Toshiba CONCEALED DUCK TYPE, CEILING TYPE service manual Check of Concentration Limit

WARNINGS ON REFRIGERANT LEAKAGE

Check of Concentration Limit

The room in which the air conditioner is to be installed requires a design that in the event of refrigerant gas leaking out, its concentration 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, and is not restricted by laws to be imposed which 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 R410A 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 replenish a large amount of refrigerant compared with conventional individual air conditioners.

If a single unit of the multi 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 with 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 R410A which is used in multi air conditioners is 0.3kg/m³.

NOTE 1 :

If there are 2 or more refrigerating systems in a single refrigerating device, the amounts of refrigerant should be as charged in each independent device.

Outdoor unit

e.g., charged

amount (10kg) e.g.,

charged amount (15kg)

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

Indoor unit

For the amount of charge in this example:

The possible amount of leaked refrigerant gas in rooms A, B and C is 10kg.

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

Important

NOTE 2 :

The standards for minimum room volume are as follows.

(1)No partition (shaded portion)

(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).

Outdoor unit

Refrigerant piping

Indoor unit

(3)If an indoor unit is installed in each partitioned room and the refrigerant piping is interconnected, the smallest room of course becomes the object.

But when a mechanical ventilation is installed interlocked with a gas leakage detector in the smallest room where the density limit is exceeded, the volume of the next smallest room becomes the object.

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

Mechanical ventilation device - Gas leak detector

NOTE 3 :

The minimum indoor floor area compared with the amount of refrigerant is roughly as follows: (When the ceiling is 2.7m high)

	40
m² 35		Range below the
		density limit
	30	of 0.3 kg/m³
		(countermeasures
	25	not needed)
area
	20
floor	15		Range above
			the density limit
indoor	10		of 0.3 kg/m³
			(countermeasures
			needed)
Min.	5
	0
		10	20	30
		Total amount of refrigerant			kg