Specifications
0.50 0.6 0.7
B
C
A
Q0
Q1
Circulation volume or flow rate
Q（L/min）
0.8
AKZ149
AKZ329・439・
569・909
External pressure loss △P（MPa）
10
mm
2
/s
10,000
5,000
3,000
2,000
1,000
500
400
300
200
150
100
75
50
40
30
20
15
10
9.0
8.0
7.0
6.0
5.0
4.0
3.0
2.0
-10 0 10 20 30 40 50 60 70℃
-10 0 10 20 30 40 50 60 70℃
20 30 40 50 60 70 80 90 100 110 120 130 140 150 °F
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 °F
68
46
32
22
10
5
2
Usable range
Unusable range
25
Supporting
information
Supporting information
Notes for installing external piping
Notes for installing external piping
If the external pressure loss （site piping resistance）
exceeds the specified use range, there may occur
phenomena such as abnormal noise of the pump （relief
noise, noise of cavitation）, decrease of cooling capacity
and control failure of oil temperature. Keep the external
pressure loss within the specified use range.
1. Suction-side piping
Keep the suction vacuum pressure within the range
between -30.7 and 0kPa.
The use of a suction filter of 100 to 150 mesh is
recommended.
2. Discharge-side piping
Keep the pressure loss of the discharge-side piping at
0.5 MPa or less.
3. Do not install a stop valve on the suction or discharge
side. When a stop valve must be installed on the
discharge side out of necessity, use a 0.5Mpa relief
valve along with the stop valve.
4. Calculation of piping resistance
Determine the oil piping size by calculating the piping
resistance according to the following equation:
Piping resistance △P=0.595 ×ν×Q×L/Ｄ
4
（For use of general hydraulic oil and lubricant）
Piping resistance（MPa）
Dynamic coefficient of viscosity（mm
2
/s）
−Refer to the Viscosity / Temperature Chart.
Flow rate （L/min）
Piping length （m）
Internal piping diameter （mm）
△ P ：
ν ：
Q ：
L ：
D ：
Design the site piping to withstand a pressure of at least 1.0 MPa.
Note）
●Relationship between oil flow rate
and external pressure loss
An AKZ 9 series Oil Cooling Unit incorporating a pump of the
circulation type has the characteristics shown below. When the
external pressure loss (△p) is 0.5 MPa or less, the rated flow rate
(Q0) is achieved, but when the external pressure loss exceeds 0.5
MPa, the flow rate becomes lower than the rated flow rate.
Good example
Bad example
△P ＞0.5MPa
↓
The oil flow rate
becomes Q1, lower
than the rated flow rate.
△P ≦0.5MPa
↓
The rated flow rate （Q0） is
achieved.
Flow rate （Q0: Rated flow rate）
External pressure loss
Status when the external pressure loss is “0”
Status when the external pressure loss is “0.5Mpa”
Status when the external pressure loss is large
and the oil flow rate is “0”.
Q（L/min） ：
△P（MPa） ：
A ：
B ：
C ：
（Cracking pressure of relief valve）
Example of viscosity
（
dynamic coefficient of
viscosity）
In winter: 195mm
2
/s
ISO VG32 Oil
（temperature 5℃）
In summer: 29mm
2
/s
ISO VG32 Oil
（temperature 40℃）
■Viscosity / Temperature Chart
Dynamic
viscosity
Temperature
Temperature