Checking The Density Limit - Sanyo SGP-E70J2GU2 User Manual

Design

(6) Checking the density limit

*The following is for R-22, but is also applicable to R-407C.
In a multi-type system, as the length of refrigerant pipes gets longer the additional charge amount of refrigerant
increases. Therefore there is a danger that if refrigerant should leak in a small room the occupants of the room could
suffocate. According to the standard "Standards for Cooling Air Conditioning Equipment" (KHK-S0010) issued by the
High Pressure Gas Safety Institute of Japan,
Total quantity of refrigerant in refrigerant equipment (kg)
Volume of the smallest room with an indoor unit installed (m
If the density is less than 0.3 kg/m
measures are required.
Guidelines for ensuring safety of multi-type package air conditioning systems during a leak of refrigerant
If the density limit does not satisfy the equation, then the following guidelines must be followed in selecting the system,
construction and setting of the mechanical ventilation system.
1Selection of air conditioning system
The maximum quantity of refrigerant that can be used for a given volume of room is as shown in Figure 1, above the sloping
lines. If this condition is not satisfied then either an effective opening must be provided to the room for ventilation, making
the volume larger, or the outdoor unit capacity or the piping length must be re-considered in order to reduce the total
quantity of refrigerant. However, if two or more independent means of securing the safety of occupants in the case of a leak
of refrigerant are taken, then this requirement need not be fulfilled.
2Selection of outdoor unit type
It is recommended that the outdoor unit is positioned 2m or higher from the floor.
3 Restrictions on pipe connections within living quarters
Pipe connections must conform to JIS-B-8607 (flare type and brazed type fittings for refrigerants), and after being properly
installed and completed, they must be tested for gas-tightness.
4
Combination with ventilation system
a) A mechanical ventilation system shall be used in combination with the air conditioning system in order to dilute the
concentration of any refrigerant leak.
b) It is desirable that the mechanical ventilation system introduces air into the room from a height of 2m or more.
c) The ventilation rate of the ventilation system shall be equal to or greater than the quantity indicated in Figure 1 for the
refrigerant quantity and room volume.
d) In the lowest part of the room there must be an opening that will permit effective ventilation (a gap under a door, etc.
e) The ventilation system must always operate, regardless of whether the air conditioning system is operating or not, or
whether the room is occupied or not. If this is not possible then a sensor system to detect refrigerant leak, and
automatically activate ventilation shall be provided.
5
Restrictions on piping installation and items for caution
a) The piping must be provided with earthquake-resistant supports, so that there will be no damage to the piping in an
earthquake or other externally applied force.
b) Where pipes are supported, they shall be provided with a clearance to allow axial movement, so that thermal stresses do
not accumulate.
6 Flowchart for dealing with refrigerant leaks
•Omitted
3 no special measures are required. If the density is greater than 0.3 kg/m
D - 11
3. Refrigerant piping design
Density limit 0.3 kg/m
3
)
3
3 then special