Heat Exchangers for Liquid-Gas Vaporization

Tube bundle for heating
Tube bundle for heat transfer.
Hydrocarbon and non-hydrocarbon based gases can be more efficiently stored and transported in a liquified state, providing higher media density and corresponding product weight per container. Upon reaching their final destination, the liquid can be reheated, returning to a gaseous state for distribution and use. Typical liquified gases include natural gas, oxygen, butane, propane, and nitrogen.

There are several ways to affect the physical change from liquid to gas, and picking the best option is dependent on criteria such as; 1) available energy sources; 2) plant location; 3) climate conditions; and 4) plant infrastructure.

The change from liquid to gas phase usually requires one or more vessels properly sized and designed to accommodate the vastly increased volume of the evaported liquid, handle the storage or distribution pressure of the gas, and be compatible with the process media. In most plants today, the gradual process of warming the liquified gases is done with steam-heated or oil-heated "heat exchangers" or "tube bundles".

Some heat exchanger systems may, instead of steam, use steam-heated intermediary fluids such as oil, water, or glycol-water solution to provide a smoother rate of heat transfer to the evaporating liquid. This method can employ two heat exchangers, one transferring heat from steam to the intermediary fluid, then another to transfer heat from the intermediary fluid to the liquified gaseous product to evaporate it.

Steam heated, closed-loop circulation systems play an important role in providing an efficient, low-cost and compact method to accommodate liquid vaporization. Steam is available in many industrial plants, providing a comparatively inexpensive and readily available source of heat energy. Heat exchangers are available in a range of pre-engineered capacities and forms, but it is quite common for these components to be custom fabricated to meet very specific requirements. Engineers can design their own systems from the component level, or provide performance requirements to the manufacturer and have a skid mounted unit produced, ready for connection to electric power (for control systems), energy source (steam, oil or water) and process inlet and outlet lines.

These systems can be quite technical, with numerous design considerations. The path to maximized safety and efficiency includes consultation with a heat exchanger expert as part of specification and design process. A combination of your high level process knowledge and their product and application expertise will yield the best outcome.

Happy Holidays and Happy New Year from Mountain States Engineering and Controls

Happy Holidays from MSEC
We at Mountain States Engineering and Controls 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.

High Performance Butterfly Valve Exploded View

Here is a short video that quickly displays the components of a high performance butterfly valve. High performance butterfly valves are used in the oil and gas, commercial HVAC, chemical processing, mining, pharmaceutical, water & wastewater industries. High performance butterfly valves come in wafer and lug bodies, have bodies made of carbon steel, stainless steel, or other alloys, and work under higher pressures and temperatures than "rubber lined" butterfly valves.

Improving Maintenance and Reliability of Bubbler Systems

According to Wikipedia "an air bubbler system uses a tube with an opening below the surface of the liquid level. A fixed flow of air is passed through the tube. Pressure in the tube is proportional to the depth (and density) of the liquid over the outlet of the tube."

A common problem with many bubbler systems used in water and wastewater systems is long term accuracy and reliability issues. The need for scheduled maintenance is required because of the possibility of  tampering, failed solenoids, changing air flow rates, or clogged downpipes due to crystal formation - particularly in wastewater applications with high entrapped solids.

A better approach is to use a level transmitter for purge control. This solution offers a highly engineered single component that is easily retrofitted to bubbler installations. These purge transmitters automatically maintain an extremely low flow continuous purge (less than 0.02 scfm) regardless of liquid depth, and minimizing formations of crystals in the downpipe. The lag time during dynamic level changes is also eliminated. Furthermore, bubbler operation is tamperproof because there is no external regulator or needle valve (or rotameter) – internally a fixed differential is maintained over a precision flow orifice.

Transmitter purge (or bubbler) technology works reliably in the presence of vapors, and, unlike ultrasonics, can be used in media temperatures of more than 350°F. Bubblers are normally used in applications where foam, solid debris, sewage sludge, or turbulence make ultrasonic, radar, or float switch devices ineffective. The purge transmitter is relative compact in size and allows for installations in tanks where other systems won’t fit.

The purge control transmitters require a compressed air supply (35-150 psig/2.4-10.3 bar) and provide a two-wire 4-20mA output that can be transmitted over substantial distances. The transmitter can be mounted directly outdoors or within small enclosed spaces at the measuring point or up to a hundred feet away.

More information on the purge transmitter may be download here.

Operation of the Spirax-Sarco 25P Pressure Reducing Valve

Spirax Sarco 25P
Spirax Sarco 25P Series
The Spirax-Sarco 25P series pilot-operated reducing valve is widely used in steam systems. Accurate and stable pressure control can be realized irrespective of a change in upstream steam pressure or fluctuation of downstream load.

The Spirax-Sarco 25P series pilot-operated reducing valve is unique in that one, or several, pilot valves can be installed or exchanged on the same valve. Besides being stable and reducing pressure, it can also control the temperature, the upstream pressure or the remote switch. 


Normal positions before start-up are with the main valve closed and the pilot valve held open by spring force or air pressure.

Entering steam passes through the pilot valve into the main diaphragm chamber and also out through the control orifice. As flow through the pilot valve exceeds flow through the orifice, control pressure increases in the diaphragm chamber and opens the main valve. As steam flows through the main valve, the increase in downstream pressure feeds back through the pressure sensing line to the underside of the pressure diaphragm. 

