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Teledyne Hastings Instruments Blog

Freeze Drying of Flowers - Happy Valentine's Day!

Posted by Doug Baker on Fri, Feb 12, 2021 @ 08:57 AM

freeze dried flowers courtsey of Flowers ForeverHappy Valentine’s Day 2021! Time for me to run out and order some freeze-dried flowers for my wife. What?... yes, it’s true! In case you have not heard of this, freeze-dried flowers can make a beautiful gift.


According to Flowers Forever – Bellabeads of Columbia SC, https://myflowersforeverjewelry.com/pages/freeze-dried-flowers, freeze-dried flowers will, “retain their beauty as if frozen in time as a lasting memento.” They can be placed in shadow boxes or frames and stored for many years.

So this is probably the best time to tell you about this fun application of vacuum technology. I recently worked with one of our vacuum customers who services freeze driers for florists, so this topic is “fresh” in my mind. Freeze drying is well-known for use in the manufacturing of food and drugs. Most likely, you have something in your house that has been processed with freeze-drying. So, let’s take a closer look.


Freeze dried raspberriesFreeze drying, also known as lyophilization, is a process in which water molecules are removed from biological cells without damaging the cell structure. For starters, the product to be freeze-dried is chilled and the water inside is completely frozen (i.e. placed in the solid state). Next, the pressure is reduced using vacuum pumps and the water molecules sublimate – that is, water goes from the solid phase directly to the gas phase.


The gas load due to the water vapor is usually very high and requires condensers to trap the liberated water and stop it from overwhelming the pumping system. Commercial freeze driers (see image below) include a heat exchanger which serves two purposes: first, the heat exchanger is used to cool the product and later, it is used to gently heat the product to drive the water sublimation.

Commercial Freeze DrierView inside commercial freeze-drier


Do you know of some other cool applications of vacuum technology, we would “love” to hear from you! Please visit Live chat with us at www.teledyne-hi.com or call 1-800-950-2468.


Special thanks to Flowers Forever – Bellabeads for the use of flower image from their beautiful website.

Tags: Vacuum gauge

Liquefied Nitrogen use in Aluminum Extrusion

Posted by Wayne Lewey on Tue, Nov 24, 2020 @ 12:22 PM

The use of Liquefied N2 (LN2) has revolutionized aluminum extrusion mold performance. CVS Corporation based in Gimpo, South Korea has developed a proprietary LN2 cooling process that allows production output to more than double for some extrusion profiles. Production times vary based on the geometry of the extrusion profile. Ram speed test data can be found in Figure 1 below.

Extrusion Profile Table

Figure 1: Extrusion Profile Table


The Aluminum Extrusion Mold Liquid Nitrogen Cooling System from CVS is designed to control the temperature of both the profile and the mold during the extrusion process. As the billet passes through the extrusion mold, the friction between the billet and the mold creates excess heat. This excess heat limits the extrusion ram speed and is the main cause of reduced productivity in the extrusion process. The CVS process maintains optimum profile and mold temperatures by using automated cryogenic proportional control valves to provide precision dosage of Liquefied N2.

Aluminum Extrustion Mold Liquid Nitrogen Cooling System from CVS

Figure 2: Aluminum Extrusion Mold Liquid Nitrogen Cooling System from CVS

Model DCVT-6 Vacuum Gauge with DV-6R



Figure 3: Model DCVT-6 Vacuum Gauge with DV-6R

To deliver LN2 to the system, CVS employs their own efficient design of vacuum insulated pipe. This design incorporates the model DV-6R thermocouple gauge tube to monitor the vacuum jacket pressure. Mr. Ko Hwa-Jin specified the model DV-6R because of its proven reliability. The CVS production team uses the model DCVT-6 vacuum gauge in conjunction with the DV-6R in manufacturing.

