R983032397 2FRM6A36-2X/6QRV-IN001 German Rexroth speed control valve

FAQ — Frequently Asked Questions

Q1: What is the difference between "A" and "B" versions of 2FRM6?

A:

• 2FRM6A…​ = Throttling in A → A₁​ direction (meter-in on Port A side). Stacked between directional valve and subplate on the A-port.

• 2FRM6B…​ = Throttling in B → B₁​ direction (meter-in on Port B side).

  For independent speed control on both extend and retract strokes, one A-version and one B-version are typically stacked together. The reverse flow always passes through a free-flow check valve with no restriction.

Q2: Why is an external drain (Y port) required and what if I don't connect it?

A:​ The pressure compensator spool​ needs a reference to tank pressure. The Y port must be plumbed directly to the reservoir with zero backpressure. If Y is blocked, the compensator spool cannot balance → flow becomes pressure-sensitive, unstable, or the valve may fail to regulate. Never omit or plug the Y port on a 2FRM valve.

Q3: How is this different from a Z2FS6 needle throttle valve?

A:​ The 2FRM6 has a pressure compensator​ maintaining constant ∆P across the metering orifice, so set flow remains constant despite load pressure changes​ on P or A ports. A Z2FS6 is a simple needle throttle — flow varies with pressure drop. Use 2FRM when consistent actuator speed under varying load is critical; use Z2FS for basic, cost-sensitive throttling.

Q4: What does the "6Q" flow code mean in practice?

A:​ /6Q​ sets the maximum adjustable flow to 6 L/min​ (usable range approx. 0.2–6.0 L/min). Select the Q-code matching your required max flow — a smaller Q-range (e.g. /1.5Q, /3Q) gives finer adjustment resolution. If your application needs >6 L/min, choose /16Q. Do not force a 6Q valve beyond its rated max or the orifice will be wide open with no regulation.

Q5: Why specify FKM (Viton) seals — is NBR not enough?

A:​ The V suffix = FKM seals, required for:

• Temperatures above +70°C (up to +80°C)

• Water glycol (HFC)​ or phosphate ester (HFD)​ fire-resistant fluids

  For standard mineral oil (HL/HLP) at normal temps, NBR is acceptable. The FKM version (this part R983032397) offers broader fluid compatibility and higher temp rating — select based on your actual hydraulic fluid.