When the force below that diaphragm balances the compression force of the spring above it, the pilot valve throttles. The control pressure maintained in the main diaphragm chamber positions the main valve to deliver just enough steam for the desired delivery pressure. Adjustment of the spring or air pressure above the pressure diaphragm changes the downstream pressure set point. 

When steam is no longer required, the sensing line pressure increases closing the pressure pilot and the control pressure bleeds back through the control orifice. This allows the main valve to hold the desired reduced pressure, and it may close tight for a dead-end shutoff.

Typical Installation Layout

Spirax Sarco 25P Operation

Mountain States Engineering & Controls carries a large stock of Spirax-Sarco steam specialties. For more information, or for help with your pressure reducing valve, contact:

Mountain States Engineering & Controls
1520 Iris Street
Lakewood, CO 80215
303.232.4100 Phone
303.232.4900 Fax
Email: info@mnteng.com

Pressure and Temperature Switches Glossary - Important Terms to Know Part 2

CCS Dualsnap pressure switch
CCS Dualsnap
pressure switch
Pressure and temperature switch terms part two, courtesy of CCS Dualsnap (Custom Control Sensors).

NACE (National Association of Corrosion Engineers) — Nonprofit technical association that develops and maintains standards that deal exclusively with protection and performance of materials in corrosive environments. The membership represents a cross–section of industry concerned with corrosion prevention and control.

NEC (National Electrical Code) — The American national standard that contains provisions considered necessary for safeguarding persons and property from hazards arising from the use of electricity. Generally, the code covers electric conductors and equipment installed within or on public and private buildings or other structures.

NEMA (National Electrical Manufacturers Association) — A voluntary organization that adopts standards for electrical equipment. NEMA standards are designed to eliminate misunderstandings between the manufacturer and the purchaser and to assist the purchaser in selecting and obtaining the proper product for a particular need.

Pressure and Temperature Switches Glossary - Important Terms to Know Part 1

Dualsnap (CCS) Pressure Switch
Dualsnap (CCS)
Pressure Switch
The following two part series, courtesy of CCS Dualsnap (Custom Control Sensors) provides some very important terms to know when applying or purchasing industrial pressure switches and temperature switches.

ACCURACY (REPEATABILITY) — Accuracy is the maximum operational set point deviation of a single sensor (a pressure, temperature, or flow switch) under one given set of environmental and operational conditions. CCS Repeatability is within +/- 1% of set point.

ACTUATION AND DEACTUATION POINT — The actuation point (sometimes called the set point) is the exact point at which the electrical circuit controlled by
the switching element is opened (or closed) on increasing pressure or temperature. The deactuation point is the opposite, or the point at which the electrical circuit is closed (or opened) on decreasing pressure or temperature.

Guided-wave Radar Level Sensing

Time domain reflectometry for guided-wave radar level
 Guided-wave Radar Level Sensing based
upon Time domain reflectometry (TDR)
(image courtesy of Wikipedia)
Guided-wave radar (GWR) uses a probe immersed in the process media to guide high-frequency electromagnetic waves into the media being measured, and then analyzes the reflected energy to determine level.

GWR is based upon the phenomena of time domain reflectometry (TDR). TDR begins with the initiation of a low-energy electromagnetic pulse of energy into a process through a probe. The subsequent measurement of the energy reflected from the surface of the medium being measured is communicated from the probe to the instrument electronics. By analyzing the reflected waveform, a calculation of level can be made. The instrument then correlates the waveform information to a continuous, or switched, output signal.

Guided-wave radar level transmitter
Guided-wave radar
level transmitter
(courtesy of King Gage)
Guided-wave radar isn’t dependent or subject to the process media properties it is sensing, unlike other electronic level sensing technologies, and can be used for both liquids and solids.

GWR is best suited for the following types of applications:

  • Processes undergoing turbulence or changing density or viscosity.
  • Moving, agitated, foaming, vaporous or circulating surfaces.
  • Processes with higher temperatures and pressures.
  • Sticky or gummy processes, such as oil, paint, rubber or tar.
  • Fine particulate processes such as carbon black, salt, or grain.

One significant advantage to guided-wave radar is that build up on the probe has no effect on the accuracy. While this might be counter-intuitive, the GWR technology “ignores” the relatively insignificant amount of probe build up. This is because the signal returned from the electromagnetic pulse corresponding from the actual process media level is always larger than any reflected signal from build up, which makes it easy for the instrument to determine the difference.

For more information on guided-wave radar level controls, contact:

Mountain States Engineering and Controls
1520 Iris Street
Lakewood, CO 80215
303.232.4100 Phone
303.232.4900 Fax
Email: info@mnteng.com

The Sliding Gate Control Valve

The sliding gate control valve is a type of high performance, variable orifice, control valve with a seat design that provides a non-turbulent, straight through flow path.
sliding gate design
Sliding Gate Design

The unique port characterization breaks the fluid flow into multiple streams creating a reduced field of energy and less turbulence. This results in greater service life, quieter operation and a control valve that performs at the highest levels possible within extreme conditions.