For more detail on effective vacuum jacket insulation, see Teledyne Application Note: Ensuring a Vacuum Jacket is Working Properly​

Mr. Ko Hwa-Jin is the President of CVS Corporation and can be reached by email or website: www.ln2doser.com

Mr. Yoonk Min is the President of Inforad Corp. which is the distributor for Teledyne Hastings Instruments for South Korea. Mr. Min can be reached by email or website: www.inforad.co.kr

Wayne Lewey is the International Sales Manager at Teledyne Hastings Instruments and can be reached by email

Tags: Vacuum gauge, Vacuum Insulated Pipe, Liquefied Nitrogen, Vacuum Gauge Tube, Aluminum Extrusion

How Vacuum Gauges are used in the production of Neon Lights

Posted by Doug Baker on Wed, Jul 01, 2020 @ 01:48 PM

Several months ago, I saw an interesting article about a cool museum called the Neon Museum which is located in Las Vegas.


According to the museum’s website, “the Neon Museum is a non-profit 501 (c) 3 organization dedicated to collecting, preserving, studying and exhibiting iconic Las Vegas signs for educational, historic, arts and cultural enrichment.” The museum holds over 250 neon signs. Tours are given both day and, of course, at night. The main collection in the “Bone Yard” includes signage from Caesar’s Palace, The Stardust Resort and Casino, and the recently added giant guitar from the now closed Hard Rock Café.

Some of the pieces are still operational and “live” shows are given nightly. Other signs are dormant and are lit up by flood lights.


(Photos Courtesy of the Neon Museum, Las Vegas, NV)


Production of neon light tubes requires vacuum pumps and, of course, reliable vacuum measurement. Typically, glass tubes are bent into shape and then pumped to around 1 Torr and energized using a glow discharge to clean up the tube. Next, the tube is evacuated to the mTorr region. Different gases are then backfilled to a few Torr which, when excited in a glow discharge, create various colors. Neon gives the classic neon red/orange glow while carbon dioxide produces white, helium gives yellow, and mercury can be blended with neon to produce blues. In some cases, coatings on the internal surface of the glass can be used to create additional colors. When using coatings, mercury is included in the gas to ensure that UV photons are created to activate the fluorescent coating.

A nice tutorial of glow discharge characteristics with some history is given starting on page 14 in the February 2020 issue of Vacuum Technology & Coating magazine.  https://digital.vtcmag.com/12727/26337/index.html

HVG 2020B Angle Finger 20.9CThe new HVG-2020B from Teledyne Hastings is a great vacuum gauge for this application. The gauge uses two vacuum sensors: a piezoresistive sensor to measure pressures from atmosphere to 10 Torr and a thermal Pirani sensor to measure from 1 Torr to 0.1 mTorr. In between 1 and 10 Torr, the gauge uses a weighted average to ensure a smooth transition between the two sensors. The piezoresistive sensor is gas species independent, so no matter what gas is being backfilled, the piezoresistive sensor gives an accurate measurement. The Pirani sensor’s response is affected by the gas species, but the user can select a gas and the correction is made.


So, the next time you see a neon light, you can think about the vacuum gauge that was probably used to manufacture the gas tube. And if you’re ever in Vegas, check out the Neon Museum!


For more information about any of our vacuum gauges or our complete line of mass flow meters and controllers, we are here to help. You can contact us at hastings_instruments@teledyne.com , Live Chat on our website www.teledyne-hi.com , or call 757-723-6531 (800-950-2468). And to learn more about the HVG-2020B Vacuum Gauge, click the link below, “5 Reasons you need the HVG-2020B Vacuum Gauge.”

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Tags: Vacuum gauge

Facts You Might Not Know about Teledyne Hastings Instruments

Posted by The Teledyne Hastings Team on Thu, May 14, 2015 @ 04:45 PM

Quality Teledyne Hastings ISO 9001 CertificationLast month, we passed our ISO 9001 surveillance audit.  It has been over twenty years since we first obtained ISO and we wanted to take a step back and review some significant accomplishments.  

Teledyne Hastings Instruments rich history and customer centric vision continues to support, influence and grow with those who depend on quality process control and automation.

That's why we wanted to take a moment and celebrate a milestone with our core clients and those considering a Teledyne Hastings Instruments Flow instrument or Vacuum Gauge for the first time.


Teledyne Hastings Instruments' has been providing quality thermal mass flow instruments and vacuum meters and controllers for applications ranging from academic research to space exploration for over 70 years.  Let us work with you to find the best solution for your process.

