2205B0JE-DA-J-N_2014.05.
2 Structure and Specifications of the Compressor
Screw Compressor J-series
2.9 Solenoid Valve
2-33
2.9.2 Explosion Proof for 170J/220J-series, Also 280J-series
The 170J/220J-series with the explosion-proof specification and the 280j-series must prepare solenoid
valves for the capacity control and the variable Vi mechanism respectively separately.
The type of solenoid valve can use any type of the poppet type and the spool type. But, because the
spool-type solenoid valve is easy to be affected by an foreign substance and the refrigerant gas in
lubricating oil, attention is necessary for the system of the dry process vaporizer using the miscible oil.
Table 2-15
Recommended Specifications of the solenoid valves for the J-series
Item
Recommended Specifications
Maximum working differential pressure
1.6 MPa
（
equal to or more than 70% of the differential
pressure between suction and discharge pressure
）
Minimum working differential pressure
0.0 MPa
Operation fluid
Lubricant (Refrigerant oil)
Fluid temperature
70
℃
and over
Ambient temperature
－
20
～
40
℃
Maximum working pressure
3.5 MPa
(See
Note
1
) and over
Maximum working viscosity
120 mm
2
/s
Proof counter pressure (See
Note 2
) 0.4
～
0.6 MPa
（
U
→
P
）
Maximum Flow rate coefficient (Cv value)
0.53 and over
Minimum Flow rate coefficient (Cv value)
0.10 or less
Note 1:
In this manual unless otherwise noted, pressure units
MPa represents the gauge pressure.
Note 2:
Under some operating conditions the pressure in the cylinder
may rise. To prevent this abnormally high pressure capacity
control system is required, which releases the pressure of U
port to P port.
When the poppet-type solenoid valve is added the pressure
from the opposite direction of the usual flow direction, it
automatically opens its plunger. Use the poppet solenoid
valves for 0.4MPa to 0.6MPa.
The spool-type Solenoid valve does not have a backflow
problem like the poppet-type solenoid valve. Provide a check
valve which has the cracking pressure of 0.4MPa to 0.6MPa
between U port and P port (indicated in the figure 2-28).
When the pressure between U port and P port is too big,
cylinders may break. Contrarily when the pressure is too
small, there may be control failures including the inability
to maintain partial loading conditions.
Dummy
Block
In case of the explosion-proof specification of the 170J and 220J, a dummy-block is installed
instead of solenoid valve. When using a dummy-block, it doesn't use a hydraulic cylinder oil supply
port, a hydraulic cylinder oil drain port.
Figure 2-30 Hydraulic Circuit for
Spool Type Solenoid Valve
