Two pressure controllers are better than one in extreme environments

Some industrial and analytical applications, especially applications with mixed phase fluids, corrosive media or extreme temperatures, can be better handled by purely mechanical classic industrial regulators than electronic pressure controllers. Purely mechanical regulators don’t usually have the same susceptibilities to these types of conditions that electronic pressure controllers do.

However, there is a trade-off. While the process gains toughness, it loses high speed control, user friendly electronic interface, onboard PID and the accuracy and resolution of pressure control that make Alicat electronic pressure controllers highly accurate, fast and easy to use.

Why don’t we have both?

One of Alicat’s partners, Equilibar, is a manufacturer of high performance mechanical industrial back pressure regulators. The Equilibar back pressure regulator (BPR) features a flexible diaphragm as its only moving part to provide frictionless, stable operation. Equilibar’s dome-loaded, multiple orifice design offers precision, as well as compatibility with mixed phase fluids, corrosive media and extreme temperatures.

One requirement of the Equilibar back pressure regulator is that a reference pressure be provided to the “dome” in order to tell the larger regulator what back pressure to control to.  This can be handled in a number of ways:

  1. Using a sample pilot pressure pneumatically routed to the dome. The limitation here is that the setpoint is subject to change as the pilot pressure changes.
  2. Pressure is provided to the dome with a mechanical pressure regulator.  While this may do a fine job in some applications, a mechanical regulator feeding the dome on another mechanical regulator still does not attain the precision and functionality of an electronic solution.
  3. Utilizing an Alicat Dual Valve Pressure controller (PCD) to perform the precise pressure manipulation of the diaphragm inside the dome.  Alicat’s sub 100ms control speeds and precision of control allows high resolution control of the Equilibar BPR diaphragm control mechanism. Alicat’s PCD series, optimized for closed volume pressure control, essentially becomes the brain of the Equilibar BPR, giving end users the ability to automate control through a computer terminal– or simply with the push button display on the Alicat PCD.

Alicat and Equilibar

When Alicat and Equilibar began working together, Equilibar had been looking for a solution to precise closed-volume pressure control for their domes that could control the pressure on the diaphragm reliably from 0 to 3000PSIG. This would give The Equilibar back-pressure user who needs 3000PSIG back pressure control, the advantages of using an electronic pressure controller.

The Equilibar BPR and the Alicat PCD3 3000 both have high resolution, so each is able to take advantage of the other’s high precision control.

  • Alicat’s sub 100ms control speeds and precision of control allows high resolution control of the Equilibar BPR diaphragm control mechanism.
  • Equilibar’s unique construction using a thin, supple diaphragm as the only moving part delivers near-zero hysteresis and will accurately repeat the high resolution pilot signal from the Alicat into a corresponding high resolution pressure within the application.
  • Alicat’s active PID control and dual valve system allows for fast and adaptive response to changing operating conditions without the need for user interference or adjustment.
  • An Equilibar back pressure regulator allows the Alicat to control pressure in applications with extreme temperatures, severe chemistry or mixed phase fluids because the Equilibar will faithfully reproduce the pilot pressure signal in these complex process conditions.
  • The Alicat PCD series allows users to automate communication. And adds the features of a lab style instrument to the Equilibar back pressure regulator.

Sometimes two technologies are better than one. Pairing Alicat’s feature-rich electronic pressure controller with Equilibar’s resilient mechanical pressure controller allows for the best of both worlds in processes that require accuracy, speed and durability.

 

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicats provide accuracy and repeatability to valve testing in space exploration

Exploring the final frontier is part of a normal day at Alicat. We work on a variety of aerospace applications, projects and experiments that help keep pilots safe, put satellites into space and launch rockets. Alicat works closely with customers in these fields to understand their problems and find straightforward solutions.