OEM, custom applications, lead time crunch, just curious:   

Contact Us

Tags: Teledyne Hastings Instruments, Flow Controller, Flow Meter, Vacuum gauge, vacuum controllers, ISO 9001 and Thermal Mass Flow, ISO 9001 and Vacuum Gauges

Understanding Piezoelectric Pressure Sensors and Piezo Pressure Vacuum Gauges

Posted by Will Harrison on Thu, Nov 20, 2014 @ 10:09 AM

Understanding Piezoelectric Pressure Sensors and Piezo Pressure Vacuum Gauges

Piezoelectric pressure sensors use a specialized material to create a small voltage when mechanical stress is applied to it. In this blog we will explain the principles behind the Piezoelectric pressure sensor, review its specific attributes and then discuss how it is used in vacuum gauge technology and industry applications.

Piezoresistive Pressure Sensors

A Piezoelectric pressure sensor functions on the principle that when mechanical stress is applied to a piezoelectric crystal, an electric potential is generated which is directly proportional to the pressure applied. A vacuum gauge that uses a piezoelectric pressure sensor typically houses the sensor in the diaphragm. This provides good linearity for vacuum transducers as the output signal correlates to the applied pressure. This signal is then used to produce an output voltage that is converted to a pressure measurement. Piezoelectric sensors are rugged and often used for measuring dynamic pressure. Because Piezoelectric sensors have a high sensitivity to dynamic changes in pressure, they are well-suited to the measurement of small changes, even in very high-pressure environments. Although they have a high sensitivity to dynamic pressure that can also be used to measure static pressures. 

Piezoelectric pressure sensors are typically used for measuring atmospheric pressure but can be paired with additional vacuum, pressure sensor technologies to create a wide-range vacuum gauge capable of measurement from vacuum to atmosphere. In some cases, a wide-range vacuum gauge can be further expanded upon by adding a 3rd technology to provide a compact solution capable of wide-range measurement from atmospheric pressure to ultra-high vacuum.

"Direct" and "Indirect" Vacuum Pressure Gauges

In vacuum technology, pressure measurement is accomplished using either  “Direct” or “Indirect” methods. Direct gauges are so-called because they directly measure the force imparted on a surface. Based on the formula: P = F /A (pressure (P) equals force (F) per unit area (A), the gauge directly measures the pressure. Some examples of direct gauges include: bourdon gauges, capacitance manometers and Piezoelectric gauges.

Bourdon Gauge Teledyne Hastings Instruments Framed

Bourdon Gauge

One of the primary benefits of a direct vacuum gauge is the ability to make accurate measurements regardless of gas type. For example, if the system has 20 Torr of argon, helium, methane, or air, a direct measurement gauge will read the same pressure. Because of this attribute, direct gauges are referred to as “gas composition independent”. These are helpful to see the operating pressure being used during the process. 

Indirect gauges do not “directly” measure the force associated with the gas in the chamber. Rather, these gauges measure a property associated with the gas. For example, thermocouple vacuum gauges measure the thermal conductivity of the gas, which is a function of the pressure. Another example of an indirect gauge is the pirani vacuum gauge which measures the pressure-dependent thermal conductivity of the gas in a vacuum using a heated element, such as a wire or thin-film membrane. The heated element is part of a resistance bridge. The temperature, and thus the resistance of the heated element in the vacuum, changes as the pressure changes. By measuring the electrical behavior of the bridge, the pressure in the vacuum can be determined. Consequently, thermocouple and Pirani vacuum gauges can both be called indirect gauges.

Thermocouple_Guage_Tubes_Teledyne_Hastings_Instruments_framed                 HVG 2020B Angle Finger 20.9C

 Thermocouple Gauge                     Pirani Gauge

Application: Vacuum Pressure Impregnation (VPI) Systems

Teledyne Hastings uses piezo sensors for pressure measurements in our HVG-2020A and HVG-2020B vacuum gauges. The HVG-2020A vacuum gauge uses a Piezoelectric sensor that provides accurate pressure measurement throughout the rough vacuum region. The HVG-2020B is a dual-sensor vacuum gauge that uses a Piezoelectric sensor and a Pirani sensor to measure a wide range.

