R900517813 Z2FS10A5-3X/SV Rexroth Germany one-way throttle valve

FAQ — Frequently Asked Questions

Q1: What does the "S" in "SV" stand for and how is this version used?

A:​ The "S"​ denotes the main flow limitation version​ — both working ports A and B are fitted with throttle/check combinations. This is installed between an NG10 directional valve and its subplate to control actuator extension/retraction speed. (Contrast with "P" or "T" versions which throttle pilot or tank lines.)

Q2: How should the sandwich valve be stacked in the hydraulic manifold?

A:​ Install the Z2FS10 directly between the NG10 directional control valve and the mounting subplate. The side marked toward the directional valve contains the throttle orifices (A₁→A₂, B₁→B₂); the opposite side (facing the subplate/actuator) contains the free-flow check valves. Ensure ISO 4401 port alignment and tighten M6 bolts evenly (recommended torque ~20–25 Nm cross pattern).

Q3: Which flow direction is throttled vs. free-flow?

A:​ Flow from the directional valve (A₁/B₁) toward the actuator (A₂/B₂)​ passes through the adjustable needle orifice — this is the throttled direction used to set cylinder/motor speed. The reverse flow (actuator → directional valve)​ opens the poppet-style check valve and returns unrestricted (no restriction).

Q4: Why might the set speed drift or the valve feel "jumpy"?

A:​ Most common causes:

• Contamination:​ Fine particles clog the small orifice — maintain ISO 4406 20/18/15 and use a 10 µm return filter.

• Improper Locking:​ After adjustment, the lock nut must be tightened gently — over-tightening can shift the spindle.

• Pressure Compensation:​ Needle-type throttles are notpressure-compensated; large pressure fluctuations will affect flow slightly.

Q5: Are the seals NBR or FKM(Viton)? Can I use this with water glycol?

A:​ This R900517813 has standard NBR seals​ (no "/V" suffix). It is suitable for mineral oils (HL/HLP). For water glycol (HFC)​ or phosphate ester (HFD)​ fluids, select the FKM-sealed version (e.g., Z2FS10A5-3X/SV /V​ or with explicit /V suffix on the complete code). Using NBR with HFC/HFD will cause seal failure.