�ǳ�web Knowledgebase - SCPV

SCPVD Proportional Valve Driver I/O Manual

Rachel Desenberg — Mon, 01 Jul 2024 17:49:26 +0000

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Installation Instructions

SCPVD Proportional Valve Driver IO Manual

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SCPV

SCPVD

Products That Provide Proportional Control of Vacuum

Rachel Desenberg — Fri, 25 Feb 2022 20:28:13 +0000

Category:

Videos

Learn more about some of the different options available for electronically controlling vacuum in this quick video from Doug Paynter, �ǳ�web's Proportional Product Manager.

Video filmed at �ǳ�web in Cincinnati, Ohio

VIDEO TRANSCRIPT:

I am Doug Paynter, Proportional Product Manager here at �ǳ�web. Today we want to talk about electronically controlling vacuum. Here at �ǳ�web, we have the ability to provide all types of levels of products that help you control vacuum. Valves can be tested and shipped with as little a leak rate at
10^-11 utilizing our clean room helium gas detector system.

Now let’s talk about �ǳ�web’s EVP and DVP proportional valves. The more current that I apply to the valve, the more of an orifice I create. So I’m able to vary the amount of flow I let into the chamber or let out of the chamber.

We also offer our unique stepper-driven proportional valves that work with vacuum very well. The Eclipse, being designed with low-flow applications in mind, utilizes a ceramic material as the wetted parts. And so, very inert, and you can run different types of hostile gasses or fluids through it. And if you need higher flows, we offer the SCPV stepper-controlled needle valve. Both of them provide significantly higher resolution and work very well with vacuum.

For closing the loop, �ǳ�web can take a vacuum sensor and work with a comparative circuit to give you closed loop vacuum control. With the Cordis, we utilize an onboard micro controller, a specific transducer that we can interface with, whether it’s pressure or flow, and our own EVP, DVP proportional valves. The Cordis can now provide you accurate, repeatable, high resolution control of your Venturi circuit, direct vacuum, or your vacuum break applications utilizing either a digital or analog command.

The Cordis pressure controller can now be calibrated to pretty much any calibration within the application of vacuum control to whatever the application really calls for. Whether it’s in millibar or torr, or inches of water column, inches of mercury, negative to positive pressure or differential, or simply absolute pressure calibrations, the Cordis can now provide you closed loop control of your vacuum circuit.

For more information on how �ǳ�web can help you better control your vacuum applications, give us a call. Be sure to subscribe to our YouTube channel so you can see more riveting videos like this one. Thank you.

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CPAP Machines for Obstructive Sleep Apnea

Rachel Desenberg — Wed, 13 Oct 2021 18:21:50 +0000

Category:

Applications

Did you know? �ǳ�web products improve sleep and health by providing treatment for obstructive sleep apnea.

Related Products
Stepper-Controlled Proportional Valve

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SCPV

SCPV Series Stepper-Controlled Proportional Valve

Rachel Desenberg — Wed, 07 Jul 2021 18:27:56 +0000

Category:

Videos

�ǳ�web’s SCPV Series stepper-controlled proportional valve provides phenomenal flow control. In this quick video, �ǳ�web Product Manager Doug Paynter provides an overview and explains four of the valve’s key advantages.

Video filmed at �ǳ�web in Cincinnati, Ohio

VIDEO TRANSCRIPT:

Hi everyone, I’m Doug Paynter, Proportional Product Manager here at �ǳ�web. Today we’re going to discuss �ǳ�web’s SCPV high flow proportional valve and some of the advantages it brings to the table.

The SCPV being a high flow proportional valve brings four different advantages to the table:
1. Ease of system integration
2. Low hysteresis
3. Low power consumption
4. The ability to provide unique flow curves?

Ease of System Integration

The SCPV provides phenomenal proportional flow control made easy when integrating into a PLC. All you need is a 12 to 40 volt unregulated power supply, a bipolar chopper driver or a chip if you decide to design your own drive circuit, and a PLC. Now, �ǳ�web does provide a bipolar chopper driver, the SCPVD-1, which is typically used in the initial testing phases of all applications.