Vacuum Pressure Impregnation VPI System

Because the HVG-2020A measures from 0.1 Torr to 1000 Torr, it is well-suited to vacuum pressure impregnation (VPI) applications. Vacuum pressure impregnation (VPI) is an important application for applying insulating materials, as well as producing void-free castings. A typical example is the encapsulation of windings in electric motors. If an insulating resin is simply “painted” on a winding, the result will be a network of uninsulated voids between the winding layers. Applying pressure may force some insulation into the voids, but the subsequent release of that pressure will cause the trapped gas to expand again, causing voids to reappear.

These voids in the insulation can lead to motor failure due to movement of the wiring during operation. Also, in high-voltage applications, these air-filled gaps can serve as sites for corona discharge formation, leading to losses in efficiency and resulting in further weakening of the dielectric.

The proper method to prepare windings, and other potted devices for impregnation, is to begin by applying vacuum.

  1. The first step is to load the assembly into a vacuum/pressure chamber and apply vacuum to remove air from the voids between the windings. A suitable pressure for this step is 5 Torr.
  2. The next step involves a two-part soak. While under vacuum, the insulating resin is introduced into the chamber from a storage vessel. The vacuum provides the additional benefit of removing any air bubbles that may be present in the resin. After a dwell period, the chamber is pressurized to 85-95 psig for another period of time. This pressurization forces the resin into the previously evacuated voids in the winding layers.
  3. After another dwell period, the pressure is relieved and the surplus resin is returned to the storage vessel. With the chamber at atmospheric pressure, it is opened and the assembly is removed. This process results in void-free application of the insulating resin on the windings.

Teledyne Hastings: HVG-2020A Vacuum Gauge

HVG 2020A_76307_fingerThe Teledyne Hastings’ HVG-2020A vacuum gauge is a media-isolated, gas composition independent, piezoresistive instrument that provides accurate pressure measurement throughout the rough vacuum region. 

The HVG-2020A is easy to install, can be configured with an optional touchscreen display to offer a choice of data views, and provides both analog and digital output for process control integration.

  • With a wide variety of linear analog output signals to select from, the HVG-2020A is an excellent choice to replace more expensive capacitance manometers.
  • Digital output options include RS232 and RS485 via a connection on the top of the gauge.  A USB connection is also available on many models to make connection and operation simple.
  • Monitor and view data remotely using our free, Microsoft® Windows®-based software and log data to Microsoft® Excel® for comprehensive diagnostics that record how the vacuum behaves over time.

Analog I/O: The HVG-2020A has a 9-pin D-sub connection on top of the gauge that allows an analog output signal to be measured amongst other features.  The selected linear analog output signal is proportional to the full-scale range of the sensor (1000 Torr).

  • HVG 2020A_topAvailable outputs include: 0-1 VDC, 0-5 VDC, 0-10 VDC, 0-20 mA, and 4-20 mA.  The vacuum gauge is factory-configured with one of these outputs “active”, but can be easily changed using the touchscreen interface (if installed), or using digital communication when not configured with a touchscreen. Digital communication with the HVG-2020A will be discussed in greater depth in the next section.  
  • The 9-pin D-sub connection has Hi and Lo setpoints which are activated when the pressure is above or below the respective setpoint. Additionally, the 9-pin D-sub has a pin for input power and can accept 12-36 VDC.  For installations without 12-36 VDC, power can be supplied using a bayonet-style connector at the 24 VDC input connection.

Digitial I O for HVG 2020ADigital I/O:  As mentioned earlier, the HVG-2020A offers a variety of digital communication options in addition to the previously discussed analog choices.


  • The micro-USB connection is the simplest method to interface the vacuum gauge and allows it to be directly connected to a PC without the need for adapters or extra wiring. 
  • The 4-conductor TRRS connection can be used to “daisy-chain” multiple gauges together using RS485 or a standard RS232 communication connection. 
  • The 9-pin D-sub connection has two pins designated for TTL serial communication.
  • LabVIEW™ Drivers

All of these digital communication options (with the exception of TTL) enable PC connection and allow monitoring and viewing of data remotely using our free Microsoft® Windows®-based software.  This software has many useful features including data logging and  customization / configuration of the vacuum gauge.  Digital communication is also used to change the analog output, adjust Hi and Lo setpoint values, stream pressure readings, or change pressure units (among many other functions), when the HVG-2020A is not configured with the optional display.