These types of valves can operate at temperatures around 975 degrees F and pressures of 1,450 psig. They are available in 1/2″ through 10″. These style valves are normally available in Carbon Steel and 316 Stainless Steel, and Hastelloy.

This type of control valve is used in a wide range of process engineering control applications and is excellent at controlling steam, fluids, and gases.

A variety of pneumatic and electric actuators can be mounted to the sliding gate control valve depending on location and available energy supply.

sliding gate control valve
Sliding Gate Control Valve
(courtesy of Schubert & Salzer)

Advantages of sliding gate control valves:
  • Sliding gate valves combined with with digital positioners provide excellent controllability and accuracy. 
  • Short opening & closing times, and maximum control performance, due to short stroke of sliding gate valve.
  • High control with low leakage rates & long service life.

Negative Rate Belleville Disc Spring for Pressure Sensing

negative rate belleville spring
Conventional pressure switches incorporate constant-rate sensing technology (Bellows, Bourdon Tube, Spring Loaded Piston). Another technology available is the negative rate Belleville disc spring, which combines a Bellville disc with a fully adjustable helical spring and a diaphragm.

negative rate belleville spring
The advantage of this technology is minimized or eliminated effects caused by vibration, low temperature, high cycle life / premature wear, contact chatter and pump ripple. The switch is either on or off and there is no “teasing” of the electrical element. There are no moving parts except during actuation and de-actuation. The total movement is typically less than .010 inches.

In this design, the diaphragm is not a sensing element. It simply seals the media and transfers force to the disc spring, which responds instantaneously when system pressure reaches the set point.
negative rate belleville spring

The Operation of Bimetallic Steam Traps

Bimetallic steam traps contain a valve that is opened and closed by the differential expansion of metallic disks.

Bimetallic steam traps are used in many industrial and commercial applications in the chemical processing, energy production, food processing, HVAC, pulp and paper, mining, petro-chemical and pharmaceutical industries.

Here is a video that illustrates how a bimetallic steam trap works. It shows the thermostatic principal involved and how two bimetallic plates interact and provide physical movement to open and close a valve seat to discharge condensate.

Basics of Heat Transfer

basic heat transfer
Heat moves from hot to cold
(image courtesy of ces.fau.edu)
In nature, the laws of physics will continually drive energy in an attempt to reach equilibrium. In a thermal loop, as long as there is a temperature difference, heat moves away from the warmer entity to the cooler entity.

Heat exchangers facilitate this phenomena with tube bundles and vessels which separates the hot medium from the cold. Heat penetrates the surface of the tubes and is transferred to the contents of the vessel, thereby heating or cooling fluids or gases in the vessel or in the tubes.

Selecting a Stainless Steel Globe or Gate Valve

stainless steel industrial valve
Stainless steel valves
(courtesy of Aloyco)
Stainless steel globe and gate valves are available in materials including CF8M, CF3M, and CN7M (Alloy 20) and in broad pressure classes including Class 150, Class 300, Class 600, and 200 CWP.

Stainless steel valves are required in many applications found in pulp and paper, mining, chemical processing,  food processing, waste water, and fertilizer processing.

Care should be taken to select the most suitable valves for your service(s). Exact specification of each valve should be made to avoid possible ambiguity. When requesting quotations and/or ordering the product a fully adequate description should be made.

Selecting the Valve Size
Nominal size of the pipeline into which the valve will be placed must be determined.

Valve Material
The following facts should be considered in determining the correct valve material:
  • the medium or media which will be controlled
  • the temperature range of the line medium (media)
  • the pressure range to which the valve will be subjected
  • possible atmospheric conditions which may affect the valve
  • possible extraordinary stresses to which the valve will be subjected
  • safety standards and/or piping codes which must be met

Advantages of a Wafer Check Valve

wafer check valve
Wafer check valve
(courtesy of Duo-Chek)
A wafer check valve is an excellent choice for applications where water hammer, mounting space and flow restriction are issues.

A wafer check is designed to be "sandwiched" inline between two pipe flanges in the piping system, adding very little additional weight or bulk to the piping layout. Wafer checks overall tend to be stronger, lighter, smaller, more efficient and less expensive than conventional swing check valves and are easier to install between standard gasket and line flanges.

Along with being lighter, easier to install and store, wafer check valves also offer the following advantages:
  1. Disc travel is short with less impact force caused by valve closing.
  2. The disc closes quickly with less water hammer pressure. Water hammer pressure is only 1/2 to 1/5 times of flange type swing check valve and flange type lift check valve.
  3. Low flow resistance.
  4. Horizontal and vertical installation available.
  5. Very low opening (cracking) pressure differential.
  6. More reliable due to lower impact forces, less water hammer.
Wafer check valves are available in many sizes, typically from 2” to 72”, in ASME pressure classes 125 through 2500 and API 6A and 6D pressure classes. DIN, JIS, BS, AS, and ISO standards are also available. Body styles include wafer, lug, double flanged and extended body. Wafer check configurations are available in retainer-less style, wafer, extended body wafer and lined. Typical body materials are cast iron, ductile iron, WCB cast steel, 316 stainless steel and other alloys. Common seating materials are EPDM, Buna-N, Neoprene, Refrigeration-grade elastomer, and Viton. The most common end connections are raised face, plain face, ring joint, weld-end, as well as hub-end.

