Check Valves Inroduction

One-way or check valves are liquid direction devices that allow one-directional flow in the pipeline.

Check valves have various uses such as:

• Controlling directions of flow of liquid in systems in which there are different sources of supply.
• Preventing reverse flow into pumps when pump operation stops.
• Maintaining down-stream pipe pressure in case of a pressure drop at the supply source.
• Preventing drainage from high to low areas.

There are various types of check valves:

1. Swing-type check valves with top covers; check valves with a tilting disc, dual-leaf check valves, wafer type check valves, springloaded check valves, etc.
All one-directional valves are built from a basic combination of a body (straight or angular) connected to piping and to a oneway sealing mechanism. The valves are distinguished from one another by the structure of the body and the various sealing
mechanisms.
The purpose of the various types of check valves is to provide solutions and adaptations for various applications.
The R&D, engineering and manufacturing divisions of A.R.I. have worked together to develop a basket of check valves for a variety
of applications. They meet the needs of designers, installers, end-users and maintenance personnel.
A.R.I. check valves are adapted for use in industry, wastewater, desalination, hot water, contaminated water, seawater, agricultural and gardening applications, potable water, water treatment systems, municipal lines and oil installations on offshore platforms.

Top-cover type check valves are designed to contend with aggressive environments
and solidsladen liquids:

1. The body and cover are cast from a variety of corrosion-resistant materials which cover a wide range of chemicals.
2. The body has a barrel-shaped structure that allows unrestricted flow.
3. The sealing mechanism incorporates a disc that opens fully even under low flow rates and swings up and out of the flow path (full flow). These two properties:
   • enable for the flow of solids-laden liquids without blockage or stagnation.
   • ensure particularly low head losses (in the range of only a few centimeters), resulting in large energy savings.
4. The top cover provides access for inspection and maintenance without the need for dismantling the valve from the pipeline.
5. The sealing seat assembly is accessible for replacement without dismantling the valve from the line.
6. The internal configuration inhibits cavitation.
7. The disc shaft extends out from the body of the valve in both directions. It serves as a mounting for counterweights which regulate the closing time of the disc and thus prevent slam and surge.
8. The enhanced bearing assembly is unique and provides for shaft sealing that is both reliable and long-lasting.
9. The hinged arm is connected to the disc by two pins that prevent premature wear of the sealing assembly.
10. A variety of structural materials are used in the sealing mechanism, the disc, and the sealing seat.
11. Interior and exterior FBE coatings are resistant to corrosion, chemicals and to UV.

Typical installation locations:

• In pumping stations for raw wastewater.
• In pumping stations for untreated water.
• In desalination installations.
• In chemical process piping systems to regulate the direction of flow.
• Dividing the pressure between the two ends of long pipe segments in which there are large differences in elevation between the ends.