VC Pro VRF 50/60Hz
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Part 3 - System Design and Installation
4.7 Refrigerant Leakage Precautions
R410A refrigerant is not flammable in air at temperatures up to 100°C at atmospheric pressure and is generally considered
a safe substance to use in air conditioning systems. Nevertheless, precautions should be taken to avoid danger to life in the
unlikely event of a major refrigerant leakage. Precautions should be taken in accordance with all applicable legislation.
Where no applicable legislation exists, the following may be used as a guide:
Air conditioned rooms should be large enough that if leakage of all the refrigerant in the system occurs, the
concentration of the refrigerant in the room does not reach a level dangerous to health.
A critical concentration (at which point R410A becomes dangerous to human health) of 0.44 kg/m
3
can be used.
The potential concentration of refrigerant in a room following a leak can be calculated as follows:
Calculate the total amount in of refrigerant in the system (“A”) as the nameplate charge (the charge in the system
when delivered from the factory) plus the additional charge added as per Part 3, 8.1 “Calculating Additional
Refrigerant Charge”.
Calculate the total volume (“B”) of the smallest room into which refrigerant could potentially leak.
Calculate the potential refrigerant concentration as A divided by B.
If A/B is not less than 0.44 kg/m
3
, countermeasures such installing mechanical ventilators (either ventilating
regularly or controlled by refrigerant leakage detectors) should be taken.
Since R410A is heavier than air, particular consideration should be given to leak scenarios in basement rooms.
Figure 3-4.6: Potential refrigerant leak scenario
Figure 3-4.7: Mechanical ventilator controlled by refrigerant leak detector
Outdoor unit
Indoor unit
Room full of leaking refrigerant
(All the refrigerant has leaked)
Leakage detector
connected to mechanical
ventilator
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