High Performance Butterfly Valves for On/Off and Throttling Service

High Performance Butterfly Valves (HPBF) are a standard in many industries including heating, ventilating and air conditioning, power generation, hydrocarbon processing, water and waste water treatment. The key features of HPBV are high performance shutoff and modulating service for standard industrial process lines, materials of construction options include carbon and stainless
steel,  sizes up to 48”, both wafer and lugged body styles available, in pressures classes 150 – 600.

Here is a short video introducing the Flowseal high performance butterfly valve.

Cooling Towers for Exothermic Reactions in Corrosive Atmospheres

plastic cooling tower
Delta Plastic Cooling Tower
The term “exothermic” describes a reaction or process that releases energy, usually in the form of heat. In chemical processing and manufacturing, controlling the heat created by an exothermic reactions is critical to preserve quality, production and safety. A common way to remove heat is the use of a cooling tower.  Cooling water is circulated through the industrial process via pipes or tubes to extract heat, and then passes through a cooling tower to remove the heat so it can then be recirculated back to the process.

Many exothermic reactions occur when mixing harsh compounds or chemicals. These harsh chemicals have a negative impact on the performance of the process equipment handling the reaction. The equipment is also exposed to vapors and contaminants in the surrounding atmosphere. Metallic structures are the most prone to attack and corrosion.

When a cooling tower is needed in a corrosive or harsh environment, metal framed cooling towers with metal walls should be avoided. Instead, cooling towers with seamless, double wall plastic (HDPE) shells, corrosion proof construction, PVC piping and water distribution systems and totally enclosed motors are recommended.

Sample industries where plastic cooling towers are used in harsh environments are water treatment, waste water treatment, pulp and paper processing, primary metals processing, plating, and corrosive chemical production.

Water Hammer in Steam Systems - Demo

According to Wikipedia, water hammer is defined as "a pressure surge or wave caused when a fluid (usually a liquid but sometimes also a gas) in motion is forced to stop or change direction suddenly (momentum change). A water hammer commonly occurs when a valve closes suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. It is also called hydraulic shock."

When improperly drained of condensate in a high pressure steam main fills with condensate and completely surrounds the steam, an implosion takes place causing devastating water hammer.

Draining condensate and keeping it away from the steam by using proper steam trapping equipment will prevent this from happening.

The following video, courtesy of Spirax Sarco USA, dramatically demonstrates the principle behind water hammer and its potentially devastating effects.

Metal Body, Industrial Diaphragm Valves

A quick video showing the basic operation of a metal body, diaphragm valve for industrial applications.

The video illustrates how the metallic lower valve body is machined for a smooth controlled flow characteristic, and how the elastomer diaphragm is controlled by the liner movement of the valve stem. Full open, full closed, or proportional flow is controlled by the relationship of the valve diaphragm and valve body.

Metal body diaphragm valves are available in many metal alloys such as brass, cast steel, and 316 stainless steel, with many different elastomers including EPDM, PTFE and Viton.

These valves are great for inert and corrosive liquid and gaseous media, are highly resistant to chemicals, are insensitive to particulate media and offer a compact  design (ideal when space is at a premium).

Shell and Tube Heat Exchangers for Industrial and Commercial Application

tubing bundle
Tube Bundle
A shell and tube heat exchanger is a type of heat exchanger consisting of a shell (a pressure vessel) with a tubing bundle (or core) inside. Two fluids are used, one inside the tubing and one outside the tubing, to change temperature of the fluid contained in the shell. The amount of surface area provided by the tubes determines the efficiency of the heat transfer, and is sometimes augmented by additional lengths of tubing, or with fins.

The function of a shell and tube heat exchanger is very basic. Two different fluids, physically isolated from each other, and at different temperatures, are allowed to transfer thermal energy from one to the other through thermal conductivity.

Cooling Tower Terms and Definitions

Delta Cooling Tower
Delta Cooling Tower
(definitions courtesy of Delta)
Cooling Tower Terms and Definitions

BTU (British Thermal Unit) A BTU is the heat energy required to raise the temperature of one pound of water one degree Fahrenheit in the range from 32° F to 212° F

Cooling Range The difference in temperature between the hot water entering the tower and the cold water leaving the tower is the cooling range.

Approach The difference between the temperature of the cold water leaving the tower and the wet- bulb temperature of the air is known as the approach. Establishment of the approach fixes the operating temperature of the tower and is a most important parameter in determining both tower size and cost.

Drift The water entrained in the air flow and discharged to the atmosphere. Drift loss does not include water lost by evaporation. Proper tower design can minimize drift loss.

Heat Load The amount of heat to be removed from the circulating water within the tower. Heat load is equal to water circulation rate (gpm) times the cooling range times 500 and is expressed in BTU/hr. Heat load is also an important parameter in determining tower size and cost.

Ton An evaporative cooling ton is 15,000 BTU’s per hour.

Wet-Bulb Temperature The lowest temperature that water theoretically can reach by evaporation. Wet-Bulb temperature is an extremely important parameter in tower selection and design and should be measured by a psychrometer

Pumping Head The pressure required to pump the water from the tower basin, through the entire system and return to the top of the tower.

Makeup The amount of water required to replace normal losses caused by bleed off, drift, and evaporation.

