Toshiba HFC R-410A manual Refrigerant piping design, Warnings on refrigerant leakage

5.Refrigerant piping design

1. Warnings on refrigerant leakage

Check of concentration limit

The room in which the air conditioner is to be installed requires a design that ensures that the concentration of refrigerant gas will not exceed a set limit if there is a leak.

Refrigerant R-410A which is used in the air conditioner is safe, without the toxicity or combustibility of ammonia, and is not restricted by laws that protect the ozone layer. However, since it contains more than air, it poses the risk of suffocation if its concentration should rise excessively. Suffocation from leakage of R-410A is almost non- existent. With the recent increase in the number of high concentration 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 contain a large amount of refrigerant compared with 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 concentration 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 concentration may exceed the limit, create an opening to adjacent rooms, or install mechanical ventilation combined with a gas leak detection device. The concentration is as given below.

Total amount of refrigerant (kg)

Min. volume of the indoor unit installed room (m³)

≤ Concentration limit (kg/m³)

The concentration limit of R-410A which is used in multi air conditioners is 0.3 kg/m³.

Note 1: If there are 2 or more refrigeration systems in a single refrigeration device, the amounts 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 10 kg.

•The possible amount of leaked refrigerant gas in rooms D, E and F is 15 kg.

Note 2: The standards for minimum room volume are as follows:

(1) No partition (shaded portion)

e.g. charged	Outdoor unit
	e.g. charged amount (15 kg)
amount (10 kg)

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

Indoor unit

(2)When there is an effective opening with the adjacent room for ventilation of leaking refrigerant gas (opening without a door, or an opening 0.15% or larger than the respective floor spaces at the top or bottom of the door).

(3)If an indoor unit is installed in each partitioned room and the refrigerant piping is interconnected, the smallest room is the critical room. But when a mechanical ventilation device is installed in combination with a gas leak detector in the smallest room where the density limit is exceeded, the volume of the next smallest room is used.

Outdoor unit

Refrigerant piping

Indoor unit

Refrigerant piping

		Outdoor unit
Very		Indoor unit
small
room
Small	Medium room	Large room
room

Mechanical ventilation device - gas leak detector

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