4 Operation
Study the instructions carefully.
The item refer to the parts and service kits section.
NO = Normally open (pneumatic movement downwards.
NC = Normally closed (pneumatic movement upwards.
4.1
Description af valve function
The SSV Two step valve has two pistons inside the actuator, which makes it possible to have an intermediate plug position
where all body ends are open.
SSV Two step valves are made in a Shut-off valve type and a Change – Over valve type.
Step 1a
Type Shut-off valve (only NC)
Two step valves as Shut-off (only as NC) can be used for reducing pressure hammers or dosing e.g. in connection with filling of
a vessel where an exact volume is required.
The degree of opening for the intermediate position can be adjusted by removing spacer rings inside the actuator (see
5.7 Dismantling of (NC) maintainable actuator).
TD 461-619_2
Throttled position can be
adjusted by removing spacers.
Plug opening will increase if
spacers are removed
TD 461-620_2
AIR
F
TD 461-621_2
S
AIR
Closed
Throttled opening
Two step stroke activated
Full open
The plug opening for different Shut-off valves and Actuator size is shown below.
Standard Actuator choice (NC)
High pressure Actuator (NC)
Dimensions =
mm
Inch tube
DIN tube
Inch tube
DIN tube
38
51
63.5
76.1
101.6
40
50
65
80
100
51
63.5
50
65
F min. Two
step stroke
(with spacers
inside Actuator)
3
3
3
2.5
2.5
3
3
3
2.5
2.5
6
6
6
6
F max. Two
step stroke
(Spacers
removed inside
Actuator)
6
11
11
14
14
6
11
11
14
14
9
9
9
9
S = full stroke
opening
20
25
25
30
30
20
25
25
30
30
25
25
25
25
14
