Mitsubishi Electric HYBRID CITY MULTI Series Manual
CONTENTS
SAFETY HANDLING FOR R32
I.SAFETY HANDLING FOR R32
1. Caution for refrigerant leakage ................................................................................................................. 2
1-1. Refrigerant property ......................................................................................................................... 2
1-2. Confirm the Critical concentration and take countermeasure .......................................................... 2
2. Installation restrictions .............................................................................................................................. 3
2-1. Installing the outdoor unit or the Hydro unit outdoor ........................................................................ 3
2-2. Installing the Hydro unit or the HBC indoor ..................................................................................... 5
3. Installation flow chart ................................................................................................................................ 6
4. Installation chart annex............................................................................................................................. 10
5. Regulatory requirements list for safety measures..................................................................................... 13
SAFETY HANDLING FOR R32
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1. Caution for refrigerant leakage
R32 refrigerant has lower flammability (A2L refrigerant: ISO817, 2014). The R32 is heavier than the indoor air in density.
Leakage of the refrigerant in a room has possibility to lead to a hypoxia situation and fire. Therefore, the critical concentration specified
below shall not be exceeded even if the leakage happens.
Critical concentration
Critical concentration hereby is the refrigerant concentration in which no human body would be hurt if immediate measures can be taken
when refrigerant leakage happens.
Critical concentration of R32: 0.063kg/m
3
(The weight of refrigeration gas per 1 m3 air conditioning space.);
* The Critical concentration is subject to ISO5149 (2014), EN378-1 (2016).
For the HYBRID CITY MULTI system, the concentration of refrigerant leaked should not have a chance to exceed the critical concentration
in any situation.
I.SAFETY HANDLING FOR R321. Caution for refrigerant leakage
The installer and/or air conditioning system specialist shall secure safety against refrigerant leakage according to local regulations or standards.
The following standard may be applicable if no local regulation or standard is available.
SAFETY HANDLING FOR R32
1-1. Refrigerant property
SAFETY HANDLING FOR R32
1-2. Confirm the Critical concentration and take countermeasure
The maximum refrigerant leakage concentration (Rmax) is defined as the result of the possible maximum refrigerant
weight (Wmax) leaked into a room divided by its room capacity (V). The refrigerant of Outdoor unit here includes its original
charge and additional charge at the site.
The additional charge is calculated according to the refrigerant charging calculation of each kind of Outdoor unit, and shall
not be over charged at the site. Procedure 1-2-1~3 tells how to confirm maximum refrigerant leakage concentration
(Rmax) and how to take countermeasures against a possible leakage.
1-2-1. Find the possible maximum leakage (Wmax) in the room. If a room has HBC(s) from more than 1 Outdoor unit, add
up the refrigerant of the Outdoor units.
1-2-2. Divide (Wmax) by (V) to get the maximum refrigerant leakage concentration (Rmax).
1-2-3. Find if there is any room in which the maximum refrigerant leakage concentration (Rmax) is over 0.063kg/m
3
.
If no, then the HYBRID CITY MULTI is safe against refrigerant leakage.
If yes, following countermeasure is recommended to do at site.
Countermeasure 1: Smaller total charge (making Wmax smaller)
e.g.Avoid connecting more than 1 Outdoor unit to one room.
e.g.Using smaller model size but more Outdoor units.
e.g.Shorten the refrigerant piping as much as possible.
Note 1. In principle, MITSUBISHI ELECTRIC requires proper piping design, installation and air-tight testing after
installation to avoid leakage happening.
In the area should earthquake happen, anti-vibration measures should be fully considered.
The piping should consider the extension due to the temperature variation.
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2. Installation restrictions
2. Installation restrictions
SAFETY HANDLING FOR R32
Observe the following restrictions that apply to the installation of units.
2-1. Installing the outdoor unit or the Hydro unit outdoor
Do not install the unit where combustible gas may leak.
- If combustible gas accumulates around the unit, fire or explosion may result.
Provide sufficient space around the unit for effective operation, efficient air movement, and ease of access for maintenance.
Note that refrigerant gas is heavier than air and will therefore tend to collect in low spots such as basements.
R32 is heavier than air—as well as other refrigerants—so tends to accumulate at the base (in the vicinity of the floor). If R32
accumulates around the base, it may reach a flammable concentration in case the room is small. To avoid ignition, maintain a
safe work environment by ensuring appropriate ventilation. If the refrigerant leaks in a room or an area that has insufficient
ventilation, refrain from using flames until the work environment is improved by ensuring appropriate ventilation.
Do not install the outdoor unit in a basement or machinery room, where the refrigerant stagnates. *1
Install the unit in a place where at least one of the four sides is open.
* Refer to the Installation manual for other general precautions on installation.
*1 In the case of hydro unit, please refer to “2-2. Installing the Hydro unit or the HBC indoor”
SAFETY HANDLING FOR R32
Figure 1
Install units in a place where at least one of the four sides is open or in a sufficiently large space without depressions.
*The following examples show an outdoor unit.
Correct installation
Wrong installation
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(Example: basement)
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2. Installation restrictions
SAFETY HANDLING FOR R32
If the unit needs to be installed in a space where all four sides are blocked, confirm that one of these situations
(A, B, or C) is satisfied.
Secure sufficient installation space (minimum installation area: Amin).
A
Install the unit in a space with an installation area of Amin or more, corresponding to the refrigerant amount (M).
(M = factory-charged refrigerant + refrigerant to be added on site)
SAFETY HANDLING FOR R32
112
223
334
445
556
667
2
]
Wall height ≤ 0.125 m
]
M [kg
Amin [m
10
20
30
40
50
60
Install the unit in a space with a wall height of ≤ 0.125 m.
B
Wall height ≤ 0.125 m
(No restrictions apply to
the refrigerant amount)
Amin
Create an appropriate ventilation open area.
C
Longitudinal
direction
Width of an opening
≥ 0.9 m
Height of an opening
≥ 0.15 m
Height from the ground to
an opening ≥ 0.125 m
Opening:
• Must occupy 80% of the
longitudinal side of a space.
• Must have an opening ratio of
75% or higher.
(Example: space with a louver)
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2. Installation restrictions
SAFETY HANDLING FOR R32
2-2. Installing the Hydro unit or the HBC indoor
When installing Hydro unit/HBC in machinery room or small room, take safety measures in accordance with the European
Standard, based on the system refrigerant amount and the room volume as shown in the figure 2.
(The installation restrictions can be simply found by using the flowchart.)
SAFETY HANDLING FOR R32
Figure 2
Refrigerant concentration and required quantity of safety measures
(height of ceiling space = 1.8 m)
80
70
60
At least two
50
safety measures
40
are required.
30
20
SyStem refrigerant amount [kg]
10
0
0 50 100 150 200 250 300 350 400 450 500 550 600 650
Do not place an ignition source in a space where Hydro unit/HBC is installed or adjacent spaces not shielded by firewalls.
Examples: Lighters, combustion heaters, combustion boilers, and combustion cookers
All of the above-mentioned restrictions apply not only to new installations but also to relocations and layout changes.
NG (ISO 5149)
At least one
safety measure
is required.
Construction guidance
Room volume [m3]
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