Fixed orifice, flow fuse valve
Flow fuse cartridges are used to maintain the position of a hydraulic actuator in the event of a hose or line break. The valve allows flow to and from the actuator but closes instantly if flow from the actuator exceeds the setting of the valve. NOTE: Because the valve responds so rapidly, it is sensitive to any transient flow above the valve setting.
- Customer must specify a flow rating. Factory set flow ratings are within +/- 10% of the requested setting.
- Valve closes when flow from port 1 to port 2 exceeds the setting of the valve. Valve resets when pressures at port 1 and port 2 are equal.
- Flow setting should be at least 25% above maximum normal system flow. Customer must specify flow when ordering valve.
- These are spool type valves, therefore there is leakage. Some actuator drift may occur.
- Incorporates the Sun floating style construction to minimize the possibility of internal parts binding due to excessive installation torque and/or cavity/cartridge machining variations.
|Capacity||6 gpm23 L/min.|
|Maximum Operating Pressure||5000 psi350 bar|
|Maximum Valve Leakage at 110 SUS (24 cSt)||2 in³/min.@1000 psi30 cc/min.@70 bar|
|Valve Hex Size||7/8 in.22,2 mm|
|Valve Installation Torque||30 - 35 lbf ft41 - 47 Nm|
|Model Weight||.20 lb0,10 kg|
|Seal kit - Cartridge||Buna: 990010007|
|Seal kit - Cartridge||Polyurethane: 990010002|
|Seal kit - Cartridge||Viton: 990010006|
What's wrong is that every time you start to lower your load, you get a flow transient that exceeds the setting of the flow fuse and trips it. Sun's flow fuses are very consistent and very fast.
There are exactly 250 Sun drops in a cubic inch or 15 in a cc.
NO! Flow fuses are meant to prevent the uncontrolled movement of an actuator in case of hose failure.
NO! Flow fuses are meant to prevent the uncontrolled movement of an actuator in case of hose failure. To avoid false tripping they must be set above the typical system flow, usually 50% above. On a 4 gpm (15 L/min.) circuit the flow fuse may need to be set at 6 gpm (23 L/min.) to avoid false tripping. Hoses do not normally fail totally, they spring a leak. If the hose springs a 5.5 gpm (21 L/min.) leak the flow fuse will not trip. 5.5 gpm (21 L/min.) of hydraulic fluid will feed a fire that would heat a small town in Ohio (Denmark) in January!
It is very, very difficult to predict the transient flows in a system. We say at least 25% above maximum normal system flow and should say 50%. Don’t back yourself into a corner by sizing a flow fuse at the top end of its range unless you can test it. If you have an FQCA in a 4 gpm (15 L/min.) circuit, set at 6 gpm (23 L/min.) and it false trips, you are out of luck. Select an FQEA and leave yourself some room for tuning.
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