Aerospace is a diverse market that utilizes flow and pressure instrumentation for a wide variety of tests and processes. Alicat has worked on projects that:

  • Ensure the oxygen masks in commercial and military airplanes flow the correct amount of gas and meet safety regulations.
  • Provide liquid mass flow controllers capable of flowing water for cooling systems in propulsion systems.
  • Control the lift of high-altitude balloons used to study and understand weather patterns and in other experiments.
  • Assist with the pitch, roll and yaw on a satellite using pressure controllers.
  • Combine mass flow and pressure control to replicate the atmospheric conditions on Mars to create an environment to test instrument performance in harsh Martian conditions.
  • Leak test and characterize the valves that are used in rocket engines.

Leak testing and characterizing the valves that are used in rocket engines.

Leak testing in a lab environment on Earth, where pressure and mass flow controllers are installed into test stands, mass flow and pressure devices do very well with the low leak rate volumes and at low pressure.

However, going to space is a little more complicated. Most rocket components must be tested to higher pressures, similar to those found in the oil and gas processes.

The equipment typically used to do this kind of testing is a dome-loaded regulator. They are used to control the pressure in these tests because they can handle high pressure and the high flow rates experienced in these processes. However, while dome-loaded regulators can handle the pressures they are working with, they suffer from hysteresis. This is due to the mechanics of the valve spring and the behavior of the valve changing depending on its current position and whether it is opening or closing. This can result in a non-repeatable process.

The Alicat solution

3000 PSI Pressure Controller

3,000 PSI Pressure Controller

To avoid hysteresis and ensure that the process is repeatable, Alicat has provided the high pressure rated dual-valve pressure controllers (PCD) that can tolerate pressures up to 3,000 PSI. To do this, the PCD uses a proportional control valve that is controlled by onboard PID tuning of the device that limits the repeatability issues found with other pressure regulators. PCDs can also be configured with a remote pressure sense port to measure the pressure at the location of regulation to reduce delay and speed up the response time of the system.

To characterize and leak check the valves used for space flight, the high pressure PCDs are used to control static and flowing processes and are paired with an Alicat flow meter. While the PCD is controlling the high pressure on the inlet port of the valve or other component, a Whisper low pressure drop meter is installed downstream of the valve to capture the leak through the valve. Since the valve is exhausting to near atmospheric pressures, a non-restrictive flow device is required to minimize back pressure in the system. The Whisper can also easily switch between N2 and He gas, the most common gases used in these tests, and maintain its accurate flow readings. Switching between gases on the fly is simple through a communication protocol from the devices to a computer or directly from the device’s front panel display.

Meeting the industry where they are: process ports

To meet the needs of this industry, Alicat pressure and mass flow devices can be configured with AS5202. Aerospace Standard and Medium-Pressure process ports are available for easy integration into a test stand. This type of porting has become more common in the aerospace industry and are available on Alicat devices.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat mass flow controllers save customers money without sacrificing accuracy, reliability or functionality

Andy is the sales director at Premier Control Technologies, a UK based process control technologies and products distributor which represents Alicat products.

Andy has over 30 years of experience with pressure and flow control instrumentation.

He can be reached at andymangell@pctflow.com.

 

My Grandad M. used to tell me: “In this life, my lad, you can’t get something for nothing!” He was, of course, referring to the benefits of hard work and his belief that if something is worth having then it is all the better for having worked hard to earn it. Having grown up with this ethos, and being a true Yorkshireman myself, I am not capable of seeing this as anything other than true.

Consider the following project:

We want to control four gasses at a high level of accuracy with a span from 0.1 millilitres per minute to 800 litres per minute. While controlling within that range, we also need to measure the pressure and temperature of each of the flowing gasses. Not a simple project, to be sure, but not outside the realm of possibility.

Let’s break down the instrumentation needed for this project. The average mass flow controller has a turn-down ratio of 50:1 of the full scale range. If our total measurement span is 0.1 millilitres per minute through to 800 litres per minute, we’re going to need a minimum of five MFCs. On the other hand, Alicat MC series mass flow controllers have a turn-down ratio of 200:1. With full scale of 20 milliltres per minute, 4 litres per minute and 800 litres per minute, a quick calculation shows that we’ll only need three Alicat instruments to perform the same task. Saving ourselves the need of two instruments is handy but it isn’t something for nothing yet.