Bleed Off The circulating water in the tower which is discharged to waste to help keep the dissolved solids concentration of the water below a maximum allowable limit. As a result of evaporation, dissolved solids concentration will continually increase unless reduced by bleed off.

Handy Conversion Formulas for Process Control

engineering calcHere are very handy conversion calculations for engineering and process control. You may want to bookmark this page for fast lookup.

Bookmark this page.

  • 1 acre = 43560 square feet = 4840 square yards = 4046.86 square meters
  • 1 inch = 2.54 centimeters 1 foot = 12 inches 
  • 1 yard  = 3 feet 
  • 1 mile  = 5280 feet 
  • 1 British thermal unit = 251.996 calories = 1055.06 joules = 1055.06 watt-seconds = 0.293071 watt-hour = 1.05506 x 1010 ergs = 778.169 foot-pound-force
  • 1 pound-force = 4.448222 newtons 
  • 1 kilogram-force = 9.80665 newtons 
  • 1 pound-mass = 0.4535924 kilogram
  • 1 horsepower = 550 foot-pounds per second = 745.7 watts = 2544.43 British thermal units per hour  = 0.0760181 boiler horsepower 
Pressure (Absolute only)
  • 1 standard atmosphere = 14.7 pounds per square inch absolute = 101.325 kilopascal absolute = 1.01325 bar absolute = 760 millimeters of mercury absolute = 760 torr
Pressure (all gauge or all absolute)
  • 1 pounds per square inch = 2.03602 inches of mercury at 0 deg. C = 27.6799 inches of water at 4 deg. C = 6.894757 kilopascal = 0.06894757 bar 
  • 1 bar = 100 kilopascal = 14.504 pounds per square inch
  • 1 meter of water at 4 deg. C = 9.80665 kilopascal
  • Fahrenheit = (deg. C)(9/5) + 32 
  • Celsius = (deg. F − 32)(5/9) 
  • Rankine = deg. F + 459.67
  • Kelvin = deg. C + 273.15
  • 1 mile per hour= 88 feet per minute= 1.46667 feet per second= 1.60934 kilometer per hour = 0.44704 meter per second = 0.868976 knot
  • 1 gallon = 231.0 cubic inches = 4 quarts = 8 pints = 16 cups = 128 fluid ounces = 3.7854 liters
  • 1 milliliter = 1 cubic centimeter

Steam Use in Industrial Process Control

(image courtesy of Pixabay)
Steam is used in many industrial processes today. It is used in the production of our food, textiles, chemicals, power generation and many other manufacturing systems. Steam is a major energy source for industry because it is cheap to create and easily transported through pipes. It can be used to provides energy for process heating, or it can provide energy to mechanical drives.

Steam uses energy in form of heat, which can be converted into other forms of energy. For example, in a power plant, steam is a medium that converts heat energy into mechanical energy (pressure that spins a turbine) and that mechanical energy is then converted into another useful form of energy - electricity.

Pressure Measurement for Industrial Applications

digital pressure gauge
Digital Pressure Gauge
Pressure measurement is critical in many processes and essential in many industries. There are many techniques used to measurement pressure and vacuum (negative pressure). Instruments used to measure pressure are called pressure gauges, switches and transmitters.

Fluid pressure is defined as the measure of force on a surface, per some unit of area, perpendicular to the surface. The standard unit of measurement for pressure measurement in the English system is PSI, or pounds per square inch. In countries that use the Metric system, the Pascal (Pa) or the Newton/meter (N/m2) is used.

Level Measurement

level measurement
Level Indicator
Level measurement is an important process measurement. In many processes, it is important to measure the level of various liquid and solid materials. Effective level measurement provides reliable and continuous operations by maintaining optimum material inventory, by maximizing plant availability, and the prevention of spillages and other process disturbances.

Level is measured at the interface between two material "phases", that is, between liquid and air or solid and air, or other different density materials. The different phases must be clearly separated. When liquids are thoroughly mixed together, level cannot be measured because there is no separation of phases. The interface must be definite in nature.

In the case of an open tank filled with water, the point at which water and air contact is the definite interface, or phase change. Another interface example would be between oil and water. In this example, the specific gravity of oil is less than water, so oil floats on top, but in separate form. Liquids that mix well together do not have a clear interface, so it is difficult to determine level of each.

Introduction to Electric Valve Actuators

electric actuator
Crane 44000 Series Electric Actuator
In many industrial control applications, a motorized valve can be used in place of a pneumatically operated valve. Motorized valves use electricity and an electric motor to operate a valve. The spindle of the valve is connected to the motorized (electric) actuator via linkages (brackets and couplings) or are directly mounted to the shaft of the valve. Valves most commonly operated by electric actuators are globe, gate ball or butterfly valves.

Electric actuators are widely used in control systems because they are easy to interface with control systems. Since the control signals are also electric, the same conduit or conduit paths can be used. Electricity is normally available and can be run over long distances, unlike fluid power (pneumatic) which requires pumps and compressors. Special construction and wiring options must be considered when working in hazardous location though.

Introduction to Actuators

pneumatic actuator
Pneumatic, quarter-turn
actuator with accessories

An actuator is a pneumatic, hydraulic or electrically operated device that supplies force and motion to open or close a valve.

