A check valve may be defined simply as a mechanical device typically used to let fluid, either in liquid or gas form, to flow through in one direction. They usually have two ports or two openings – one for the fluid entry and the other for passing through it. Often part of household items, they are generally small, simple, and inexpensive components. They also come in various sizes and costs. Following is a review of some of the models available in the market.
Integral Fitting: These are the compact and lightweight models that come with a built in instant fitting feature. To install, just push the tubing in and the device is ready for action. Most users find this one way valve very useful for tough surrounding conditions because the body is made of Delrin. The fitting and the valve are both rated only for condensed air; pressures range from -14.5 to 45 psi. With prices beginning at less than 8 dollars, this is considered by many as great value for all its practical uses. Available stock sizes include 5/32”, ¼”, 3/8”, 4 mm, 6 mm, and 8 mm.
Miniature: The F-2804 series miniature valve operates based on small disc movement that shifts inside the casing because of changes in pressure differential from a forward direction to the opposite. The flat surface on one end seals off the flow while the other end allows it to go by. Its advantages include a low minimum differential needed for onward direction (under 0.005 psi for standard units); and that there is no residual differential throughout the device once the flow stops. Onward flow is comparatively unobstructed which is more or less equal to the 0.04” standard opening. This check valve is available in stock on standard (F-2804-401, 402, and 403), and high flow (F-2804-404) models.
NAK Series: Depending on the underlying conditions, the Series AK/AKH/AKB control valves provide the design solutions through its different configurations. The units are lightweight, compact, low cracking pressure, and small parts of a check valve. People who use the NAK series say that the AKH is easy to install in pipes with its straight one-touch fitting, and the male connector type easily attaches to the equipment directly. On the other hand, the AKB is the bushing type which can be utilized in applications that require spatters and splashing coolants.
AKM Series: This valve features an intermediate air release dock and can be effortlessly installed to stop lubricant backflow while redirecting the flow of air. Buyers normally apply this non-return valve between a regulator and a lubricator to ensure a supply of air that is free from lubricants. The device prevents lubricated air from penetrating clean lines.
Bi-Directional: As the name suggests, this model allows differential flow in both directions. In free flow, the check valve allows passage of more than 1000 liter per minute. When in controlled flow, it allows a flow of one liter per minute or less with a differential in pressure of 5 PSIG. The umbrella-like flow disc allows for the flow in two directions.