Shut-Off, Control and Safety Valves

Check Valves

A check valve lets coolant pass in one direction only and closes by itself as soon as the flow reverses. In a data centre it sits downstream of pumps and where risers tie into the header, so that a circuit taken out of service is not back-fed. The group holds 623 items: inline RUCK check valves in brass with a G 1/4 female thread rated PN 40, angle-seat versions such as RUCK 34 SS ES in stainless steel with G 3/4 and PN 40, full-bore valves, and one-way flow control valves of the Blue Series.

Three points drive the choice: body style, cracking pressure and material. An angle seat turns the flow less sharply and costs less pressure drop than an inline seat, while full-bore versions crack open at 0.01 to 0.03 bar and suit circuits with little pump head to spare. Stainless steel is the uncritical choice for water-glycol, brass only where the material pairing stays consistent. The Blue Series flow control valves with 10 and 12 mm push-in ports belong in compressed air and control lines, not in the cooling circuit.

381 items
3 manufacturers
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Buying guide

How to choose Check Valves

What matters when choosing: properties, comparison and typical applications.

How to choose a check valve

⚙ Inline or angle seat - The angle seat guides the medium with less deflection and therefore less pressure drop; the inline body is shorter.

↕ Watch the cracking pressure - Full-bore versions open from 0.01 to 0.03 bar. A higher cracking pressure costs pump energy every hour of operation.

✓ Material follows the circuit - Stainless versions such as RUCK SS ES fit without restriction, brass versions only in a single-alloy circuit.

⚡ Pressure rating - The RUCK series is rated PN 40, well above the working pressure of a normal closed cooling circuit.

⚑ Check the mounting position - Spring-loaded valves work in any position, gravity-closing ones do not. The flow direction is marked on the body and must be verified on installation.

↻ Do not mix them up - One-way flow control valves with 10 and 12 mm push-in ports are pneumatic components for cylinder speed control.

Body styles compared

Check valves by design, rating and material

Criterion	Inline RUCK (brass)	Angle seat RUCK SS ES (stainless)	Full bore	Blue Series flow control
Connection in stock	G 1/4 female	G 3/4	G 1	G/R 1/4 to 1/2 onto 10 and 12 mm
Pressure rating	PN 40	PN 40	per version	pneumatic range
Cracking pressure	per version	per version	0.01 to 0.03 bar	not relevant
Material	brass	stainless steel	brass	nickel-plated brass
Fit for water-glycol	single-alloy only	unrestricted	single-alloy only	not intended

Typical applications

Backflow protection downstream of circulation pumps in redundant cooling circuits
Tying individual rack circuits into a shared header
Protecting circuits that are switched off against backflow from the running plant
Separating supply and return on heat exchangers connected in parallel
Securing the make-up line against coolant being pushed back
Speed control of pneumatic actuators through one-way flow control valves