Alicat's Gas Select menu

Alicat’s Gas Select menu

The second piece of our project is the gases. Let’s say we need to flow four gases: nitrogen, carbon dioxide, argon and hydrogen. Most bypass MFCs are limited by precalibration per gas and require conversion factors between these gases. Unfortunately, our gas control project needs the ultimate in accuracy. The measurement uncertainty introduced by the k-factors is just too great. Argon alone can have a conversion factor error of as much as 2.8% above standard calibration uncertainty. So now we need separate instruments for each gas to get reliable data. Four gases times five instruments and our cart is getting full. Even if just flowing one instrument at a time, a total of twenty instruments would be required to cover the whole spectrum.

Alicat MFCs are preset with over 98 gases and gas mixtures – all certified within the standard calibration accuracy. So for the same process as above, flowing just one instrument at a time, would still only require three instruments needed to cover the whole spectrum. Assuming a cost of £1000 per MFC, we can see that if we used average instruments, our costs would be at least £20,000. And with Alicat devices? A much more palatable £3000.

But controlling the flow is not all we need our MFCs to do. We also need to measure both pressure and temperature per gas. A pressure transducer, a temperature transmitter, the fittings required, the cables and installation costs could amount to at least £400, probably more. Times four.

Not so with an Alicat. Their mass flow controller includes pressure and temperature measurement so there is no additional cost whatsoever. Plus, with the push of a couple of buttons, it can be reset to perform the opposite action and control the pressure whilst measuring the flow.

With our average MFCs we have to have a system to control the two dozen devices we’d need for this project. An Alicat device, on the other hand, is easy to integrate into a preexisting setup with analog or serial communication protocols, but if we didn’t have a system in place, we can control our three Alicats right from the front screen of the devices.

Pulling all of the above together we can see that for our gas control project, using the average MFCs will need at the very minimum an investment of £20,000 for the instruments themselves, £1,600 for pressure and temperature measurement and £2,000 for a readout and control module. A total of £23,600. By using Alicat instruments an investment of £3,000 would achieve the same results.

All Alicat instruments come with the industry’s only lifetime warranty.

It’s simple maths. Even Grandad M. would agree that Alicat instruments have so many additional features and capabilities you get, if not something for nothing, so much more for so much less.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Trigas FI becomes first factory-authorized Alicat Calibration Center

European Calibrations!

Trigas FI, our Alicat distributor based in Münich, Germany, is now Alicat’s first authorized Calibration Center. Trigas calibrates all manner of gas and liquid flow instruments and has a well-equipped lab with one of the best calibration standards in Europe. With lead times as short as 48 hours, Alicat customers in Europe may save time and cost versus shipping the units to America.

  • DAkkS accredited to ISO 17025 for all their calibrations
  • 20 years of experience in calibration business
  • certified in best practices for Alicat instruments

Trigas distributes Alicat instruments for automation and process control applications in Germany, Austria, Switzerland, Albania, Bosnia and Herzegovina, Bulgaria, Croatia, Greece, Macedonia, Montenegro, Romania, Serbia and Slovenia. Contact tfinfo@TrigasFI.com for more information or see their representative listing for further contact information.

 

 

 

 

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Troubleshooting vs. repairing an Alicat device

Alicat mass flow meters and pressure controllers are precisely engineered and rigorously tested. These devices are designed to maintain high accuracy calibrations while mitigating the effects of environmental factors. Because we believe it is important that our devices maintain performance after purchase, we have a team of Application Engineers to help customers get the most out of their instruments. In the event an Alicat device isn’t working as expected, we’re here to help identify and resolve the issue as quickly as possible.

If it ain’t broke… troubleshoot!

