Leak Test - Toshiba MMU-AP0091H Installation Manual

5-15. Leak Test

A leak test must be performed when connecting pipes to the refrigerant pipes in use at a site.
[1] Leak test pressure
For Super MMS air conditioner systems: 3.73MPa (38kg/cm
[2] Test method
After the refrigerant piping has finished, execute an airtight test. For an airtight test, connect a nitrogen gas bomb as
shown in the figure below, and apply pressure.
• Be sure to apply pressure from the service ports of the packed valves (or ball valves) at liquid side, gas side, and
balance pipe side.
• An airtight test can be only performed to the service ports at liquid side, gas side, and balance side of the header unit.
• Close fully valves at liquid side, gas side, and balance side. As there is possibility that nitrogen gas enters in the
refrigerant cycle, re-tighten the valve rods before applying pressure. (Re-tightening of the valve rods are
unnecessary for valves at gas side of MMY-MAP0501
• For each refrigerant line, apply pressure gradually with steps at liquid side, gas side, and balance side.
Be sure to apply pressure to liquid side, gas side, and balance side.
Never use "Oxygen", "Flammable gas" and "Noxious gas" in an airtight test.
Detailed drawing of packed valve
To gauge manifold
Liquid-side
service port
Liquid-side
packed valve
Balance
service port
Balance
packed valve
Piping at site
STEP 1 : Apply pressure 0.3MPa (3.0kg/cm
STEP 2 : Apply pressure 1.5MPa (15kg/cm
STEP 3 : Apply pressure 3.73MPa (38kg/cm
• Check pressure down.
No pressure down: Accepted

However, if there is difference of ambient temp. between when pressure has been applied and when

24 hours passed, pressure changes by approx. 0.01MPa (0.1kg/cm²G) per 1°C. Correct the pressure.
Leaked position check
When a pressure-down is detected in STEP 1, STEP 2, or STEP 3, check the leakage at the connecting points.
Check leakage with hearing sense, feeler, foaming agent, etc, and perform re-brazing or re-tightening of flare if
leakage is detected.
REQUIREMENT
Connected to indoor unit
Main pipe
Gas-side
service port
Gas-side
packed valve
To outdoor
unit
To
outdoor
unit
Piping
Piping
at site
at site
To outdoor unit
Connected to other follower outdoor units
2 G) for 3 minutes or more.
2
G) for 3 minutes or more.
2 G) for approx. 24 hours.
Pressure down: Check the leaked position.
2 G)
∗ ∗
and MAP0601 because they are ball valves.)
Packed valve fully closed
(gas side)
Header outdoor unit
Brazed
Service
port
Fully
closed
Service port
Packed valve fully closed
(liquid side)
Fully
closed
Packed valve fully closed
(balance)

Available to detect a gross leakage

Available to detect slow leakage
32
Low- High-
pressure pressure
gauge gauge
Gauge
V V
L H
manifold
Reducing
valve
Ø6.4
Copper pipe
Ø6.4
Copper
pipe
Nitrogen
gas

