Tuesday, December 30, 2014

Electric Heating Systems for Liquid-Gas Vaporization

Liquid-Vapor Gas Heater
Electric Circulation Heater
Hydrocarbon and non-hydrocarbon based gas products are transported and stored at low temperatures. The most common examples of liquified gasses are liquified natural gas, butane, propane, nitrogen, and oxygen. In liquid form gases are more convenient and efficient to transport, however once at their destination, they must be changed back to the gaseous state.

There are many ways to accommodate the phase change from liquid to gas and picking the best option is dependent on many criteria including plant location, climate conditions, available energy sources, and infrastructure available.

Transitioning from liquid phase to gas phase is a gradual process usually taking place at higher pressures, through several containment vessels, heat exchangers or heating coils which slowly warms the liquified gas.

Some thermal heat exchanging systems use fluids such as hot oil, hot water or a glycol-water solution to efficiently transfer heat to the liquified gas.

Wednesday, December 24, 2014

Happy Holidays and Happy New Year from Belilove Company-Engineers

Happy Holidays from Belilove
We at Belilove Company-Engineers believe the magic of the holidays never really ends, and the most important gifts we share are family and friends. Thank you for a wonderful 2014 and we wish you peace, love, and prosperity in the upcoming year.

Friday, December 19, 2014

Control Valve Challenge in Rocket Propulsion Application

cryogenic control valve
Control Valve
Challenge: To provide a bubble-tight shutoff control valve for liquid oxygen being used in a chemical steam generator in a rocket propulsion testing facility.

Customer requirements: A cage-less design, cryogenic globe control valve that would safely provide fast and consistent Class VI shutoff of liquid Oxygen.

The Solution: Control valve manufacturer Trimteck designed and manufactured a custom 2”, CL300, cryogenic angle/split body valve fitted with piston cylinder actuators. The seat is held in place by the rugged split body configuration without the need for a cage or retainer (normally required for liquid Oxygen valves). The seat maintains its position and is kept at even pressure with the help of eight (8) equidistant bolts that tie together the upper and lower body pieces. Additionally, this “sandwiching” reduces line torsion effects and the adverse effects of vibration on the valve seal. Finally, a custom designed soft wafer seat insert is provided so that seat maintenance can be done quickly and inexpensively.

Wednesday, December 10, 2014

Advantages of Epoxy Electrical Feedthroughs Over Glass-to-Metal and Ceramic Seals

epoxy vacuum feedthrough
Epoxy Electrical
Vacuum Feedthrough
Advances in semiconductor and medical device development has continually challenged manufacturing processes in ultra-clean environments. Getting power and control signals into high vacuum chambers has always been difficult. The vacuum seal has to be tight and not allow any contamination so that product quality is maintained.

Historically glass-to-metal seals for wire feedthroughs have been the choice in these industries, but are constrained in size, geometry, flexibility and electro-magnetic shielding. At the same time, semiconductor and medical device equipment have an increasing need for higher power, more control, better monitoring, and increased signal shielding. These ever changing requirements, which push the capability of glass-to-metal seals,  open up opportunity for an alternative technology - epoxy electrical vacuum feedthroughs.

Engineered epoxy electrical feedthroughs offer the best of all technologies. Shapes, angles and curves are not a problem. Virtually any kind of shielded wire or cable can be used and still maintain a tight seal. And as equipment design requirements continue to challenge vacuum seals with space and shielding requirements, the advantages of epoxy vacuum seals look to be a promising solution as the technology itself continues to advance.

While glass-to-metal feedthroughs have advantages in high temperature and corrosive applications, many of todays semiconductor and medical device applications don’t see these conditions. In these lower temperature, and non-corrosive applications, the lower cost, easy prototyping and more flexible design capability of epoxy feedthroughs make them very attractive alternatives.

The epoxy's ability to flow and fill spaces completely make it an excellent choice for any special shapes and sizes a vacuum chamber may require for access.  For the most part, epoxy feedthroughs can be used in most applications where glass-to-metal or ceramic feedthroughs are used (with the exception of temperature and corrosion issues outlined above). In some applications, organics are not allowed, and the epoxy feedthrough would be excluded from these as well.

One additional advantage is that custom epoxy vacuum feedthroughs can be quickly provided in very small quantities for prototyping and R&D.

For more information on epoxy feedthroughs, visit this page.

Saturday, December 6, 2014

Selecting and Calibrating a Pneumatic Valve Positioner

Most pneumatic valve positioners are designed to work on both rotary control valves and linear control valves. While the linkage and orientation are different, the calibration procedure is the same.