Low Hysteresis

Hysteresis can be a programmer’s nightmare. Virtually all proportional valves that are in the field have some inherent mechanical or magnetic hysteresis. What it means is that each valve is going to have different flow characteristics at the same set point. The SCPV has virtually zero hysteresis. It utilizes a 3-1/2 degree needle that’s being positioned through a 152 thousandths orifice with incremental changes of one thousandths of an inch. This gives very tight control when opening and closing of the SCPV flow path.

Low Power Consumption

Another nice advantage of the SCPV is low power consumption and latching ability. The SCPV utilizes less than 4 watts of power when in transition. Just like a needle valve, the SCPV requires no power when holding a closed, open, or flowing position. No other proportional product on the market actually offers that. Fail-safes can be created, now the natural fail-safe of the SCPV is to fail in the last known position. However, with simple modifications to the PLC you can have a fail-safe to fail fully closed or fail in predetermined positions.

The Ability to Provide Unique Flow Curves

Flow characteristics are an obvious decision factor when trying to choose the proper valve for the application. Here at �ǳ�web, we can change the needle, we can change the taper, we can change the orifice. All these components are manufactured right here at �ǳ�web. Bringing manufacturing versatility to the table allows for the customer engineering team to decide how best to design our product around the application requirements. Designing a product that actually can provide 1,000 l/min or 500 l/min, changing that needle profile is key to the application’s success.No other competitor can boast of high flow, proportional control with low hysteresis, low power consumption and manufacturing versatility for the cost.

Remember, �ǳ�web is known for being a strong partner to OEMs who want to design a solution to their application needs. Give us a call with any questions, and be sure to subscribe to our YouTube channel. I am Doug Paynter, �ǳ�web Product Manager and all-around good guy. Thank you very much for your time.

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SCPV

Proportional

How Stepper Motors Provide Precision Control

Rachel Desenberg — Fri, 20 Sep 2019 18:45:56 +0000

Category:

Product Information

Stepper motors are used in a variety of applications to provide a means for tightly controlled motion. But what is a stepper motor, and how does it work? This paper will discuss bipolar motors in detail, explaining what they are and how they work, and providing examples of how they're used with different types of proportional valves to provide precise control.

What is a Stepper Motor?

Stepper motors are brushless DC motors that rotate in steps electronically set by a controller or drive, which provides the necessary current through electromagnets that are arranged in a ring as part of the stator assembly (the stationary portion of the motor). Stepper motors are ideal for applications that require speed and position control, especially at low speeds such as in automation, motion systems, and 3D printers. Due to their internal design which minimizes mechanical and electrical "delays" that occur in other motors, stepper motors have remarkable stopping accuracy and responsiveness. Often, this makes stepper motors an ideal choice for synchronous and high precision operations.

How do Stepper Motors Work?

Figure 1. Diagram of a Stepper Motor

At the core of a stepper motor is a permanent magnet and shaft down the center of two or more toothed rotors. These rotors have different polarities because of the enclosed magnet and are offset from one another to allow themselves to be better drawn to the electro-magnetized teeth that cover the internal surface of the stator. The stator has fewer teeth than each rotor to ensure full alignment can only occur in sections (stator plates) along coil pairs. Energizing and de-energizing in-turn coil pairs causes the shaft to rotate a full step due to the attraction and repulsion of the magnetized teeth.

How to Calculate Stepper Motor Steps

Figure 2. Step Angle Calculation

A step angle is the angle of rotation traveled in a single step. This can be calculated one of two ways—either by dividing the motor's full 360 degrees by the number of steps the motor takes to complete one revolution, or by dividing the motor's full 360 degrees by two times the number of rotor teeth times the number of stator phases (Fig. 2).

Microstepping

Simultaneously manipulating the currents through multiple coil pairs reduces the overall travel/rotation by attracting the teeth in two directions instead of just one, creating new half, quarter, eighth, or one-sixteenth step set transitions known as microsteps. Microstepping provides better resolution and reduces resonance/vibrations, but also decreases torque and can be detrimental to bare accuracy.