In a typical control loop, the controller compares a signal parameter from the process to a desired set parameter (set point) and then provides some output which drives some control element, so that the process signal parameter eventually achieves the set point parameter. In most cases, the device that corrects the control element is an actuator. 

Actuators are manually operated, pneumatically operated, electrically operated or hydraulically operated. The primary function of any actuator is to adjust position as to control and regulate the process parameter through some type of control element, such as a valve, to regulate temperature, pressure or flow.

Introduction to Ball Valves

blaa valve
Trunnion type ball valve
Industrial ball valves are among the most cost-effective and most widely used type of industrial valve. A ball valve is a quarter-turn rotational motion valve, that uses a ball shaped disk to stop or start flow thorough the valve. When ball valve is opened, the ball rotates such that the hole through the ball is in line with the valve body inlet and outlet. If the valve is closed, the ball is rotated so that the hole is perpendicular to the flow openings of the valve body and the flow is stopped.

The basic design of a ball valve is similar to that of a plug valve. Instead of a plug though, a ball valve uses a spherical ball sandwiched between two sealing rings in a the valve body. This ball has a hole to allow the fluid to flow through. When the valve is closed, isolation is provided by the sealing rings and the solid side of the ball.

Basics of Flow Meters

flow meter
Flow Meter

Measuring the flow rate of solids, liquids, and gases is referred to as flow measurement, and is a very important and widely used control variable. Many industries such as power, chemical, water, waste-water treatment, energy, mining and petroleum have many requirements for flow measurement and control.

A flow meter is a device that measures the rate of flow or quantity of a moving fluid in an open or closed conduit. There are two basic ways of measuring flow: volumetric basis and weight basis.

Flow measuring devices are generally classified into four groups:
  1. Mechanical type flow meters: Fixed restriction, variable head type flow meters using different sensors such as orifice plates, venturi tubes, flow nozzles, pitot tubes, quantity meters such as positive displacement meters, mass flow meters, etc. 
  2. Inferential type flow meters: Variable area flow meters (Rotameters), turbine flow meters, target flow meters, etc.
  3. Electrical type flow meters:  Electromagnetic flow meters, Ultrasonic flow meters, laser doppler anemometers etc.
  4. Other flow meters: Purge flow regulators, flow meters for solids flow measurement, cross-correlation flow meter, vortex shedding flow meters, flow switches, etc.
Flowmeters need to be integrated into existing piping or new installation. There are two methods for flowmeter installation: inline and insertion. With the inline method, connectors are provided for upstream and downstream pipes. For the insertion method, a sensor probe is inserted into the pipe.

Most flowmeters are installed with straight sections of pipe on either side for flow to normalize. For the inline method, the diameter of pipes should be same as the flowmeter size. Insertion design is easier to install and more economical in large diameter pipes.

To select the suitable flowmeters many factors should be taken in mind. The most important is fluid phase (solid, liquid, gas, steam) and the other is flow condition (clean, dirty, viscous, open channel etc.). The next important factor is line size and flow rate. Other properties that will affect the selection of flowmeter are density, pressure, temperature, viscosity etc. You should consult an application engineer before specifying a flow meter to assure proper installation, lowest installed cost and safety.

The Virtues of Angle Seat Valves

Gemu angle seat valve
GEMU Angle Seat Valve
“Angle valves” or “angle seat valves” are a family of on-off and control valves that have utilize a “Y” pattern body style, and a linear action to raise the disk from the seat to open and close the valve. By positioning the seat on an angle, the piston is pulled out of the flow path clearing the way for maximum flow. Angle valve provides tight shutoff, high cycle rate capability and very long service life. Here are other design features that make an angle valve a top performer:

The Importance of Auditing and Maintaining Your Steam System

Steam Trap
A blocked or leaky steam trap increases production times, reduce performance and wastes energy. By quickly identifying bad steam traps, you can save energy, optimize your process and improve safety. A well audited steam system reduces steam production costs, maintenance costs, repair costs, and possible environmental impact costs.

Saving money has always been a good thing and now saving energy is more important than ever. Going "Green" and staying "Green" is the mantra of todays eco-responsible organization. Improving the efficiency of your steam production and management system is an easy place to find big savings. Steam trap monitoring is a basic way to reduce waste, costs and environmental liability. It needs to be done.

Normal wear takes its toll and will cause steam traps to fail in either an open or closed configuration. Failed-closed traps create poor quality steam and effects steam efficiency, productivity, reliability and safety. Failed-open traps release live steam to atmosphere that wastes energy and money. Failed-open traps are very costly.

Statistics show 3 and 10 percent of steam traps fail each year, resulting in a 10 to 33 year life cycle. For a large facility with 10,000 steam traps, 300 to 1,000 traps may fail every year.

Below are tables that point out, in real terms, how much poor performing traps cost an organization.

Click for larger view (table courtesy of Spirax Sarco)
Click for larger view (table courtesy of Spirax Sarco)
As you can see from the data in the tables, it's very important to regularly audit your steam system and replace faulty or leaky steam traps. The short term costs of auditing and repairing will be repaid many times over in lower fuel costs, maintenance outages and environmental liability. 

Hydrostatic Tank Level Measurement

pressure transmitter
King-Gage pressure transmitter
One of the most proven and reliable methods of continuous tank level monitoring is remotely monitoring hydrostatic pressure.