When selecting an industrial valve positioner you should choose one that provides the following features:
  • Easy to install, calibrate and maintain.
  • An auto-calibration feature.
  • Be able to accommodate double acting (DA) or reverse acting (RA) set-up.
  • Error messages for troubleshooting.
  • Allow for fixed input signal testing.
  • Have a programmable characteristic curve with multiple points.
  • Have programming built-in to eliminate overshoot and hunting.
  • Low air consumption.
  • Have NAMUR mounting.
This video demonstrates the typical steps in calibrating a pneumatic valve positioner (in this case, an AT Controls SS2).

Sunday, November 30, 2014

Advancements in Electric Resistance Heaters - Ceramic Heating Elements

Aluminum nitride, high performance electric heating elements using Tungsten traces on ALN. Product manufactured by Durex and Oasis Materials.
  • Power Densities up to 2500 Watts per square inch
  • 0-400º C in a quarter of a second
  • Extreme temperature uniformity
  • Inert in acidic solutions
  • Custom line widths and resistance values available
  • Encapsulated Tungsten RTD trace
  • 3D shapes and configurations
  • Thermal conductivity of Oasis' Aluminum Nitride (ALN) is 190 W/mK
  • Thermal conductivity of pure tungsten is 170 W/mK

Selection Criteria for Mass Flow Meters

mass flow controller
Brooks Mass Flow Controller
There are four primary areas to consider when specifying a thermal mass flow controller (MFC).
  • Flow range
  • Gas conditions
  • Desired accuracy
  • Communications
Additionally, you must take in to consideration the interior finish for high and ultra high purity applications, materials used in the flow path, the environment (high temp ambient conditions, water-tight, dust-tight, etc …), mounting position and serviceability.


Mass flow controllers are used to measure and control the flow of gasses in a process. The overall flow rate must be considered since some processes require very low flows measured in SCCM (cubic centimeters per minute). Larger flows are usually expressed in SLPM (standard liters per minute) or SCFM (standard cubic feet per minute). Many devices able to measure flows of 200 SCCM up to 30 SLPM using the same body size, however, the internal components are changed to allow a more specific flow range. In most cases, once you establish your maximum flow, you have the ability to measure and control down within a certain band. A 10 to 1 turndown ratio is fairly common, and 50:1 or 100:1 is available from some of the leading MFC manufactures. Setting a maximum flow very low such as 10 SCCM or 3 SCCM while being able to measure and control down to 2% is remarkable. When desired flow reaches more than 30 SLPM (or 1 scfm), the physical size of the MFC body usually changes to allow for greater flow through larger passageways inside the MFC. When flow becomes higher than  200 SLPM, the MFC body size increases significantly to allow for controllable flows up to 2500 SLPM  and measured flows up to 9000 SLPM, without the use of a control valve.

Tuesday, November 25, 2014

Basics of OEM and Industrial Electric Heating Elements - Part 2

This blog entry, reproduced from an electric heating element basics white-paper from Hotwatt, a leading US manufacturer of OEM and industrial heating elements. To download the PDF version, click this link.

Basic Heat Equations

electric heating elements
Electric Heating Elements
It would appear at first that calculating all of the heat transfers and losses in a design would be a daunting task. Fortunately a number of equations were developed that help simplify this task. First the equations were divided into three tasks: the wattage needed to heat a material to a specific temperature in a given amount of time; the wattage needed to overcome the losses at operating temperature; and a special calculation needed to reach a melting or vaporizing point.

This equation calculates the amount of wattage (W) needed to raise the temperature of a material a specific amount in °F (ΔF) in a given number of hours (T), you first need to know the mass (m) of the material being heated and its specific heat value (c):

m × c ×ΔF
W=  -------------------
3.412 × T

The mass and specific heat of some materials may be found at www.hotwatt.com/table1.htm for metallic solids, www.hotwatt.com/table2.htm for solids other than metals, and www.hotwatt.com/table3.htm for certain liquids and gases.

Friday, November 21, 2014

Basics of OEM and Industrial Electric Heating Elements - Part 1

This blog entry, reproduced from an electric heating element basics white-paper from Hotwatt, a leading US manufacturer of OEM and industrial heating elements. To download the PDF version, click this link.

Electric heating elements for OEM and Industry
Electric heating elements
for OEM and Industry
(courtesy of Hotwatt)
The simplest definition of an electric heater is any device that changes electrical energy into heat energy. But from that simple explanation, electric heaters explode into a myriad of types, sizes, applications, and designs depending upon what’s being heated, the degree of heating needed, and the method by which the heat is applied.