Many problems can be fixed without having to return the device to the factory. We’ve outlined some common issues and their solutions below:

Alicat's Gas Select™ menu

Alicat’s Gas Select™ menu

Incorrect Gas Selected

Alicat devices can flow over 98 gases and gas mixes, but it is important to verify that the gas selected on the device matches the gas used with the device. Flowing a different gas than selected usually won’t have any negative effect on the device itself. However, the measured flow readings will be off by approximately the ratio of the viscosities of the two gases. The data can be brought to near correct readings by multiplying each reading by the ratio of the selected gas’s viscosity to the desired gas’s viscosity.

To prevent the problem from occurring again, update the gas selection in the Gas Select™ menu as soon as possible.

Negative Flow Readings

A negative reading when there is no flow usually means the meter was flowing when it was last tared. To fix the problem, make sure there is no flow and give the instrument a fresh tare by selecting MENU > TARE from the home screen to correct the problem.

Tuning Issues

When an Alicat unit leaves the factory, the valve is configured to operate at certain standard conditions.  Sometimes these valve characterization conditions do not match the actual operating conditions. When this happens, it is possible the device won’t control with the speed or stability typical to an Alicat controller. Don’t panic! With Alicat devices, it is possible to change gains in the control algorithm from the front panel and via serial communication. More often than not what seems to be a non-functional unit is just a controller configured for a different specific application.

Having trouble troubleshooting?

We have a growing knowledge base online to make operating the instrument easier. However, some problems require more in depth knowledge on how the Alicat is (or isn’t) working. If that is the case, Applications Engineers are available to help by chat (in the bottom right corner of the page) or by phone +1.888.290.6060.

When it is broke… We’ll fix it.

Sometimes troubleshooting can’t fix the problem. For a variety of reasons, Alicat devices must be returned to the factory for repairs. To speed up a repair, include as much information about the failure or error and any troubleshooting that has already been performed so our team can focus on finding and resolving the issue.

The most frequently seen failures, how to spot them and how to avoid them in the first place are outlined below:

Contamination

The most common service issue we see is contamination in the flow path. Without the proper precautions, foreign particles and debris collect in the valve and flow body and can cause the unit to clog or read erroneous flow rates.

Contamination can be as severe as a spiderweb inside the device.

Contamination can be as severe as a spiderweb inside the device.

To help prevent this, always clean fittings before installation and make sure to flow the appropriate gases from clean sources. We also recommend that appropriately-sized filters be installed throughout the process to protect against contamination.

Over-pressurization

Running the device at pressures beyond its specifications may damage the sensors. If the Alicat is reading strange values when no pressure is applied, it is possible that the sensor has been over-pressurized and is no longer functional.

To avoid damaging the sensor, always remember to use your Alicat device within the stated operating conditions. Refer to the device’s manual for these conditions. Exceeding them puts the Alicat device at risk of catastrophic failure

Electrical Issues or a Blown Transient Voltage Suppressor (TVS)

Failure to follow the correct power and communication specifications can result in catastrophic failure to the electronics in your device. Alicat devices contain TVSs to help protect the unit from power issues. Signs of blown TVS include anomalous voltage input/output readings to total loss of communication. If the device expresses one of these symptoms or seems to be pulling excessive current do not continue to operate the device.

To prevent electrical issues be mindful of what power source is being used to operate an Alicat device and take extra care to ensure wiring from the power source match the correct specifications.

Drifting Sensor Readings

All Alicat device readings will drift a little, well within specified accuracy. Drift is due to limitations of the sensor and is not cause for concern. To ensure accuracy of readings, always tare the Alicat device before use when the sensor is depressurized (and not in flow conditions).

If the device seems to be drifting more than the allowable specification, take note of flow and pressure readings at power up of the device and log these readings every five minutes for an hour. Deviation greater than 0.2% of the full scale range may mean that the sensor is defective.

Don't let this happen to your Alicat...

Recalibration

To ensure that every device maintains specified performance and within warranty, we recommend annual recalibration of every Alicat device. By recalibrating annually, slight changes in flow readings that are within specification but are showing signs of drift can be corrected. It is also an opportunity to reconfigure the device to a new experiment or process, upgrade features and catch potential issues before they become problems.