Touchscreen Display:  The most powerful feature of the HVG-2020A is the optional touchscreen display which allows monitoring of pressure measurements in a variety of combinations and graphic representations while operating. The display is powered off the vacuum gauge power supply (no additional power supply needed) and is especially useful for installations in which a remote display would be inconvenient. Five different display modes (shown left to right below) include: Pressure, Pressure and Temperature, Setpoint, Bar Graph, and Pressure over Time.  Note that the pressure measurement is always displayed in each mode. 

The touchscreen’s Menu Button allows the user to cycle through a selection of submenus to change the screen orientation (should the gauge be mounted in a position other than vertical), zero the gauge (only performed if the system pressure is known to be well below 0.1 Torr), view device information (serial number and firmware level), change the analog output, select RS232 or RS485 and a number of baud rates, and restore the vacuum gauge’s configuration to factory default settings.  The straight-forward arrangement of measurements and easy to read display, lets you “see clearly”, similar to 20/20 vision!

Applications and Industries

  • Rough Vacuum Monitoring

  • Semiconductor
  • Laser Systems
  • Chemical Research
  • Air Sampling
  • Central Vacuum Monitoring
  • Oil Reprocessing
  • Medical Research

Tags: Vacuum gauge, Sensor, pressure, vacuum pressure, vacuum instruments

Happy 45th Birthday Teledyne Hastings Instruments

Posted by Doug Baker on Tue, Feb 26, 2013 @ 03:17 PM


The entries in these blog pages are intended to provide helpful knowledge regarding vacuum gauges, vacuum instruments, gas mass flow meters, and flow controllers. But we could not pass an opportunity to celebrate an anniversary of sorts – on January 30th, 1968, Teledyne and Hastings - Raydist, Inc. announced that Teledyne would acquire the Hastings - Raydist company. According to the announcement in the Wall Street Journal, Hastings shareholders would receive one share of Teledyne stock for each 2.98 shares of Hastings – Raydist stock. So Hastings has been a part of Teledyne for 45 years…

Happy 45th birthday Teledyne Hastings Instruments!


Teledyne Hastings Vacuum gauge Apollo 11The history of the Hastings Instruments Company stretches all the way back to 1944. Next year, Hastings will celebrate its 70th birthday. But while we are in a corporate history mood, it might be fun to recall everybody’s favorite Hastings’ story:  In 1967, Hastings vacuum sensors were designed to travel to the moon and back. One of the objectives of the Apollo missions was to bring lunar samples back to earth. Special boxes, fitted with Hastings vacuum thermocouples were designed and built by Oak Ridge National Labs. Each box was required to be vacuum sealed; the Hastings thermocouple ensured that the seal was good before launch, and after splash down. The box and sensor worked perfectly.  Today, the thermopiles from the Apollo 14 mission are on display on a wall between one of the company’s conference rooms and a hallway. A magnifying lens and lamp installed in the display allows visitors to see the vacuum sensor.

Carol Hastings Saunders, daughter of Charles and Mary Hastings, recounts an interesting story in her book, “The Story of Hastings Raydist”. Two years prior to the acquisition of Hastings by Teledyne, Hastings was looking for an acquisition of its own to handle military contracts. The company considered Automated Specialties in Charlottesville Virginia. In 1965, Hastings began to acquire Automated Specialties by investing $100,000.But before the year was over, Automated Specialties was itself acquired by Teledyne. As a result, Hastings then held 11,948 shares of Teledyne. In late 1966, Hastings sold the shares and recognized $800,000 after taxes. Not bad on a $100K investment.

Today, Hastings Instruments is part of the Instrumentation Segment of Teledyne Technologies Incorporated (NYSE: TDY). The Instrumentation Segment provides measurement, monitoring and control instruments for marine, environmental, scientific and industrial applications. The Segment also provides power and communications connectivity devices for distributed instrumentation systems and sensor networks deployed in mission critical, harsh environments.  A complete history of Teledyne is given in Dr. George A. Robert’s book, “Distant Force – A Memoir of the Teledyne Corporation and the Man Who Created It”.