The measure of electrical energy is called the Joule after its discoverer, James Prescott Joule. Through numerous experiments, Joule determined that the quantity

(Q) of heat transferred from electrical energy is proportional to the square of the current (I2 ) multiplied by the resistance (R) for the period of time (t) through which it passes:

Q ∝ I2 × R × t

However, one seldom sees a reference to Joules used in modern electric circuits. Instead, the controlling factor becomes that of power (P):

P = I2 × R

You’ll note the only difference between the formula for determining power and that of determining Joules is the time component. The time factor in heating becomes readily apparent in any device that gets hot when an electric current flows through it: its temperature rises as time passes.

Wednesday, November 19, 2014

Extremely Fast Mass Flow Controller Response

In this video you will see how quickly a mass flow controller (in this case a Brooks Instrument's SLA5800) responds to set point changes. From 0 to 100%, and through many set point changes, the mass flow controller responds well under 1 second.

If you have a challenging mass flow application, or would like more information, contact:

Belilove Company Engineers
21060 Corsair Blvd
Hayward, CA 94545
Phone: (510) 274-1990
Fax: (510) 274-1999
E-mail: sales@belilove.com

Tuesday, November 11, 2014

Thermal Solutions for Condensate and Particulate Control in Semiconductor Vacuum Pumps and Lines

semiconductor gas line heaters
Semiconductor Gas & Pump
Line Heaters (courtesy of Durex)
Low vapor pressure gas delivery lines must be held at elevated temperatures (higher than the gas vaporization point) in order to prevent condensation that adversely effects process yields. Similarly, sublimation (transition of a substance directly from the solid to the gas phase) occurs when the vapor phase materials are allowed to cool in a vacuum line.  The most common types of sublimation in the semiconductor process is of ammonium chloride (AlCl2) and nitrides (NH4) (NH4Cl).

The more common semiconductor processing applications requiring unique thermal solutions for condensate and sublimation prevention are PECVD, LPCVD, MOCVD, ALD, plasma etch and other vacuum applications.

Keeping temperatures elevated along the vacuum lines, and in the vacuum pump, assures gas temperature above the vapor condensation point, thus keeping condensate at bay.  Heating the vacuum lines, vacuum pumps, and forelines, also substantially reduces sublimation in these areas.

By controlling condensate and sublimation, the need for frequent preventive maintenance is dramatically reduced and subsequently, the costs. Additionally, the life of associated valves and vacuum pumps is increased as well.

The ideal heater should be self contained, be easy to install and remove,  fit tightly on the lines and pumps, and provide optimum heat transfer. It should be powered by readily available voltages (120, 240), have built-in fasteners, and provide over-temperature limit control. It should provide process temperatures up to 200°C and have the ability to distribute wattage along the length of the process line to compensate for colder line sections. The backside of the heater should include thermal insulation that can withstand the operating temperatures, while still providing good thermal insulation.

For more information on semiconductor line, pump and valve heating contact Belilove Company-Engineers at (510) 274-1990 or at sales@belilove.com.

Thursday, November 6, 2014

A Demo of the Brooks Instrument MultiFlo Configurator

The Brooks Instrument MultiFlo Configurator is software for Windows operating systems that provides the user with a fast and simple method to reprogram the gas and range on the Brooks Instrument GF100 Series, GF40/80 and Celerity / Unit brand mass flow controllers without removing them from the gas line.

The following video demonstrates how to use the software with a MultiFlo ready Brooks MFC.

For more information, contact:

Belilove Company-Engineers
21060 Corsair Blvd
Hayward, CA 94545

Phone: (510) 274-1990
Fax: (510) 274-1999
E-mail: sales@belilove.com

Tuesday, November 4, 2014

Custom Industrial Control Valve Bodies Made from Bar Stock

control valve with bar stock body
Control valve with
bar stock body
Most globe control valves are built with cast bodies in stainless or carbon steels. But when these valves don’t meet the demands of your application, you need an exotic alloy, or if you need something in a hurry, considered a custom sliding stem valve with a bar stock fabricated body.

Why use a custom engineered
bar stock body control valve?

  • Quick Lead Time – fabricated bar stock bodies are not subject to foundry delays
  • Availability of Exotic Alloys – no limitation on construction material, which allows quick turnaround of valves fabricated from uncommon alloys
  • Availability of High Pressure Valves – can be machined up to ANSI Class 4500; again, with a faster turnaround than cast valves
  • Customizability – body styles, end connections, and face-to-face dimensions can all be customized as required
  • Severe Service – available with an array of severe service trims including venturi seats for flashing service - as well as oversized wall thickness for noise abatement and added durability

Friday, October 31, 2014

A Tutorial on Replacing the Tube in the Brooks Instrument Sho-Rate 1350G & 1355G Glass Tube Flow Meters

For anyone using the Brooks Instrument "Sho-Rate" 1350G or 1355G glass tube flow meter, here is a handy video on how to replace the tubes.