 

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Using a Dual Valve Pressure Controller and the Venturi effect to create a vacuum

Recently we worked with a customer that needed to control the pressure in a reaction chamber between -200 to +200 cmH2O. However, though the customer’s building had an ample supply of compressed air, they had no vacuum source. Without suction, they were unable to reach negative gauge pressures. We went to work finding a solution that not only met the customer’s needs but could be added directly to the product they were purchasing. By installing a Venturi vacuum generator on an Alicat Dual Valve Pressure Controller (PCD), the customer was able to use their compressed air source on the system to create the necessary suction for controlling to sub-atmospheric test pressures.

Alicat PCD-Series dual-valve pressure controller

Alicat PCD-Series dual-valve pressure controller

What is the Venturi effect?

When fluid flow moves from a less restrictive to a more restrictive environment, its velocity must increase – such as spraying water from a garden hose by placing your thumb over the open end. According to Bernoulli’s Principle, this increase in velocity is associated with a drop in pressure. Thus, fluid flow passing through a restriction will have a resultant pressure drop – this is the Venturi effect.

How to use the Venturi effect to create a vacuum

For our customer above, we added a third party Venturi vacuum generator on the exhaust valve of a Dual Valve Pressure Controller. This turned out to be a size-conscious and cost-effective way to create a vacuum without adding a vacuum pump into the system.

It works like this: The Dual Valve Pressure Controller is designed to allow flow to easily escape through the second valve as needed to maintain constant or near constant pressure in the system. In this case, the Venturi vacuum generator accepts a compressed air inlet and flows this through a restriction to create an induced vacuum of about one PSIA, which is plumbed to the exhaust valve of the Dual Valve Pressure Controller, utilizing the compressed air flow to create a vacuum.

 Alicat Sense

The Alicat team works tirelessly to not only engineer and produce the fastest flow and pressure controllers in the world but to find solutions to problems for specific experiments or process set ups and do what makes the most sense for every customer.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat is going to Pittcon 2018!

See just how fast the fastest mass flow meters are, in person, at Pittcon 2018®. We can’t wait to share our mass flow and pressure controllers with visitors, scientists and customers. Stop by Booth 1830 to see demos of Alicat products and chat with our flow and pressure experts about your applications and how to make them more accurate and efficient.

Pittcon, or the Pittsburg Conference on Analytical Chemistry and Applied Spectroscopy, is an annual conference for analytical and laboratory scientists. As science and technology progress, Pittcon is where scientists, researchers and manufacturers can stay up to date with discoveries and advances in instrumentation. Alicat instruments are used in analytical and laboratory instruments, including aroma mixers, chromatographs and spectrographs—and for calibrating them as well.

The Expo will run for three days, Tuesday, February 27 through Thursday, March 1, from 9 am to 5 pm daily at the Orange County Convention Center – West in Orlando, Florida. And it wouldn’t be Florida without the opportunity to meet and greet with an American Alligator between product demos.

If you are attending Pittcon 2018, stop by and say hello to us and check out our newest and coolest products. Or get in touch with one of our Application Engineers online or on the phone at +1.888.290.6060 to learn how the fastest mass flow controllers in the world can make experiments, regulatory instrumentation and other fluid and gas control applications faster and more accurate while saving time and operational expense.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Why Recalibrate Your Alicat Device Annually?

When exact measurements and highly accurate data is critical to the success of an experiment, test, calibration or other application, maintaining a precisely calibrated device is key. To meet the demands put on them, we recommend that all Alicat meters and controllers are recalibrated annually.

When a device is sent in for recalibration it is an opportunity not only to maintain the quality and precision of the device, but also an opportunity to update firmware or, if your application needs have changed, the perfect time to work with our Application Engineers to find a solution that allows your Alicat to be adjusted or upgraded to meet your evolving needs without the hassle and expense of buying a whole new instrument.

Why Recalibrate?

