Atos ADR In-Line Check Valve, G1/4 to G1 1/4

A threaded check valve in six sizes

The Atos ADR is a direct-operated, spring-loaded check valve for in-line mounting between hydraulic pipes or hoses. Flow passes freely in one direction once the cracking pressure is overcome and is blocked in the other. It comes in six sizes from G1/4 to G1 1/4 and four cracking pressures, and the hexagonal body makes it easy to fit with a spanner.

Typical uses are keeping pump circuits from back-flowing, holding pressure in accumulator branches, isolating a pump from a common line and bypass lines around filters or coolers (where a higher cracking pressure makes it act as a simple pressure-opening bypass).

Technical specifications

Sizing and cracking pressure

Size the valve from the flow you pass and the pressure loss you can accept; each size has its own flow-versus-pressure-drop curve for the four cracking pressures, plotted on ISO VG 46 oil at 50 degC. The order code ADR-10/4 reads as valve type, size and cracking pressure, so ADR-10/4 is a G3/8 valve cracking at 4 bar.

A 0.5 bar spring is the normal choice for a plain non-return function. Higher cracking pressures (2, 4 and 8 bar) suit pilot lines that must stay primed, return-line backpressure, and bypass service where the valve is deliberately held shut until a set differential is reached.

Size and weight rise quickly with the port: the datasheet lists 0.2 kg for ADR-06 and 2.5 kg for ADR-32, so check the space and the pipe support at the larger sizes. Fit the valve with the flow arrow in the direction of free flow, and keep the hexagon accessible for a spanner. The spring and poppet are not adjustable, so the cracking pressure you order is the cracking pressure you get. When the valve sits in a long return or pump line, add the cracking pressure to the line losses before you size the pump.

What to confirm before ordering

State the size, cracking pressure and seal option, and mark the flow direction on your drawing, since the valve is not symmetrical. Check the maximum pressure for your size in the datasheet. See also the wider hydraulic valves and components range.

How the Atos ADR check valve works

Inside the body is a poppet pressed on a seat by a spring. When the pressure at the inlet is higher than the spring force, the poppet lifts and the oil flows through. In the other direction the pressure presses the poppet on the seat, and the valve blocks the flow. The pressure at which it starts to open is the cracking pressure. The hexagonal body is threaded at both ends, so the valve is screwed straight into the line.

Where the Atos ADR is used

• Pump outlets, to stop back-flow when the pump stops
• Accumulator branches, to hold the pressure
• Isolation of a pump from a common line
• Bypass lines around filters and coolers
• Pilot lines that must stay primed

Selection checklist for the Atos ADR

• Size from ADR-06 (G1/4) to ADR-32 (G1 1/4)
• Maximum flow of the size, from 40 to 500 l/min
• Cracking pressure: 0.5, 2, 4 or 8 bar
• Working pressure up to 400 bar, with the limit checked for the size
• Fluid temperature, standard or /BT option for -40 degrees C
• Pressure drop at the working flow
• Mounting space and weight of the size
• Oil cleanliness of ISO 4406 class 20/18/15

Installation, commissioning and maintenance notes

Fit the valve with the flow in the direction shown on the datasheet symbol. It can be mounted in any position. Tighten the threaded ports with a spanner on the hexagon. Flush the line before fitting, and keep the oil clean, since dirt on the seat will cause leakage. Check the valve for leakage and noise during service rounds.

Requesting a quotation for the Atos ADR

Please send the size, the cracking pressure, the flow and the quantity. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

ADR order code

The code ADR-10/4 means the ADR valve, size 10 and a cracking pressure of 4 bar. A valve with no pressure code cracks at 0.5 bar.

ADR weights

The ADR-06 weighs 0.2 kg, the ADR-10 0.4 kg, the ADR-15 0.6 kg, the ADR-20 0.9 kg, the ADR-25 2.1 kg and the ADR-32 2.5 kg.

ADR fluid and seals

The valve is for hydraulic oil to DIN 51524 with a viscosity of 15 to 100 mm2/s recommended. The seals are NBR.

ADR compliance

The datasheet states compliance with RoHS 2 and REACH.

Valve records for ADR

Keep the size and the cracking pressure of each valve with the hydraulic circuit drawing.

Choosing the right Atos ADR cracking pressure

Use the 0.5 bar spring when the valve only has to stop reverse flow. A higher spring gives a pressure drop even at low flow, so it adds heat in the circuit. Choose 2, 4 or 8 bar when the valve must keep a pilot line primed or hold back a set pressure before it opens.

Atos ADR flow limits

The maximum flow is 40 l/min for the ADR-06, 80 for the ADR-10, 150 for the ADR-15, 300 for the ADR-20, 360 for the ADR-25 and 500 l/min for the ADR-32.

Documents and quotation

The attached Atos technical table C406 (revision 7.0, September 2026) lists the symbol, hydraulic data, dimensions and flow-pressure curves for all sizes. Send the size, cracking pressure and quantity for a quotation.