For more information contact:

Belilove Company Engineers 
21060 Corsair Blvd
Hayward, CA 94545
Phone: 510) 274-1990
Fax: (510) 274-1999
E-mail: sales@belilove.com

Saturday, October 18, 2014

2-Wire and 4-Wire Transmitters and Control Loops

field transmitter
Digital Meters
Industrial process control transmitters commonly provide analog signals, such as 4-20 milliamps (mA), 1-5 volts DC, and 10-50 milliamps as outputs which can be scaled to the control range of the process variable they are sensing. Industrial transmitters are either “4-wire” or “2-wire” which defines how the transmitter gets its supply or “excitation” voltage.

4-wire transmitters have four wires exiting the device. Two wires are for the supply power of the device, typically 120 volts AC, 240 volts AC or and external 24 volts DC supply. The other two wires provide the analog output signal provided by the transmitter circuitry.

loop power
2-wire, loop power example
2-wire transmitters have only two wires exiting the device and rely upon the control “loop” for the excitation voltage - typically 24 volts DC which normally comes from the loop controller, PLC or DCS.

4-wire devices are also classified as “active” (supplying power) devices, while 2-wire devices are classified as “passive” (loop powered) devices.

For example, a digital meter (active) may provide loop power to a pressure transmitter. The pressure transmitter regulates the current on the loop to send the signal back to the digital meter, but since the transmitter does not provide power to the control loop, it is deemed passive. In another example, a passive (loop powered) digital meter and a passive pressure transmitter may be used in the same loop, but uses a 24 V battery as the active device to power the loop.

Monday, October 13, 2014

Industrial Electric Immersion Heaters

electric immersion heaters
Screw plug and flanged
immersion heaters
(courtesy of Durex)
Electric immersion heaters are used in a myriad of industrial applications. From drying industrial gasses, to freeze protecting cooling tower sumps, to heating acids in plating applications, the versatility of electric heating element can save time, energy and space.

Industrial immersion heaters are used to directly heat a standing or moving fluid by using electric heating elements. There are three primary types of industrial electric immersion heaters; screw-plug heaters, flanged immersion heater, and over-the-side heaters.

At the heart of industrial immersion heaters are the individual heating elements, normally constructed from a stainless steel or Inconel tube containing a magnesium oxide filler and a nichrome resistance wire. Current is applied to the wire which produces the heat, while the compacted magnesium oxide powder provides the electrical insulation, and the metallic tube provides the physical protection.

Thursday, October 9, 2014

Mounting a Rack and Pinion Pneumatic Actuator to a Ball Valve

This video, courtesy of AT Controls,  introduces the viewer to the steps in mounting a pneumatic rack and pinion actuator to an industrial ball valve. Steps include matching valve and actuator, checking fit, connecting mounting hardware (brackets and couplings), assuring position, assembly and test.

Sunday, October 5, 2014

Analytical Measurement for Fluids and Processes

The need to perform chemical analysis on samples or sample streams exist in virtually all process systems, large and small. Whether a solid, liquid, or gas, the use of an analyzer to automatically provide detailed process information is required for product quality, manufacturing efficiency and safety. In many situations, sampling be done automatically.

In situ analyzer
In Situ Analyzer
Analyzers connected to a process and providing automatic sampling are called in situ analyzers. For these, the sensor is placed in the process vessel or stream of a flowing material to be analyzed.

A second online method, fluid sampling, passes a sample of the process directly into an analyzer where the handling pressure and temperate can be controlled. This is normally done for for fluids (liquids or gases). The sample stream can then be returned to the process or discarded. It is common for these type of analyzers to incorporate pressure reducing valves, small pumps and perhaps internal electric heating elements that prepare the samples for testing.

Thursday, October 2, 2014

Industrial Ball Valves

industrial ball valve
Internal view of an industrial ball
valve (courtesy of Cameron TBV)
Ball valves are defined by their body style, the five major styles being: Uni-body; 3-piece; split-body; top-entry; and welded body. They are further defined by the machined hole in their ball (also known as the port); the categories being "standard port" or "full port".

On a full port valve, the port is the same size as the pipeline, resulting in a better flow profile and no restriction or pressure drop. A full ported ball valve, with better flow coefficients, comes at a higher price. In many application they are necessary because a reduction in diameter, or the resulting change in flow, can be detrimental.

The reduction in a standard port valve is one pipe size smaller than the pipe connected to the valve, resulting in restricted flow and increased velocity through the valve.