Hydrostatic pressure is defined as "The pressure exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity. Hydrostatic pressure increases in proportion to depth measured from the surface because of the increasing weight of fluid exerting downward force from above.

Pressure transmitters are a simple and accurate choice for measuring liquid level in storage tanks or processing tanks.

hydrostatic level
Typical hydrostatic level application
The principle behind hydrostatic, pressure-based, liquid level measurement is simple since pressure is proportional to the level of liquid multiplied by the specific gravity. The specific gravity of a liquid is the ratio of its own density to the density of water.

Alternatively, level equals the hydrostatic head pressure value divided by the density of the liquid.

Resilient Seated and High Performance Butterfly Valves

Lug Body Resilient
Seated Butterfly Valve
(Crane Centerline)

A butterfly valve uses a round, thin disk to control flow through a pipe. The disk is connected to the stem via a shaft completely through the disk, or at the top and bottom of the valve. 

The butterfly disk is continuously in the flow path, but because of its thin profile, has minimal impact on flow. Butterfly valves are popular because they offer very tight shut-off, are available in a wide range of materials and sizes, and can be automated inexpensively with many types of quarter-turn electric and pneumatic actuators.

Butterfly valves are used in many industrial applications today, from controlling the flow of water to handling much more severe industrial fluids. Butterfly valves are extensively used in water treatment, chemical processing, pulp and paper making, food processing, power generation and many other industries.

Swing Check Valve Operation - The Basics

check valve symbol
Check Valve Symbol
There are several types of industrial check valves such as piston, ball, diaphragm, wafer and swing. The following video introduces the viewer to the inner workings of the swing check valve.

According to Wikipedia, "Check valves are used in many fluid systems such as those in chemical and power plants, and in many other industrial processes.

Check valves are also often used when multiple gases are mixed into one gas stream. A check valve is installed on each of the individual gas streams to prevent mixing of the gases in the original source.

The swing check uses the directional flow to push open a swinging disk. As long as flow continues, the disk stays raised. But as flow stops, gravity allows the disk to re-seat itself and any reverse flow is prevented by the closed disk. As reverse flow pressure increases, the swing check valves seating increases as well.

A Fluid Velocity Tutorial

Here is another video describing the concepts of fluid velocity, pressure, and flow. It's from the Hydraulics collection offered by Columbia Gorge Community College.  In this video,  Instructor Jim Pytel, drives home fluid velocity concepts in a very entertaining and easy to understand way.  The video uses a humorous "application", where Mr. Pytel equates pressure to the system "strength", and flow as the system "speed". The video then goes on to explain the roles of pressure relief valves and flow control valves and how they allow for changes in force and speed of the sample system. It also introduces parallel and series hydraulic circuits, laminar and turbulent flow, flow rate, and flowmeters.

Electromechanical Pressure, Differential Pressure and Temperature Switches - The Basics

Most industrial applications require the monitoring of pressure and temperature of a process. Pressure and temperature measurement can be accomplished either by transmitters, gauges or by switches. This post will provide a quick introduction of industrial electromechanical pressure switches and temperature switches.

An industrial pressure and temperature switch is made up of the three main components: 1) the sensor, 2) the housing and 3) the switching element.

The correct combination of each component assures proper application of the device for its intended use.

Natural Draft and Mechanical Draft Cooling Tower Fundamentals

Cooling Tower
Delta Cooling Tower
In many industrial facilities, various pieces of equipment, as well as many fluids used in process systems need to be cooled.  This cooling is mostly done with water. However, as cooling water is used, it absorbs heat, and loses its cooling effectiveness. The water needs to be kept cool.

Disposing of hot water in to ponds or basins can be detrimental to the environment. It’s also costly to replace the discharged water. The more efficient means is to cool the hot water and reuse it.

The equipment most commonly used to do this is the cooling tower. Cooling towers are part of a cooling water system in a commercial or industrial facility.

The main components of a typical cooling tower are a circulating pump, a shell and tube heat exchanger, and fluid lines.

Pressure Reducing Valves for Steam Opimization

pressure reducing valve
Pressure Reducing
Valve (PRV)
A well designed steam system should produce clean, dry steam ready for distribution at high pressure through the steam distribution network. This maximizes the potential to generate and supply quality saturated steam at the lowest total cost.

Most applications require a pressure reduction at the point of use.

Significant benefits include:

1) A reduction in the cost of capital equipment; 2) Plant costs decreases by reducing flash steam; 3) Since saturated steam pressure is directly related to temperature, controlling pressure will automatically control temperature thus avoiding the need for supplemental temperature controls; and 4) The ability to supply optimized steam pressure for any individual application.

Weld In-Place Ball Valves - A Unique Design Approach

Weld In-Place Ball Valve
Weld In-Place Ball Valve
Historically, weld-end ball valves presented challenges to users in process control applications because of the high temperatures during the weld, which would damage the temperature sensitive parts of the valve (seals and seats).

One work-around is to extend the piping to the valves ends, but this adds cost and time. Another solution is to dis-assemble the valves and remove the seals and seats prior to welding. Then, after welding, re-assembling the valve when the valve after everything has cooled down. This is much more complicated, takes more time and can be very problematic if the valve is part of an automated package.

