Checking The Density Limit - Sanyo SGP-EW120M2G2W Technical Data Manual

System Design

(7) Checking the density limit

* The following is for R22, but is also applicable to R410A.
With a multi-type system, the total length of refrigerant tubing is longer, and the almost of additional
refrigerant charge is more. For this reason, there is danger that refrigerant leaking into a small room may
cause persons in the room to be asphyxiated. The density limit is dermined as follows according to the
"Installation Standards for Refrigeration and Air Conditioning Equipment (KHK-S0010)" - voluntary
standards created by the High Pressure Gas Safety Institute of Japan.
Total amount of refrigerant charge (kg) for the system
Smallest room volume (m
No special measures are required if the concentration is at or below the density limit of 0.3 kg/m
However, special measures are required if the density is above 0.3 kg/m
1. Selecting the A/C system
The maximum values for the refrigerant charge that can be selected for each room volume and
ventilation rate are indicated by the area outside the range of diagonal lines in Fig. 1. If the value is within
the range of the diagonal lines, then either effective opening for ventilation must be created to increase
the room volume or the outdoor unit capacity and/or piping length must be changed to reduce the amount
of total refrigerant charge. However, this is not necessarily the case when 2 or more independent
measures are taken to ensure the safety of persons inside the room in the event of refrigerant leakage.
2. Selecting an indoor unit type
An indoor unit with an installation position 2 m or higher above the floor is recommended.
3. Restrictions on the tubing connections between living spaces
Tubing connections must be subjected to a reliable airtightness test after the completion of work. The test
must conform to JIS-B-8607 (refrigerant flared and brazed joints).
4. Combined use of a ventilation system
(a) Mechanical ventilation devices must be used in order to reduce the concentration of leaked
refrigerant.
(b) Mechanical ventilation devices which introduce outside air at a location 2 m or higher above the room
floor are recommended.
(c) The ventilation volume of the mechanical ventilation devices must be at or above the volume shown in
Fig. 1, according to the amount of refrigerant gas and room volume.
(d) Be sure to create openings that improve ventilation (such as the bottom gap of room doors).
(e) The ventilation system must operate at all times, regardless of whether the A/C device is in use or not,
and regardless of whether there are persons in the room or not. If this is not possible, a sensor system
must be used to automatically operate the ventilation system when refrigerant leakage is detected.
5. Restrictions and precautions for tubing installation
(a) Tubing must include earthquake-resistant support to prevent damage resulting from earthquakes or
other external forces.
(b) When adding support to the tubing, create relief in the axial direction to prevent the occurrence of
thermal stress.
6. Flowchart showing refrigerant leakage measures:
Omitted
3
) where an indoor unit is installed
D-13
3. Refrigerant piping design
Density limit 0.3 kg/m
3
3
3.