Saturday, September 27, 2014

Custom Electric Heaters for Unique Thermal Systems Require the Right Thermal System Partner

Thermal System PartnerOEMs in the analytical, semiconductor, biomedical, life-science, food service and environmental industries continually design new pieces of equipment offering their customers greater efficiencies, smaller foot prints and greater production rates. When the piece of OEM equipment requires precise heating, consultation with an experienced thermal systems engineer will provide significant time savings and budget control.

More specifically, working with an experienced thermal system consultant provides these important benefits: front-end, practical design review to optimize manufacturability; timely prototype development; partnerships and alliances with platers, brazers, casters and heating element manufacturers; single source responsibility; testing and calibration; inventory management; value-added assembly; and cleaning and packaging.

Friday, September 26, 2014

Flow Measurement for Industrial and Municipal Water Treatment Systems

Accurate and reliable liquid flow measurement for municipal and industrial water and wastewater treatment systems present interesting challenges. A cost effective, and very accurate flow meter is essential to assure proper flow measurement of water resources and wastewater effluent.

In water and wastewater treatment, accurate flow measurement is critical to the following to applications:

Water Treatment
  • UV Dosing 
  • Filter Balancing and Backwash
  • Effluent
  • Distribution 
  • Wells & Booster Stations 
  • Potable Water
Wastewater Treatment
  • Effluent 
  • Recycle / Reclaim
Accurate flow measurement is a critical control variable for the following industries: chemical & petrochemical plants, metals & mining, power plants (and cogeneration), paper mills, food & beverage.

Industrial Applications include:
  • Fire Water 
  • Raw Water 
  • Inlet to Surge Basin 
  • Cooling Water
  • Feed Water
  • Effluent
One particularly well suited flow meter for these applications is the FPI Mag Flow Meter from McCrometer. It provides simple installation, lower costs, unmatched accuracy, a very robust construction, and the versatility to solve many flow metering applications.

Check out this video to learn more:

Tuesday, September 16, 2014

Safety Showers and Eyewash Stations - The Unsung Heros of the Plant Floor

Safety showers
Hughes Safety Shower
Safety showers and eyewash stations might just be the most forgotten, but most important piece of equipment on the factory floor. They can save someone's life, or greatly reduce the amount of injury resulting from a spill or splash of hazardous material.  Plant managers and safety officers must comply with OSHA (Occupational Safety and Health Administration) mandates for safety showers and wash stations with the help of ANSI (American National Standards Institute) standard Z358.1-2009.

This standard requires that all flushing equipment must be in easy to find areas, and accessible in 10 seconds (The Ten Second Rule). This equipment must be installed in well-lit areas and have an established flow rate of 0.4 gallons per minute at 30 PSI for eyewash stations and 20 gallons per minute at 30 PSI for drenching showers.

Wednesday, September 10, 2014

Aluminum Nitride Ceramic Heaters Open Doors to Better Machine Design

Aluminum Ceramic Heaters
Aluminum Ceramic Heaters
(Courtesy of Durex)
Aluminum Nitride (AlN) Ceramic heaters are a relatively new entry in the very high watt density heater market and are an attractive alternative to traditional metal sheathed heaters. Capable of achieving up to 2000 watts per square inch, and operating temperatures of up to 1000 deg. C, these heaters show great promise for semiconductor processing applications such as crucible heating, fluid and gas handling and chemical vapor deposition. 

The heaters are made by "tracing" a resistance material (Tungsten) on a the ceramic base at various thicknesses, corresponding to the performance requirements of the heater. The Tungsten and AIN expand and contract at very similar rates, which greatly reduces the mechanical concerns of delamination. Binders and trace additives are added to the ceramic and Tungsten for additional strength. The resulting construction allows for some pretty impressive thermal cycling - one example is an application with a 200 deg. C temperature swing every 30 seconds.

AIN ceramic heaters offer significant advantages over metal sheathed heaters and their inherent performance limitations. Material compatibility, fatigue, outgassing and thermal lag must be considered when applying metal sheath heaters. Ceramic heaters combine excellent thermal conductivity with outstanding chemical resistance, strength, inertness and design flexibility. Additionally, RTD sensors can be deposited right on the ceramic heater itself for optimum control. 

Capable of forming virtually any shape, along with their excellent mechanical, thermal, dielectric, chemical resistant and embedded sensors, Aluminum Nitride Ceramic heaters open the doors for engineers to design equipment to new levels of performance.

Saturday, September 6, 2014

Thermal Mass Flow Controller Choices

Here is a video, originally produced by AZoTV for Brooks Instrument. The video, through the various Brooks Instrument models of mass flow controllers,  gives a quick overview of the selection criteria for thermal mass flow controllers.

