Integrated bypass
developed by
Hydac SA
Paolo 2
Integrated bypass
Time schedule
• What is an integrated bypass
• Why this development
• How do the IBP & IBT valves function
Paolo 3
Integrated bypass
What is an
integrated bypass
A bypass is necessary to limit the inlet pressure and to help the rig’s
startup with cold liquid.
Hydac’s integrated bypass is a standard bypass mounted inside a special
radiator expressly designed for this.
Paolo 4
Integrated bypass
Why ?
...only advantages !
TO REDUCE :
• Problems
• Space
• Cost
With easy
maintenance
>>
Paolo 5
Integrated bypass
Even better
than the standard external bypass
10
Standard radiator
Standard radiator
with external
bypass 3 bar
Radiator with
integrated bypass
Radiator with
IBP3
Radiator with
IBP3
pressure drop [bar] at 430 mm2/s
9
8
7
6
5
4
3
2
1
0
0
20
40
60
80
100
oil flow [l/min]
120
140
160
180
Paolo 6
Integrated bypass
IBP operation
action values set
Oil flow
When the bypass is open the liquid flows through the element and the
bypass channel.
Close valve
The IBP valve opens
if the pressure drop
in the element goes
over the action set
valve.
Valve open
The IBP valve is
closed if the
pressure drop in the
element is lower than
the action set valve.
Pressure drop
Pressure drop depending
Paolo 7
Integrated bypass
IBP action
Valve & channel pressure drop
Available valves :
Tolerance ± 5 %
• 2 bar >> IBP2
This holds into account the spring variability
action and the channel dimensions.
Pressure drop at 30 mm2/s [bar]
• 3 bar >> IBP3
6
IBP3
5
4
IBP2
3
2
Dp opening valve action
1
Dp with valve compleatly open
0
0
20
40
60
80
100
120
140
Oil flow [l/min]
160
180
200
220
240
260
Paolo 8
Integrated bypass
IBP estimated
Element pressure drop
Combine the curves to
obtain the element
pressure drop.
7
6
Pressure drop [bar]
To do this it is only
necessary to translate the
valve pressure drop curve
parallel to the oil flow axis
until it is tangent to the
pressure drop matrix.
8
5
4
3
2
1
0
0
100
200
Oil flow [l/min]
300
400
Paolo 9
Integrated bypass
IBT operation
Temperature depending
The IBT valve is
closed if the inlet oil
temperature is above
that of the action
set valve (hot liquid).
The IBT valve is
open if the inlet oil
temperature is below
that of the action
set valve (cold liquid).
To have the maximal
power heat exchange.
To reduce the
pressure drop
consequent to the
viscosity increase.
Paolo 10
Integrated bypass
IBT action
Temperature settings
Available with closing temperatures of :
45 °C >>
IBT45
50 °C >>
IBT50
60 °C >>
IBT60
This means that, for an IBT45 the bypass is open until 45 °C and after
this it will start to close. It takes 5°C to close the valve completely
(IBT45 is completely closed at 50 °C and IBT60 at 65°C)
The tolerance is 3 °C
Now we are checking for the pressure drop on the
elements with open bypass (low temperature).
Paolo 11
Integrated bypass
IBT operation
Pressure drop depending
When the IBT valve is closed because the
temperature is above the action set valve,
Available valves :
> 2 bar (like an IBP2)
Pressure drop at 30 mm2/s [bar]
the valve action is the same of an IBP valve
(it opens if the pressure drop in the element
goes over the action set valve).
6
5
4
3
2
1
0
0
50
100
150
Oil flow [l/min]
200
250
300
Paolo 12
Integrated bypass
IBT estimation
Element pressure drop
Combine the curves to
obtain the same element
pressure drop as for the
IBP element.
7
6
Pressure drop [bar]
Take care of the viscosity
of the liquid (declared
values at 30 mm2/s)
8
5
4
3
2
1
0
0
100
200
Oil flow [l/min]
300
400