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Specialty Valves for Medical Device Manufacturing

Over probably the past decade, the medical field has been moving to smaller devices and at-home care. Many of these devices are now required to run on battery power at least part of the time and must be conducive to the at-home patient setting. These requirements have pushed the valve market to develop new products that are smaller, lighter and require significantly less power to run.

Humphrey’s entry to this arena started with a portable Oxygen concentrator. The valves for this device needed to be smaller than we had produced before and of lighter material. Additionally, they need to provide a high level of flow within the small package size. These requirements were driven both by the need for the overall package to be light enough to be carried easily by the patient over their shoulder, and to allow for maximum hours of use out of a single battery charge.

From these requirements, Humphrey developed the CSV 10mm cartridge valve. The cartridge aspect of the design allowed the customer to apply the valve in several special manifold configurations while still only needing to purchase a single valve part number. The valve itself employs several plastic parts which significantly reduces the weight the valve adds to the overall package. The Humphrey design team was able to develop the valve technology to produce a significant flow rate of 40 lpm at only 30 psi. Additionally, the valve was designed to run with PWM, which can drop the power requirement from the standard 2 watts per valve to a running wattage of less than ½ watt.

One final important aspect that has been true to almost all recent medical applications Humphrey has been involved in is the need for quiet operation. As so many of the new device applications are designed for home use, quiet operation has worked its way to the top of the requirements list. Many of these devices such as Oxygen concentrators and dialysis machines are running while the patient is sleeping.  Therefore, it is vital that the previously normal “clicking” noise of a valve be significantly reduced. Customer responses to the noise variable of the CSV valves has been overwhelmingly positive. Even in the case of some dialysis machines with up to 22 valves running, the noise level was reported to be low enough to not disturb the patient.

In summary, the CSV valves offered by Humphrey can provide the user with:

  • Small package size
  • High flow
  • Quiet operation
  • Low power

Additionally, the CSV line has been expanded to now include a 12mm version, providing all the above benefits in an even higher flow package. The 12mm CSV valve can provide 125 lpm flow rates at 30 psi – more than three times the 10mm version.

Overall, the CSV valves have been a great starting point for Humphrey’s journey into the new medical device market. Expect that the CSV valves will be the lead for a number of other new advances designed specifically for this growing important market group.

 

Top Benefits of Pressure Balanced Direct-Acting Solenoid Valves

Do you need a compact valve that can achieve high flows, fast response times and tight sealing, no matter the media or pressure? Pressure "balanced" direct-acting solenoid valves may be the right choice for your application.

These universal, multi-purposed valves are available in inline, direct piping or manifold, subbase piping. Some specialized models offer protection against moisture-laden and dusty ambient environments.

Balanced Solenoid Valves offer several benefits:

Multi-Purpose Versatility – The balanced solenoid series is versatile with its many functions, including Normally Closed or Normally Open; 2- or 3-way; Diverter or Selector.

Optimum Performance, No Matter the Media – The series’ balanced poppet design achieves optimum performance whether the media is air or inert gases, clean, dry, lubricated, or contains some airline impurities.

Reliable Shifts, Tight Seals – Balanced solenoid valves neutralize internal forces generated by pressurized media. The shifting forces of the coil and return spring are optimized and need only seal the poppet to meet tight leakage specifications.

High Flow Capacity, Smaller Size – Balanced solenoid valves maximize internal flow path management. The balanced design coupled with an optimized solenoid magnetic circuit achieves significantly greater flow, within a reduced overall size.

Ease of Use – All electric and pneumatic connections of balanced solenoid valves are on opposing surfaces, minimizing total space occupied, and simplifying mounting and connections during installation.

 

Applications

Balanced Solenoid Valves can be applied to factory automation uses, packaging and testing equipment, as well as medical device and analytical instruments to accomplish a variety of functions. 

Are balanced solenoid valves right for you? Whether you need off-the-shelf or tailored valves to meet your exact requirements, Humphrey can help you design or select the ideal solution. Browse our online catalog to identify the products that meet the requirements for your specific application. Or contact us at 1-800-477-8707 for help in choosing the best products for your application.

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Proper Design Requires Knowledge of Valve Types

Some pneumatic valves are depended upon for saving lives—so don’t take chances when selecting the right one for your application.

Valves used in the medical device industry are designed with precise specifications so they are compatible with the requirements of the applications. Meanwhile, valves used in factory automation are designed to work within specific safety regulations. Every project has unique requirements and choosing the best pneumatic valve design for your application will provide optimum results. 

While each design has its strengths and weakness to be considered, knowing your application’s requirements is essential. For example, the media of the application varies between industries. Compressed air and other gases can be extremely powerful—even fatal—so understanding how the valve will be used is important. Certain valve designs are compatible but limited by specific media. Some other factors that dictate the required valve are the external variables such as temperature range of the application, and purity of the air or media (moisture, contamination). Once you know the critical requirements for the application, the valve design can be chosen based on its specific features.