Thursday, September 4, 2014

Friday, August 29, 2014

MEMS Cutting Edge Technology for Winemaking

MEMS Technology for wine making
MEMS Technology for
Integrated Sensing Systems provides technology for the winemaking industry to measure brix (sugar content), concentration, specific gravity, viscosity and density at various stages of fermentation and aging.

ISSYS is currently developing a new MEMS (microelectromechanical systems) technology called WineSense™ to analyze the ethanol content and concentration during the wine production cycle. Using the proven distillation method, the WineSense™analyzer is designed to provide a cost effective and single source solution with outstanding performance and reliability. 

MEMS stands for microelectromechanical systems and is a technology that, in general, is defined as miniaturized mechanical and electro-mechanical elements made using techniques of micro-fabrication.

The new ISSYS ethanol analyzer will also for used for ciders and other fermented beverages. Accurate knowledge of ethanol concentration during various stages of fermentation is extremely important for the quality, blending and production of fermented beverages.

For more information about this new technology, contact a BCE representative.

photo credit: via photopin cc

Thursday, August 28, 2014

Industrial Check Valve Function and Operation

A check valve is used to allow flow in one direction, but prevent flow in the opposite direction. There are several types of industrial check valves including the piston check, ball check, diaphragm check, wafer check and swing check valves.

They are used in industries such as chemical, petrochemical, pharmaceutical, power, biofuels, food & beverage and water treatment.

They are available with metal-to-metal or soft seats, in sizes from 1/8" NPT to 20" flanged connections, with pressure ratings from full vacuum to 10,000 PSI.

Below is a video courtesy of  Columbia Gorge Community College.  In this video, Instructor Jim Pytel, explains the basic operation of check valves and how they are used in hydraulics.

If you have any questions about the use or application of industrial check valves, please contact BCE with your question. Belilove proudly represents Check-All Valve, a premier manufacturer of check valves.

Saturday, August 23, 2014

Introduction to Programmable Logic Controllers (PLC)

Typical Modular PLC
Programmable logic controls, or PLC's, are used for plant automation and control. The PLC is a specialized, industrial computer which includes onboard random access memory (RAM) and read only memory (ROM). As with any other computer, the PLC has a central processor unit (CPU) for data processing. A single PLC has the switching and logic capability to replace thousands of control relays. PLC's are ubiquitous and are used in many different applications in all industries including semiconductor manufacturing, pharmaceutical production, chemical processing, food production, primary metals, and HVAC. Because of their wide industry use, they are manufactured in many shapes and sizes.

Monday, August 18, 2014

Basic Concepts of PID Control

pid control
PID control loop diagram
(courtesy of Wikipedia)
PID is short for "proportional plus integral and derivative control", the three actions used in managing a control loop. Process loop controllers use one, two or all three of these to optimally control the process system. PID control is used in a wide variety of applications in industrial control and process system management.

Many types of PID controllers exist on the market and are used for controlling temperature, pressure, flow, and just about every other process variable. Here is a brief explanation of the three actions that make up PID.

Proportional Control Action (P):  The controller output responds in proportion to error signal. The characteristic equation for this action is:
  • Where, Kp is called proportional gain, e is the error magnitude and B is the output from controller when there is no error. It is also called bias. 
  • In a proportional controller, the value of gain is set as required by the process and can be varied from 0 to ∞. 
Integral Control Action (I): The control system will respond if the error is present over a period of time. This type of control action is called Integral Control Action. The integral action is defined mathematically as:
  • Where, e= error, Ti= Time interval of integral action.
  • Purpose of integral action is to provide adequate control action on varying demands of process. In this type of action, output varies as per the time integral of error. This action does not exist independently and always associated with proportional control. 
Derivative Control Action (D): To achieve a stable process, wide proportional band and low integral action are set. Due to these settings, the control system can be too slow. If large system disturbances occur over a wide interval, PI controllers are inadequate. These large system disturbances can be managed if the controller output responds not only to the magnitude of deviation, but also to the rate of change of deviation. Derivative control action is that control action. 

Today's loop controllers are much easier to set the PID, thanks to auto-tuning algorithms. What used to be a very time consuming and tedious job can now be done with the push of a button and allowing the controller to "learn" the process dynamics. PID controllers minimize error and optimize the accuracy of any process.

Wednesday, August 13, 2014

Need a Very Accurate, Harsh Environment Dissolved Oxygen Sensor?

fluorescence quenching dissolved oxygen sensor
Fluorescence Quenching
Dissolved Oxygen Sensor
(courtesy of ECD)
If you’re looking for exceptionally accurate dissolved oxygen measurement suitable for a wide range of municipal and industrial water treatment applications, you may want to consider a fluorescence quenching (FQ) sensing element. Along with great accuracy, these sensors also provide exceptionally long life and are available with internal electronics that allow the units to self-calibrate, which eliminates costly and time consuming calibration.

