system that produces airflow from the
appliance interior to outside the space, through a ventilation duct.
The manufacturer shall specify the ventilation duct by size and number of bends. The negative pressure
measurement in the interior of the appliance enclosure shall be 20 Pa or more and the flow rate to the exterior
shall be at least Qmin. There shall be no ignition sources located in the duct.
Qmin = 15·× s × (mc/ρ) (with a minimum of 2 m3/h)
where
Qmin is the volume flow of the ventilation (m³/h);
s is 4 (safety factor);
mc is refrigerant charge mass (kg);
ρ is density of the refrigerant at atmospheric pressure at 25 °C (kg/m³).
Compliance is determined by test.
NOTE The constant, 15, above is based on the assumptions used for the charge size formulas, i.e. releasing the full
charge amount within 4 min.
The ventilation system shall be operated as follows:
⎯ fan is operated permanently and the fan speed or air flow is monitored. In case of failure the
appliance or the motor compressor is switched off within 10 s in, or
⎯ fan is switched on by a refrigerant detector at a value above 25 % of the LFL (see EN 378-1:2008, Annex
E). The detector shall be located at a suitable point according to the density of the refrigerant. The detector
and ventilation function shall be checked at regular intervals according to the manufacturer’s
instructions. A failure shall be indicated and the system shall be switched in a safe mode.

[dannycool]

Definition of an occupied space:3.2.3
occupied space (occupancy)
complete enclosed space which is occupied for a significant period by people. Where the spaces around the
apparent occupied space are, by construction or design, not adequately tight, these are also considered as
part of the occupied space. These can be for example voids above false ceilings, crawl ways, ducts and
movable partitions. The occupied space may be accessible to the public (for example supermarket) or only to
trained persons (for example cutting up of meat). In an occupied space, both parts of a refrigerating system or
the complete refrigerating system may be located/installed

[frozenfingers]

All you need to do is calculate the room volume in m3 and multiply by 0.44, this gives you the maximum refrigerant mass in kg allowed in the space.

When working out the room volume you can also allow for any area which is connected but not air tight, eg false ceilings,voids,ducts,movable partitions and doors with transfer grills. If mechanical ventilation is installed, the volume of air it moves in 10 minutes of operation can be added to room volume.

It is a recommendation that if the charge exceeds the limit of 0.44kgm3 a leak detection system with audible alarm should be fitted.

[RSTC]

How do you confirm that the room is unoccupied? motion sensor, key card reader, what if that fails? If it's setting back the temperature you'll complain ... but your clients guests won't ring reception if they're already dead from asphyxiation.

Seems a big risk to reduce motor running costs - maybe you should look at heat recovery between the supply and extract maybe change the supply/extract ahu for something like a Flakt woods sting or PM Luft Gold (or UK made similar)