42. The standards for minimum room volume are as follows.(1) No partition (shaded portion)(2) When there is an effective opening with the adjacent roomfor ventilation of leaking refrigerant gas (opening withouta door, or an opening 0.15% or larger than the respectivefloor spaces at the top or bottom of the door).(3) If an indoor unit is installed in each partitioned room andthe refrigerant tubing is interconnected, the smallest roomof course becomes the object. But when mechanicalventilation is installed interlocked with a gas leakagedetector in the smallest room where the density limit isexceeded, the volume of the next smallest room becomesthe object.3. The minimum indoor floor space compared with theamount of refrigerant is roughly as follows: (When theceiling is 2.7 m high)40.554.027.013.50.0 20100 30 40 60 70 80 90 1005067.581.094.5108.0121.5135.0148.5162.0175.5189.0202.5216.0229.5243.0256.0270.0m2 m315105020253035404550556065707580859095100105110115120125283.5297.0310.5324.0337.5kgCheck of Density LimitThe room in which the air conditioner is to be installedrequires a design that in the event of refrigerant gasleaking 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, andis not restricted by laws imposed to protect the ozone layer.However, since it contains more than air, it poses the risk ofsuffocation if its density should rise excessively. Suffocationfrom leakage of refrigerant is almost non-existent. With therecent increase in the number of high density buildings,however, the installation of multi air conditioner systems ison the increase because of the need for effective use of floorspace, individual control, energy conservation by curtailing heatand carrying power, etc.Most importantly, the multi air conditioner system is ableto replenish a large amount of refrigerant compared toconventional individual air conditioners. If a single unit of themulti air conditioner system is to be installed in a small room,select a suitable model and installation procedure so that if therefrigerant accidentally leaks out, its density does not reach thelimit (and in the event of an emergency, measures can be madebefore injury can occur).In a room where the density may exceed the limit, create anopening with adjacent rooms, or install mechanical ventilationcombined with a gas leak detection device. The density is asgiven below.Total amount of refrigerant (kg)Min. volume of the indoor unit installed room (m3 )< Density limit (kg/m3 )The density limit of refrigerant which is used in multi airconditioners is 0.3 kg/m 3 (ISO 5149).NOTE1. If there are 2 or more refrigerating systems in a singlerefrigerating device, the amount of refrigerant should be ascharged 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 10 kg.The possible amount of leaked refrigerant gas in rooms D,E and F is 15 kg.e.g., chargedamount (10 kg)Indoor unitOutdoor unite.g., chargedamount (15 kg)Room A Room B Room C Room D Room E Room FOutdoor unitRefrigerant tubingIndoor unitMechanical ventilation device – Gas leak detectorRefrigerant tubingOutdoor unitIndoor unitVerysmallroomSmallroomMediumroomLarge roomRange below thedensity limit of0.3 kg/m³(Countermeasuresnot needed)Range above thedensity limit of 0.3kg/m³(Countermeasuresneeded)Total amount of refrigerantMin. indoor volumeMin. indoor floor area(when the ceiling is 2.7 m high)