Stepper Motor Drives and Control

Energizing the coils of a stepper motor in the right sequence to achieve a single step is a complex task. As such, the actual control of the motor coils is typically achieved using a driver. There are two types of stepper motor drives—constant voltage (L/R drive) and constant current (chopper drive). L/R drives are primarily limited to low-speed applications, therefore, we will focus on chopper drives. If you're interested in learning more, this article provides a good overview of the difference between an L/R drive and a chopper drive.

Figure 3. Relationship Between Current Rise and Inductance

Drivers simplify the operation of a stepper motor by interpreting a digital step and direction signal from a controller and energizing the motor coils accordingly. All electronics are governed by Ohm's Law and the relationship between current rise and inductance (Fig. 3). With stepper motors, the motor's design (in regard to its coils) prevents current from increasing quickly during pulses (command signals), which means the current can never reach its peak value without very high voltage. This is a problem because without sufficient current, the torque will be low, especially at high motor speeds. To combat this, chopper drives perform what is known as Pulse Width Modulation (PWM).

Figure 4. Chopper Drive Voltage and Current

Pulse Width Modulation (PWM)

Pulse Width Modulation (PWM) involves turning the output voltage to the motor on and off very quickly at each step. This provides very high voltage to the motor's coils (usually 8 times more than the motor's nominal voltage) which causes the current to rise rapidly and be higher than it would be otherwise. This on-and-off action typically occurs at a frequency of 20 kHz or higher, but the voltage "on-time" is influenced by the coil's impedance and motor speed—thus at higher speeds the voltage is on longer (larger pulse widths) to produce an average current at the correct level (Fig. 3).

Stepper Motor Chopper Drives

Stepper motor chopper drives are regulated by a current-sensing resistor placed in series with each coil. The resistor develops voltage across itself which is then monitored by a comparator. When this voltage reaches a preset reference voltage, it is "chopped" (turned off) until the next pulse occurs. This enables the average current to be stable despite any variations in the power supply voltage and increases efficiency by ensuring the shortest possible intervals between current peaks and valleys.

Stepper Motor Linear Actuators

A stepper motor can have a threaded shaft attached to its rotating core which can then be used to push or pull a nut placed upon it, moving it axially. The pitch of the thread controls how far the nut can move per step, with the resolution/precision dictated in part by the step angle utilized by the stepper motor (full, half, quarter, etc.). Like most linear systems, a stepper driven linear actuator can be susceptible to backlash. Backlash is caused by "slop" or "play" between the threads on the nut and the threads on the lead screw. Having clearance between threads results in a dead zone when the direction of travel is changed. When reversing direction, there will be no movement in the linear actuator until the clearance between threads is removed (the threads make contact again). For this reason, it is recommended that the threads have as tight a tolerance as possible. Designers must work to balance the backlash and the friction that is introduced when tolerances are tightened.

Stepper-Controlled �ǳ�web Proportional Valves

�ǳ�web offers two different stepper-controlled proportional flow control valves, the SCPV Series proportional needle valve and the new Eclipse Series proportional isolation valve. �ǳ�web's SCPV Series uses a stepper motor to control the distance between a needle and a valve seat. Precise proportional flow is achieved by adjusting the position of the needle. Due to the type of stepper motor linear actuator used on the SCPV, it is not recommended to implement microstepping beyond a half step. Full stepping is recommended and equates to 0.001" of linear travel which will result in a flow resolution of 0.7 slpm air.

With �ǳ�web's new Eclipse Series, the stepper motor features a fine pitch linear actuator which travels a mere 0.00006" per step to move a special slotted ceramic plate. The ceramic is used to bridge two ports through a second ceramic plate beneath it. Proportional flow is achieved by adjusting the amount of overlap ("eclipse") between the slot and the ports. The Eclipse is designed to go from closed to open in approximately one-sixteenth of an inch, which equates to 1,125 steps of resolution. That number can be increased dramatically by implementing microstepping—switching to a one-sixteenth step will result in 18,000 steps of resolution. A single one-sixteenth step with this unique proportional isolation valve will adjust flow by roughly 13 microliters (µl/min) of water.