Poppet-design valves

Poppet-design valves use a rubber molded poppet wrapped around the stem that moves along the bore of the valve, creating a seal when the poppet is in its seat. One specific advantage to using a valve with this type of internal design is the compatibility with a variety of media other than compressed air. The unique feature that allows this compatibility is less lubrication sensitivity due to few sliding parts or (dynamic seals).

Valves with a basic poppet design feature few sliding seals, and are pressure unbalanced.

Another benefit to this poppet design is that the valves are more tolerant of minor air sediment or debris. They also have excellent exhaust capacity and are capable of high flow rates. The poppet design provides a faster response rate due to short stroke and can be mounted in several ways.

Poppet valves more readily lend themselves to 2-or 3-way configurations, although 4-way configurations can be achieved by using dual 3-way poppet sets in one valve body. Poppet valves are typically unbalanced designs, which use the air pressure as the primary force to return the valve to a given position. This concept provides assurances that the valve will return to the desired position, even if the return spring fails. Balanced poppet valves are used to reduce actuation force and achieve lower current consumption in solenoid valves. Balanced valves typically provide smaller overall physical size and produce greater flow capacity.

Applications in which this design are most commonly found are in the medical device and analytical instrumentation industries, where air purity is required (absence of dirty or wet media/air), the need for reliability is mandatory (could be saving lives), low leakage rate is critical, and gases other than compressed air will be used as a medium.

Diaphragm-poppet design valves

Diaphragm-poppet design valves expand the poppet valves’ design by the use of a diaphragm. Its outer webbing guides the poppet to its seat without using sliding seals. Diaphragm-poppet designs are usually unbalanced providing the same assurance of return to a given position as the poppet valve. The diaphragm increases durability especially with different or non-lubricated media.

The diaphragm-poppet valve design has no sliding seals and is pressure unbalanced.

A variety of durameter and diaphragm compounds make it simple to modify a valve based on the environmental or application requirements for operation. Also, expect extremely low leak rates due to strong sealing control. Diaphragm-poppet valves make 2-way or 3-way configurations available, as well as the possibility of 4-way valves, by using dual 3-way diaphragm poppet sets in one valve body. This valve’s durability and reliability make it a great candidate for applications such as critical life support devices (e.g. heart ventricular support assistance or pulmonary supply devices).

Its non-lubrication capability makes it appealing to be used with devices used for respiratory and anesthesia gases. Diaphragm-poppet designs are great solutions in leak testing devices, due to the very low leak rate. Lastly, these designs are suitable for critical or contaminated vacuum applications.

Spoppet-design valves

Spoppet-design valves combine two designs to provide a blend of primary poppet sealing in conjunction with a minimal number of sliding seals, thus emulating characteristics of a poppet and spool valve design. Spoppet designs retain some unbalance characteristics but with some balance of pressure to reduce actuation forces. This design provides the benefits of the poppet valve with a reduced sensitivity to lubrication.

Spoppet-design valves combine spool and poppet concepts.

Only one sliding seal engaged at a time reduces the drag within the valve body. These designs can sometimes bridge the gaps or limitations of poppet and spool valves making them more useable in numerous critical applications. By blending the designs, spoppets provide more cost efficient 3-way and 4-way valves, and can be used in many different environments and applications.

Spool-design valves

Spool-design valves are available in two types: lapped-/shear-design with no seals or dynamic seals/O-rings. Spool valves are designed to be more cost-effective when manufacturing for 4-way valves and are conversely less adaptable for 2-or 3-way configurations. Spool valves can be either balanced or unbalanced, depending on desired position control required. Therefore, understanding this valves’ function is critical to the application requirements. Lapped- or shear-design spool valves can operate without lubrication but are less tolerant of variations in lubrication or by-products of compressing the air at the air compressor. Hence, further conditioning of the compressed air is required prior to use.

Valves featuring the spool design with dynamic seals require lubrication in balanced or unbalanced configurations.

Dynamic seal spool valves generally require lubrication. Lapped spool valves have higher leak rates that may make them unacceptable for control of medias other than air, or limited media sources (air/gas tanks/bottles). Consequently, these valve designs are better suited to applications in factory automation where the leak rates are not critical. The requirement for conditioned media also limits their use for vacuum where contaminates are ingested into the vacuum lines and valves.

Custom-designed valves

Custom-designed valves are becoming more common, using a combination of the fore-mentioned design technologies to provide solutions unique to the customers’ challenges. In a perfect world, off-the-shelf components would meet every application’s need. But that doesn’t often happen, especially when faced with trade-offs such as space constraints versus performance. Sometimes a complex solution is needed, such as squeezing multiple components into a small space or incorporating multiple valve designs for a solution.

Custom valve designs combine technologies for unique solutions.

