Atlas Copco LE11, Instruction Book

Industrial Air Division

3

2920 5997 03

1 Leading particulars

1.2 Air flow

1.2.1 LE and LEN (Fig. 2a)

Air drawn through air filter (2) 

1)

, intake silencer (1) and inlet valves

into cylinders (8) is compressed, then discharged through the
delivery valves to discharge collector (7) and temperature reducer
(6), where the compressed air is cooled.  The compressed air is
discharged via check valve (13) into air receiver (16).

1.2.2 LT (Fig. 2b)

Air drawn through air filter (2) 

1)

, intake silencer (1) and inlet valve

into LP cylinder (8) is compressed, then discharged through the
delivery valve to intercooler (23).

The cooled air then flows via pulsation damper (26) and the inlet
valve to HP cylinder (24), where it is further compressed and
discharged through the delivery valve to temperature reducer (22),
where the compressed air is cooled. The compressed air is
discharged via check valve (13) into air receiver (16).

1.3 Regulating system

1.3.1 LE/LT5 and -6 (Fig. 2a)

The regulating system includes:
-

Check valve (13)

-

Air pressure switch (PSR19) with pressure release valve (20)
and ON/OFF buttons (S1-O and S1-I).  The pressure switch
also incorporates an overload relay (e1).

Operation

Air pressure switch (PSR19) opens and closes its contacts at pre-
set pressures. During loaded operation, the contacts are closed;
the motor is running.

When the pressure in the air receiver reaches the pre-set
maximum pressure, the contacts as well as pressure release valve
(20) are opened.  Under this condition, the motor stops, the air at
the delivery side of the compressor is vented to atmosphere and
check valve (13) closes to prevent venting of the receiver.

When the pressure in the air receiver decreases to the pre-set
minimum pressure, the air pressure switch trips to its original
position, pressure release valve (20) closes and the motor restarts.

1.3.2 LE/LT7 up to -12 and LEN (Fig. 2b) 2)

The regulating system mainly comprises:
-

Motor starter

-

Air pressure switch (PSR19)

-

Solenoid valve (Y1)

-

Unloader (29)

Operation

Air pressure switch (PSR19) opens and closes its contacts at pre-
set pressures.

2)

LE/LT7 and -8, equipped with a direct-on-line motor starter,
have the same regulating system as described in section 1.3.1.

1.1 General description

LE, LEN and LT are two-cylinder, air-cooled, single-acting piston
compressors.  LE and LEN are single-stage compressors; LT are
two-stage compressors.  LEN are oil-less compressors delivering
oil-free air.

LE and LEN are built for effective working pressures up to 10 bar.
LT5 up to -12 are built for effective working pressures up to 20 bar;
LT530, -730, -930 and -1230 up to 30 bar.

To avoid large enumerations in the text, following abbreviations are
used:

LEN

 stands for LE7N and LE9N

LE/LT5, -6

 stands for LE5, LE6, LT5, LT6 and LT530.

LE/LT7 up to -12 

stands for LE7, LE8, LE9, LE11, LE12, LT7,

LT8, LT9, LT11, LT12, LT730, LT930 and LT1230.

1.1.1 Compressor variants

The compressor block

 includes besides the crankcase and

cylinders (Fig. 1a):
-

air intake filter (2) and silencer (3)

-

fan (34)

-

air cooler(s) (25)

-

unloader (22, for LE/LT7 up to -12)

-

relief valve (27, for LT7 up to -12)

It can also be supplied with a V-belt pulley and an extra support.

The power pack

 consists of (Fig. 1b):

-

For LE/LT5, -6:

 the compressor block as described above, with

flanged-on electric motor (M), a check valve (8-Fig. 1c) and an
air pressure switch (PSR19-Fig. 1c).

-

For LE/LT7 up to -12:

 the compressor block as described

above, with flanged-on electric motor (M), a solenoid valve (Y1-
Fig. 1d) and an air pressure switch (PSR19-Fig. 1d).  The
motor starter is not included.

The complete unit

 (Figs. 1c and 1d) is the power pack mounted

on an air receiver (9) with air outlet valve (15), pressure gauge
(13), safety valve (12) and condensate drain cock (10).

LE/LT5, -6 are equipped with a direct-on-line motor starter.  LE/LT7
and -8 may be equipped with a direct-on-line or a star-delta motor
starter which is considered being standard for further description.
LE/LT9 up to -12 and LE7N/LE9N are equipped with a star-delta
motor starter.

An optional sound-insulated hood is available.

The Pack unit

 (Fig. 1e) is the power pack with its regulating

equipment and a small air receiver enclosed in a sound-insulated
bodywork.  The motor starter is mounted at the rear.  The bodywork
has a hinged top and service panel to allow easy access for
maintenance.

1)

For Pack units and for units with an optional silencing hood the
air is drawn through the air filter via the fan guard.