Although stepper motors may seem complicated compared to a standard DC motor, as we have shown, their basic operation is actually quite simple. Their unique internal design enables remarkable stopping accuracy and responsiveness, making stepper motors an ideal choice for use in a wide variety of applications requiring precise control.

If you have questions about stepper motors or want to learn more about using a stepper-controlled proportional flow control valve in your application, locate your nearest �ǳ�web distributor or contact �ǳ�web today.

By Jess Koeniguer • Design Engineer • �ǳ�web

Related Products
SCPV Series Proportional Valve	Eclipse Proportional Isolation Valve

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eclipse

Pneumatic Solutions for Oxygen Mixing & Blending

Rachel Desenberg — Mon, 24 Nov 2014 20:03:46 +0000

Category:

Applications

The terms mixers, blenders and proportioners are synonymous when it comes to mixing two gases. Mixers are used in many applications across many industries; medical, welding, heat treating and food packaging to name a few. In the medical industry, O2 mixers are use to mix oxygen with other gases, including ambient air, for patient treatment. The mixers allow the doctor to go from a mixture of oxygen, typically from 21% to 100%. Most manufacturers are accomplishing this with modified needle valves that they manufacture.

easy replacement
needle valves

�ǳ�web has been manufacturing and supplying needle valves for a wide variety of applications for over 50 years. We now offer a cartridge style needle valve—the GNV Series—that is especially well-suited for these types of mixing applications. The standard GNV stem will allow knobs to be put onto the end, and added mounting features make it an easy replacement in most situations.

Need help incorporating a �ǳ�web needle into your product? Since we're the manufacturer, modifications are no problem.

proportional control for advanced mixing

For more advanced mixing, �ǳ�web offers two electronic proportional valves. The EVP Series is a #10-32 ported valve and is small in size. The EVP provides air or gas flow control and varies the output flow based on the current input to the solenoid. The consistent gain of the valve provides a high degree of control for mixing applications. The typical flow capabilities for this valve are 0 bubble tight to a maximum flow of about 23 l/min, based on pressures up to 100 psig.

Controllability and overall value are the main features of the EVP Proportional Series valves. The EVP Proportional valve may be controlled by using DC current, open or closed-loop control and even PWM (pulse with modulation).

For higher flow applications we have developed an innovative stepper-controlled needle valve, the SCPV Series. The flow of this valve is again 0 bubble tight to 300 l/min based on 100 psig inlet pressure. The flow resolution is 0.56 slpm per step, with a position resolution of 0.001 per step.

Contact �ǳ�web
Locate a Distributor
Download Whitepaper (PDF)

For more advanced mixing and blending applications that require media isolation,
check out the Eclipse proportional isolation valve.

Relevant Product Lines:
GNV Series	EV Series	EVP Series	SCPV Series

Toggle Valves	Flow Controls	Eclipse Proportional Isolation Valve

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SCPV

eclipse

Pneumatic Solutions for Wound Therapy

Chris Agricola — Tue, 25 Jun 2013 20:08:50 +0000

Category:

Applications

The lack of standardized wound therapy methods and care contributes to unnecessarily long treatment and healing times. In addition, these factors contribute to excessively high costs borne by patients and health plans. Various new technologies and discoveries are bringing to patients the ability to work with their doctors to get wounds under control with pneumatics.

Hyperbaric Oyxgen Therapy for Wound Healing (HBO2)
Oxygen is one of the most versatile and powerful agents available to the modern medical device manufacturers. The therapeutic use of oxygen under pressure has been used to assist wound healing for almost 40 years. HBO2 provides pharmacological doses of oxygen to stimulate the tissue, thereby promoting a much quicker healing process.

Negative-Pressure Wound Therapy (NPWT)
Negative-pressure wound therapy is a therapeutic technique using a vacuum source that creates continuous or intermittent negative pressure inside the wound to remove fluid, exudates, and infectious materials to prepare the wound for healing and closure.

�ǳ�web has been successfully partnering with progressive companies in the design and development of innovative pneumatic solutions for both stationary and portable non-invasive topical wound therapy equipment.

�ǳ�web’s miniature valves, actuators, fittings and regulators are ideal for these types of applications, especially with the addition of the Oxygen Clean and Analytical Series Electronic valves.

