4-6
4.2 Automatic Pumpdown
An automatic pump down is performed to prevent damage to compressor due to extremely low suction
pressure.
●Access to Automatic Pumpdown
Note ;
1.
When PTI starts soon after pressing I/O switch ON,
"Preparation" is displayed due to actuation of start
control. (Refer to startup control in paragraph 1.4.6)
2. "GOOD" is displayed after completion of
automatic pump down. Then press I/O switch
OFF for the termination.
●Automatic Pumpdown Operation
Automatic Pump Down operation consists of
5 steps as below. It is normally terminated for
a several minutes but more longer under low
ambient temperature (≦0℃ ).
LPT
kPa
−27kPa
LPT
0〜350kPa
①②③④⑤
0kPa
30s
20s
40s
＋
0
−
① In the case of HPT≦700kPa, unit operates
normally for 30 seconds.
② Pump Down Operation
Unit conducts pump down operation with
closing LSV and compressor will stop when
LPT drops to ≦-27kPa.
③ Leakage Check
Keep unit stopping for 20 seconds and check if
LPT does not rise.
Repeat ② and ③ 9 times when ambient
temperature<0℃ or RS<0℃ .
④ Pressure Equalizing
Keep EFM and CFM stopping for 40 seconds,
then if LPT<0kPa, open HSV and increase
LPT until LPT≧0〜350kPa.
⑤ Termination
Close HSV when LPT becomes 0〜350kPa,
then close EEV. "GOOD" is displayed and
automatic pumpdown will be terminated.
●Use of Automatic Pumpdown
1. Replacement of Dryer
Replace Dryer after automatic pump down
is completed. The pressure in the pipe in
and out of the Dryer is slightly higher than
the atmospheric pressure. Thus, although no
ambient air will enter into the piping, replace
Dryer quickly in a short period.
CAUTION !!
Ambient air may enter into piping if it is opened
for long time after removing Dryer. In this
case vacuum and dehydrate the piping after
replacement of Dryer.
2.
Checking the entering of non-condensable gas
After completion of automatic pumpdown,
operate CFM and stabilize the pressure in
condenser, then check the entering of non-
condensable gas. (Refer to paragraph 4.4.)
0〜350 kPa after completion
of automatic pumpdown
Dryer
EEV
HSV
LSV
DMV
LPT
CFM
③
Service
port
Preparation
Under preparation
Note 1
Auto Pump down
SET-MODE
SET
POINT
SUPPLY -18.6C DEF-INT 12HR
-18.0C
FULL COOLFROZEN
HP:1200KP LP: 20KPa
▲
▼
RETURN
-18.1C
Operation display
Menu
Service Menu
Trip Start
Auto P.down
Menu
Setpoint
Service Menu
Auto Pump down
Pump Down
Activated
Auto Pumpdown
During operation
Auto Pump down
Press
ENTER to Start
ESC to Cancel
Select Service Menu Select Auto Pumpdown
0401-26LX10F11BEn.indd4-60401-26LX10F11BEn.indd4-6 2014/11/1916:42:092014/11/1916:42:09
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