Over time, minor physical changes to the laminar flow elements and pressure sensors inside the device, such as particulate deposits or damaged flow elements, can alter the flow characteristics of the device’s flow path. These altered flow characteristics can affect the pressures transmitted to the absolute and differential pressure sensors in the device’s flow body, causing the calibrated flow curve to inaccurately represent the actual flow rate. With an annual recalibration, out-of-calibration instruments are brought back to their optimal and exact calibration specifications and, if need be, can be cleaned.

Even if the device arrives at our factory or a service center within its prescribed flow tolerance, our service technicians recalibrate the device to be truer to the actual flow rates read by the calibration standard at the necessary calibration points. Alicat can also provide additional or replacement calibration points, if something other than the standard five calibration points is required. Additional calibration points or upgrade of accuracy to ‘high accuracy’ specification can be requested for instruments.

A calibration procedure is demonstrated in this video about accuracy:

Standard calibration typically takes fifteen business days to complete once the device arrives at one of our facilities. With such a quick turnaround time, you can be back to fully operational with a highly calibrated instrument with minimum interruption. For around the clock use of an Alicat, our Application Engineers will work with you to find a suitable and cost effective solution and the right back up device to keep the process running and the instruments in peak calibration.

If ISO-17025 calibration is required by your organization, Alicat can provide this kind of calibration through trusted third party calibration services. ISO-17025 calibration can add about 10 business days to the standard calibration lead time.

Sending your instrument back for recalibration every year keeps the lifetime warranty of your Alicat in place.

Where can Alicat instruments be calibrated?

We recommend that all devices come back to one of Alicat’s approved facilities for recalibration. Most devices will be recalibrated in our Tucson, Arizona headquarters and factory. However, if you are not located in North or South America, there may be a closer location you can send instruments for faster shipping. Alicat currently has service centers in China and India and has a factory authorized service center in Europe.

Getting recalibration started

More information about the costs and benefits of recalibration can be found on the Alicat website or by contacting one of our expert Applications Engineers. To send your instrument in for calibration to Alicat, fill out the service request form. The form lets us assign a Return of Materials Authorization (RMA) number, which is needed for us to receive and process your instruments at the factory. After sending in the form, we can send you instructions for packing and shipping your instruments.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Four kinds of intelligent pressure control

Four kinds of intelligent pressure control

Posted by: Leigh Moyer

From nitrogen purging or filter characterization, through vessel pressure control and leak testing applications, Alicat instruments are versatile and easy to use, while still providing excellent process control. This is because they operate with very fast control response (50-100 milliseconds) and high accuracy.

Our products are easy to program through a display interface, a serial connection or an analog connection, and we are dedicated to fast-turn-around on customized products to meet unique and variable specifications and requirements across industries. Pressure control applications can be enhanced by multivariate, rapid control, as demonstrated with these four examples.

Filter Characterization

An Alicat Pressure Controller can be used to set the pressure drop across the filter by measuring pressure before and after the filter while an Alicat mass flow meter can be used to measure the flow rate required to generate the needed pressure drop. Because mass in equals mass out, the flow meter can be placed upstream of the pressure controller as well.

Filter Test

Diagram 1

Diagram 1 illustrates a filter test using a differential pressure controller to regulate pressures before and after the filter while a mass flow meter measures flow-through at that pressure combination.

Manufactured Component Leak Characterization

Diagram 2

Diagram 2

Using an Alicat Mass Flow Meter and an Alicat Pressure Control Device, the user has a fast, accurate and reliable method for leak checking components. Our mass flow meters have full scale ranges as small as 0.5 sccm with 200:1 turndown ratio, meaning that flows as low as 0.0025 sccm (2.5 sμlm) can be resolved. If plumbed as shown in Diagram 2, the pressure is controlled at the entrance to the Device Under Test (DUT). A constant bleed though the needle valve allows the pressure controller to precisely hold the pressure at the DUT, ensuring that any flow through the meter after the bypass valve is closed is caused either by a leak or due to a cooling of the volume of the DUT. As long as the temperature of the DUT is constant, the flow reported at the meter will be the leak rate of the DUT.