• Saves production time
• Reduces cost and labor for piping
• One part number reduces purchasing and assembly resources
• Complete “plug-and-play” assemblies
• Optimized system design increases performance
• �ǳ�web products and assemblies are 100% tested

Contact �ǳ�web today to see how our engineering and application expertise can assist in the development of efficient, compact pneumatic assemblies for your next critical project.

View more information

Relevant Product Lines:
Electronic Valves	Stepper-Controlled Needle Valves	10 mm & 15 mm Valves
Acrylic Subplates	Exhaust Valves

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�ǳ�web Stepper-Controlled Proportional Valve

Rob �ǳ�web — Wed, 11 Jan 2012 19:13:54 +0000

Category:

Product Information


The SCPV Series Valve High Flow Proportional Valve The SCPV incorporates the industries most robust and powerful stepper powered linear actuator. This actuator is used to control �ǳ�web’s proven needle valve technology. Imagine the control of a needle valve with an ultra fine thread. It is smooth, proportional, accurate, and stays in the position you leave it. Now, couple that with a stepper motor that gives you precision, speed, and is ultimately automated with any bipolar chopper drive you wish to use. Anywhere there is a needle valve that is controlling the flow of gas, can now be remotely located, automated, monitored and automatically adjusted to meet what ever demand you have in your application.
This product answers the need for a reasonably priced - high flow proportional flow control that comes with some great advantages. Four of the main advantages of this new product are; System Integration, Very Low Hysteresis, Low Power consumption, & Specific Flow Curve cababilities exceeding 500 LPM.
	Simplicity of integrating to a PLC All that is needed is a 12-40 VDC unregulated power supply, a bipolar chopper drive (or chip if designing your own drive circuit) and a PLC. �ǳ�web also offers a variety of boards and resources for boards to control this valve.
View pdf File View Design Engineer's Comments View Ordering Information

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Proportional

SCPV

Video

�ǳ�web SCPV Cartridge & Manifold Configurations

Rachel Desenberg — Wed, 27 Sep 2000 16:50:54 +0000

Category:

Product Information

�ǳ�web SCPV Stepper-Controlled Needle Valves

Utilizing the industry's most robust and powerful linear actuator, the high-flow stepper-controlled proportional valves outperform the competition in performance and durability.

This valve is ideal in critical applications such as gas delivery, medical, analytical, and industrial automation requiring high resolution, high flow, and low hysteresis. In addition, the unique design allows for custom flow profiles when required.

• 2% hysteresis
• Excellent Linearity—2.5% of full-scale
• 2 ms reaction time
• Millions of cycles
• Holds position for power savings or at loss of power
• In-line, manifold and cartridge styles available

Control Data

A Bipolar Chopper Drive (not included) is a power-efficient method of using current to drive a stepping motor to obtain high stepping rates. The chopper gets its name from the technique of rapidly turning the output voltage on and off (chopping) to control motor current.

Stepper motors require some external electrical components in order to operate. These components typically include a power supply, logic sequencer switching components and a clock pulse source to determine the step rate. Many commercially available drives have integrated these components into a complete package.

View Data Sheet
View Product Video
View Design Engineer's Comments
View Ordering Information

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�ǳ�web Knowledgebase - SCPV

SCPVD Proportional Valve Driver I/O Manual

Products That Provide Proportional Control of Vacuum

CPAP Machines for Obstructive Sleep Apnea

SCPV Series Stepper-Controlled Proportional Valve

Ease of System Integration

Low Hysteresis

Low Power Consumption

The Ability to Provide Unique Flow Curves

How Stepper Motors Provide Precision Control

What is a Stepper Motor?

How do Stepper Motors Work?

Stepper Motor Drives and Control

Pneumatic Solutions for Oxygen Mixing & Blending

easy replacement needle valves

proportional control for advanced mixing

Pneumatic Solutions for Wound Therapy

Relevant Product Lines:

�ǳ�web Stepper-Controlled Proportional Valve

�ǳ�web SCPV Cartridge & Manifold Configurations

Control Data

easy replacement
needle valves