These sensors are highly accurate. They provide a maximum error of less than 2 percent, repeatability of ±0.5 percent and resolution of 0.01 ppm or 0.01 percent saturation. They operates over a wide measurement range with three different outputs from 0 to 20 mg/l (0-20 ppm), 0-200 percent saturation or 0-400 hPa (0-6 psi).

Saturday, August 9, 2014

Remote Tank Level and Leak Detection

In large tank farms, or plants with remotely located tanks, audio and visual alarms are ineffective. The reason is obvious. There's no one around who can see or hear an alarm condition. In these situations, remote, central monitoring is required.

Remote tank monitoring systems allow for multiple tank monitoring via hard-wired installations, or where that's not possible, through wireless connections.

One manufacturer, OMNTEC, offers a broad variety of tank monitoring and leak detection products. The product video below introduces the Proteus Mini-Me system.

Tuesday, August 5, 2014

Bi-Metal Thermostats

bi-metallic thermostat
Bi-metallic Thermostats
Bi-metallic (bi-met) temperature controls (thermostats) have been around for a very long time, but their simplicity, dependability, size and cost still make them a good choice for certain applications.

Also known as "thermoswitches", bi-metal thermostats come in  two primary styles - a "disk" type, which looks more like a button, and a "cartridge" style. Both operate on the same basic principle of differential expansion. Disk type devices are used in many household appliances, such as clothes dryers or coffee pots, as temperature control or as hi-limits. Cartridge style thermostats are used in more industrial applications and OEM equipment.

Friday, August 1, 2014

Thermocouples, RTD's and Thermistors

This post explains the basic operation of the three most common temperature sensing elements - thermocouples, RTD's and thermistors.

A thermocouple is a temperature sensor that produces a micro-voltage from a phenomena called the Seebeck Effect. In simple terms, when the junction of two different (dissimilar) metals varies in temperature from a second junction (called the reference junction), a voltage is produced. When the reference junction temperature is known and maintained, the voltage produced by the sensing junction can be measured and directly applied to the change in the sensing junctions' temperature.

Tuesday, July 29, 2014

High Purity Fluid Electric Heaters

custom electric gas heater
Transfer Line
Heater Assembly
In many biomedical, pharmaceutical, semiconductor, electronics or R&D laboratory applications, special purpose electric heaters are required for heating high purity fluids. These heaters typically must be ruggedly designed, made from materials immune to process contamination and be vacuum tight. They can be subject to high temperatures, harsh solvents, and corrosive gases. Many times they must maintain a seal for full vacuum, demonstrate a unique or even heating profile and be able to be closely controlled.

The misapplication of screw plug immersion heaters, screwed into a stainless steel welded vessel, offer more problems than solutions due to leaks, material compatibility, poor controllability, and bulky size.

custom electric fluid heater
Transfer line
heater assembly
The answer is in a custom high purity fluid heater designed with the process in mind.

Custom electric heating elements are available designed to handle high vacuum, high temperatures, utilize glass liners for ultra-pure gases, offer 316 stainless steel parts, provide internal RTDs for control and can be temperature profiled.

General Specs for these types of custom fluid heaters are:

  • Variety of voltages.
  • Wide range of watt densities.
  • Temperatures up to 350°C.
  • Heater length can be profiled to generate a liner temperature profile.
  • Vacuum compatible up to 1.0 x 10-8  STD. CC/SEC Helium.
  • Can be provided with internal sensors (RTD or thermocouples).
  • Can be glass lined for ultra pure gas application.

Careful review of the application is important and the help of an experienced application engineer is required, but the outcome of the test, process or product will be infinitely improved.

Friday, July 25, 2014

Intro to Direct Liquid Injection (DLI) Vaporizer

DLI vaporizer
Direct Liquid Injection Vaporizer
Conventional vaporizing technologies have many limitations. Vapor draw systems or bubblers are difficult to start and stop, require very close control of temperature and pressure, and are inefficient at generating well controlled vapor mass flow. Flash vaporizers applying heat via hot metal surface, which cause problems with thermal breakdown of liquid precursors. It also can cause liquid buildup on the treatment surface, causing problems in deposition.

It's also very challenging to precisely measure the amount of vapor mass that is actually being delivered from a conventional vaporizer. In applications where precise vapor mass addition is required, a measurement/control device such as vapor mass flow controllers must be used. This significantly increases the cost and complexity of the vapor system.

Tuesday, July 22, 2014

Have You Considered a Cast-in Heated Part?

