Checked Orifices consist of a check valve and a precision orifice in series. 

Incorporated in a single construction, the Checked Orifice allows metered flow in one direction and no flow in the opposite direction. Metered flow is achieved by a precision orifice while reverse flow is prevented by an integral check valve in series. Fluid flows first through the check valve mechanism in the free flow direction and is then metered by the precision orifice.

Bidirectional Fixed Flow Controls are a checked orifice and a precision orifice in parallel.

Incorporated in a single construction, the Bidirectional Fixed Flow Control allows metered flow in one direction and a separate metered free flow in the opposite direction. Metered flow is achieved by a precision orifice within the checked orifice portion and metered flow in the opposite direction is achieved by a separate precision orifice.

Liquid dispensing is a common application for a Checked Orifice. The device allows a metered flow in one direction to dispense the fluid, while back flow or dripping is prevented by the check valve mechanism when the source is shut off.  A Checked Orifice’s flow characteristics are also useful when the process demands metering out a very specific amount of a substance and the accuracy and portions are critical. While this functionality can be achieved using a combination of other valves, having two metering devices in one body offers a distinct advantage in terms of simplification of design, as well as maintenance.

Additionally, mixing of liquids or gases with fluid source isolation can be achieved by using multiple Checked Orifices connected in parallel.

Speed Control – Controlling the rate at which an actuator moves is crucial to optimum operation of pneumatic machinery.  A common example is controlling a double-acting pneumatic cylinder. Simply put, pressurized fluid enters a port in the cylinder causing extension of the rod and at the same time allows the opposite cylinder port to vent. The opposite pressure and vent condition causes cylinder rod retraction. Control of the speed of extension and retraction of the cylinder rod is achieved using Fixed Flow Controls which can allow free flow into the extend and retract ports while restricting the exhaust rates. In this example, two Fixed Flow Controls are required, one for each cylinder rod direction.

Time delay – In automated processes, the timing of certain actions can be critical. Timing allows for sequences to complete before the next step, or to start only after certain conditions have been met. Thus, time delay is another use of the Fixed Flow Control. A Fixed Flow Control in series with a volume can provide a time delay on startup of a pneumatic circuit, or as the circuit is depressurized. On-delays or off-delays can be used to prevent immediate change in state in pressurized circuits.

Process control can also be achieved by use of Fixed Flow Controls, such as in desiccant air dryers. A typical system consists of two towers, one for drying the air and the other for regenerating the desiccant. The drying tower contains a porous desiccant material that adsorbs water molecules as compressed air from the inlet passes over it. To regenerate the desiccant material, a small portion of dried air is expanded and blown over the desiccant bed in the offline tower. The water vapor is exhausted out. 

Ideal for this type of operation., the Fixed Flow Control allows free flow through the drying tower in the forward direction and metered flow in the reverse or purging direction. O’Keefe Controls Co. manufactures Fixed Flow Controls in a wide choice of sizes and connections, allowing us to handle applications from large dryers in factory settings to small appliances employed for point-of-use dry air, requiring sub-miniature Fixed Flow Controls.   

Applications for Bidirectional Fixed Flow Controls are similar to those of Fixed Flow Controls. However, the Bidirectional Fixed Flow Control’s feature of flow metering in both directions offers a distinct advantage for specific applications. What is known as free flow in a Fixed Flow Control is replaced by a metered flow, allowing precise fluid control in both directions. This can be helpful in dampening using a three-way valve as a pressure source.

Speed control of a single acting, spring return cylinder using a single Fixed Flow Control may cause excessive speed in the free flow direction, resulting in unwanted slamming. The addition of a second Fixed Flow Control in series can eliminate the slamming but at additional cost and space. Instead, the installation can be simplified using a Bidirectional Fixed Flow Control. Proper selection of forward and reverse flow capacities will keep actuation rates within desired times.

Whether you’re boxing orders at a warehouse and moving them down the assembly line, dispensing exact quantities of yogurt into containers in a dairy factory, or controlling the speed of metal-stamping machinery, Flow Controls play a key role in keeping automated processes moving without worry. As differing processes have unique requirements in how motion is controlled, various flow controls, each with specific characteristics, have been developed to answer the challenges among industrial applications.

Our whitepaper explores the three types of Flow Controls offered by O’Keefe Controls Co. and the crucial role they play in automated processes. Once process speed and timing is established to maximum efficiency with minimum waste, these inherently tamperproof devices ensure those controls remain constant. Manufactured to standards of unsurpassed accuracy and repeatability, utilizing O’Keefe Controls Co. Flow Controls helps reduce machinery wear and tear, automation breakdowns, loss of product and overall cost of operation.

Flow Controls manufactured by O’Keefe Controls Co. are designed to ensure tamperproof operation with accurate, repeatable flow characteristics. This enables us to help industries across the world achieve the exact flow control required in their processes. Our Flow Controls pass stringent quality control testing to ensure they operate exactly as specified, with consistent performance. 

With a quality management system that is ISO 9001:2015 registered, all processes are held to the highest standards of quality. But perhaps of even greater benefit to our customers, the engineers at O’Keefe Controls Co. are technical experts in the field — knowledgeable about not only our products, but also the science behind their use. As such, we are able to assist customers in diverse practical applications across the industrial, analytical and medical sciences landscape. In all we do, we stand proudly by our tagline: If it’s about precision, it’s O’Keefe.