I.safety Handling For R32; Caution For Refrigerant Leakage; Refrigerant Property; Confirm The Critical Concentration And Take Countermeasure - Mitsubishi Electric HYBRID CITY MULTI PURY-M200-300YNW-A Data Book

1. Caution for refrigerant leakage

The installer and/or air conditioning system specialist shall secure safety against refrigerant leakage according to local regulations or standards.

I.SAFETY HANDLING FOR R32

1. Caution for refrigerant leakage
The following standard may be applicable if no local regulation or standard is available.

1-1. Refrigerant property

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
* 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.

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
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.
MEES18K044
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(The weight of refrigeration gas per 1 m
SAFETY HANDLING FOR R32
3 air conditioning space.);
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