Cast-in semiconductor chuck heater
When OEMs (original equipment manufacturer's) look for the best way of adding heat to their equipment, they're faced with the same choices - clamping, bonding or inserting. But there's another, more efficient and productive way to go - cast-in aluminum or bronze heaters.

Friday, July 11, 2014

Custom-Fabricated, Mass Flow Controller (MFC) Flow Validation Cart Allows for Easy Servicing, Reduced Downtime, and Reduced Inventory

The process of calibrating, servicing and troubleshooting mass flow controllers is a time consuming and expensive endeavor. The typical scenario requires stopping the process and removing the MFC for accuracy checks. The downtime and labor required is very costly, and the advantages for in-situ (without removing it from the process) flow accuracy checks and troubleshooting is quite clear.

An innovative approach for in-place accuracy checks has been developed by Belilove Company. Their solution is a mobile station that includes multiple thermal mass flow meters connected via RS-485, power supplies, software and all the necessary plumbing.

Tuesday, July 1, 2014

Flow, Pressure, Pneumatics, and Process Control Basics Tutorials Videos

If you're interested in the principles of pressure control, flow control, pneumatics, hydraulics and other process control subjects, the Columbia Gorge Community College offers a wonderful selection of videos. They are presented by a teacher named Jim Pytel who does a very nice job. We'll repost one on flow control valve basics here and suggest you recommend them to any new engineering student, tech, or service rep you know.

Wednesday, June 25, 2014

Custom Epoxy Vacuum Feedthroughs - A Great Alternative

custom epoxy feedthrough
Epoxy feedthrough on circuit board
Custom epoxy feedthroughs offer some excellent advantages when compared to ceramic and metal seals and should be considered whenever the need for a high integrity feedthrough is required. Below is a rundown of the advantages and specification for epoxy vacuum feedthroughs:

Thursday, June 19, 2014

Low Flow Liquid Mass Measurement Using MEMS Technology Sensor

Size comparison of low mass flow sensor
A low flow sensor, patented by Integrated Sensing Systems Inc. (ISSYS), utilizing silicon MEMS technology provides low mass flow measurement in a package smaller than a dime.

MEMS stands for microelectromechanical systems and is a technology that, in general, is defined as miniaturized mechanical and electro-mechanical elements made using techniques of micro-fabrication.

Tuesday, June 17, 2014

Thermal Mass Flow Controllers and Sensors - An Introduction

Brooks Thermal Mass Flow
Brooks Thermal Mass Flow Meter
Operating upon the thermodynamic principle of differential temperature, thermal mass flow meters combine a flow sensor, a valve, and a PID controller for very accurate and efficient means of controlling gasses and liquid over a wide range of flows.

The following are the primary elements to a thermal mass flow meter:

Friday, June 13, 2014

Common Ways to Electrically Heat a Semiconductor Chuck - The Basics

A semiconductor wafer platform, know as a chuck, is used to support and hold in place (usually by means of applied vacuum), a silicon wafer. A chuck heater is used to uniformly and accurately distribute heat (and cooling) to a semiconductor wafer chuck.  This is done during the manufacturing, characterization, testing, and failure analysis of semiconductor wafers.

Semiconductor wafers contain many electronic devices or electronic circuits, known as dies. Each die has to be carefully tested through a range of temperatures. Precise and uniform temperature control is a requirement. The simplest, and most common way to apply heat (and cooling) is through a chuck incorporating an electric resistance heating element.

Monday, June 2, 2014

Welcome to the The Process Control and Applied Resistance Heat Blog

We're setting off here to provide an informative and interesting place for visitors to learn about the process control industry as well as to educate on applied resistance (electrical) heating.

We have a unique background in both industrial instrumentation and process heating because of our geographic location (Northern California), and because of our product mix which includes pressure, temperature, level, and flow instrumentation, control valves, analytical instruments, as well as engineered electric heating elements, temperature sensors and controls. We also have expertise in a broad array of industries, including:
  • Bio-Tech
  • Chemical
  • Engineering Design Groups
  • Food & Beverage Processing Industry
  • Glass and Coating Industry
  • Industrial & Natural Gas Production & Transportation
  • Mining and Metals Industry
  • Original Equipment Manufacturers
  • Petrochemical / Refining / Petroleum Pipeline
  • Pharmaceutical
  • Power Generation
  • Research / National Labs
  • Semiconductor
  • TMT Cleaning, Repair and Recalibration Services
  • Transportation Industry
  • Water and Waste Water
We plan on providing interesting application notes, custom solutions to challenging process control problems, new product developments and news. We hope you find our information helpful and informative. If you like it, please refer us to your industry friends and peers.