We welcome your comments on this history topic. Please complete the form below:

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Douglas Baker used his first vacuum gauge while an undergraduate physics major at Indiana University of Pennsylvania. In graduate school at William and Mary, Teledyne Hastings vacuum gauges monitored the forelines in the vacuum systems in the atomic and molecular lab where he worked. Today, Doug is the Director of Sales & Business Development at Teledyne Hastings Instruments and he can be reached at dbaker@teledyne.com

Tags: Teledyne Hastings Instruments, Vacuum gauge, Sensor

FAQ Corner – How Accurate is My Thermocouple Vacuum Gauge

Posted by Vikki Jewell on Tue, Feb 05, 2013 @ 08:24 AM


Recently, I found myself pouring through dozens of website posts comparing watches used by long distance runners.  This year I am pursuing, perhaps in vain, a new PB at my favorite 10K; this will require a boost from technology.  Now, if I have learned nothing in the last decade working with measurement instrumentation, it is that if a process can be measured, it can be improved.  Understanding those measurements can be a challenge.    Repeatedly, bloggers on running sites have been asking if the race course mileage should closely match the mileage on a GPS watch.  Reminding me, no matter the application, a key selection criterion for a measurement instrument is accuracy.

 Accuracy is the deviation of a reading when compared to a standard.  In general, better accuracy requires higher instrument costs.   However, too little accuracy and process efficiency, production costs, and user satisfaction may suffer. So many users want to know, “What is the accuracy of my thermocouple vacuum gauge”?   In this blog, I will discuss the accuracy of thermocouple vacuum gauges.

In the low to medium vacuum range, many users select thermocouple vacuum gauges for their long-life, rugged performance, and low cost. Typical applications in the low to medium vacuum range include lighting, monitoring cryogenic jackets, vacuum pump performance, and HVAC/refrigeration.   

Vacuum Gauge OutputIn  order to better understand the accuracy of a thermocouple vacuum gauge, it is helpful to review the response curve of these vacuum gauges. In the accompanying figure, we show the output of three of Teledyne Hastings most popular vacuum gauges. Note that each vacuum gauge tube family (DV-4, DV-5, and DV-6) has a range of pressures where the sensitivity, defined as the change in output as a function of pressure is very good. In this pressure region, the output is very repeatable and gives the best accuracy. Note that at the far ends of the curves, the sensitivity flattens out which in turn causes more uncertainty in the pressure measurement. So in general, the best accuracy of the thermocouple gauge is found in the middle of the curve. This fact can help the user select the best vacuum gauge tube family for a given application.  Note that the measurement accuracy reflects the gauge as a whole system (meter, cable, and thermocouple gauge tube) and not the individual components.  (So, it does not make sense to ask, what the accuracy of a thermocouple gauge tube is.)   Users can look up their pressures by reading their output voltages.  The voltage shown here is an amplified signal derived from the thermocouple output. 

In Nitrogen with a new vacuum gauge tube and 8 feet of meter cable, the anticipated accuracies* of the Teledyne Hastings Vacuum products are over some given range of pressures  However, as we discussed previously, in the middle of the response curve, the user can expect to have better accuracy:

VT-4 Series ± (20% of reading + 0.01 Torr) (max)

VT-5 Series ± (20% of reading + 0.2 mTorr) (max)

VT-6 Series ± (15% of reading + 1 mTorr) (max)             

*Data collected with digital meters

 It might be helpful at this point to review some of the factors that can affect thermocouple gauge accuracy. The accuracy statements shown in the chart above are for nitrogen. Since thermocouple gauges are gas species dependent (in other words, the output that the gauge will give will depend on the composition of the gas for a given pressure), the use of the gauge in gases other than nitrogen will affect the accuracy.  Also, the condition of the gauge tube is important. A gauge tube that is contaminated with pump oil and/or process material may not provide the expected accuracy. Temperature variations can also cause changes in thermocouple gauge output. Applications engineers at Teledyne Hastings are available to help you understand these effects.

                                                       Let's Talk!

                  We would like to hear from you.  Contact us with your vacuum experiences.

 Vikki Jewell is a part time 10K runner and a full time applications engineer at Teledyne Hastings. She has been helping users of scientific instrumentation for twenty years.  Vikki can be reached at victoria.jewell@teledyne.com or hastings_instruments@teledyne.com.

Tags: Teledyne Hastings Instruments, Vacuum gauge, accuracy