The isolator valve type SV is a releasable check valve for subplate mounting. It is used for the leakage-free blocking of one actuator port, also in case of longer standstill times.
The valve basically consists of a housing (1), a seat poppet (2), a compression spring (3), a control spool (4) as well as of a pre-opening as ball seat valve (7), which is optional.
The seat valve can be flown through from direction A to B without external pilot pressure.
Condition: pA > pB + cracking pressure (compression spring). In the opposite direction, the seat valve closes hydraulically tight.
A sufficiently high pilot pressure at port X moves the control spool (4) in the direction of the seat valve and pushes the seat poppet (2) out of its seat. This allows for a free flow in both directions (active keeping open).
In order to ensure that the seat valve actively opens, the pressure ratios on both sides of the control spool (4) are just as important as the area ratios at the seat poppet (2) or (7).
This results in the following available options for the types
- SV (large spool face A2 (6) connected to pA ) or
as well as for the versions with pre-opening "A" and without pre-opening "B".
Version "A" (with pre-opening)
This valve is provided with an additional pre-opening. By pressurization at port X, the control spool (4) is moved to the right. As a result, the ball (7) is pushed off the seat first and the seat poppet (2) afterwards.
Notes!
Version "A":
- The two-stage set-up with an increased control open ratio means even low pilot pressure can be unloaded securely.
- Avoidance of switching shocks due to dampened decompression of the pressure volume on the actuator side.
Version "B":
- In case of valves without pre-opening, the included pressure volume may be unloaded suddenly. Resulting switching shocks may lead to premature wear on installed components, as well as noise formation.
The modification of type SV to type SL is possible by exchange of plugs (9) and (10). One of the both plugs must always be installed!
Type SL 6 PB.‑6X/…
| Type
|
Plug
(9)
|
Plug
(10)
|
| SL
|
M3 (closed)
|
M6 x 1 (open)
|