High-Efficiency Helium Leak Testing

Alicat’s Dual Valve Pressure Controller is designed to prevent inefficient off gassing and to save costly gases like helium in closed-volume applications. In one kind of test, the pressure controller first removes all the air out of the test chamber then refills the chamber with helium to the desired test pressure. The gas analyzer records any helium that passes through the test device. The integrated exhaust valve of the pressure controller opens only when needed, so it maintains test pressures without continuously wasting gas through a bleed valve. See Diagram 3.

Helium leak testing using a dual valve pressure controller with pressure sensing to a helium chamber.

Diagram 3

Backpressure Control with Flow Monitoring

Backpressure control using a mass flow controller set to control on pressure.

Diagram 4

Instead of using a dedicated pressure controller and a separate mass flow meter, Alicat’s mass flow controllers (MFC) reduce equipment needs to a single instrument. This can be accomplished by setting the MFC to control for absolute pressure. The instrument will now control pressure while simultaneously displaying flow rates. As illustrated in Diagram 4, the mass flow controller allows pressure inside the system to build, simulating the internal pressure of a tire versus the air compressor that is attempting to fill it.

Conclusions

Specialized application engineering knowledge acquired by Alicat, for measuring and control techniques used in a wide spectrum of pressure and flow control processes, ensures that Alicat can quickly provide the optimum solution to your specific need and application, helping you create the most cost- and time-efficient system.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
Email: sales@sensorguys.com Website: www.sensorguys.com

Alicat Electronic Pressure Controllers

Alicat Electronic Pressure Controllers

Posted by: Jesse Arenstein

The new Alicat Electronic Pressure Controller (EPC) packs all the analytical stability and accuracy of our standard pressure controller, but in a compact form ideal for installing in high volume original equipment manufacturing (OEM) applications, ensuring that the end product is outfitted with the best components available.

From bioreactors to chemical analysis, quality control to metrology and beyond, Alicat customers are building pressure based OEM systems that require greater and greater levels of accuracy and control stability.

Dual valve pressure control for OEM applications.

Dual valve pressure control for OEM applications.

Sold in batches of 25 units or more, the fully customizable EPC is an economical solution to pressure control in OEM applications. Three varieties of EPC—single proportional valve, dual proportional valve and back-pressure—allow for customized pressure control in embedded systems.

A single valve device is ideal for regulating straightforward applications, like using a pressure regulator to knock down inlet pressure off a gas bottle, or providing volumetric flow control against a calibrated orifice. With control times faster than 100 milliseconds, it adds control stability and responsiveness to any desktop analyzer, lab in a box, reactor or sample preparer for chemical separation processes like gas chromatographs or mass spectrometers.

A dual valve system adds a second valve directly into the component, allowing for real time pressure control of flows into and out of a process, without the waste found in using a single valve pressure controller and a continuous bleed. Dual valve controllers are used to precisely control dome-loaded industrial processes involving high volumes at high pressure—as well as in tiny capillary tubes for cancer cell analysis, where miniscule amounts of fluids are moved around.

A back-pressure controller operates proportionally to increase frictional resistance on the outlet of a fluid control system. By taking advantage of a wide range of orifice sizes, EPC back-pressure solutions vent-down systems with many different flow requirements, while maintaining speed, accuracy and a full range of pressure and vacuum controls. No matter what back-pressure process users are controlling, the Alicat EPC can provide deep resolution and granularity improvements while maintaining speed, accuracy and a full range of back-pressure and vacuum back-pressure control.

The number of applications for pressure control in the scientific and industrial world are staggering and the EPC allows companies to integrate the fastest pressure control meter into products. As the world of technology continues to miniaturize and pack more and more performance into smaller packages, Alicat EPC’s are an invaluable tool for pressure control needs in OEM technologies.

Reference: click here.

D&D Engineering – “W’ere YOUR Sensor Guys”
3835 E. Thousand Oaks Blvd. Suite 464 Westlake Village, CA 91362  – Voice: (818) 772-8720 Fax: (818) 772-2477 Toll Free: (888) 333-6474
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