Custom designs using known and proven design technologies offer the potential of lower cost pneumatic systems. Once the specifications are agreed upon with the manufacturer’s design engineers and the application’s product engineers, a custom designed solution may be the best way to meet the applications’ challenges if a specific design is close but not does not meet exact specifications.

Ultimately when it comes to valves, each design technology offers unique capabilities but not every design suits specific applications. No matter whether you are replacing a component or designing a pneumatic system, consult a valve manufacturer who has knowledge in many different design principles so that the best solution can be achieved.

by Willie Miller, Humphrey Products

Published October 19, 2011 in DesignWorld

Five Factors to Consider When Choosing a Pneumatic Valve

When it comes to selecting the right type of pneumatic directional control valve for any application, you have many options at your disposal. Each comes with its own specific function, so it is helpful to understand differences and pick the type best-suited for your requirements.

To help you arrive at the valve “type” that’s right for your pneumatic application, this post will highlight five basic requirements to consider.

Media

The first and most obvious question is—what gas (or liquid) will be controlled by this valve, and at what input pressure? Compressed Air? Water? Negative Pressure? Gas? Before checking for any additional factors, ensure that the valve is compatible with the media and pressure passing through.

Method of Valve Actuation

There are a variety of methods available to open or close a valve. The four most common are Solenoid operated (via electrical current), Manually operated (by skilled labor and via a lever, pushbutton, foot peddle, etc.), Mechanically operated (via tooling or work pieces in contact with a cam, ball or plunger), or Remote Air operated (from an output signal of another valve).

Spring-Return or Detented Actuation

This is the return method the valve will take “back” to its original, un-actuated state. Typically, this is either a mechanical spring, or a separate form of the same actuation method described above. Manufacturers call these methods “spring return” and “detented” valve types. Said another way, are you looking for a “momentary contact, momentary output” or “momentary contact, maintained output”? Decide whether you want your valve to return to its initial position or stay in its last position after actuation.

Valve Configuration

Most pneumatic directional control valves are 2-way, 3-Way or 4-Way and, as a rule of thumb, it is a count of their active media ports.

2-Way valves have one INLET and one OUTLET port and, upon actuation, allow media to pass through (known as a 2-way Normally Closed), or to stop flow (2-way Normally Open)

3-Way valves add a third port to allow for venting (EXHAUST port) of pressure at the OUTLET port, when the INLET port is blocked. 3-Way valves are offered Normally Closed or Normally Open, as well.

4-Way valves add a second OUTLET and corresponding second EXHAUST port to the 3-Way function, and are most commonly used for control of double acting pneumatic cylinders and actuators. Upon 4-Way Valve actuation, INLET pressure switches from one OUTLET port to the other.

Note:  As an option, 4-way valves can be configured with 3 positions, where the center position is forms a “neutral” position choice of three options (either all OUTLET ports exhausted, pressurized, or checked).

Flow Capacity (Valve Size)

Flow capacity is a fifth factor to address in valve selection.  An undersized valve will slow down fill time or cause other forms of inefficiency in the system while an oversized valve can be classified as a form of waste in the system. It’s important to estimate a maximum flow capacity for your application and select the valve size with enough capacity. All valve suppliers provide a flow capacity, and have easy reference material to assist you, but essentially your valve will need to fill a specific downstream volume within your acceptable period of time.

Tip: Most manufacturers state a “Cv” value, which is a universally accepted flow capacity index, known as “flow coefficient”. It forms an easy way for you to compare similar sized valves.

Once you’ve used these five factors to identify the valve type you need, then weigh specific performance and integration attributes of matching brands and models available from valve manufacturers. Still a bit overwhelmed? Don’t worry! We’ve made it easy to browse our online catalog and narrow your results until you have found the exact products needed for your specific application. You can even search within results for the exact terms you’re looking for.

If you’d like more help choosing the right valve, or have questions about any of our products, please contact us at 1-800-477-8707.

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Use Caution in Sizing Proportional Valves

In the pneumatic valve world, we often oversize valves for applications. Many times we size the valve strictly off of the port size that the customer wants to use, which can make the valve significantly higher in flow than is needed. This is not generally a problem in industrial applications as actuators can easily be slowed down using flow controls and the oversize situation will never be noticed. 

While oversizing is not usually an issue with in on/off valves, correct sizing is necessary for proportional valves.  Remember that a proportional valve allows the control of flow out of the valve based on the electrical input signal given.  Oversizing of a proportional valve can cause loss of fine control in the output of the valve.  For instance, if the valve is greatly oversized to the application, a signal to open 10% of the flow range of the valve will be a much greater flow than what may be needed.  Therefore, opening the valve further will show no difference on the total system operation.

With a valve properly sized to the system requirements, the system will have the full range of adjustment that the valve will allow, making the system it is working in much more responsive and accurate.  So, when specifying a proportional valve for a system, take the extra time to determine what is really needed and avoid the oversize dilemma. 

For more information on sizing a proportional valve, please contact a factory representative or a local distributor. 

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