A unique approach for socket weld and three piece valves, pioneered by valve manufacturer Flow-Tite, that uses integrated extended end-caps with heat sink rings. The design provides much more surface area, thus allowing the heat to dissipate during welding. Any heat conducted to the seat area does not have a high enough temperature to damage the valve seating or sealing material.

With this novel and common sense approach approach, soft-seated, three-piece ball valves that were once a problem to weld, can now be welded in-place without disassembly, extended time and related costs.

Basics of Safety Relief Valves

Kunkle Relief Valve
Typical Safety Relief Valve
Gases and steam are compressible. It is normal that when gas reaches the disc in a valve, it compresses and builds up before passing through the valve. This compression may cause a rapid build up of system pressure and be potentially harmful.

A conventional liquid type relief type relief valve doesn't open fast enough to relieve gas or steam pressure. The slower action may actually contribute to pressure build-up. A compressible gas system requires a valve that will pop wide open under excessive pressure. That's the design principle behind a pressure safety valve also known as a PSV.

Safety relieve valves and relief valves are similar and share common design and components. The direct acting safety valve is made up of a inlet, outlet, housing, disk, seat, spindle, a cap, and in some instances, a manual operating lever. The safety valve assembly is protected by the housing which has a threaded or flanged pipe connection to the system. The cap protects the top of the valve and reduces the chance of inadvertently changing the valve setting. The disk stays in place until the system pressure increases to the point when the disk “pops” off the seat. The spindle aligns the disk. An adjusting screw is used to set the valves' set point or popping pressure. Spring tension can change over time an require the recalibration of the adjusting screw.

Explaining Heat Exchanger Stall

Spirax APT
Spirax Sarco APT
The most common process heating, heat exchanger hookup uses a temperature control valve on the steam line to the heat exchanger, and a steam trap on the condensate line from the heat exchanger.

The shell side is this steam space. A control sensor signal at the tube side outlet is used to throttle the steam control valve to maintain set point temperature. Higher pressure in the steam space than in the condensate recovery line produces effective condensate removal and lift to the return system.

Under a steady high load, differential pressure removes the condensate from the heat exchanger. Under reduced heating load, the control valve throttles down, reducing the steam pressure inside the heat exchanger. This also reduces the differential pressure across the steam trap making the trap unable to remove the condensate. This happens in all heat exchangers, whether properly sized or oversized.

This causes condensate to flood the steam space, known as heat exchanger stall. In other words, the pressure in the heat exchanger is equal to, or less than, the total back-pressure imposed on the steam trap, sometimes even attaining vacuum.

Some operators address vacuum in the steam space by installing a vacuum breaker on the shell. This practice introduces atmospheric gases that dissolve readily into the cooler condensate. These dissolved gases form corrosives that attack wetted surfaces, while doing nothing to eliminate the stall condition.

The simplest way to cure stall is to install a steam-powered automatic pump trap, such as a Spirax Sarco APT series. Pump trap operation is based on condensate level alone, with live steam pressure removing condensate under all load conditions, even vacuum.

By not using a vacuum breaker, you can reduce condensate acidity and large temperature swings in the heat exchange equipment. Heat transfer and control improve. Corrosion, water hammer, tube failure, excessive treatment chemical dosing, and high maintenance costs become distant memories.

A survey of your heat exchanger and condensate return system operating and maintenance data can uncover the below-par performance that indicates stall. If present an automatic pump trap is an easy solution that quickly returns dividends in process quality, energy savings, and reduced maintenance costs.

For more information on how to prevent heat exchanger stall, contact Mountain States Engineering and Controls at 303-232-4100 or visit www.mnteng.com.

A Specialty Electric Actuator for Linear Valves with Precise Control and Failsafe

Warren Controls’ compact AMURACT electrically operates 1/2” through 4”control valves quickly, reliably, accurately and with shutoff capability rivaling pneumatics. Works with multiple supply voltages and signals. Electronic fail-safe needs no operating force to maintain lockup against elevated water or steam pressures. Stainless steel construction is maintenance-free. Purchase price is competitive and operating costs are extremely low. Here's a demo:

Great Flow Control Tutorial Series on YouTube

Came across a great tutorial series of flow control basics, control valve basics, check valve basics and a bunch of other stuff. The videos are from the Columbia Gorge Community College and are done by a teacher there named Jim Pytel. Here's one on Flow Control Valve basics. Enjoy.

Always Looking for Ways to Add Value and Help Customers Solve Industrial Process Control Challenges

We opened our doors in 1978 with the mission of creating the most technically competent and application savvy industrial process control rep in the Mountain States. Headquartered in Lakewood, Colorado, MSEC established itself as a premier Manufacturer's Representative and Distributor of process equipment, industrial controls, engineered valves, heat exchangers and cooling towers. Serving the markets of Colorado, Wyoming, Montana, Utah, Nevada, Southern Idaho, Western Dakotas and the Panhandle of Nebraska, we earned a reputation for outstanding customer service. Now, with the reach and convenience of the Internet, we'll use this blog as another way to provide value to our customers - both existing and prospective.

We plan on sharing years of experience and knowledge here. Steam management experiences, process control application case histories, new industrial control products, automated valve packages and interesting jobs we've done. We hope this will be a place where information can be exchanged. If you like what you see, please tell others in your industry about us.